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  • Articles  (4,683)
  • Copernicus  (3,132)
  • Institute of Physics  (786)
  • Oxford University Press  (765)
  • 2010-2014  (4,683)
  • 1950-1954
  • 2014  (4,683)
  • Geography  (4,021)
  • Economics  (765)
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  • Articles  (4,683)
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  • 2010-2014  (4,683)
  • 1950-1954
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  • 1
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    Technical Note: Reducing the spin-up time of integrated surface water–groundwater models (2014)
    Copernicus
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    Publication Date: 2014-12-13
    Description: Technical Note: Reducing the spin-up time of integrated surface water–groundwater models Hydrology and Earth System Sciences, 18, 5169-5179, 2014 Author(s): H. Ajami, J. P. Evans, M. F. McCabe, and S. Stisen One of the main challenges in the application of coupled or integrated hydrologic models is specifying a catchment's initial conditions in terms of soil moisture and depth-to-water table (DTWT) distributions. One approach to reducing uncertainty in model initialization is to run the model recursively using either a single year or multiple years of forcing data until the system equilibrates with respect to state and diagnostic variables. However, such "spin-up" approaches often require many years of simulations, making them computationally intensive. In this study, a new hybrid approach was developed to reduce the computational burden of the spin-up procedure by using a combination of model simulations and an empirical DTWT function. The methodology is examined across two distinct catchments located in a temperate region of Denmark and a semi-arid region of Australia. Our results illustrate that the hybrid approach reduced the spin-up period required for an integrated groundwater–surface water–land surface model (ParFlow.CLM) by up to 50%. To generalize results to different climate and catchment conditions, we outline a methodology that is applicable to other coupled or integrated modeling frameworks when initialization from an equilibrium state is required.
    Print ISSN: 1027-5606
    Electronic ISSN: 1607-7938
    Topics: Geography , Geosciences
    Published by Copernicus on behalf of The European Geosciences Union (EGU).
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  • 2
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    Extending periodic eddy covariance latent heat fluxes through tree sapflow measurements to estimate long-term total evaporation in a peat swamp forest (2014)
    Copernicus
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    Publication Date: 2014-12-13
    Description: Extending periodic eddy covariance latent heat fluxes through tree sapflow measurements to estimate long-term total evaporation in a peat swamp forest Hydrology and Earth System Sciences Discussions, 11, 13607-13661, 2014 Author(s): A. D. Clulow, C. S. Everson, M. G. Mengistu, J. S. Price, A. Nickless, and G. P. W. Jewitt A combination of measurement and modelling was used to find a pragmatic solution to estimate the annual total evaporation (ET) from the rare and indigenous Nkazana Peat Swamp Forest (PSF) on the east coast of Southern Africa to improve the water balance estimates within the area. Total evaporation was measured during three window periods (between seven and nine days each) using an eddy covariance (EC) system on a telescopic mast above the forest canopy. Sapflow of an understory and an emergent tree was measured using a low maintenance heat pulse velocity system for an entire hydrological year (October 2009 to September 2010). An empirical model was derived, describing the relationship between the observed ET of the Nkazana PSF measured during two of the window periods ( R 2 = 0.92 and 0.90) which, overlapped with sapflow measurements, thereby providing hourly estimates of predicted ET of the Nkazana PSF for a year, totalling 1125 mm (while rainfall was 650 mm). In building the empirical model, it was found that including the understory tree sapflow provided no benefit to the model performance. In addition, the observed emergent tree sapflow relationship with observed ET between the two field campaigns was consistent and could be represented by a single empirical model ( R 2 = 0.90; RMSE = 0.08 mm). During the window periods of EC measurement, no single meteorological variable was found to describe the Nkazana PSF ET satisfactorily. However, in terms of evaporation models, the hourly FAO56 Penman–Monteith equation best described the observed ET from EC during the August 2009 ( R 2 = 0.75), November 2009 ( R 2 = 0.85) and March 2010 ( R 2 = 0.76) field campaigns, compared to the Priestley–Taylor model ( R 2 = 0.54, 0.74 and 0.62 during the respective field campaigns). From the empirical model of ET and the FAO56 Penman–Monteith equation, a monthly crop factor ( K c ) was derived for the Nkazana PSF providing a method of estimating long-term swamp forest ET from meteorological data. The monthly crop factor indicated two distinct periods. From February to May, it was between 1.2 and 1.4 compared with June to January, when the crop factor was 0.8 to 1.0. The derived monthly K c values were verified as accurate (to one significant digit) using historical data measured at the same site, also using EC, from a~previous study. The measurements provided insights into the microclimate within a subtropical peat swamp forest and the contrasting sapflow of emergent and understory trees. They showed that expensive, high maintenance equipment can be used during manageable window periods in conjunction with low maintenance systems, dedicated to individual trees, to derive a model to estimate long-term ET over remote heterogeneous forests. In addition, the contrast in ET and rainfall emphasises the reliance of the Nkazana PSF on groundwater.
    Print ISSN: 1812-2108
    Electronic ISSN: 1812-2116
    Topics: Geography , Geosciences
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  • 3
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    Long-term variability of storm surge frequency in the Venice Lagoon: an update thanks to eighteenth century sea level observations (2014)
    Copernicus
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    Publication Date: 2014-12-13
    Description: Long-term variability of storm surge frequency in the Venice Lagoon: an update thanks to eighteenth century sea level observations Natural Hazards and Earth System Sciences Discussions, 2, 7465-7486, 2014 Author(s): F. Raicich Sea level observations made in the Venice Lagoon between 1751 and 1792 have been recovered, consisting of two time series of daily data on high and low waters at Venice and Chioggia. From comparisons with modern observations the quality of the 18th century data appears to be good enough to allow a useful analysis. A composite time series of daily mean sea level is obtained by merging the 18th century data and 1872–2004 observations at Venice Punta della Salute. The absence of reliable information on vertical references prevents the connection of the two 18th century time series with each other and with modern observations. However, daily sea level anomalies relative to the mean sea level enable to recognize storm surge events, that appear to occur more frequently in the second half of the 18th century than in the late 19th and 20th centuries, particularly during the 1751–1769 period. The record-breaking storm surge of 4 November 1966 turns out to be a remarkable event also in comparison with the events extracted from the 18th century time series. Further work is required to fill the gap between the old and modern observations.
    Electronic ISSN: 2195-9269
    Topics: Geography , Geosciences
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  • 4
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    Ground-penetrating radar observations for estimating the vertical displacement of rotational landslides (2014)
    Copernicus
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    Publication Date: 2014-12-13
    Description: Ground-penetrating radar observations for estimating the vertical displacement of rotational landslides Natural Hazards and Earth System Sciences Discussions, 2, 7487-7506, 2014 Author(s): C. Lissak, O. Maquaire, J.-P. Malet, F. Lavigne, C. Virmoux, C. Gomez, and R. Davidson The objective of this paper is to demonstrate the applicability of Ground Penetrating Radar (GPR) for monitoring the displacement of slow-moving landslides. GPR data is used to estimate the vertical movement of rotational slides in combination with other surveying techniques. The experimental site is located along the Normandy coast (North East France) here several rotational landslides are continuously affected by a seasonal kinematic pattern (low displacement rates of 0.01 to 0.10 m yr −1 ) and periodically by major acceleration events (high displacement of 1.0 to 7.0 m per event).
    Electronic ISSN: 2195-9269
    Topics: Geography , Geosciences
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  • 5
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    Continental Portuguese Territory Flood Susceptibility Index – contribution for a vulnerability index (2014)
    Copernicus
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    Publication Date: 2014-12-16
    Description: Continental Portuguese Territory Flood Susceptibility Index – contribution for a vulnerability index Natural Hazards and Earth System Sciences Discussions, 2, 7521-7552, 2014 Author(s): R. Jacinto, N. Grosso, E. Reis, L. Dias, F. D. Santos, and P. Garrett This work defines a national flood susceptibility index for the Portuguese continental territory, by proposing the aggregation of different variables which represent natural conditions for permeability, runoff and accumulation. This index is part of the national vulnerability index developed in the scope of Flood Maps in Climate Change Scenarios (CIRAC) project, supported by the Portuguese Association of Insurers (APS). This approach expands on previous works by trying to bridge the gap between different floods mechanisms (e.g. progressive and flash floods) occurring at different spatial scales in the Portuguese territory through: (a) selecting homogeneously processed datasets, (b) aggregating their values to better translate the spatially continuous and cumulative influence in floods at multiple spatial scales. Results show a good ability to capture, in the higher susceptibility classes, different flood types: progressive floods and flash floods. Lower values are usually related to: mountainous areas, low water accumulation potential and more permeable soils. Validation with independent flood datasets confirmed these index characteristics, although some overestimation can be seen in the southern region of Alentejo where, due to a dense hydrographic network and an overall low slope, floods are not as frequent as a result of lower precipitation mean values. Future work will focus on: (i) including extreme precipitation datasets to represent the triggering factor, (ii) improving representation of smaller and stepper basins, (iii) optimizing variable weight definition process, (iii) developing more robust independent flood validation datasets.
    Electronic ISSN: 2195-9269
    Topics: Geography , Geosciences
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  • 6
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    Dye tracing for investigating flow and transport properties of hydrocarbon-polluted Rabots glaciär, Kebnekaise, Sweden (2014)
    Copernicus
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    Publication Date: 2014-12-16
    Description: Dye tracing for investigating flow and transport properties of hydrocarbon-polluted Rabots glaciär, Kebnekaise, Sweden Hydrology and Earth System Sciences Discussions, 11, 13711-13744, 2014 Author(s): C. C. Clason, C. Coch, J. Jarsjö, K. Brugger, P. Jansson, and G. Rosqvist Over 11 000 L of hydrocarbon pollution was deposited on the surface of Rabots glaciär on the Kebnekaise Massif, northern Sweden, following the crash of a Royal Norwegian Air Force aircraft in March 2012. An environmental monitoring programme was subsequently commissioned, including water, snow and ice sampling. The scientific programme further included a series of dye tracing experiments during the 2013 melt season, conducted to investigate flow pathways for pollutants through the glacier hydrological system, and to gain new insight to the internal hydrological system of Rabots glaciär. Results of dye tracing reveal a degree of homogeneity in the topology of the drainage system throughout July and August, with an increase in efficiency as the season progresses, as reflected by decreasing temporary storage and dispersivity. Early onset of melting likely led to formation of an efficient, discrete drainage system early in the melt season, subject to decreasing sinuosity and braiding as the season progressed. Analysis of turbidity-discharge hysteresis further supports the formation of discrete, efficient drainage, with clockwise diurnal hysteresis suggesting easy mobilisation of readily-available sediments in channels. Dye injection immediately downstream of the pollution source zone revealed prolonged storage of dye followed by fast, efficient release. Twinned with a low dye recovery, and supported by sporadic detection of hydrocarbons in the proglacial river, we suggest that meltwater, and thus pollutants in solution, may be released periodically from this zone of the glacier hydrological system. The here identified dynamics of dye storage, dispersion and breakthrough indicate that the ultimate fate and permanence of pollutants in the glacier system is likely to be governed by storage of pollutants in the firn layer and ice mass, or within the internal hydrological system, where it may refreeze. This shows that future studies on the fate of hydrocarbons in pristine, glaciated mountain environments should address the extent to which pollutants in solution act like water molecules or whether they are more susceptible to, for example, refreezing into the surrounding ice, becoming stuck in micro-fractures and pore spaces, or sorption onto subglacial sediments.
    Print ISSN: 1812-2108
    Electronic ISSN: 1812-2116
    Topics: Geography , Geosciences
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  • 7
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    Air temperature variability over three glaciers in the Ortles-Cevedale (Italian Alps): effects of glacier disintegration, intercomparison of calculation methods, and impacts on mass balance modeling (2014)
    Copernicus
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    Publication Date: 2014-12-16
    Description: Air temperature variability over three glaciers in the Ortles-Cevedale (Italian Alps): effects of glacier disintegration, intercomparison of calculation methods, and impacts on mass balance modeling The Cryosphere Discussions, 8, 6147-6192, 2014 Author(s): L. Carturan, F. Cazorzi, F. De Blasi, and G. Dalla Fontana Glacier mass balance models rely on accurate spatial calculation of input data, in particular air temperature. Lower temperatures (the so-called glacier cooling effect), and lower temperature variability (the so-called glacier damping effect) generally occur over glaciers, compared to ambient conditions. These effects, which depend on the geometric characteristics of glaciers and display a high spatial and temporal variability, have been mostly investigated on medium- to large-size glaciers so far, while observations on smaller ice bodies are scarce. Using a dataset from 8 on-glacier and 4 off-glacier weather stations, collected in summer 2010 and 2011, we analyzed the air temperature variability and wind regime over three different glaciers in the Ortles-Cevedale. The magnitude of the cooling effect and the occurrence of katabatic boundary layer (KBL) processes showed remarkable differences among the three ice bodies, suggesting the likely existence of important reinforcing mechanisms during glacier decay and disintegration. None of the methods proposed in the literature for calculating on-glacier temperature from off-glacier data fully reproduced our observations. Among them, the more physically-based procedure of Greuell and Böhm (1998) provided the best overall results where the KBL prevail, but it was not effective elsewhere (i.e. on smaller ice bodies and close to the glacier margins). The accuracy of air temperature estimations strongly impacted the results from a mass balance model which was applied to the three investigated glaciers. Most importantly, even small temperature deviations caused distortions in parameter calibration, thus compromising the model generalizability.
    Print ISSN: 1994-0432
    Electronic ISSN: 1994-0440
    Topics: Geography , Geosciences
    Published by Copernicus on behalf of The European Geosciences Union (EGU).
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  • 8
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    Are seasonal calving dynamics forced by buttressing from ice mélange or undercutting by melting? Outcomes from full-Stokes simulations of Store Glacier, West Greenland (2014)
    Copernicus
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    Publication Date: 2014-12-17
    Description: Are seasonal calving dynamics forced by buttressing from ice mélange or undercutting by melting? Outcomes from full-Stokes simulations of Store Glacier, West Greenland The Cryosphere, 8, 2353-2365, 2014 Author(s): J. Todd and P. Christoffersen We use a full-Stokes 2-D model (Elmer/Ice) to investigate the flow and calving dynamics of Store Glacier, a fast-flowing outlet glacier in West Greenland. Based on a new, subgrid-scale implementation of the crevasse depth calving criterion, we perform two sets of simulations: one to identify the primary forcing mechanisms and another to constrain future stability. We find that the mixture of icebergs and sea ice, known as ice mélange or sikussak, is principally responsible for the observed seasonal advance of the ice front. On the other hand, the effect of submarine melting on the calving rate of Store Glacier appears to be limited. Sensitivity analysis demonstrates that the glacier's calving dynamics are sensitive to seasonal perturbation, but are stable on interannual timescales due to the strong topographic control on the flow regime. Our results shed light on the dynamics of calving glaciers and may help explain why neighbouring glaciers do not necessarily respond synchronously to changes in atmospheric and oceanic forcing.
    Print ISSN: 1994-0416
    Electronic ISSN: 1994-0424
    Topics: Geography , Geosciences
    Published by Copernicus on behalf of The European Geosciences Union (EGU).
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  • 9
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    Deglaciation of the Caucasus Mountains, Russia/Georgia, in the 21st century observed with ASTER satellite imagery and aerial photography (2014)
    Copernicus
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    Publication Date: 2014-12-17
    Description: Deglaciation of the Caucasus Mountains, Russia/Georgia, in the 21st century observed with ASTER satellite imagery and aerial photography The Cryosphere, 8, 2367-2379, 2014 Author(s): M. Shahgedanova, G. Nosenko, S. Kutuzov, O. Rototaeva, and T. Khromova Changes in the map area of 498 glaciers located on the Main Caucasus ridge (MCR) and on Mt. Elbrus in the Greater Caucasus Mountains (Russia and Georgia) were assessed using multispectral ASTER and panchromatic Landsat imagery with 15 m spatial resolution in 1999/2001 and 2010/2012. Changes in recession rates of glacier snouts between 1987–2001 and 2001–2010 were investigated using aerial photography and ASTER imagery for a sub-sample of 44 glaciers. In total, glacier area decreased by 4.7 ± 2.1% or 19.2 ± 8.7 km 2 from 407.3 ± 5.4 km 2 to 388.1 ± 5.2 km 2 . Glaciers located in the central and western MCR lost 13.4 ± 7.3 km 2 (4.7 ± 2.5%) in total or 8.5 km 2 (5.0 ± 2.4%) and 4.9 km 2 (4.1 ± 2.7%) respectively. Glaciers on Mt. Elbrus, although located at higher elevations, lost 5.8 ± 1.4 km 2 (4.9 ± 1.2%) of their total area. The recession rates of valley glacier termini increased between 1987–2000/01 and 2000/01–2010 (2000 for the western MCR and 2001 for the central MCR and Mt.~Elbrus) from 3.8 ± 0.8, 3.2 ± 0.9 and 8.3 ± 0.8 m yr −1 to 11.9 ± 1.1, 8.7 ± 1.1 and 14.1 ± 1.1 m yr −1 in the central and western MCR and on Mt. Elbrus respectively. The highest rate of increase in glacier termini retreat was registered on the southern slope of the central MCR where it has tripled. A positive trend in summer temperatures forced glacier recession, and strong positive temperature anomalies in 1998, 2006, and 2010 contributed to the enhanced loss of ice. An increase in accumulation season precipitation observed in the northern MCR since the mid-1980s has not compensated for the effects of summer warming while the negative precipitation anomalies, observed on the southern slope of the central MCR in the 1990s, resulted in stronger glacier wastage.
    Print ISSN: 1994-0416
    Electronic ISSN: 1994-0424
    Topics: Geography , Geosciences
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  • 10
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    Inversion method for initial tsunami waveform reconstruction (2014)
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    Publication Date: 2014-12-18
    Description: Inversion method for initial tsunami waveform reconstruction Natural Hazards and Earth System Sciences Discussions, 2, 7735-7772, 2014 Author(s): V. V. Voronin, T. A. Voronina, and V. A. Tcheverda This paper deals with the application of r-solution method to recover the initial tsunami waveform in a tsunami source area by remote water-level measurements. Wave propagation is considered within the scope of a linear shallow-water theory. An ill-posed inverse problem is regularized by means of least square inversion using a truncated SVD approach. The properties of obtained solution are determined to a large extent by the properties of an inverse operator, which were numerically investigated. The method presented allows one to control instability of the numerical solution and to obtain an acceptable result in spite of ill-posedness of the problem. It is shown that the accuracy of tsunami source reconstruction strongly depends on the signal-to-noise ratio, the azimuthal coverage of recording stations with respect to the source area and bathymetric features along the wave path. The numerical experiments were carried out with synthetic data and various computational domains including a real bathymetry. The method proposed allows us to make a preliminary prediction of the efficiency of the inversion with a given set of the recording stations and to find out the most informative part of the existing observation system. This essential property of the method can prove to be useful in designing a monitoring system for tsunamis.
    Electronic ISSN: 2195-9269
    Topics: Geography , Geosciences
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  • 11
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    Glacier-like forms on Mars (2014)
    Copernicus
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    Publication Date: 2014-11-06
    Description: Glacier-like forms on Mars The Cryosphere, 8, 2047-2061, 2014 Author(s): B. Hubbard, C. Souness, and S. Brough More than 1300 glacier-like forms (GLFs) are located in Mars' mid-latitudes. These GLFs are predominantly composed of ice–dust mixtures and are visually similar to terrestrial valley glaciers, showing signs of downhill viscous deformation and an expanded former extent. However, several fundamental aspects of their behavior are virtually unknown, including temporal and spatial variations in mass balance, ice motion, landscape erosion and deposition, and hydrology. Here, we investigate the physical glaciology of martian GLFs. We use satellite images of specific examples and case studies to build on existing knowledge relating to (i) GLF current and former extent, exemplified via a GLF located in Phlegra Montes; (ii) indicators of GLF motion, focusing on the presence of surface crevasses on several GLFs; (iii) processes of GLF debris transfer, focusing on mapping and interpreting boulder trains on one GLF located in Protonilus Mensae, the analysis of which suggests a best-estimate mean GLF flow speed of 7.5 mm a −1 ; and (iv) GLF hydrology, focusing on supra-GLF gulley networks. On the basis of this information, we summarize the current state of knowledge of the glaciology of martian GLFs and identify future research avenues.
    Print ISSN: 1994-0416
    Electronic ISSN: 1994-0424
    Topics: Geography , Geosciences
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  • 12
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    Strategy of valid 14 C dates choice in syngenetic permafrost (2014)
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    Publication Date: 2014-11-06
    Description: Strategy of valid 14 C dates choice in syngenetic permafrost The Cryosphere Discussions, 8, 5589-5621, 2014 Author(s): Y. K. Vasil'chuk and A. C. Vasil'chuk The main problem of radiocarbon dating within permafrost is the uncertain reliability of the 14 C dates. Syngenetic sediments contain allochthonous organic deposit that originated at a distance from its present position. Due to the very good preservation of organic materials in permafrost conditions and numerous re-burials of the fossils from ancient deposits into younger ones the dates could be both younger and older than the true age of dated material. The strategy for the most authentic radiocarbon date selection for dating of syncryogenic sediments is considered taking into account the fluvial origin of the syngenetic sediments. The re-deposition of organic material is discussed in terms of cyclic syncryogenic sedimentation and also the possible re-deposition of organic material in subaerial-subaqueous conditions. The advantages and the complications of dating organic micro-inclusions from ice wedges by the accelerator mass spectrometry (AMS) method are discussed applying to true age of dated material search. Radiocarbon dates of different organic materials from the same samples are compared. The younger age of the yedoma from cross-sections of Duvanny Yar in Kolyma River and Mamontova Khayata in the mouth of Lena River is substantiated due to the principle of the choice of the youngest 14 C date from the set.
    Print ISSN: 1994-0432
    Electronic ISSN: 1994-0440
    Topics: Geography , Geosciences
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  • 13
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    Modeling the elastic transmission of tidal stresses to great distances inland in channelized ice streams (2014)
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    Publication Date: 2014-11-06
    Description: Modeling the elastic transmission of tidal stresses to great distances inland in channelized ice streams The Cryosphere, 8, 2007-2029, 2014 Author(s): J. Thompson, M. Simons, and V. C. Tsai Geodetic surveys suggest that ocean tides can modulate the motion of Antarctic ice streams, even at stations many tens of kilometers inland from the grounding line. These surveys suggest that ocean tidal stresses can perturb ice stream motion at distances about an order of magnitude farther inland than tidal flexure of the ice stream alone. Recent models exploring the role of tidal perturbations in basal shear stress are primarily one- or two-dimensional, with the impact of the ice stream margins either ignored or parameterized. Here, we use two- and three-dimensional finite-element modeling to investigate transmission of tidal stresses in ice streams and the impact of considering more realistic, three-dimensional ice stream geometries. Using Rutford Ice Stream as a real-world comparison, we demonstrate that the assumption that elastic tidal stresses in ice streams propagate large distances inland fails for channelized glaciers due to an intrinsic, exponential decay in the stress caused by resistance at the ice stream margins. This behavior is independent of basal conditions beneath the ice stream and cannot be fit to observations using either elastic or nonlinear viscoelastic rheologies without nearly complete decoupling of the ice stream from its lateral margins. Our results suggest that a mechanism external to the ice stream is necessary to explain the tidal modulation of stresses far upstream of the grounding line for narrow ice streams. We propose a hydrologic model based on time-dependent variability in till strength to explain transmission of tidal stresses inland of the grounding line. This conceptual model can reproduce observations from Rutford Ice Stream.
    Print ISSN: 1994-0416
    Electronic ISSN: 1994-0424
    Topics: Geography , Geosciences
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  • 14
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    Simulating the Antarctic ice sheet in the Late-Pliocene warm period: PLISMIP-ANT, an ice-sheet model intercomparison project (2014)
    Copernicus
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    Publication Date: 2014-11-06
    Description: Simulating the Antarctic ice sheet in the Late-Pliocene warm period: PLISMIP-ANT, an ice-sheet model intercomparison project The Cryosphere Discussions, 8, 5539-5588, 2014 Author(s): B. de Boer, A. M. Dolan, J. Bernales, E. Gasson, H. Goelzer, N. R. Golledge, J. Sutter, P. Huybrechts, G. Lohmann, I. Rogozhina, A. Abe-Ouchi, F. Saito, and R. S. W. van de Wal In the context of future climate change, understanding the nature and behaviour of ice sheets during warm intervals in Earth history is of fundamental importance. The Late-Pliocene warm period (also known as the PRISM interval: 3.264 to 3.025 million years before present) can serve as a potential analogue for projected future climates. Although Pliocene ice locations and extents are still poorly constrained, a significant contribution to sea-level rise should be expected from both the Greenland ice sheet and the West and East Antarctic ice sheets based on palaeo sea-level reconstructions. Here, we present results from simulations of the Antarctic ice sheet by means of an international Pliocene Ice Sheet Modeling Intercomparison Project (PLISMIP-ANT). For the experiments, ice-sheet models including the shallow ice and shelf approximations have been used to simulate the complete Antarctic domain (including grounded and floating ice). We compare the performance of six existing numerical ice-sheet models in simulating modern control and Pliocene ice sheets by a suite of four sensitivity experiments. Ice-sheet model forcing fields are taken from the HadCM3 atmosphere–ocean climate model runs for the pre-industrial and the Pliocene. We include an overview of the different ice-sheet models used and how specific model configurations influence the resulting Pliocene Antarctic ice sheet. The six ice-sheet models simulate a comparable present-day ice sheet, although the models are setup with their own parameter settings. For the Pliocene simulations using the Bedmap1 bedrock topography, some models show a small retreat of the East Antarctic ice sheet, which is thought to have happened during the Pliocene for the Wilkes and Aurora basins. This can be ascribed to either the surface mass balance, as the HadCM3 Pliocene climate shows a significant increase over the Wilkes and Aurora basin, or the initial bedrock topography. For the latter, our simulations with the recently published Bedmap2 bedrock topography indicate a significantly larger contribution to Pliocene sea-level rise from the East Antarctic ice sheet for all six models relative to the simulations with Bedmap1.
    Print ISSN: 1994-0432
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    Topics: Geography , Geosciences
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  • 15
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    Fluctuations of a Greenlandic tidewater glacier driven by changes in atmospheric forcing: observations and modelling of Kangiata Nunaata Sermia, 1859–present (2014)
    Copernicus
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    Publication Date: 2014-11-06
    Description: Fluctuations of a Greenlandic tidewater glacier driven by changes in atmospheric forcing: observations and modelling of Kangiata Nunaata Sermia, 1859–present The Cryosphere, 8, 2031-2045, 2014 Author(s): J. M. Lea, D. W. F. Mair, F. M. Nick, B. R. Rea, D. van As, M. Morlighem, P. W. Nienow, and A. Weidick Many tidewater glaciers in Greenland are known to have undergone significant retreat during the last century following their Little Ice Age maxima. Where it is possible to reconstruct glacier change over this period, they provide excellent records for comparison to climate records, as well as calibration/validation for numerical models. These glacier change records therefore allow for tests of numerical models that seek to simulate tidewater glacier behaviour over multi-decadal to centennial timescales. Here we present a detailed record of behaviour from Kangiata Nunaata Sermia (KNS), SW Greenland, between 1859 and 2012, and compare it against available oceanographic and atmospheric temperature data between 1871 and 2012. We also use these records to evaluate the ability of a well-established one-dimensional flow-band model to replicate behaviour for the observation period. The record of terminus change demonstrates that KNS has advanced/retreated in phase with atmosphere and ocean climate anomalies averaged over multi-annual to decadal timescales. Results from an ensemble of model runs demonstrate that observed dynamics can be replicated. Model runs that provide a reasonable match to observations always require a significant atmospheric forcing component, but do not necessarily require an oceanic forcing component. Although the importance of oceanic forcing cannot be discounted, these results demonstrate that changes in atmospheric forcing are likely to be a primary driver of the terminus fluctuations of KNS from 1859 to 2012. We propose that the detail and length of the record presented makes KNS an ideal site for model validation exercises investigating links between climate, calving rates, and tidewater glacier dynamics.
    Print ISSN: 1994-0416
    Electronic ISSN: 1994-0424
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    Hydrogeology of an Alpine rockfall aquifer system and its role in flood attenuation and maintaining baseflow (2014)
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    Publication Date: 2014-11-07
    Description: Hydrogeology of an Alpine rockfall aquifer system and its role in flood attenuation and maintaining baseflow Hydrology and Earth System Sciences, 18, 4437-4452, 2014 Author(s): U. Lauber, P. Kotyla, D. Morche, and N. Goldscheider The frequency and intensity of extreme hydrological events in Alpine regions is projected to increase with climate change. The goal of this study is to better understand the functioning of aquifers composed of complex alluvial and rockfall deposits in Alpine valleys and to quantify the role of these natural storage spaces in flood attenuation and baseflow maintenance. Geomorphological and hydrogeological mapping, tracer tests, and continuous flow measurements were conducted in the Reintal (German Alps), where runoff from a karst spring infiltrates a series of postglacial alluvial/rockfall aquifers. During high-flow conditions, groundwater velocities of 30 m h −1 were determined along 500 m; hydrograph analyses revealed short lag times (5 h) between discharge peaks upstream and downstream from the aquifer series; the maximum discharge ratio downstream (22) and the peak recession coefficient (0.196 d −1 ) are low compared with other Alpine catchments. During low-flow conditions, the underground flow path length increased to 2 km and groundwater velocities decreased to 13 m h −1 . Downstream hydrographs revealed a delayed discharge response after 101 h and peaks damped by a factor of 1.5. These results indicate that alluvial/rockfall aquifers might play an important role in the flow regime and attenuation of floods in Alpine regions.
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    Observed groundwater temperature response to recent climate change (2014)
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    Publication Date: 2014-11-07
    Description: Observed groundwater temperature response to recent climate change Hydrology and Earth System Sciences, 18, 4453-4466, 2014 Author(s): K. Menberg, P. Blum, B. L. Kurylyk, and P. Bayer Climate change is known to have a considerable influence on many components of the hydrological cycle. Yet, the implications for groundwater temperature, as an important driver for groundwater quality, thermal use and storage, are not yet comprehensively understood. Furthermore, few studies have examined the implications of climate-change-induced groundwater temperature rise for groundwater-dependent ecosystems. Here, we examine the coupling of atmospheric and groundwater warming by employing stochastic and deterministic models. Firstly, several decades of temperature time series are statistically analyzed with regard to climate regime shifts (CRSs) in the long-term mean. The observed increases in shallow groundwater temperatures can be associated with preceding positive shifts in regional surface air temperatures, which are in turn linked to global air temperature changes. The temperature data are also analyzed with an analytical solution to the conduction–advection heat transfer equation to investigate how subsurface heat transfer processes control the propagation of the surface temperature signals into the subsurface. In three of the four monitoring wells, the predicted groundwater temperature increases driven by the regime shifts at the surface boundary condition generally concur with the observed groundwater temperature trends. Due to complex interactions at the ground surface and the heat capacity of the unsaturated zone, the thermal signals from distinct changes in air temperature are damped and delayed in the subsurface, causing a more gradual increase in groundwater temperatures. These signals can have a significant impact on large-scale groundwater temperatures in shallow and economically important aquifers. These findings demonstrate that shallow groundwater temperatures have responded rapidly to recent climate change and thus provide insight into the vulnerability of aquifers and groundwater-dependent ecosystems to future climate change.
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    Snow mass decrease in the Northern Hemisphere (1979/80–2010/11) (2014)
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    Publication Date: 2014-11-07
    Description: Snow mass decrease in the Northern Hemisphere (1979/80–2010/11) The Cryosphere Discussions, 8, 5623-5644, 2014 Author(s): Z. Li, J. Liu, L. Huang, N. Wang, B. Tian, J. Zhou, Q. Chen, and P. Zhang Snow cover has a key effect on climate change and hydrological cycling, as well as water supply to a sixth of the world's population across the Northern Hemisphere. However, reliable data on trends in snow cover in the Northern Hemisphere is lacking. Snow water equivalent (SWE) is a common measure of the amount of equivalent water of the snow pack. Here we verify the accuracy of three existing global SWE products and merge the most accurate aspects of them to generate a new SWE product covering the last 32 years (1979/80–2010/11). Using this new SWE product, we show that there has been a significant decreasing trend in the total mass of snow in the Northern Hemisphere. The most notable changes in total snow mass are −16.45 ± 6.68 and −13.55 ± 7.80 Gt year −1 in January and February, respectively. These are followed by March and December, which have trends of −12.58 ± 6.88 and −10.70 ± 5.62 Gt year −1 , respectively, from 1979/80 to 2010/11. During the same period, the temperature in the study area raised 0.17 °C decade −1 , which is thought to be the main reason of SWE decline.
    Print ISSN: 1994-0432
    Electronic ISSN: 1994-0440
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    Factors controlling Slope Environmental Lapse Rate (SELR) of temperature in the monsoon and cold-arid glacio-hydrological regimes of the Himalaya (2014)
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    Publication Date: 2014-11-07
    Description: Factors controlling Slope Environmental Lapse Rate (SELR) of temperature in the monsoon and cold-arid glacio-hydrological regimes of the Himalaya The Cryosphere Discussions, 8, 5645-5686, 2014 Author(s): R. J. Thayyen and A. P. Dimri Moisture, temperature and precipitation interplay forced through the orographic processes sustains the Himalayan cryospheric system. However, factors controlling the Slope Environmental Lapse Rate (SELR) of temperature along the higher Himalayan mountain slopes across various glacio-hydrologic regimes remain as a key knowledge gap. Present study dwells on the orographic processes driving the moisture–temperature interplay in the monsoon and cold-arid glacio-hydrological regimes of the Himalaya. Systematic data collection at three altitudes between 2540 and 3763 m a.s.l. in the Garhwal Himalaya (hereafter called monsoon regime) and between 3500 and 5600 m a.s.l. in the Ladakh Himalaya (herefater called cold-arid regime) revealed moistrue control on temperature distribution at temporal and spatial scales. Observed daily SELR of temperature ranges between 9.0 to 1.9 °C km −1 and 17.0 to 2.8 °C km −1 in the monsoon and cold-arid regimes respectively highlighting strong regional variability. Moisture influx to the region, either from Indian summer monsoon (ISM) or from Indian winter monsoon (IWM) forced lowering of SELR. This phenophena of "monsoon lowering" of SELR is due to the release latent heat of condensation from orographically focred lifted air parcel. Seasonal response of SELR in the monsoon regime is found to be closly linked with the variations in the local lifting condensation levels (LCL). Contrary to this, cold-arid system is characterised by the extremely high values of daily SELR upto 17 °C km −1 signifying the extremely arid conditions prevailing in summer. Distinctly lower SELR devoid of monsoon lowering at higher altitude sections of monsoon and cold-arid regimes suggests sustained wetter high altitude regimes. We have proposed a SELR model for both glacio-hydrological regimes demostrating with two sections each using a derivative of the Clausius–Clapeyron relationship by deriving monthly SELR indices. It has been proposed that the manifestations of presence or absence of moisture is the single most important factor determining the temperature distribution along the higher Himalayan slopes driven by the orographic forcings. This work also suggests that the arbitary use of temperature lapse rate to extrapolate temperature to the higher Himalaya is extremely untenable.
    Print ISSN: 1994-0432
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    Evaluation of the satellite-based Global Flood Detection System for measuring river discharge: influence of local factors (2014)
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    Publication Date: 2014-11-08
    Description: Evaluation of the satellite-based Global Flood Detection System for measuring river discharge: influence of local factors Hydrology and Earth System Sciences, 18, 4467-4484, 2014 Author(s): B. Revilla-Romero, J. Thielen, P. Salamon, T. De Groeve, and G. R. Brakenridge One of the main challenges for global hydrological modelling is the limited availability of observational data for calibration and model verification. This is particularly the case for real-time applications. This problem could potentially be overcome if discharge measurements based on satellite data were sufficiently accurate to substitute for ground-based measurements. The aim of this study is to test the potentials and constraints of the remote sensing signal of the Global Flood Detection System for converting the flood detection signal into river discharge values. The study uses data for 322 river measurement locations in Africa, Asia, Europe, North America and South America. Satellite discharge measurements were calibrated for these sites and a validation analysis with in situ discharge was performed. The locations with very good performance will be used in a future project where satellite discharge measurements are obtained on a daily basis to fill the gaps where real-time ground observations are not available. These include several international river locations in Africa: the Niger, Volta and Zambezi rivers. Analysis of the potential factors affecting the satellite signal was based on a classification decision tree (random forest) and showed that mean discharge, climatic region, land cover and upstream catchment area are the dominant variables which determine good or poor performance of the measure\-ment sites. In general terms, higher skill scores were obtained for locations with one or more of the following characteristics: a river width higher than 1km; a large floodplain area and in flooded forest, a potential flooded area greater than 40%; sparse vegetation, croplands or grasslands and closed to open and open forest; leaf area index 〉 2; tropical climatic area; and without hydraulic infrastructures. Also, locations where river ice cover is seasonally present obtained higher skill scores. This work provides guidance on the best locations and limitations for estimating discharge values from these daily satellite signals.
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    Sampling frequency trade-offs in the assessment of mean transit times of tropical montane catchment waters under semi-steady-state conditions (2014)
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    Publication Date: 2014-11-08
    Description: Sampling frequency trade-offs in the assessment of mean transit times of tropical montane catchment waters under semi-steady-state conditions Hydrology and Earth System Sciences Discussions, 11, 12443-12488, 2014 Author(s): E. Timbe, D. Windhorst, R. Celleri, L. Timbe, P. Crespo, H.-G. Frede, J. Feyen, and L. Breuer Stream and soil waters were collected on a weekly basis in a tropical montane cloud forest catchment for two years and analyzed for stable water isotopes in order to infer transit time distribution functions and to define the mean transit times. Depending on the water type (stream or soil water), lumped distribution functions such as Exponential-Piston flow, Linear-Piston flow and Gamma models using temporal isotopic variations of precipitation event samples as input, were fitted. Samples were aggregated to daily, weekly, biweekly, monthly and bimonthly time scales in order to check the sensitivity of temporal sampling on model predictions. The study reveals that the effect of decreasing sampling frequency depends on the water type. For soil waters with transit times in the order of weeks to months, there was a clear trend of over prediction. In contrast, the trend of prediction for stream waters, with a dampened isotopic signal and mean transit times in the order of 2 to 4 years, was less clear and depending on the type of model used. The trade-off to coarse data resolutions could potentially lead to misleading conclusions on how water actually moves through the catchment, while at the same time predictions can reach better fitting efficiencies, lesser uncertainties, errors and biases. For both water types an optimal sampling frequency seems to be one or at most two weeks. The results of our analyses provide information for the planning (in particular in terms of cost-benefit and time requirements) of future fieldwork in similar Andean or other catchments.
    Print ISSN: 1812-2108
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    A model study of Abrahamsenbreen, a surging glacier in northern Spitsbergen (2014)
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    Publication Date: 2014-11-08
    Description: A model study of Abrahamsenbreen, a surging glacier in northern Spitsbergen The Cryosphere Discussions, 8, 5687-5726, 2014 Author(s): J. Oerlemans and W. J. J. van Pelt The climate sensitivity of Abrahamsenbreen, a 20 km long surge-type glacier in northern Spitsbergen, is studied with a simple glacier model. A scheme to describe the surges is included, which makes it possible to account for the effect of surges on the total mass budget of the glacier. A climate reconstruction back to AD 1300, based on ice-core data from Lomonosovfonna and climate records from Longyearbyen, is used to drive the model. The model is calibrated by requesting that it produces the correct Little Ice Age maximum glacier length and simulates the observed magnitude of the 1978-surge. Abrahamsenbreen is strongly out of balance with the current climate. If climatic conditions will remain as they were for the period 1989–2010, the glacier will ultimately shrink to a length of about 4 km (but this will take hundreds of years). For a climate change scenario involving a 2 m yr −1 rise of the equilibrium line from now onwards, we predict that in the year 2100 Abrahamsenbreen will be about 12 km long. The main effect of a surge is to lower the mean surface elevation and to increase the ablation area, thereby causing a negative perturbation of the mass budget. We found that the occurrence of surges leads to a somewhat stronger retreat of the glacier in a warming climate. Because of the very small bed slope, Abrahamsenbreen is sensitive to small perturbations in the equilibrium-line altitude E . For a decrease of E of only 160 m, the glacier would steadily grow into the Woodfjorddalen until after 2000 years it would reach the Woodfjord and calving could slow down the advance.
    Print ISSN: 1994-0432
    Electronic ISSN: 1994-0440
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    Technical Note: On the Matt–Shuttleworth approach to estimate crop water requirements (2014)
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    Publication Date: 2014-11-05
    Description: Technical Note: On the Matt–Shuttleworth approach to estimate crop water requirements Hydrology and Earth System Sciences, 18, 4341-4348, 2014 Author(s): J. P. Lhomme, N. Boudhina, and M. M. Masmoudi The Matt–Shuttleworth method provides a way to make a one-step estimate of crop water requirements with the Penman–Monteith equation by translating the crop coefficients, commonly available in United Nations Food and Agriculture Organization (FAO) publications, into equivalent surface resistances. The methodology is based upon the theoretical relationship linking crop surface resistance to a crop coefficient and involves the simplifying assumption that the reference crop evapotranspiration (ET 0 ) is equal to the Priestley–Taylor estimate with a fixed coefficient of 1.26. This assumption, used to eliminate the dependence of surface resistance on certain weather variables, is questionable; numerical simulations show that it can lead to substantial differences between the true value of surface resistance and its estimate. Consequently, the basic relationship between surface resistance and crop coefficient, without any assumption, appears to be more appropriate for inferring crop surface resistance, despite the interference of weather variables.
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    Variational assimilation of remotely sensed flood extents using a 2-D flood model (2014)
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    Publication Date: 2014-11-05
    Description: Variational assimilation of remotely sensed flood extents using a 2-D flood model Hydrology and Earth System Sciences, 18, 4325-4339, 2014 Author(s): X. Lai, Q. Liang, H. Yesou, and S. Daillet A variational data assimilation (4D-Var) method is proposed to directly assimilate flood extents into a 2-D dynamic flood model to explore a novel way of utilizing the rich source of remotely sensed data available from satellite imagery for better analyzing or predicting flood routing processes. For this purpose, a new cost function is specially defined to effectively fuse the hydraulic information that is implicitly indicated in flood extents. The potential of using remotely sensed flood extents for improving the analysis of flood routing processes is demonstrated by applying the present new data assimilation approach to both idealized and realistic numerical experiments.
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    Quantitative high-resolution observations of soil water dynamics in a complicated architecture with time-lapse Ground-Penetrating Radar (2014)
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    Publication Date: 2014-11-05
    Description: Quantitative high-resolution observations of soil water dynamics in a complicated architecture with time-lapse Ground-Penetrating Radar Hydrology and Earth System Sciences Discussions, 11, 12365-12404, 2014 Author(s): P. Klenk, S. Jaumann, and K. Roth High-resolution time-lapse Ground-Penetrating Radar (GPR) observations of advancing and retreating water tables can yield a wealth of information about near-surface water content dynamics. In this study, we present and analyze a series of imbibition, drainage and infiltration experiments which have been carried out at our artificial ASSESS test site and observed with surface based GPR. The test site features a complicated but known subsurface architecture constructed with three different kinds of sand. It allows studying soil water dynamics with GPR under a wide range of different conditions. Here, we assess in particular (i) the accurate determination of soil water dynamics averaged over the whole vertical extent by evaluating the bottom reflection and (ii) the feasibility of monitoring the dynamic shape of the capillary fringe reflection. The phenomenology of the GPR response of a dynamically changing capillary fringe is developed from a soil physical point of view. We then explain experimentally observed phenomena based on numerical simulations of both the water content dynamics and the expected GPR response.
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    Translating aboveground cosmic-ray neutron intensity to high-frequency soil moisture profiles at sub-kilometer scale (2014)
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    Publication Date: 2014-11-05
    Description: Translating aboveground cosmic-ray neutron intensity to high-frequency soil moisture profiles at sub-kilometer scale Hydrology and Earth System Sciences, 18, 4363-4379, 2014 Author(s): R. Rosolem, T. Hoar, A. Arellano, J. L. Anderson, W. J. Shuttleworth, X. Zeng, and T. E. Franz Above-ground cosmic-ray neutron measurements provide an opportunity to infer soil moisture at the sub-kilometer scale. Initial efforts to assimilate those measurements have shown promise. This study expands such analysis by investigating (1) how the information from aboveground cosmic-ray neutrons can constrain the soil moisture at distinct depths simulated by a land surface model, and (2) how changes in data availability (in terms of retrieval frequency) impact the dynamics of simulated soil moisture profiles. We employ ensemble data assimilation techniques in a "nearly-identical twin" experiment applied at semi-arid shrubland, rainfed agricultural field, and mixed forest biomes in the USA. The performance of the Noah land surface model is compared with and without assimilation of observations at hourly intervals, as well as every 2 days. Synthetic observations of aboveground cosmic-ray neutrons better constrain the soil moisture simulated by Noah in root-zone soil layers (0–100cm), despite the limited measurement depth of the sensor (estimated to be 12–20cm). The ability of Noah to reproduce a "true" soil moisture profile is remarkably good, regardless of the frequency of observations at the semi-arid site. However, soil moisture profiles are better constrained when assimilating synthetic cosmic-ray neutron observations hourly rather than every 2 days at the cropland and mixed forest sites. This indicates potential benefits for hydrometeorological modeling when soil moisture measurements are available at a relatively high frequency. Moreover, differences in summertime meteorological forcing between the semi-arid site and the other two sites may indicate a possible controlling factor to soil moisture dynamics in addition to differences in soil and vegetation properties.
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    Large-scale 3-D modeling by integration of resistivity models and borehole data through inversion (2014)
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    Publication Date: 2014-11-05
    Description: Large-scale 3-D modeling by integration of resistivity models and borehole data through inversion Hydrology and Earth System Sciences, 18, 4349-4362, 2014 Author(s): N. Foged, P. A. Marker, A. V. Christansen, P. Bauer-Gottwein, F. Jørgensen, A.-S. Høyer, and E. Auken We present an automatic method for parameterization of a 3-D model of the subsurface, integrating lithological information from boreholes with resistivity models through an inverse optimization, with the objective of further detailing of geological models, or as direct input into groundwater models. The parameter of interest is the clay fraction, expressed as the relative length of clay units in a depth interval. The clay fraction is obtained from lithological logs and the clay fraction from the resistivity is obtained by establishing a simple petrophysical relationship, a translator function, between resistivity and the clay fraction. Through inversion we use the lithological data and the resistivity data to determine the optimum spatially distributed translator function. Applying the translator function we get a 3-D clay fraction model, which holds information from the resistivity data set and the borehole data set in one variable. Finally, we use k -means clustering to generate a 3-D model of the subsurface structures. We apply the procedure to the Norsminde survey in Denmark, integrating approximately 700 boreholes and more than 100 000 resistivity models from an airborne survey in the parameterization of the 3-D model covering 156 km 2 . The final five-cluster 3-D model differentiates between clay materials and different high-resistivity materials from information held in the resistivity model and borehole observations, respectively.
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    Simulating long-term past changes in the balance between water demand and availability and assessing their main drivers at the river basin management scale (2014)
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    Publication Date: 2014-11-05
    Description: Simulating long-term past changes in the balance between water demand and availability and assessing their main drivers at the river basin management scale Hydrology and Earth System Sciences Discussions, 11, 12315-12364, 2014 Author(s): J. Fabre, D. Ruelland, A. Dezetter, and B. Grouillet The aim of this study was to assess the balance between water demand and availability and its spatial and temporal variability from 1971 to 2009 in the Herault (2500 km 2 , France) and the Ebro (85 000 km 2 , Spain) catchments. Natural streamflow was evaluated using a conceptual hydrological model. The regulation of river flow was accounted for through a widely applicable demand-driven reservoir management model applied to the largest dam in the Herault basin and to 11 major dams in the Ebro basin. Urban water demand was estimated from population and monthly unit water consumption data. Water demand for irrigation was computed from irrigated area, crop and soil data, and climatic forcing. Finally, a series of indicators comparing water supply and water demand at strategic resource and demand nodes were computed at a 10 day time step. Variations in water stress in each catchment over the past 40 years were successfully modeled, taking into account climatic and anthropogenic pressures and changes in water management strategies over time. Observed changes in discharge were explained by separating human and hydro-climatic pressures on water resources: respectively 20 and 3% of the decrease in the Ebro and the Herault discharges were linked to human-induced changes. Although key areas of the Herault basin were shown to be highly sensitive to hydro-climatic variability, the balance between water uses and availability in the Ebro basin appears to be more critical, owing to high agricultural pressure on water resources. The proposed modeling framework is currently being used to assess water stress under climatic and socio-economic prospective scenarios. Further research will investigate the effectiveness of adaptation policies aimed at maintaining the balance between water use and availability.
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    Time-series analysis of the long-term hydrologic impacts of afforestation in the Águeda watershed of North-Central Portugal (2014)
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    Publication Date: 2014-11-05
    Description: Time-series analysis of the long-term hydrologic impacts of afforestation in the Águeda watershed of North-Central Portugal Hydrology and Earth System Sciences Discussions, 11, 12223-12256, 2014 Author(s): D. Hawtree, J. P. Nunes, J. J. Keizer, R. Jacinto, J. Santos, M. E. Rial-Rivas, A.-K. Boulet, F. Tavares-Wahren, and K.-H. Feger The north-central region of Portugal has undergone significant afforestation of the species Pinus pinaster and Eucalyptus globulus since the early 1900s; however, the long-term hydrologic impacts of this land cover change are not fully understood. To contribute to a better understanding of the potential hydrologic impacts of this land cover change, this study examines the temporal trends in 7 years of data from the Águeda watershed (part of the Vouga Basin) over the period of 1936 to 2010. Meteorological and hydrological records were analysed using a combined Thiel–Sen/Mann–Kendall trend testing approach, to assess the magnitude and significance of patterns in the observed data. These trend tests indicated that there had been no significant reduction in streamflow yield over either the entire test period, or during sub-record periods, despite the large-scale afforestation which had taken place. This lack of change is attributed to both the characteristics of the watershed and the nature of the land cover change. By contrast, a number of significant trends were found for baseflow index, which showed positive trends in the early data record (primarily during Pinus pinaster afforestation), followed by a reversal to negative trends later in the data record (primarily during Eucalyptus globulus afforestation). These changes are attributed to vegetation impacts on streamflow generating processes, both due to the species differences and to alterations in soil properties (i.e. promoting water repellency of the topsoil). These results highlight the importance of considering both vegetation types/dynamics and watershed characteristic when assessing hydrologic impacts, in particular with respect to soil properties.
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    Reply to D. L. Peters' comment on "Streamflow input to Lake Athabasca, Canada" by Rasouli et al. (2013) (2014)
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    Publication Date: 2014-11-05
    Description: Reply to D. L. Peters' comment on "Streamflow input to Lake Athabasca, Canada" by Rasouli et al. (2013) Hydrology and Earth System Sciences Discussions, 11, 12257-12270, 2014 Author(s): K. Rasouli, M. A. Hernández-Henríquez, and S. J. Déry This paper provides a reply to a comment from Peters (2014) on our recent effort focused on evaluating changes in streamflow input to Lake Athabasca, Canada. Lake Athabasca experienced a 21.2% decline in streamflow input between 1960 and 2010 that has led to a marked decline in its water levels in recent decades. A reassessment of trends in naturalized Lake Athabasca water levels shows insignificant changes from our previous findings reported in Rasouli et al. (2013), and hence our previous conclusions remain unchanged. The reply closes with recommendations for future research to minimize uncertainties in historical assessments of trends in Lake Athabasca water levels and to better project its future water levels driven by climate change and anthropogenic activities in the Athabasca Lake Basin.
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    Is sinuosity a function of slope and bankfull discharge? – A case study of the meandering rivers in the Pannonian Basin (2014)
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    Publication Date: 2014-11-05
    Description: Is sinuosity a function of slope and bankfull discharge? – A case study of the meandering rivers in the Pannonian Basin Hydrology and Earth System Sciences Discussions, 11, 12271-12290, 2014 Author(s): J. Petrovszki, G. Timár, and G. Molnár Pre-regulation channel sinuosities of the meandering rivers of the Pannonian Basin are analysed in order to define a mathematical model to estimate the influence of the bankfull discharge and the channel slope on them. As a primary database, data triplets of slope, discharge and sinuosity values were extracted from historical and modern datasets and pre-regulation historical topographic maps. Channel slope values were systematically modified to estimate figures valid before the river regulation works. The bankfull discharges were estimated from the average discharges using a robust yet complex method. The "classical" graphs of Leopold and Wolman (1957), Ackers and Charlton (1970b) and Schumm and Khan (1972) were compiled to a set up a theoretical surface, whose parameters are estimated by the real values of the above database, containing characteristics of the Pannonian Basin rivers. As a result it occurred that there is a two-dimensional function of the bankfull discharges, which provides a good estimation of the most probable sinuosity values of the rivers with the given slope and discharge characteristics. The average RMS error of this estimation is around 15% on this dataset and believed to be the effect of the non-analysed changes in the sediment discharge and size distribution.
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    Technical Note: Field experiences using UV/VIS sensors for high-resolution monitoring of nitrate in groundwater (2014)
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    Publication Date: 2014-11-05
    Description: Technical Note: Field experiences using UV/VIS sensors for high-resolution monitoring of nitrate in groundwater Hydrology and Earth System Sciences Discussions, 11, 12291-12314, 2014 Author(s): M. Huebsch, F. Grimmeisen, M. Zemann, O. Fenton, K. G. Richards, P. Jordan, A. Sawarieh, P. Blum, and N. Goldscheider Two different in-situ spectrophotometers are compared that were used in the field to determine nitrate-nitrogen (NO 3 -N) concentrations at two distinct spring discharge sites. One sensor was a double wavelength spectrophotometer (DWS) and the other a multiple wavelength spectrophotometer (MWS). The objective of the study was to review the hardware options, determine ease of calibration, accuracy, influence of additional substances and to assess positive and negative aspects of the two sensors as well as troubleshooting and trade-offs. Both sensors are sufficient to monitor highly time-resolved NO 3 -N concentrations in emergent groundwater. However, the chosen path length of the sensors had a significant influence on the sensitivity and the range of detectable NO 3 -N. The accuracy of the calculated NO 3 -N concentrations of the sensors can be affected, if the content of additional substances such as turbidity, organic matter, nitrite or hydrogen carbonate significantly varies after the sensors have been calibrated to a particular water matrix. The MWS offers more possibilities for calibration and error detection, but requires more expertise compared with the DWS.
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    A catalog of high-impact windstorms in Switzerland since 1859 (2014)
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    Publication Date: 2014-11-05
    Description: A catalog of high-impact windstorms in Switzerland since 1859 Natural Hazards and Earth System Science, 14, 2867-2882, 2014 Author(s): P. Stucki, S. Brönnimann, O. Martius, C. Welker, M. Imhof, N. von Wattenwyl, and N. Philipp In recent decades, extremely hazardous windstorms have caused enormous losses to buildings, infrastructure and forests in Switzerland. This has increased societal and scientific interest in the intensity and frequency of historical high-impact storms. However, high-resolution wind data and damage statistics mostly span recent decades only. For this study, we collected quantitative (e.g., volumes of windfall timber, losses relating to buildings) and descriptive (e.g., forestry or insurance reports) information on the impact of historical windstorms. To define windstorm severity, normalized and declustered quantitative data were processed by extreme value statistics. Descriptive information was classified using a conceptual guideline. Validation with independent damage information, as well as comparison with wind measurements and a reanalysis, indicates that the most hazardous winter storms are captured, while too few moderate windstorms are detected. Strong storms in the wind measurements and reanalysis are thus added to the catalog. The final catalog encompasses approximately 240 high-impact windstorms in Switzerland since 1859. It features three robust severity classes and contains eight extreme windstorms. Evidence of high winter storm activity in the early and late 20th century compared to the mid-20th century in both damage and wind data indicates a co-variability of hazard and related damage on decadal timescales.
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    Generalized drought assessment in Dongliao river basin based on water resources system (2014)
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    Publication Date: 2014-11-05
    Description: Generalized drought assessment in Dongliao river basin based on water resources system Natural Hazards and Earth System Sciences Discussions, 2, 6703-6746, 2014 Author(s): B. S. Weng, D. H. Yan, H. Wang, T. L. Qin, and J. Yin Drought is firstly a resource issue, and with its development it transforms into a disaster issue. The occurrences of drought events usually feature determinacy and randomness. Drought issue has become one of the major factors to affect sustainable economic and social development. In this paper, we propose the generalized drought assessment index (GDAI) based on water resources system for assessing drought events. The GDAI considers water supply and water demand using a distributed hydrological model. We demonstrate the use of the proposed index in the Dongliao river basin (DRB) in the northeast China. The results simulated by the GDAI are then compared to observed drought disaster records in DRB. As second, the temporal distribution of drought events and the spatial distribution of drought frequency from the GDAI are compared with the traditional approach (i.e. the SPI, the PDSI, and the RWD). Then, generalized drought times (GDT), generalized drought duration (GDD), and generalized drought severity (GDS) were calculated by theory of runs. Application of the GDT, the GDD, and the GDS of various drought levels (i.e. mild drought, moderate drought, severe drought, and extreme drought) to the period 1960–2010 shows that the centers of gravity of them are all distributed in the middle reached of DRB, and change with time. The proposed methodology helps water managers in water-stressed regions to quantify the impact of drought, consequently, to make decisions regarding coping with drought issue.
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    A GIS-based model to estimate flood consequences and the degree of accessibility and operability of strategic emergency response structures in urban areas (2014)
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    Publication Date: 2014-11-05
    Description: A GIS-based model to estimate flood consequences and the degree of accessibility and operability of strategic emergency response structures in urban areas Natural Hazards and Earth System Science, 14, 2847-2865, 2014 Author(s): R. Albano, A. Sole, J. Adamowski, and L. Mancusi Efficient decision-making regarding flood risk reduction has become a priority for authorities and stakeholders in many European countries. Risk analysis methods and techniques are a useful tool for evaluating costs and benefits of possible interventions. Within this context, a methodology to estimate flood consequences was developed in this paper that is based on GIS, and integrated with a model that estimates the degree of accessibility and operability of strategic emergency response structures in an urban area. The majority of the currently available approaches do not properly analyse road network connections and dependencies within systems, and as such a loss of roads could cause significant damages and problems to emergency services in cases of flooding. The proposed model is unique in that it provides a maximum-impact estimation of flood consequences on the basis of the operability of the strategic emergency structures in an urban area, their accessibility, and connection within the urban system of a city (i.e. connection between aid centres and buildings at risk), in the emergency phase. The results of a case study in the Puglia region in southern Italy are described to illustrate the practical applications of this newly proposed approach. The main advantage of the proposed approach is that it allows for defining a hierarchy between different infrastructure in the urban area through the identification of particular components whose operation and efficiency are critical for emergency management. This information can be used by decision-makers to prioritize risk reduction interventions in flood emergencies in urban areas, given limited financial resources.
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    Modeling rapid mass movements using the shallow water equations (2014)
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    Publication Date: 2014-11-05
    Description: Modeling rapid mass movements using the shallow water equations Natural Hazards and Earth System Sciences Discussions, 2, 6775-6809, 2014 Author(s): S. Hergarten and J. Robl We propose a new method to model rapid mass movements on complex topography using the shallow water equations in Cartesian coordinates. These equations are the widely used standard approximation for the flow of water in rivers and shallow lakes, but the main prerequisite for their application – an almost horizontal fluid table – is in general not satisfied for avalanches and debris flows in steep terrain. Therefore, we have developed appropriate correction terms for large topographic gradients. In this study we present the mathematical formulation of these correction terms and their implementation in the open source flow solver GERRIS. This novel approach is evaluated by simulating avalanches on synthetic and finally natural topographies and the widely used Voellmy flow resistance law. The results are tested against analytical solutions and the commercial avalanche model RAMMS. The overall results are in excellent agreement with the reference system RAMMS, and the deviations between the different models are far below the uncertainties in the determination of the relevant fluid parameters and involved avalanche volumes in reality. As this code is freely available and open source, it can be easily extended by additional fluid models or source areas, making this model suitable for simulating several types of rapid mass movements. It therefore provides a valuable tool assisting regional scale natural hazard studies.
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    Magnetotelluric investigation in the High Agri Valley (southern Apennine, Italy) (2014)
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    Publication Date: 2014-11-05
    Description: Magnetotelluric investigation in the High Agri Valley (southern Apennine, Italy) Natural Hazards and Earth System Sciences Discussions, 2, 6747-6773, 2014 Author(s): M. Balasco, A. Giocoli, S. Piscitelli, G. Romano, A. Siniscalchi, T. A. Stabile, and S. Tripladi In this paper we present the result of a Magnetotelluric (MT) investigation carried out across the High Agri Valley (HAV), southern Italy. Several MT soundings were carried out in order to obtain a ~15 km long 2-D resistivity model with an investigation depth of ~10 km. The main aim was to provide valuable data on the geological and structural setting of the HAV. The MT model was compared with pre-existing geological, geophysical and seismic data. The MT model can be schematized as a superposition of three stack lateral varying layers with different thickness and resistivity values: a surficial low-medium resistivity layer, associated to the Quaternary deposits and to the allochthonous units, and a deeper high resistivity layer, related to the Apulia Platform, separated by a thin layer connected to the mélange zone and to the Pliocene terrigenous marine deposits. Sharp lateral resistivity variations are interpreted as faults that, on the basis of accurate focal mechanism computations, display normal-faulting kinematics.
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    Regional parent flood frequency distributions in Europe – Part 2: Climate and scale controls (2014)
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    Publication Date: 2014-11-06
    Description: Regional parent flood frequency distributions in Europe – Part 2: Climate and scale controls Hydrology and Earth System Sciences, 18, 4391-4401, 2014 Author(s): J. L. Salinas, A. Castellarin, S. Kohnová, and T. R. Kjeldsen This study aims to better understand the effect of catchment scale and climate on the statistical properties of regional flood frequency distributions. A database of L-moment ratios of annual maximum series (AMS) of peak discharges from Austria, Italy and Slovakia, involving a total of 813 catchments with more than 25 yr of record length is presented, together with mean annual precipitation (MAP) and basin area as catchment descriptors surrogates of climate and scale controls. A purely data-based investigation performed on the database shows that the generalized extreme value (GEV) distribution provides a better representation of the averaged sample L-moment ratios compared to the other distributions considered, for catchments with medium to higher values of MAP independently of catchment area, while the three-parameter lognormal distribution is probably a more appropriate choice for drier (lower MAP) intermediate-sized catchments, which presented higher skewness values. Sample L-moment ratios do not follow systematically any of the theoretical two-parameter distributions. In particular, the averaged values of L-coefficient of skewness (L-Cs) are always larger than Gumbel 's fixed L-Cs. The results presented in this paper contribute to the progress in defining a set of "process-driven" pan-European flood frequency distributions and to assess possible effects of environmental change on its properties.
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    Wind waves in the Black Sea: results of a hindcast study (2014)
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    Publication Date: 2014-11-06
    Description: Wind waves in the Black Sea: results of a hindcast study Natural Hazards and Earth System Science, 14, 2883-2897, 2014 Author(s): V. S. Arkhipkin, F. N. Gippius, K. P. Koltermann, and G. V. Surkova In this study we describe the wind wave fields in the Black Sea. The general aims of the work were the estimation of statistical wave parameters and the assessment of interannual and seasonal wave parameter variability. The domain of this study was the entire Black Sea. Wave parameters were calculated by means of the SWAN wave model on a 5 × 5 km rectangular grid. Initial conditions (wind speed and direction) for the period between 1949 and 2010 were derived from the NCEP/NCAR reanalysis. According to our calculations the average significant wave height on the Black Sea does not exceed 0.7 m. Areas of most significant heavy sea are the southwestern and the northeastern parts of the sea as expressed in the spatial distribution of significant wave heights, wave lengths and periods. Besides, long-term annual variations of wave parameters were estimated. Thus, linear trends of the annual total duration of storms and of their quantity are nearly stable over the hindcast period. However, an intensification of storm activity is observed in the 1960s–1970s.
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    Estimation of three-dimensional crustal movements in the 2011 Tohoku-oki, Japan earthquake from TerraSAR-X intensity images (2014)
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    Publication Date: 2014-12-12
    Description: Estimation of three-dimensional crustal movements in the 2011 Tohoku-oki, Japan earthquake from TerraSAR-X intensity images Natural Hazards and Earth System Sciences Discussions, 2, 7383-7408, 2014 Author(s): W. Liu, F. Yamazaki, M. Matsuoka, T. Nonaka, and T. Sasagawa The Tohoku-Oki earthquake on 11 March 2011 caused significant widespread crustal movements. In a previous study, we proposed a method for capturing two-dimensional (2-D) surface displacements from a pair of pre- and post-event TerraSAR-X (TSX) intensity images. However, it is difficult to detect three-dimensional (3-D) displacements from one pair of TSX images. In this study, three pairs of pre- and post-event TSX images taken on different paths were used to estimate 3-D crustal movements. The relationship between the actual 3-D displacements and the converted 2-D movements in the SAR images was derived based on the observation model of a SAR sensor. The 3-D movements were then calculated from three sets of detected 2-D movements that occurred within a short time period. Compared with GPS observations, the proposed method was found to be capable of detecting the 3-D crustal movements with sub-pixel accuracy.
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    Quantification of hydrologic impacts of climate change in a Mediterranean basin in Sardinia, Italy, through high-resolution simulations (2014)
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    Publication Date: 2014-12-16
    Description: Quantification of hydrologic impacts of climate change in a Mediterranean basin in Sardinia, Italy, through high-resolution simulations Hydrology and Earth System Sciences, 18, 5201-5217, 2014 Author(s): M. Piras, G. Mascaro, R. Deidda, and E. R. Vivoni Future climate projections robustly indicate that the Mediterranean region will experience a significant decrease of mean annual precipitation and an increase in temperature. These changes are expected to seriously affect the hydrologic regime, with a limitation of water availability and an intensification of hydrologic extremes, and to negatively impact local economies. In this study, we quantify the hydrologic impacts of climate change in the Rio Mannu basin (RMB), an agricultural watershed of 472.5 km 2 in Sardinia, Italy. To simulate the wide range of runoff generation mechanisms typical of Mediterranean basins, we adopted a physically based, distributed hydrologic model. The high-resolution forcings in reference and future conditions (30-year records for each period) were provided by four combinations of global and regional climate models, bias-corrected and downscaled in space and time (from ~25 km, 24 h to 5 km, 1 h) through statistical tools. The analysis of the hydrologic model outputs indicates that the RMB is expected to be severely impacted by future climate change. The range of simulations consistently predict (i) a significant diminution of mean annual runoff at the basin outlet, mainly due to a decreasing contribution of the runoff generation mechanisms depending on water available in the soil; (ii) modest variations in mean annual runoff and intensification of mean annual discharge maxima in flatter sub-basins with clay and loamy soils, likely due to a higher occurrence of infiltration excess runoff; (iii) reduction of soil water content and actual evapotranspiration in most areas of the basin; and (iv) a drop in the groundwater table. Results of this study are useful to support the adoption of adaptive strategies for management and planning of agricultural activities and water resources in the region.
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    Complex networks, streamflow, and hydrometric monitoring system design (2014)
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    Publication Date: 2014-12-16
    Description: Complex networks, streamflow, and hydrometric monitoring system design Hydrology and Earth System Sciences Discussions, 11, 13663-13710, 2014 Author(s): M. Halverson and S. Fleming Network theory is applied to an array of streamflow gauges located in the Coast Mountains of British Columbia and Yukon, Canada. The goal of the analysis is to assess whether insights from this branch of mathematical graph theory can be meaningfully applied to hydrometric data, and more specifically, whether it may help guide decisions concerning stream gauge placement so that the full complexity of the regional hydrology is efficiently captured. The streamflow data, when represented as a complex network, has a global clustering coefficient and average shortest path length consistent with small-world networks, which are a class of stable and efficient networks common in nature, but the results did not clearly suggest a scale-free network. Stability helps ensure that the network is robust to the loss of nodes; in the context of a streamflow network, stability is interpreted as insensitivity to station removal at random. Community structure is also evident in the streamflow network. A community detection algorithm identified 10 separate communities, each of which appears to be defined by the combination of its median seasonal flow regime (pluvial, nival, hybrid, or glacial, which in this region in turn mainly reflects basin elevation) and geographic proximity to other communities (reflecting shared or different daily meteorological forcing). Betweenness analyses additionally suggest a handful of key stations which serve as bridges between communities and might therefore be highly valued. We propose that an idealized sampling network should sample high-betweenness stations, as well as small-membership communities which are by definition rare or undersampled relative to other communities, while retaining some degree of redundancy to maintain network robustness.
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    Assessing winter cover crop nutrient uptake efficiency using a water quality simulation model (2014)
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    Publication Date: 2014-12-17
    Description: Assessing winter cover crop nutrient uptake efficiency using a water quality simulation model Hydrology and Earth System Sciences, 18, 5239-5253, 2014 Author(s): I.-Y. Yeo, S. Lee, A. M. Sadeghi, P. C. Beeson, W. D. Hively, G. W. McCarty, and M. W. Lang Winter cover crops are an effective conservation management practice with potential to improve water quality. Throughout the Chesapeake Bay watershed (CBW), which is located in the mid-Atlantic US, winter cover crop use has been emphasized, and federal and state cost-share programs are available to farmers to subsidize the cost of cover crop establishment. The objective of this study was to assess the long-term effect of planting winter cover crops to improve water quality at the watershed scale (~ 50 km 2 ) and to identify critical source areas of high nitrate export. A physically based watershed simulation model, Soil and Water Assessment Tool (SWAT), was calibrated and validated using water quality monitoring data to simulate hydrological processes and agricultural nutrient cycling over the period of 1990–2000. To accurately simulate winter cover crop biomass in relation to growing conditions, a new approach was developed to further calibrate plant growth parameters that control the leaf area development curve using multitemporal satellite-based measurements of species-specific winter cover crop performance. Multiple SWAT scenarios were developed to obtain baseline information on nitrate loading without winter cover crops and to investigate how nitrate loading could change under different winter cover crop planting scenarios, including different species, planting dates, and implementation areas. The simulation results indicate that winter cover crops have a negligible impact on the water budget but significantly reduce nitrate leaching to groundwater and delivery to the waterways. Without winter cover crops, annual nitrate loading from agricultural lands was approximately 14 kg ha −1 , but decreased to 4.6–10.1 kg ha −1 with cover crops resulting in a reduction rate of 27–67% at the watershed scale. Rye was the most effective species, with a potential to reduce nitrate leaching by up to 93% with early planting at the field scale. Early planting of cover crops (~ 30 days of additional growing days) was crucial, as it lowered nitrate export by an additional ~ 2 kg ha −1 when compared to late planting scenarios. The effectiveness of cover cropping increased with increasing extent of cover crop implementation. Agricultural fields with well-drained soils and those that were more frequently used to grow corn had a higher potential for nitrate leaching and export to the waterways. This study supports the effective implementation of cover crop programs, in part by helping to target critical pollution source areas for cover crop implementation.
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    Amalgamation in landslide maps: effects and automatic detection (2014)
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    Publication Date: 2014-12-17
    Description: Amalgamation in landslide maps: effects and automatic detection Natural Hazards and Earth System Sciences Discussions, 2, 7651-7678, 2014 Author(s): O. Marc and N. Hovius Inventories of individually delineated landslides are a key to understanding landslide physics and mitigating their impact. They permit assessment of area-frequency distributions and landslide volumes, and testing of statistical correlations between landslides and physical parameters such as topographic gradient or seismic strong motion. Amalgamation, i.e. the mapping of several adjacent landslides as a single polygon, can lead to potentially severe distortion of the statistics of these inventories. This problem can be especially severe in datasets produced by automated mapping. We present 5 inventories of earthquake-induced landslides mapped with different materials and techniques and affected by varying degrees of amalgamation. Errors on the total landslide volume and power-law exponent of the area-frequency distribution, resulting from amalgamation, may be up to 200 and 50%, respectively. We present an algorithm based on image and DEM analysis, for automatic identification of amalgamated polygons. On a set of about 2000 polygons larger than 1000 m 2 , tracing landslides triggered by the 1994 Northridge earthquake, the algorithm performs well, with only 2.7–3.6% wrongly amalgamated landslides missed and 3.9–4.8% correct polygons wrongly identified as amalgams. This algorithm can be used broadly to check landslide inventories and allow faster correction by automating the identification of amalgamation.
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    Factors affecting flood insurance purchase in residential properties in Johor, Malaysia (2014)
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    Publication Date: 2014-12-18
    Description: Factors affecting flood insurance purchase in residential properties in Johor, Malaysia Natural Hazards and Earth System Science, 14, 3297-3310, 2014 Author(s): U. G. Aliagha, T. E. Jin, W. W. Choong, M. Nadzri Jaafar, and H. M. Ali High-impact floods have become a virtually annual experience in Malaysia, yet flood insurance has remained a grossly neglected part of comprehensive integrated flood risk management. Using discriminant analysis, this study seeks to identify the demand-side variables that best predict flood insurance purchase and risk aversion between two groups of residential homeowners in three districts of Johor State, Malaysia: those who purchased flood insurance and those who did not. Our results revealed an overall 34% purchase rate, with Kota Tinggi district having the highest (44%) and thus the highest degree of flood risk aversion. The Wilks' lambda F test for equality of group means, standardised discriminant function coefficients, structure correlation, and canonical correlation has clearly shown that there are strong significant attribute differences between the two groups of homeowners, based on the measures of objective flood risk exposure, subjective risk perception, and socio-economic cum demographic variables. However, the measures of subjective risk perception were found to be more predictive of flood insurance purchase and flood risk aversion.
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    Derivation and evaluation of landslide-triggering thresholds by a Monte Carlo approach (2014)
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    Publication Date: 2014-12-09
    Description: Derivation and evaluation of landslide-triggering thresholds by a Monte Carlo approach Hydrology and Earth System Sciences, 18, 4913-4931, 2014 Author(s): D. J. Peres and A. Cancelliere Assessment of landslide-triggering rainfall thresholds is useful for early warning in prone areas. In this paper, it is shown how stochastic rainfall models and hydrological and slope stability physically based models can be advantageously combined in a Monte Carlo simulation framework to generate virtually unlimited-length synthetic rainfall and related slope stability factor of safety data, exploiting the information contained in observed rainfall records and field-measurements of soil hydraulic and geotechnical parameters. The synthetic data set, dichotomized in triggering and non-triggering rainfall events, is analyzed by receiver operating characteristics (ROC) analysis to derive stochastic-input physically based thresholds that optimize the trade-off between correct and wrong predictions. Moreover, the specific modeling framework implemented in this work, based on hourly analysis, enables one to analyze the uncertainty related to variability of rainfall intensity within events and to past rainfall (antecedent rainfall). A specific focus is dedicated to the widely used power-law rainfall intensity–duration ( I – D ) thresholds. Results indicate that variability of intensity during rainfall events influences significantly rainfall intensity and duration associated with landslide triggering. Remarkably, when a time-variable rainfall-rate event is considered, the simulated triggering points may be separated with a very good approximation from the non-triggering ones by a I – D power-law equation, while a representation of rainfall as constant–intensity hyetographs globally leads to non-conservative results. This indicates that the I – D power-law equation is adequate to represent the triggering part due to transient infiltration produced by rainfall events of variable intensity and thus gives a physically based justification for this widely used threshold form, which provides results that are valid when landslide occurrence is mostly due to that part. These conditions are more likely to occur in hillslopes of low specific upslope contributing area, relatively high hydraulic conductivity and high critical wetness ratio. Otherwise, rainfall time history occurring before single rainfall events influences landslide triggering, determining whether a threshold based only on rainfall intensity and duration may be sufficient or it needs to be improved by the introduction of antecedent rainfall variables. Further analyses show that predictability of landslides decreases with soil depth, critical wetness ratio and the increase of vertical basal drainage (leakage) that occurs in the presence of a fractured bedrock.
    Print ISSN: 1027-5606
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    Climate change and stream temperature projections in the Columbia River basin: habitat implications of spatial variation in hydrologic drivers (2014)
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    Publication Date: 2014-12-09
    Description: Climate change and stream temperature projections in the Columbia River basin: habitat implications of spatial variation in hydrologic drivers Hydrology and Earth System Sciences, 18, 4897-4912, 2014 Author(s): D. L. Ficklin, B. L. Barnhart, J. H. Knouft, I. T. Stewart, E. P. Maurer, S. L. Letsinger, and G. W. Whittaker Water temperature is a primary physical factor regulating the persistence and distribution of aquatic taxa. Considering projected increases in air temperature and changes in precipitation in the coming century, accurate assessment of suitable thermal habitats in freshwater systems is critical for predicting aquatic species' responses to changes in climate and for guiding adaptation strategies. We use a hydrologic model coupled with a stream temperature model and downscaled general circulation model outputs to explore the spatially and temporally varying changes in stream temperature for the late 21st century at the subbasin and ecological province scale for the Columbia River basin (CRB). On average, stream temperatures are projected to increase 3.5 °C for the spring, 5.2 °C for the summer, 2.7 °C for the fall, and 1.6 °C for the winter. While results indicate changes in stream temperature are correlated with changes in air temperature, our results also capture the important, and often ignored, influence of hydrological processes on changes in stream temperature. Decreases in future snowcover will result in increased thermal sensitivity within regions that were previously buffered by the cooling effect of flow originating as snowmelt. Other hydrological components, such as precipitation, surface runoff, lateral soil water flow, and groundwater inflow, are negatively correlated to increases in stream temperature depending on the ecological province and season. At the ecological province scale, the largest increase in annual stream temperature was within the Mountain Snake ecological province, which is characterized by migratory coldwater fish species. Stream temperature changes varied seasonally with the largest projected stream temperature increases occurring during the spring and summer for all ecological provinces. Our results indicate that stream temperatures are driven by local processes and ultimately require a physically explicit modeling approach to accurately characterize the habitat regulating the distribution and diversity of aquatic taxa.
    Print ISSN: 1027-5606
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    Monitoring and modelling of soil–plant interactions: the joint use of ERT, sap flow and Eddy Covariance data to characterize the volume of an orange tree root zone (2014)
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    Publication Date: 2014-12-09
    Description: Monitoring and modelling of soil–plant interactions: the joint use of ERT, sap flow and Eddy Covariance data to characterize the volume of an orange tree root zone Hydrology and Earth System Sciences Discussions, 11, 13353-13384, 2014 Author(s): G. Cassiani, J. Boaga, D. Vanella, M. T. Perri, and S. Consoli Mass and energy exchanges between soil, plants and atmosphere control a number of key environmental processes involving hydrology, biota and climate. The understanding of these exchanges also play a critical role for practical purposes e.g. in precision agriculture. In this paper we present a methodology based on coupling innovative data collection and models in order to obtain quantitative estimates of the key parameters of such complex flow system. In particular we propose the use of hydro-geophysical monitoring via 4-D Electrical Resistivity Tomography (ERT) in conjunction with measurements of plant transpiration via sap flow and evapotranspiration from Eddy Covariance (EC). This abundance of data is fed to a spatially distributed soil model in order to characterize the distribution of active roots. We conducted experiments in an orange orchard in Eastern Sicily (Italy), characterized by the typical Mediterranean semi-arid climate. The subsoil dynamics, particularly influenced by irrigation and root uptake, were characterized mainly by the ERT setup, consisting of 48 buried electrodes on 4 instrumented micro boreholes (about 1.2 m deep) placed at the corners of a square (about 1.3 m in side) surrounding the orange tree, plus 24 mini-electrodes on the surface spaced 0.1 m on a square grid. During the monitoring, we collected repeated ERT and TDR soil moisture measurements, soil water samples, sap flow measurements from the orange tree and EC data. We conducted a laboratory calibration of the soil electrical properties as a function of moisture content and pore water electrical conductivity. Irrigation, precipitation, sap flow and ET data are available allowing knowledge of the system's long term forcing conditions on the system. This information was used to calibrate a 1-D Richards' equation model representing the dynamics of the volume monitored via 3-D ERT. Information on the soil hydraulic properties was collected from laboratory and field experiments. The successful results of the calibrated modeling exercise allow the quantification of the soil volume interested by root water uptake. This volume is much smaller (with a surface area less than 2 m 2 , and about 40 cm thickness) than expected and assumed in the design of classical drip irrigation schemes that prove to be losing at least half of the irrigated water that is not uptaken by the plants.
    Print ISSN: 1812-2108
    Electronic ISSN: 1812-2116
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    Moraine-dammed lake failures in Patagonia and assessment of outburst susceptibility in the Baker Basin (2014)
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    Publication Date: 2014-12-06
    Description: Moraine-dammed lake failures in Patagonia and assessment of outburst susceptibility in the Baker Basin Natural Hazards and Earth System Science, 14, 3243-3259, 2014 Author(s): P. Iribarren Anacona, K.P. Norton, and A. Mackintosh Glacier retreat since the Little Ice Age has resulted in the development or expansion of hundreds of glacial lakes in Patagonia. Some of these lakes have produced large (≥ 10 6 m 3 ) Glacial Lake Outburst Floods (GLOFs) damaging inhabited areas. GLOF hazard studies in Patagonia have been mainly based on the analysis of short-term series (≤ 50 years) of flood data and until now no attempt has been made to identify the relative susceptibility of lakes to failure. Power schemes and associated infrastructure are planned for Patagonian basins that have historically been affected by GLOFs, and we now require a thorough understanding of the characteristics of dangerous lakes in order to assist with hazard assessment and planning. In this paper, the conditioning factors of 16 outbursts from moraine-dammed lakes in Patagonia were analysed. These data were used to develop a classification scheme designed to assess outburst susceptibility, based on image classification techniques, flow routine algorithms and the Analytical Hierarchy Process. This scheme was applied to the Baker Basin, Chile, where at least seven moraine-dammed lakes have failed in historic time. We identified 386 moraine-dammed lakes in the Baker Basin of which 28 were classified with high or very high outburst susceptibility. Commonly, lakes with high outburst susceptibility are in contact with glaciers and have moderate (〉 8°) to steep (〉 15°) dam outlet slopes, akin to failed lakes in Patagonia. The proposed classification scheme is suitable for first-order GLOF hazard assessments in this region. However, rapidly changing glaciers in Patagonia make detailed analysis and monitoring of hazardous lakes and glaciated areas upstream from inhabited areas or critical infrastructure necessary, in order to better prepare for hazards emerging from an evolving cryosphere.
    Print ISSN: 1561-8633
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    Seismology of the Oso-Steelhead landslide (2014)
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    Publication Date: 2014-12-06
    Description: Seismology of the Oso-Steelhead landslide Natural Hazards and Earth System Sciences Discussions, 2, 7309-7327, 2014 Author(s): C. Hibert, C. P. Stark, and G. Ekström We carry out a combined analysis of the short- and long-period seismic signals generated by the devastating Oso-Steelhead landslide that occurred on 22 March 2014. The seismic records show that the Oso-Steelhead landslide was not a single slope failure, but a succession of multiple failures distinguished by two major collapses that occurred approximately three minutes apart. The first generated long-period surface waves that were recorded at several proximal stations. We invert these long-period signals for the forces acting at the source, and obtain estimates of the first failure runout and kinematics, as well as its mass after calibration against the mass-center displacement estimated from remote-sensing imagery. Short-period analysis of both events suggests that the source dynamics of the second are more complex than the first. No distinct long-period surface waves were recorded for the second failure, which prevents inversion for its source parameters. However, by comparing the seismic energy of the short-period waves generated by both events we are able to estimate the volume of the second. Our analysis suggests that the volume of the second failure is about 15–30% of the total landslide volume, which is in agreement with ground observations.
    Electronic ISSN: 2195-9269
    Topics: Geography , Geosciences
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    Comparison of aeolian snow transport events and snow mass fluxes between observations and simulations made by the regional climate model MAR in Adélie Land, East Antarctica (2014)
    Copernicus
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    Publication Date: 2014-12-06
    Description: Comparison of aeolian snow transport events and snow mass fluxes between observations and simulations made by the regional climate model MAR in Adélie Land, East Antarctica The Cryosphere Discussions, 8, 6007-6032, 2014 Author(s): A. Trouvilliez, H. Gallée, F. Naaim-Bouvet, C. Genthon, C. Amory, V. Favier, C. Agosta, L. Piard, and H. Bellot The regional climate model MAR including a coupled snow pack/aeolian snow transport parameterisation is compared with aeolian snow mass fluxes at a fine spatial resolution (5 km horizontally and 2 m vertically) and at a fine temporal resolution (30 min) over 1 month in Antarctica. Numerous feedbacks are taken into account in the MAR including the drag partitioning caused by the roughness elements. Wind speed is correctly simulated with a positive value of the Nash test (0.60 and 0.37) but the wind speeds above 10 m s −1 are underestimated. The aeolian snow transport events are correctly reproduced with a good temporal resolution except for the aeolian snow transport events with a particles' maximum height below 1 m. The simulated threshold friction velocity, calculated without snowfall, is overestimated. The simulated aeolian snow mass fluxes between 0 to 2 m have the same variations but are underestimated compared to the second-generation FlowCapt values and so is the simulated relative humidity at 2 m. This underestimation is not entirely due to the underestimation of the simulated wind speed. The MAR underestimates the aeolian snow quantity that pass through the first two meters by a factor ten compared to the second-generation FlowCapt value (13 990 kg m −1 and 151 509 kg m −1 respectively). It will conduct the MAR, with this parametrisation, to underestimate the effect of the aeolian snow transport on the Antarctic surface mass balance.
    Print ISSN: 1994-0432
    Electronic ISSN: 1994-0440
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    Influence of weak layer heterogeneity and slab properties on slab tensile failure propensity and avalanche release area (2014)
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    Publication Date: 2014-12-06
    Description: Influence of weak layer heterogeneity and slab properties on slab tensile failure propensity and avalanche release area The Cryosphere Discussions, 8, 6033-6057, 2014 Author(s): J. Gaume, G. Chambon, N. Eckert, M. Naaim, and J. Schweizer Dry-snow slab avalanches are generally caused by a sequence of fracture processes including failure initiation in a weak snow layer underlying a cohesive slab followed by crack propagation within the weak layer (WL) and tensile fracture through the slab. During past decades, theoretical and experimental work has gradually improved our knowledge of the fracture process in snow. However, our limited understanding of crack propagation and fracture arrest propensity prevents the evaluation of avalanche release sizes and thus impedes hazard assessment. To address this issue, slab tensile failure propensity is examined using a mechanically-based statistical model of the slab–WL system based on the finite element method. This model accounts for WL heterogeneity, stress redistribution by elasticity of the slab and the slab possible tensile failure. Two types of avalanche release are distinguished in the simulations: (1) full-slope release if the heterogeneity is not sufficient to stop crack propagation and to trigger a tensile failure within the slab, (2) partial-slope release if fracture arrest and slab tensile failure occurs due to the WL heterogeneity. The probability of these two release types is presented as a function of the characteristics of WL heterogeneity and of the slab. One of the main outcomes is that, for realistic values of the parameters, the tensile failure propensity is mainly influenced by slab properties. Hard and thick snow slabs are more prone to wide-scale crack propagation and thus lead to larger avalanches (full-slope release). In this case, the avalanche size is mainly influenced by topographical and morphological features such as rocks, trees, slope curvature and the spatial variability of the snow depth as it is often claimed in the literature.
    Print ISSN: 1994-0432
    Electronic ISSN: 1994-0440
    Topics: Geography , Geosciences
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    Epic landslide erosion from mountain roads in Yunnan, China – challenges for sustainable development (2014)
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    Publication Date: 2014-11-28
    Description: Epic landslide erosion from mountain roads in Yunnan, China – challenges for sustainable development Natural Hazards and Earth System Science, 14, 3093-3104, 2014 Author(s): R. C. Sidle, M. Ghestem, and A. Stokes Expanding systems of mountain roads in developing countries have significantly increased the risk of landslides and sedimentation, and have created vulnerabilities for residents and aquatic resources. We measured landslide erosion along seven road segments in steep terrain in the upper Salween River basin, Yunnan, China and estimated sediment delivery to channels. Landslide erosion rates along the roads ranged from 2780 to 48 235 Mg ha −1 yr −1 , the upper end of this range being the highest rate ever reported along mountain roads. The two roads with the highest landslide erosion (FG1 = 12 966 Mg ha −1 yr −1 ; DXD = 48 235 Mg ha −1 yr −1 ) had some of the highest sediment delivery rates to channels (about 80 and 86%, respectively). Overall, 3 times more landslides occurred along cut slopes compared to fill slopes, but fill slope failures had a combined mass 〉 1.3 times that of cut slope failures. Many small landslides occurred along road cuts, but these were often trapped on the road surface. Given the magnitude of the landslide problem and the lack of attention to this issue, a more sustainable approach for mountain road development is outlined based on an analysis of landslide susceptibility and how thresholds for landslide trigger mechanisms would be modified by road location and different construction techniques.
    Print ISSN: 1561-8633
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    Evaluation of forest fire models on a large observation database (2014)
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    Publication Date: 2014-11-28
    Description: Evaluation of forest fire models on a large observation database Natural Hazards and Earth System Science, 14, 3077-3091, 2014 Author(s): J. B. Filippi, V. Mallet, and B. Nader This paper presents the evaluation of several fire propagation models using a large set of observed fires. The observation base is composed of 80 Mediterranean fire cases of different sizes, which come with the limited information available in an operational context (burned surface and approximative ignition point). Simulations for all cases are carried out with four different front velocity models. The results are compared with several error scoring methods applied to each of the 320 simulations. All tasks are performed in a fully automated manner, with simulations run as first guesses with no tuning for any of the models or cases. This approach leads to a wide range of simulation performance, including some of the bad simulation results to be expected in an operational context. Disregarding the quality of the input data, it is found that the models can be ranked based on their performance and that the most complex models outperform the more empirical ones. Data and source codes used for this paper are freely available to the community.
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    Monitoring and prediction in Early Warning Systems (EWS) for rapid mass movements (2014)
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    Publication Date: 2014-11-28
    Description: Monitoring and prediction in Early Warning Systems (EWS) for rapid mass movements Natural Hazards and Earth System Sciences Discussions, 2, 7149-7179, 2014 Author(s): M. Stähli, M. Sättele, C. Huggel, B. W. McArdell, P. Lehmann, A. Van Herwijnen, A. Berne, M. Schleiss, A. Ferrari, A. Kos, D. Or, and S. M. Springman Rapid mass movements (RMM) pose a substantial risk to people and infrastructure. Reliable and cost-efficient measures have to be taken to reduce this risk. One of these measures includes establishing and advancing the State of Practice in the application of Early Warning Systems (EWS). EWS have been developed during the past decades and are rapidly increasing. In this document, we focus on the technical part of EWS, i.e. the prediction and timely recognition of imminent hazards, as well as on monitoring slopes at risk and released mass movements. Recent innovations in assessing spatial precipitation, as well as monitoring and modelling precursors, the triggering and deformation of RMM offer new opportunities for next-generation EWS. However, technical advancement can only be transferred into more reliable, operational EWS with an intense dialog between scientists, engineers and those in charge of warning. To this end, further experience with new comprehensive prototype systems jointly operated by scientists and practitioners will be essential.
    Electronic ISSN: 2195-9269
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    A new approach to mapping permafrost and change incorporating uncertainties in ground conditions and climate projections (2014)
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    Publication Date: 2014-11-28
    Description: A new approach to mapping permafrost and change incorporating uncertainties in ground conditions and climate projections The Cryosphere, 8, 2177-2194, 2014 Author(s): Y. Zhang, I. Olthof, R. Fraser, and S. A. Wolfe Spatially detailed information on permafrost distribution and change with climate is important for land use planning, infrastructure development, and environmental assessments. However, the required soil and surficial geology maps in the North are coarse, and projected climate scenarios vary widely. Considering these uncertainties, we propose a new approach to mapping permafrost distribution and change by integrating remote sensing data, field measurements, and a process-based model. Land cover types from satellite imagery are used to capture the general land conditions and to improve the resolution of existing permafrost maps. For each land cover type, field observations are used to estimate the probabilities of different ground conditions. A process-based model is used to quantify the evolution of permafrost for each ground condition under three representative climate scenarios (low, medium, and high warming). From the model results, the probability of permafrost occurrence and the most likely permafrost conditions are determined. We apply this approach at 20 m resolution to a large area in Northwest Territories, Canada. Mapped permafrost conditions are in agreement with field observations and other studies. The data requirements, model robustness, and computation time are reasonable, and this approach may serve as a practical means to mapping permafrost and changes at high resolution in other regions.
    Print ISSN: 1994-0416
    Electronic ISSN: 1994-0424
    Topics: Geography , Geosciences
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    Results from a full coupling of the HIRHAM regional climate model and the MIKE SHE hydrological model for a Danish catchment (2014)
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    Publication Date: 2014-11-29
    Description: Results from a full coupling of the HIRHAM regional climate model and the MIKE SHE hydrological model for a Danish catchment Hydrology and Earth System Sciences, 18, 4733-4749, 2014 Author(s): M. A. D. Larsen, J. C. Refsgaard, M. Drews, M. B. Butts, K. H. Jensen, J. H. Christensen, and O. B. Christensen A major challenge in the emerging research field of coupling of existing regional climate models (RCMs) and hydrology/land-surface models is the computational interaction between the models. Here we present results from a full two-way coupling of the HIRHAM RCM over a 4000 km × 2800 km domain at 11 km resolution and the combined MIKE SHE-SWET hydrology and land-surface models over the 2500 km 2 Skjern River catchment. A total of 26 one-year runs were performed to assess the influence of the data transfer interval (DTI) between the two models and the internal HIRHAM model variability of 10 variables. DTI frequencies between 12 and 120 min were assessed, where the computational overhead was found to increase substantially with increasing exchange frequency. In terms of hourly and daily performance statistics the coupled model simulations performed less accurately than the uncoupled simulations, whereas for longer-term cumulative precipitation the opposite was found, especially for more frequent DTI rates. Four of six output variables from HIRHAM, precipitation, relative humidity, wind speed and air temperature, showed statistically significant improvements in root-mean-square error (RMSE) by reducing the DTI. For these four variables, the HIRHAM RMSE variability corresponded to approximately half of the influence from the DTI frequency and the variability resulted in a large spread in simulated precipitation. Conversely, DTI was found to have only a limited impact on the energy fluxes and discharge simulated by MIKE SHE.
    Print ISSN: 1027-5606
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    Seasonal cycle and long-term trend of solar energy fluxes through Arctic sea ice (2014)
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    Publication Date: 2014-11-29
    Description: Seasonal cycle and long-term trend of solar energy fluxes through Arctic sea ice The Cryosphere, 8, 2219-2233, 2014 Author(s): S. Arndt and M. Nicolaus Arctic sea ice has not only decreased in volume during the last decades, but has also changed in its physical properties towards a thinner and more seasonal ice cover. These changes strongly impact the energy budget, and might affect the ice-associated ecosystems. In this study, we quantify solar shortwave fluxes through sea ice for the entire Arctic during all seasons. To focus on sea-ice-related processes, we exclude fluxes through open water, scaling linearly with sea ice concentration. We present a new parameterization of light transmittance through sea ice for all seasons as a function of variable sea ice properties. The maximum monthly mean solar heat flux under the ice of 30 × 10 5 Jm −2 occurs in June, enough heat to melt 0.3 m of sea ice. Furthermore, our results suggest that 96% of the annual solar heat input through sea ice occurs during only a 4-month period from May to August. Applying the new parameterization to remote sensing and reanalysis data from 1979 to 2011, we find an increase in transmitted light of 1.5% yr −1 for all regions. This corresponds to an increase in potential sea ice bottom melt of 63% over the 33-year study period. Sensitivity studies reveal that the results depend strongly on the timing of melt onset and the correct classification of ice types. Assuming 2 weeks earlier melt onset, the annual transmitted solar radiation to the upper ocean increases by 20%. Continuing the observed transition from a mixed multi-year/first-year sea ice cover to a seasonal ice cover results in an increase in light transmittance by an additional 18%.
    Print ISSN: 1994-0416
    Electronic ISSN: 1994-0424
    Topics: Geography , Geosciences
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    Farmland Prices: Is This Time Different? (2014)
    Oxford University Press
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    Publication Date: 2014-12-03
    Description: The historical behavior of farmland prices, rental rates, and rates of return are examined by treating farmland as an asset with an infinitely long life. It is found that high (low) farmland prices relative to rents have historically preceded extended periods of low (high) net rates of return, rather than greater (smaller) growth in rents. Our analysis shows that this attribute is shared with stocks and housing, and the financial literature provides ample evidence that other assets feature it as well. The long-run relationship linking farmland prices, rents, and rates of return is analyzed. Based on this relationship, we conclude that recent trends are unlikely to be sustainable. The study explores the expected paths that farmland prices and rates of return might follow if they were to eventually conform to the average values observed in the historical sample, and concludes with a discussion of the policy implications. Recommendations for policy makers include close monitoring of farmland lending practices and institutions to allow early identification of potential problems, and identifying in advance appropriate interventions in case recent farmland market trends were to suddenly change.
    Keywords: Q14 - Agricultural Finance
    Print ISSN: 2040-5790
    Electronic ISSN: 2040-5804
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition , Economics
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    Subscription Page (2014)
    Oxford University Press
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    Publication Date: 2014-12-03
    Print ISSN: 2040-5790
    Electronic ISSN: 2040-5804
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition , Economics
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    Some Comments on "Taxes, Subsidies, and Advertising Efficacy in Changing Eating Behavior: An Experimental Study" (2014)
    Oxford University Press
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    Publication Date: 2014-12-03
    Print ISSN: 2040-5790
    Electronic ISSN: 2040-5804
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition , Economics
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    Hispanic American Opinions toward Immigration and Immigration Policy Reform Proposals (2014)
    Oxford University Press
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    Publication Date: 2014-12-03
    Description: This study presents evidence from a survey and choice experiment on the preferences of Hispanic immigrants who entered the United States illegally for different immigration reform proposal attributes. Key components of the current competing US Senate and House immigration reform bills are considered including pathways to legal permanent residence, temporary work visas, family visitation rights, and access to medical care. The results quantify the value Hispanic immigrants place on different policy attributes and suggest that longer-term work visas are highly valued. Ability to legally work in the United States and a pathway to citizenship are substantially more valued than social services such as medical care and social security benefits.
    Keywords: J15 - Economics of Minorities and Races ; Non-labor Discrimination, K37 - Immigration Law, Q18 - Agricultural Policy ; Food Policy
    Print ISSN: 2040-5790
    Electronic ISSN: 2040-5804
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition , Economics
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    What to Do about the "Cult of Statistical Significance"? A Renewable Fuel Application using the Neyman-Pearson Protocol (2014)
    Oxford University Press
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    Publication Date: 2014-12-03
    Description: This research adapts the Neyman-Pearson testing protocol commonly used in biomedical research for ex post evaluation of the employment impacts of new ethanol bio-refineries in the U.S. Great Plains and the Midwest. By calculating the power of the test, the suggested protocol may provide policy-relevant information, even in the event of nonsignificant findings. The main obstacle to applying this protocol has been the need to posit an explicit alternative distribution, which runs counter to the empiricist tradition of mainstream econometrics. We resolve this problem by applying a data generating process with known parameters anchored to sample data to compute power.
    Keywords: C12 - Hypothesis Testing, Q42 - Alternative Energy Sources, R11 - Regional Economic Activity: Growth, Development, and Changes
    Print ISSN: 2040-5790
    Electronic ISSN: 2040-5804
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition , Economics
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    Reply to Comment on Taxes, Subsidies, and Advertising Efficacy in Changing Eating Behavior: An Experimental Study (2014)
    Oxford University Press
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    Publication Date: 2014-12-03
    Keywords: C91 - Laboratory, Individual Behavior, I18 - Government Policy ; Regulation ; Public Health
    Print ISSN: 2040-5790
    Electronic ISSN: 2040-5804
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition , Economics
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    Testing gridded land precipitation data and precipitation and runoff reanalyses (1982–2010) between 45° S and 45° N with Normalized Difference Vegetation Index data (2014)
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    Publication Date: 2014-12-03
    Description: Testing gridded land precipitation data and precipitation and runoff reanalyses (1982–2010) between 45° S and 45° N with Normalized Difference Vegetation Index data Hydrology and Earth System Sciences Discussions, 11, 13175-13205, 2014 Author(s): S. O. Los The realistic simulation of key components of the land-surface hydrological cycle – precipitation, runoff, evaporation and transpiration – in general circulation models of the atmosphere is crucial to assess adverse weather impacts on environment and society. Here, gridded precipitation data from observations and precipitation and runoff fields from reanalyses were tested with satellite-derived global vegetation index data for 1982–2010 and latitudes between 45° S and 45° N. Data were obtained from the Climate Research Unit (CRU), the Global Precipitation Climatology Project (GPCP) and Tropical Rainfall Monitoring Mission (TRMM; analysed for 1998–2010 only) and (precipitation and runoff) reanalyses were obtained from the National Centers for Environmental Prediction/National Center for Atmospheric Research (NCEP/NCAR), the European Centre for Medium-Range Weather Forecasts (ECMWF) and the NASA Global Modelling and Assimilation Office (GMAO). Annual land-surface precipitation was converted to annual potential vegetation net primary productivity (NPP) and was compared to mean annual Normalized Difference Vegetation Index data measured by the Advanced Very High Resolution Radiometer (1982–1999) and MODIS (2001–2010). The effect of spatial resolution on the agreement between NPP and NDVI was investigated as well. The CRU and TRMM derived NPP agreed most closely with the NDVI data. The GPCP data showed weaker spatial agreement, largely because of their lower spatial resolution, but similar temporal agreement. MERRA Land and ERA Interim precipitation reanalyses showed similar spatial agreement as the GPCP data and good temporal agreement in semi-arid regions of the Americas, Asia, Australia and southern Africa. The NCEP/NCAR reanalysis showed the lowest spatial agreement which could only in part be explained by its lower spatial resolution. No reanalysis showed realistic interannual precipitation variations for northern tropical Africa. Inclusion of runoff in the NPP prediction resulted only in (marginally) better agreement for the MERRA Land reanalysis and worse agreement for the NCEP/NCAR and ERA Interim reanalyses.
    Print ISSN: 1812-2108
    Electronic ISSN: 1812-2116
    Topics: Geography , Geosciences
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    A global dataset of the extent of irrigated land from 1900 to 2005 (2014)
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    Publication Date: 2014-12-03
    Description: A global dataset of the extent of irrigated land from 1900 to 2005 Hydrology and Earth System Sciences Discussions, 11, 13207-13258, 2014 Author(s): S. Siebert, M. Kummu, M. Porkka, P. Döll, N. Ramankutty, and B. R. Scanlon Irrigation intensifies land use by increasing crop yield but also impacts water resources. It affects water and energy balances and consequently the microclimate in irrigated regions. Therefore, knowledge of the extent of irrigated land is important for hydrological and crop modelling, global change research, and assessments of resource use and management. Information on the historical evolution of irrigated lands is limited. The new global Historical Irrigation Dataset (HID) provides estimates of the temporal development of the area equipped for irrigation (AEI) between 1900 and 2005 at 5 arc-minute resolution. We collected subnational irrigation statistics from various sources and found that the global extent of AEI increased from 63 million ha (Mha) in 1900 to 112 Mha in 1950 and 306 Mha in 2005. We developed eight gridded versions of time series of AEI by combining subnational irrigation statistics with different data sets on the historical extent of cropland and pasture. Different rules were applied to maximize consistency of the gridded products to subnational irrigation statistics or to historical cropland and pasture data sets. The HID reflects very well the spatial patterns of irrigated land in the western United States as shown on historical maps. Mean aridity on irrigated land increased and river discharge decreased from 1900–1950 whereas aridity decreased from 1950–2005. The dataset and its documentation are made available in an open data repository at https://mygeohub.org/publications/8 (doi: 10.13019/M2MW2G ).
    Print ISSN: 1812-2108
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    Debris flows in the Eastern Italian Alps: seasonality and atmospheric circulation patterns (2014)
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    Publication Date: 2014-12-02
    Description: Debris flows in the Eastern Italian Alps: seasonality and atmospheric circulation patterns Natural Hazards and Earth System Sciences Discussions, 2, 7197-7224, 2014 Author(s): E. I. Nikolopoulos, M. Borga, F. Marra, S. Crema, and L. Marchi The work examines the seasonality and large-scale atmospheric circulation patterns of debris flows in the Trentino-Alto Adige region (Eastern Italian Alps). Analysis is based on classification algorithms applied on a uniquely dense archive of debris flows and hourly rain gauge precipitation series covering the period 2000–2009. Results highlight the seasonal and synoptic forcing patterns linked to debris flows in the study area. Summer and fall season account for 92% of the debris flows in the record, while atmospheric circulation characterized by Zonal West, Mixed and Meridional South, Southeast patterns account for 80%. Both seasonal and circulation patterns exhibit geographical preference. In the case of seasonality, there is a strong north–south separation of summer–fall dominance while spatial distribution of dominant circulation patterns exhibits clustering, with both Zonal West and Mixed prevailing in the northwest and central east part of the region, while the southern part relates to Meridional South, Southeast pattern. Seasonal and synoptic pattern dependence is pronounced also on the debris flow triggering rainfall properties. Examination of rainfall intensity–duration thresholds derived for different data classes (according to season and synoptic pattern) revealed a distinct variability in estimated thresholds. These findings imply a certain control on debris-flow events and can therefore be used to improve existing alert systems.
    Electronic ISSN: 2195-9269
    Topics: Geography , Geosciences
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    Climatic signals from 76 shallow firn cores in Dronning Maud Land, East Antarctica (2014)
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    Publication Date: 2014-12-03
    Description: Climatic signals from 76 shallow firn cores in Dronning Maud Land, East Antarctica The Cryosphere Discussions, 8, 5961-6005, 2014 Author(s): S. Altnau, E. Schlosser, E. Isaksson, and D. Divine The spatial and temporal distribution of surface mass balance (SMB) and δ 18 O were investigated in the first comprehensive study of a set of 76 firn cores retrieved by various expeditions during the past three decades in Dronning Maud Land, East Antarctica. The large number of cores was used to calculate stacked records of SMB and δ 18 O, which considerably increased the signal-to-noise ratio compared to earlier studies and facilitated the detection of climatic signals. Considerable differences between cores from the interior plateau and the coastal cores were found. The δ 18 O of both the plateau and the ice shelf cores exhibit a slight positive trend over the second half of the 20th century. In the corresponding period, the SMB has a negative trend in the ice shelf cores, but increases on the plateau. Comparison with meteorological data from Neumayer Station revealed that for the ice shelf regions atmospheric dynamic effects are more important than thermodynamics, while on the plateau, the temporal variations of SMB and δ 18 O occur mostly in parallel, thus can be explained by thermodynamic effects. The Southern Annular Mode (SAM) exhibits a positive trend since the mid-1960s, which is assumed to lead to a cooling of East Antarctica. This is not confirmed by the firn core data in our data set. Changes in the atmospheric circulation that result in a changed seasonal distribution of precipitation/accumulation could partly explain the observed features in the ice shelf cores.
    Print ISSN: 1994-0432
    Electronic ISSN: 1994-0440
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    Post-LIA glacier changes along a latitudinal transect in the Central Italian Alps (2014)
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    Publication Date: 2014-12-03
    Description: Post-LIA glacier changes along a latitudinal transect in the Central Italian Alps The Cryosphere, 8, 2235-2252, 2014 Author(s): R. Scotti, F. Brardinoni, and G. B. Crosta The variability of glacier response to atmospheric temperature rise in different topo-climatic settings is still a matter of debate. To address this question in the Central Italian Alps, we compile a post-LIA (Little Ice Age) multitemporal glacier inventory (1860–1954–1990–2003–2007) along a latitudinal transect that originates north of the continental divide in the Livigno Mountains and extends south through the Disgrazia and Orobie ranges, encompassing continental-to-maritime climatic settings. In these sub-regions, we examine the area change of 111 glaciers. Overall, the total glacierized area has declined from 34.1 to 10.1 km 2 , with a substantial increase in the number of small glaciers due to fragmentation. The average annual decrease (AAD) in glacier area has risen by about 1 order of magnitude from 1860–1990 (Livigno: 0.45; Orobie: 0.42; and Disgrazia: 0.39 % a −1 ) to 1990–2007 (Livigno: 3.08; Orobie: 2.44; and Disgrazia: 2.27 % a −1 ). This ranking changes when considering glaciers smaller than 0.5 km 2 only (i.e., we remove the confounding caused by large glaciers in Disgrazia), so that post-1990 AAD follows the latitudinal gradient and Orobie glaciers stand out (Livigno: 4.07; Disgrazia: 3.57; and Orobie: 2.47 % a −1 ). More recent (2007–2013) field-based mass balances in three selected small glaciers confirm post-1990 trends showing the consistently highest retreat in continental Livigno and minimal area loss in maritime Orobie, with Disgrazia displaying transitional behavior. We argue that the recent resilience of glaciers in Orobie is a consequence of their decoupling from synoptic atmospheric temperature trends, a decoupling that arises from the combination of local topographic configuration (i.e., deep, north-facing cirques) and high winter precipitation, which ensures high snow-avalanche supply, as well as high summer shading and sheltering. Our hypothesis is further supported by the lack of correlations between glacier change and glacier attributes in Orobie, as well as by the higher variability in ELA,sub〉0 positioning, post-LIA glacier change, and interannual mass balances, as we move southward along the transect.
    Print ISSN: 1994-0416
    Electronic ISSN: 1994-0424
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    High-resolution land surface modeling utilizing remote sensing parameters and the Noah UCM: a case study in the Los Angeles Basin (2014)
    Copernicus
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    Publication Date: 2014-12-04
    Description: High-resolution land surface modeling utilizing remote sensing parameters and the Noah UCM: a case study in the Los Angeles Basin Hydrology and Earth System Sciences, 18, 4791-4806, 2014 Author(s): P. Vahmani and T. S. Hogue In the current work we investigate the utility of remote-sensing-based surface parameters in the Noah UCM (urban canopy model) over a highly developed urban area. Landsat and fused Landsat–MODIS data are utilized to generate high-resolution (30 m) monthly spatial maps of green vegetation fraction (GVF), impervious surface area (ISA), albedo, leaf area index (LAI), and emissivity in the Los Angeles metropolitan area. The gridded remotely sensed parameter data sets are directly substituted for the land-use/lookup-table-based values in the Noah-UCM modeling framework. Model performance in reproducing ET (evapotranspiration) and LST (land surface temperature) fields is evaluated utilizing Landsat-based LST and ET estimates from CIMIS (California Irrigation Management Information System) stations as well as in situ measurements. Our assessment shows that the large deviations between the spatial distributions and seasonal fluctuations of the default and measured parameter sets lead to significant errors in the model predictions of monthly ET fields (RMSE = 22.06 mm month −1 ). Results indicate that implemented satellite-derived parameter maps, particularly GVF, enhance the capability of the Noah UCM to reproduce observed ET patterns over vegetated areas in the urban domains (RMSE = 11.77 mm month −1 ). GVF plays the most significant role in reproducing the observed ET fields, likely due to the interaction with other parameters in the model. Our analysis also shows that remotely sensed GVF and ISA improve the model's capability to predict the LST differences between fully vegetated pixels and highly developed areas.
    Print ISSN: 1027-5606
    Electronic ISSN: 1607-7938
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    Comprehensive evaluation of water resources security in the Yellow River basin based on a Fuzzy Multi-Attribute Decision Analysis Approach (2014)
    Copernicus
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    Publication Date: 2014-01-11
    Description: Comprehensive evaluation of water resources security in the Yellow River basin based on a Fuzzy Multi-Attribute Decision Analysis Approach Hydrology and Earth System Sciences Discussions, 11, 371-410, 2014 Author(s): K. K. Liu, C. H. Li, Y. P. Cai, M. Xu, and X. H. Xia In this paper, a Fuzzy Multi-Attribute Decision Analysis Approach (FMADAA) was adopted in water resources security evaluation for the nine provinces in the Yellow River basin in 2006. A numerical approximation system and a modified left-right scoring approach were adopted to cope with the uncertainties in the acquired information. Four multi-attribute decision making methods were implemented in the evaluation model for impact evaluation, including simple weighted addition (SWA), weighted product (WP), cooperative game theory (CGT) and technique for order preference by similarity to ideal solution (TOPSIS) which could be used for helping rank the water resources security in those nine provinces as well as the criteria alternatives. Moreover, several aggregation methods including average ranking procedure, borda and copeland methods were used to integrate the ranking results. The ranking results showed that the water resources security of the entire basin is in critical, insecurity and absolute insecurity state, especially in Shanxi, Inner Mongolia and Ningxia provinces in which water resources were lower than the average quantity in China. Hence, future planning of the Yellow River basin should mainly focus on the improvement of water eco-environment status in the provinces above.
    Print ISSN: 1812-2108
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    Impact of the Hoa Binh Dam (Vietnam) on water and sediment budgets in the Red River basin and delta (2014)
    Copernicus
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    Publication Date: 2014-01-11
    Description: Impact of the Hoa Binh Dam (Vietnam) on water and sediment budgets in the Red River basin and delta Hydrology and Earth System Sciences Discussions, 11, 333-370, 2014 Author(s): D. V. Vu, S. Ouillon, D. T. Tran, and V. C. La The Hoa Binh Dam, located on a tributary of the Red River in Vietnam, has a capacity of 9.45 × 10 9 m 3 and was commissioned in December 1988. Although being important for flood prevention, electricity production, and irrigation in northern Vietnam, the Hoa Binh Dam has also highly influenced the suspended sediment distribution in the lower Red River basin, in the delta and in the coastal zone. Its impact was analysed from 50 yr dataset of water discharge and suspended sediment concentration (1960–2010) and the distribution of water and sediment across the nine mouths of the delta was calculated using the MIKE 11 numerical model before and after the dam settlement. Although water discharge at the delta inlet decreased by only 8.8%, the yearly suspended sediment flux dropped, on average from 119 to 43 × 10 6 t yr −1 at Son Tay near Hanoi, and from 85 to 35 × 10 6 t yr −1 in the river mouths. Water regulation has led to decreased water discharge in the wet season and increased water discharge in the dry season. Suspended sediment discharge proportionally increased in northern and southern estuaries and decreased through the main and central Ba Lat mouth. Tidal pumping, which causes a net sediment flux from the coast to the estuary at low discharge, is high in the northern delta, as a consequence of the high tidal range (up to 4.5 m in spring tide; diurnal tide). The shifts in the dynamic and characteristics of the turbidity maximum zone in the Cam-Bach Dang estuary are probably the cause of the enhanced sediment deposition in the Haiphong harbor. Along the coast, the reduced sedimentation rates are coincident with the lower sediment delivery that has been observed since the impoundment of the Hoa Binh Dam.
    Print ISSN: 1812-2108
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    Theory of the generalized chloride mass balance method for recharge estimation in groundwater basins characterised by point and diffuse recharge (2014)
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    Publication Date: 2014-01-11
    Description: Theory of the generalized chloride mass balance method for recharge estimation in groundwater basins characterised by point and diffuse recharge Hydrology and Earth System Sciences Discussions, 11, 307-332, 2014 Author(s): N. Somaratne and K. R. J. Smettem Application of the conventional chloride mass balance (CMB) method to point recharge dominant groundwater basins can substantially under-estimate long-term average annual recharge by not accounting for the effects of localized surface water inputs. This is because the conventional CMB method ignores the duality of infiltration and recharge found in karstic systems, where point recharge can be a contributing factor. When point recharge is present in groundwater basins, recharge estimation is unsuccessful using the conventional CMB method with, either unsaturated zone chloride or groundwater chloride. In this paper we describe a generalized CMB that can be applied to groundwater basins with point recharge. Results from this generalized CMB are shown to be comparable with long-term recharge estimates obtained using the watertable fluctuation method, groundwater flow modelling and Darcy flow calculations. The generalized CMB method provides an alternative, reliable long-term recharge estimation method for groundwater basins characterised by both point and diffuse recharge.
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    Brief Communication: Light-absorbing impurities can reduce the density of melting snow (2014)
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    Publication Date: 2014-01-11
    Description: Brief Communication: Light-absorbing impurities can reduce the density of melting snow The Cryosphere Discussions, 8, 259-271, 2014 Author(s): O. Meinander, A. Kontu, A. Virkkula, A. Arola, L. Backman, P. Dagsson-Waldhauserová, O. Järvinen, T. Manninen, J. Svensson, G. de Leeuw, and M. Leppäranta Climatic effects of Black Carbon (BC) deposition on snow have been proposed to result from reduced snow albedo and increased melt due to light-absorbing particles. In this study, we hypothesize that BC may decrease the liquid water retention capacity of melting snow, and present our first data, where both the snow density and elemental carbon content were measured. In our experiments, artificially added light-absorbing impurities decreased the density of seasonally melting natural snow. We also suggest three possible processes that might lead to the lower snow density.
    Print ISSN: 1994-0432
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    Hard paths, soft paths or no paths? Cross-cultural perceptions of water solutions (2014)
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    Publication Date: 2014-01-14
    Description: Hard paths, soft paths or no paths? Cross-cultural perceptions of water solutions Hydrology and Earth System Sciences, 18, 109-120, 2014 Author(s): A. Wutich, A. C. White, D. D. White, K. L. Larson, A. Brewis, and C. Roberts In this study, we examine how development status and water scarcity shape people's perceptions of "hard path" and "soft path" water solutions. Based on ethnographic research conducted in four semi-rural/peri-urban sites (in Bolivia, Fiji, New Zealand, and the US), we use content analysis to conduct statistical and thematic comparisons of interview data. Our results indicate clear differences associated with development status and, to a lesser extent, water scarcity. People in the two less developed sites were more likely to suggest hard path solutions, less likely to suggest soft path solutions, and more likely to see no path to solutions than people in the more developed sites. Thematically, people in the two less developed sites envisioned solutions that involve small-scale water infrastructure and decentralized, community-based solutions, while people in the more developed sites envisioned solutions that involve large-scale infrastructure and centralized, regulatory water solutions. People in the two water-scarce sites were less likely to suggest soft path solutions and more likely to see no path to solutions (but no more likely to suggest hard path solutions) than people in the water-rich sites. Thematically, people in the two water-rich sites seemed to perceive a wider array of unrealized potential soft path solutions than those in the water-scarce sites. On balance, our findings are encouraging in that they indicate that people are receptive to soft path solutions in a range of sites, even those with limited financial or water resources. Our research points to the need for more studies that investigate the social feasibility of soft path water solutions, particularly in sites with significant financial and natural resource constraints.
    Print ISSN: 1027-5606
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    Goal-oriented networks and capacity building for natural hazards – examples in the Dresden region (2014)
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    Publication Date: 2014-01-15
    Description: Goal-oriented networks and capacity building for natural hazards – examples in the Dresden region Natural Hazards and Earth System Science, 14, 81-94, 2014 Author(s): G. Hutter Networks and networking are important for building social capacities for natural hazards. However, up to now, it has been an open question which types of networks contribute to capacity building under certain circumstances. The paper focuses on the type of a goal-oriented network. The distinction between goal orientation and goal directedness is used to show the following: goal directedness of networks to build capacities for natural hazards involves intensive and continuous processes of "sensemaking" (Weick, 1995) to specify the network goal. This process of specifying an initial goal statement is important in small and large networks at the regional level. The governance form of a lead organization network facilitates goal specification. The paper illustrates these findings through evidence from two case studies conducted in the Dresden region in Germany.
    Print ISSN: 1561-8633
    Electronic ISSN: 1684-9981
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    A decade (2002–2012) of supraglacial lake volume estimates across Russell Glacier, West Greenland (2014)
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    Publication Date: 2014-01-15
    Description: A decade (2002–2012) of supraglacial lake volume estimates across Russell Glacier, West Greenland The Cryosphere, 8, 107-121, 2014 Author(s): A. A. W. Fitzpatrick, A. L. Hubbard, J. E. Box, D. J. Quincey, D. van As, A. P. B. Mikkelsen, S. H. Doyle, C. F. Dow, B. Hasholt, and G. A. Jones Supraglacial lakes represent an ephemeral storage buffer for meltwater runoff and lead to significant, yet short-lived, episodes of ice-flow acceleration by decanting large meltwater and energy fluxes into the ice sheet's hydrological system. Here, a methodology for calculating lake volume is used to quantify storage and drainage across Russell Glacier, West Greenland, between 2002 and 2012. Using 502 MODIS scenes, water volume at ~200 seasonally occurring lakes was derived using a depth–reflectance relationship, which was independently calibrated and field validated against lake bathymetry. The inland expansion of lakes is strongly correlated with air temperature: during the record melt years of 2010 and 2012, lakes formed and drained earlier, attaining their maximum volume 38 and 20 days earlier than the 11 yr mean, as well as occupying a greater area and forming at higher elevations (〉 1800 m) than previously. Despite occupying under 2% of the study area, lakes delay the transmission of up to 7–13% of the bulk meltwater discharged. Although the results are subject to an observational bias caused by periods of cloud cover, we estimate that across Russell Glacier, 28% of supraglacial lakes drain rapidly ( 〈 4 days). Clustering of such events in space and time suggests a synoptic trigger mechanism. Further, we find no evidence to support a unifying critical size or depth-dependent drainage threshold.
    Print ISSN: 1994-0416
    Electronic ISSN: 1994-0424
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    Fabric measurement along the NEEM ice core, Greenland, and comparison with GRIP and NGRIP ice cores (2014)
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    Publication Date: 2014-01-15
    Description: Fabric measurement along the NEEM ice core, Greenland, and comparison with GRIP and NGRIP ice cores The Cryosphere Discussions, 8, 307-335, 2014 Author(s): M. Montagnat, N. Azuma, D. Dahl-Jensen, J. Eichler, S. Fujita, F. Gillet-Chaulet, S. Kipfstuhl, D. Samyn, A. Svensson, and I. Weikusat Fabric (distribution of crystallographic orientations) profile along the full NEEM ice core, Greenland, is presented in this work. Data were measured in the field by an Automatic Ice Texture Analyzer every 10 m, from 33 m down to 2461 m depth. The fabric evolves from a slightly anisotropic fabric at the top, toward a strong single maximum at about 2300 m, which is typical of a deformation pattern mostly driven by uniaxial compression and simple shearing. A sharp increase in the fabric strengthening is observed at the Holocene to Wisconsin climatic transition. A similar strengthening, toward an anisotropic single maximum-type fabric, has been observed in several ice cores from Greenland and Antarctica, and can be attributed to a positive feedback between changes in ice viscosity at the climatic transition, and the impact of a shear component of stress. Centimeter scale abrupt texture (fabric and microstructure) variations are observed in the bottom part of the core. Their positions are in good agreement with the folding hypothesis used for a climatic reconstruction by Dahl-Jensen et al. (2013). Comparison is made to two others ice cores drilled along the same ridge; the GRIP ice core drilled at the summit of the ice sheet, and the NorthGRIP ice core, drilled 325 km to the NNW of the summit along the ridge, and 365 km upstream from NEEM. The fabric profile clearly reflects the increase in shear deformation when moving NW along the ridge from GRIP to NorthGRIP and NEEM. The difference in fabric profiles between NEEM and NorthGRIP also evidences a stronger lateral extension associated with a sharper ridge at NorthGRIP.
    Print ISSN: 1994-0432
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    Parameterization of basal hydrology near grounding lines in a one-dimensional ice sheet model (2014)
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    Publication Date: 2014-01-15
    Description: Parameterization of basal hydrology near grounding lines in a one-dimensional ice sheet model The Cryosphere Discussions, 8, 363-419, 2014 Author(s): G. R. Leguy, X. S. Asay-Davis, and W. H. Lipscomb Ice sheets and ice shelves are linked by the transition zone, the region where the grounded ice lifts off the bedrock and begins to float. Adequate resolution of the transition zone is necessary for numerically accurate ice sheet–ice shelf simulations. The required resolution depends on how the basal physics is parameterized. We propose a new, simple parameterization of the basal hydrology in a one-dimensional vertically integrated model. This parameterization accounts for connectivity between the basal hydrological system and the ocean in the transition zone. Our model produces a smooth transition between finite basal friction in the ice sheet and zero basal friction in the ice shelf. Through a set of experiments based on the Marine Ice Sheet Model Intercomparison Project (MISMIP), we show that a smoother basal shear stress, in addition to adding physical realism, significantly improves the numerical accuracy of our fixed-grid model, allowing for reliable grounding-line dynamics at resolutions ~1 km.
    Print ISSN: 1994-0432
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    A spurious jump in the satellite record: is Antarctic sea ice really expanding? (2014)
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    Publication Date: 2014-01-14
    Description: A spurious jump in the satellite record: is Antarctic sea ice really expanding? The Cryosphere Discussions, 8, 273-288, 2014 Author(s): I. Eisenman, W. N. Meier, and J. R. Norris Recent estimates indicate that the Antarctic sea ice cover is expanding at a statistically significant rate with a magnitude one third as large as the rapid rate of sea ice retreat in the Arctic. However, during the mid-2000s, with several fewer years in the observational record, the trend in Antarctic sea ice extent was reported to be considerably smaller and statistically indistinguishable from zero. Here, we show that the increase in the reported trend occurred primarily due to the effect of a previously undocumented change in the way the satellite sea ice observations are processed for the widely-used Bootstrap algorithm dataset, rather than a physical increase in the rate of ice advance. Although our analysis does not definitively identify whether this undocumented change introduced an error or removed one, the resulting difference in the trends suggests that a substantial error exists in either the current dataset or the version that was used prior to the mid-2000s, and numerous studies that have relied on these observations should be reexamined to determine the sensitivity of their results to this change in the dataset. Furthermore, a number of recent studies have investigated physical mechanisms for the observed expansion of the Antarctic sea ice cover. The results of this analysis raise the possibility that this expansion may be a spurious artifact of an error in the satellite observations, and that the actual Antarctic sea ice cover may not be expanding at all.
    Print ISSN: 1994-0432
    Electronic ISSN: 1994-0440
    Topics: Geography , Geosciences
    Published by Copernicus on behalf of The European Geosciences Union (EGU).
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    Comparison of different evaporation estimates over the African continent (2014)
    Copernicus
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    Publication Date: 2014-01-16
    Description: Comparison of different evaporation estimates over the African continent Hydrology and Earth System Sciences, 18, 193-212, 2014 Author(s): P. Trambauer, E. Dutra, S. Maskey, M. Werner, F. Pappenberger, L. P. H. van Beek, and S. Uhlenbrook Evaporation is a key process in the water cycle with implications ranging, inter alia, from water management to weather forecast and climate change assessments. The estimation of continental evaporation fluxes is complex and typically relies on continental-scale hydrological models or land-surface models. However, it appears that most global or continental-scale hydrological models underestimate evaporative fluxes in some regions of Africa, and as a result overestimate stream flow. Other studies suggest that land-surface models may overestimate evaporative fluxes. In this study, we computed actual evaporation for the African continent using a continental version of the global hydrological model PCR-GLOBWB, which is based on a water balance approach. Results are compared with other independently computed evaporation products: the evaporation results from the ECMWF reanalysis ERA-Interim and ERA-Land (both based on the energy balance approach), the MOD16 evaporation product, and the GLEAM product. Three other alternative versions of the PCR-GLOBWB hydrological model were also considered. This resulted in eight products of actual evaporation, which were compared in distinct regions of the African continent spanning different climatic regimes. Annual totals, spatial patterns and seasonality were studied and compared through visual inspection and statistical methods. The comparison shows that the representation of irrigation areas has an insignificant contribution to the actual evaporation at a continental scale with a 0.5° spatial resolution when averaged over the defined regions. The choice of meteorological forcing data has a larger effect on the evaporation results, especially in the case of the precipitation input as different precipitation input resulted in significantly different evaporation in some of the studied regions. ERA-Interim evaporation is generally the highest of the selected products followed by ERA-Land evaporation. In some regions, the satellite-based products (GLEAM and MOD16) show a different seasonal behaviour compared to the other products. The results from this study contribute to a better understanding of the suitability and the differences between products in each climatic region. Through an improved understanding of the causes of differences between these products and their uncertainty, this study provides information to improve the quality of evaporation products for the African continent and, consequently, leads to improved water resources assessments at regional scale.
    Print ISSN: 1027-5606
    Electronic ISSN: 1607-7938
    Topics: Geography , Geosciences
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    Parameterizing complex root water uptake models – the arrangement of root hydraulic properties within the root architecture affects dynamics and efficiency of root water uptake (2014)
    Copernicus
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    Publication Date: 2014-01-16
    Description: Parameterizing complex root water uptake models – the arrangement of root hydraulic properties within the root architecture affects dynamics and efficiency of root water uptake Hydrology and Earth System Sciences Discussions, 11, 757-805, 2014 Author(s): M. Bechmann, C. Schneider, A. Carminati, D. Vetterlein, S. Attinger, and A. Hildebrandt Detailed three-dimensional models of root water uptake have become increasingly popular for investigating the process of root water uptake. However they suffer from a lack of information in important parameters, especially distribution of root hydraulic properties. In this paper we explore the role that arrangement of root hydraulic properties and root system topology play for modelled uptake dynamics. We apply microscopic models of single root structures to investigate the mechanisms shaping uptake dynamics and demonstrate the effects in a complex three dimensional root water uptake model. We introduce two efficiency indices, for (a) overall plant resistance and (b) water stress and show that an appropriate arrangement of root hydraulic properties can increase modelled efficiency of root water uptake in single roots, branched roots and entire root systems. The average uptake depth of the complete root system was not influenced by parameterization. However, other factors such as evolution of collar potential, which is related to the plant resistance, root bleeding and redistribution patterns were strongly affected by the parameterization. Root systems are more efficient when they are assembled of different root types, allowing for separation of root function in uptake (short young) roots and transport (longer mature) roots. Results become similar, as soon as this composition is accounted for to some degree (between 40 and 80% of young uptake roots). Overall resistance to root water uptake was decreased up to 40% and total transpiration was increased up to 25% in these composed root systems, compared to homogenous root systems. Also, one parameterization (homogenous young root system) was characterized by excessive bleeding (hydraulic lift), which was accompanied by lowest efficiency. We conclude that heterogeneity of root hydraulic properties is a critical component of complex three dimensional uptake models. Efficiency measures together with information on critical xylem potentials may be useful in parameterizing root property distribution.
    Print ISSN: 1812-2108
    Electronic ISSN: 1812-2116
    Topics: Geography , Geosciences
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    Present and future variations in Antarctic firn air content (2014)
    Copernicus
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    Publication Date: 2014-01-16
    Description: Present and future variations in Antarctic firn air content The Cryosphere Discussions, 8, 421-451, 2014 Author(s): S. R. M. Ligtenberg, P. Kuipers Munneke, and M. R. van den Broeke A firn densification model (FDM) is used to assess spatial and temporal (1979–2200) variations in the depth, density and temperature of the firn layer covering the Antarctic ice sheet (AIS). Results from a time-dependent version of the FDM are compared to more commonly used steady-state FDM results. Although the average AIS firn air content (FAC) between both models is similar (22.5 m), large spatial differences are found: in the ice-sheet interior, the steady-state model underestimates the FAC by up to 2 m, while the FAC is overestimated by 5–15 m along the ice-sheet margins, due to significant surface melt. Applying the steady-state FAC values to convert surface elevation to ice thickness (i.e. assuming flotation at the grounding line) potentially results in an underestimation of ice discharge at the grounding line, and hence an underestimation of current AIS mass loss by 23.5%, or 16.7 Gt yr −1 (with regard to the reconciled estimate over 1992–2011, Shepherd et al., 2012). The timing of the measurement is also important as temporal FAC variations of 1–2 m are simulated within the 33 yr period. Until 2200, the Antarctic FAC is projected to change due to a combination of increasing accumulation, temperature and surface melt. The latter two result in a decrease of FAC, due to (i) more refrozen meltwater, (ii) a higher densification rate and (iii) a faster firn-to-ice transition at the bottom of the firn layer. These effects are however more than compensated by increasing snowfall, leading to a 4–14% increase in FAC. Only in melt-affected regions, future FAC is simulated to decrease, with the largest changes (−50 to −80%) on the ice shelves in the Antarctic Peninsula and Dronning Maud Land. Integrated over the AIS, increased precipitation results in a combined ice and air volume increase of ∼300 km 3 yr −1 until 2100, equivalent to an elevation change of +2.1 cm yr −1 . This shows that variations in firn depth remain important to consider in future mass balance studies using (satellite) altimetry.
    Print ISSN: 1994-0432
    Electronic ISSN: 1994-0440
    Topics: Geography , Geosciences
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    Dynamic mapping of flood boundaries: current possibilities offered by Earth Observation System and Cellular Automata (2014)
    Copernicus
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    Publication Date: 2014-01-17
    Description: Dynamic mapping of flood boundaries: current possibilities offered by Earth Observation System and Cellular Automata Hydrology and Earth System Sciences Discussions, 11, 833-860, 2014 Author(s): A. Gerardi, M. Ioannilli, and F. Del Frate Flooding is an ongoing and complex problem in Italy. Very large floods caused inundation of the closest areas to the city centre in Rome in 1937, 1976, 1992, 2005 and most recently in 2008. Rome is located at the bottom of the Tiber River catchment, which cover an area of 16 000 km 2 . Intense precipitations struck the Tyrrhenian Sea side of the peninsula inducing a flood event on the Tiber and Aniene's (Tiber's tributary) basins – which captured the attention of the national and international media. Actually there is no validated model in operation for real-time flood forecasting. This research aims at comparing the Cellular Model CAESAR (Cellular Automation Evolutionary Slope And River) application on a reach of the Aniene River with Earth Observation Systems. The main result expected is the prediction of future channel dynamics on short and medium time scale.
    Print ISSN: 1812-2108
    Electronic ISSN: 1812-2116
    Topics: Geography , Geosciences
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    Water footprints of cities – indicators for sustainable consumption and production (2014)
    Copernicus
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    Publication Date: 2014-01-17
    Description: Water footprints of cities – indicators for sustainable consumption and production Hydrology and Earth System Sciences, 18, 213-226, 2014 Author(s): H. Hoff, P. Döll, M. Fader, D. Gerten, S. Hauser, and S. Siebert Water footprints have been proposed as sustainability indicators, relating the consumption of goods like food to the amount of water necessary for their production and the impacts of that water use in the source regions. We further developed the existing water footprint methodology, by globally resolving virtual water flows from production to consumption regions for major food crops at 5 arcmin spatial resolution. We distinguished domestic and international flows, and assessed local impacts of export production. Applying this method to three exemplary cities, Berlin, Delhi and Lagos, we find major differences in amounts, composition, and origin of green and blue virtual water imports, due to differences in diets, trade integration and crop water productivities in the source regions. While almost all of Delhi's and Lagos' virtual water imports are of domestic origin, Berlin on average imports from more than 4000 km distance, in particular soy (livestock feed), coffee and cocoa. While 42% of Delhi's virtual water imports are blue water based, the fractions for Berlin and Lagos are 2 and 0.5%, respectively, roughly equal to the water volumes abstracted in these two cities for domestic water use. Some of the external source regions of Berlin's virtual water imports appear to be critically water scarce and/or food insecure. However, for deriving recommendations on sustainable consumption and trade, further analysis of context-specific costs and benefits associated with export production will be required.
    Print ISSN: 1027-5606
    Electronic ISSN: 1607-7938
    Topics: Geography , Geosciences
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    Subscription Page (2014)
    Oxford University Press
    Details
    Publication Date: 2014-01-22
    Print ISSN: 0002-9092
    Electronic ISSN: 1467-8276
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition , Economics
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    Towards an Understanding of The Performance of Ambient Tax Mechanisms in The Field:Evidence from Upstate New York Dairy Farmers (2014)
    Oxford University Press
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    Publication Date: 2014-01-22
    Description: Using a design characterized by heterogeneous firms and stochastic ambient pollution, this study explores how results from ambient tax experiments with student subjects translate to a richer field context with dairy farmers in Upstate New York. Results suggest that the ambient tax induces group-level compliance among students and farmers. However, relative to students, farmers operating "small" firms pollute less and farmers operating "large" firms tend to pollute more. Deviations from theory among farmers are tied to beliefs about the impacts of farming on water pollution, as well as knowledge of neighbors’ pollution. This study highlights the importance of framed field experiments in the policy test-bedding process.
    Keywords: C91 - Laboratory, Individual Behavior, C92 - Laboratory, Group Behavior, H23 - Externalities ; Redistributive Effects ; Environmental Taxes and Subsidies, Q52 - Pollution Control Costs ; Distributional Effects ; Employment Effects, Q53 - Air Pollution ; Water Pollution ; Noise ; Hazardous Waste ; Solid Waste ; Recycling, Q58 - Government Policy
    Print ISSN: 0002-9092
    Electronic ISSN: 1467-8276
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition , Economics
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    The Benefits of Spatially Differentiated Regulation: The Response to Acid Rain by U.S. States Prior to the Acid Rain Program (2014)
    Oxford University Press
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    Publication Date: 2014-01-22
    Description: Location is a crucial driver of both the marginal abatement and damage costs of sulfur dioxide emissions by U.S. coal-fired power plants. Before the start of the Acid Rain Program in 1995, old boilers were subject to emission rate standards set by individual states. We investigate how individual states adjusted their sulfur regulation laws in response to acid rain, and whether they accounted for differences in marginal abatement costs, vulnerability to agricultural damages, special industry interests, or inter-state externalities. The welfare gain compared to a uniform reduction in emission rate standards is estimated to be $21 million (in 1995 dollars) annually.
    Keywords: H77 - Intergovernmental Relations ; Federalism ; Secession, Q53 - Air Pollution ; Water Pollution ; Noise ; Hazardous Waste ; Solid Waste ; Recycling, Q58 - Government Policy, R50 - General
    Print ISSN: 0002-9092
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    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition , Economics
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    Cooperation against theft: A test of incentives for water management In Tunisia (2014)
    Oxford University Press
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    Publication Date: 2014-01-22
    Description: Water theft carried out by manipulating water meters constrains volumetric pricing in semi-arid regions. Cooperative management can reduce theft and improve incentives for efficient water use by inducing peer monitoring. Using a theoretical model, we show that theft is more likely when prices are high, punishments are weak, and cooperatives are large. We also show how cooperative membership and punishment levels are determined endogenously by constraints on monitoring. We test the model on data from Tunisia for the years 2001–2003, relying on instruments that proxy for unobservable monitoring costs. The results confirm that well-designed incentives can reduce theft, and that constraints on monitoring costs affect institutional design.
    Keywords: D82 - Asymmetric and Private Information, Q13 - Agricultural Markets and Marketing ; Cooperatives ; Agribusiness, Q15 - Land Ownership and Tenure ; Land Reform ; Land Use ; Irrigation, Q25 - Water
    Print ISSN: 0002-9092
    Electronic ISSN: 1467-8276
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition , Economics
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  • 90
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    When are Private Standards more Stringent than Public Standards? (2014)
    Oxford University Press
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    Publication Date: 2014-01-22
    Description: Retailers’ private standards are increasingly important for addressing consumer concerns about safety, quality, and social and environmental issues. Empirical evidence shows that these private standards are frequently more stringent than their public counterparts. This article develops a political economy model that helps explain this stylized fact. We show that if producers exercise their political power to persuade the government to impose a lower public standard, retailers may apply their market power to install a private standard at a higher level than the public one, depending on several factors.
    Keywords: D72 - Models of Political Processes: Rent-Seeking, Elections, Legislatures, and Voting Behavior, L15 - Information and Product Quality ; Standardization and Compatibility
    Print ISSN: 0002-9092
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    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition , Economics
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    Is Timber Insurable? A Study of Wildfire Risks in the U.S. Forest Sector Using Spatio-Temporal Models (2014)
    Oxford University Press
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    Publication Date: 2014-01-22
    Description: In the U.S. forest products industry, wildfire is one of the leading causes of damage and economic losses. While individual wildfire behavior is well studied, new literature is emerging on broad-scale (e.g., county-level) wildfire risks. Our paper studies wildfire risks using crucial informational variables across both spatial units and time periods. Several statistical models are used to quantify the risks. We develop several maximum likelihood estimation methods to account for spatio-temporal auto-correlation in conditional risks. A group index insurance scheme is proposed, and its associated actuarially fair premium rates are estimated and presented. Implications for wildfire management policies are also discussed.
    Keywords: G22 - Insurance ; Insurance Companies, Q23 - Forestry
    Print ISSN: 0002-9092
    Electronic ISSN: 1467-8276
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition , Economics
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    Spatial Pattern of Yield Distributions: Implications for Crop Insurance (2014)
    Oxford University Press
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    Publication Date: 2014-01-22
    Description: Crop insurance is similar to flood and hurricane insurance in that spatially correlated weather tends to cause violations of the independence assumption. Ideally, one would seek to pool uncorrelated risk drawn from the same distribution in crop insurance. This article proposes a testing procedure for the cross-sectional pooling of group units, and empirically analyzes whether the proposed test improves out-of-sample rating performance. We utilize a balanced panel of U.S. county-level corn yields for 510 counties, and the results of an out-of-sample crop insurance rating performance exercise provide economic significance to the proposed pooling methodology and results.
    Keywords: C12 - Hypothesis Testing, Q18 - Agricultural Policy ; Food Policy
    Print ISSN: 0002-9092
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    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition , Economics
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    Cover Page (2014)
    Oxford University Press
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    Publication Date: 2014-01-22
    Print ISSN: 0002-9092
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    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition , Economics
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    Input Subsidies, Cash Constraints, and Timing of Input Supply (2014)
    Oxford University Press
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    Publication Date: 2014-01-22
    Description: Is low input use by poor, smallholder farmers caused by time-inconsistent behavior or by limited ability to buy inputs? Are input subsidies the best solution to stimulate input demand or are there smarter solutions? These issues are investigated by combining survey data, stated preference questions, and randomized experiments in Malawi. The demand for fertilizer at harvest time and at planting time, farm gate shadow prices for fertilizer, and the gap between the willingness-to-accept (WTA) and willingness-to-pay (WTP) prices for a standard input package were investigated. Significant effects of timing and of cash constraints were found, suggesting the possibility that smarter designs exist, such as distribution of smaller packages from harvest time to planting time.
    Keywords: Q12 - Micro Analysis of Farm Firms, Farm Households, and Farm Input Markets, Q18 - Agricultural Policy ; Food Policy
    Print ISSN: 0002-9092
    Electronic ISSN: 1467-8276
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition , Economics
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    A Regional Bio-economic Model of Nitrogen Use in Cropping (2014)
    Oxford University Press
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    Publication Date: 2014-01-22
    Description: We develop a programming model of crop production to predict the effects of environmental policies on agriculture and the environment. The model is calibrated against acreages, yields, and exogenous supply elasticities following positive mathematical programming. In addition, crop production functions are calibrated to yield elasticities with respect to nitrogen and irrigation obtained from a biogeochemical model. We study the effects of a nitrogen tax in Yolo County, California, intended to mitigate nitrogen pollution from field crops. The behavioral and environmental responses to the tax are largely due to intensive margin adjustments. Sizable reductions in nitrate leaching are achieved at a low social cost.
    Keywords: C60 - General, Q10 - General, Q50 - General
    Print ISSN: 0002-9092
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    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition , Economics
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    Predicting the Effects of Sugar-Sweetened Beverage Taxes on Food and Beverage Demand in a Large Demand System (2014)
    Oxford University Press
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    Publication Date: 2014-01-22
    Description: A censored Exact Affine Stone Index incomplete demand system is estimated for 23 packaged foods and beverages and a numéraire good. Instrumental variables are used to control for endogenous prices. A half-cent per ounce increase in sugar-sweetened beverage prices is predicted to reduce total calories from the 23 foods and beverages but increase sodium and fat intakes as a result of product substitution. The predicted decline in calories is larger for low-income households than for high-income households, although welfare loss is also higher for low-income households. Neglecting price endogeneity or estimating a conditional demand model significantly overestimates the calorie reduction.
    Keywords: D12 - Consumer Economics: Empirical Analysis, D61 - Allocative Efficiency ; Cost-Benefit Analysis, H20 - General
    Print ISSN: 0002-9092
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    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition , Economics
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    The System of Rice Intensification and its Impacts on Household Income and Child Schooling: Evidence from Rural Indonesia (2014)
    Oxford University Press
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    Publication Date: 2014-01-22
    Description: The yield potential of a set of improved rice management practices, known as the System of Rice Intensification (SRI), has attracted much attention. Yet we know surprisingly little about SRI's socio-economic impact. Using data from Indonesia in 2009, this study assesses the impact of SRI on household incomes and child schooling. We find that SRI generates significant estimated yield gains. However, because SRI induces a reallocation of family labor from non-farm to farm, SRI users enjoy no household income gains. Despite the increased labor demand for farming, we find no evidence that SRI has a child labor effect.
    Keywords: D10 - General, O13 - Agriculture ; Natural Resources ; Energy ; Environment ; Other Primary Products, O33 - Technological Change: Choices and Consequences ; Diffusion Processes, Q12 - Micro Analysis of Farm Firms, Farm Households, and Farm Input Markets
    Print ISSN: 0002-9092
    Electronic ISSN: 1467-8276
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition , Economics
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    Do Neighborhood Parks and Playgrounds Reduce Childhood Obesity? (2014)
    Oxford University Press
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    Publication Date: 2014-01-22
    Description: Using the 2007 National Survey of Children's Health data, we find a statistically and economically significant effect of neighborhood parks and playgrounds on childhood obesity based on covariate matching estimators. The park/playground effect depends on gender, age, race, household income, neighborhood safety, and other neighborhood amenities. The results suggest that adding a neighborhood park/playground may reduce the obesity rate and make children more fit, but relevant interventions must consider socioeconomic status of the targeted children as well as other neighborhood amenities.
    Keywords: I18 - Government Policy ; Regulation ; Public Health, I38 - Government Policy ; Provision and Effects of Welfare Programs, R53 - Public Facility Location Analysis ; Public Investment and Capital Stock
    Print ISSN: 0002-9092
    Electronic ISSN: 1467-8276
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition , Economics
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    The role of Amazon Basin moisture on the atmospheric branch of the hydrological cycle: a Lagrangian analysis (2014)
    Copernicus
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    Publication Date: 2014-01-23
    Description: The role of Amazon Basin moisture on the atmospheric branch of the hydrological cycle: a Lagrangian analysis Hydrology and Earth System Sciences Discussions, 11, 1023-1046, 2014 Author(s): A. Drumond, J. Marengo, T. Ambrizzi, R. Nieto, L. Moreira, and L. Gimeno We used a Lagrangian model (FLEXPART) and the 1979–2012 ERA Interim reanalysis data to investigate the role of Amazon Basin moisture in the regional hydrological budget along the year. FLEXPART computes budgets of evaporation minus precipitation by calculating changes in the specific humidity along forward and backwards trajectories. The Tropical Atlantic (TA) is the major remote moisture source for Amazon Basin. Northern TA contributes during the Austral Summer mainly, while the contribution of southern TA prevails in the rest of the year. On the other hand, moisture contribution from Amazon Basin occurs for southeastern South America predominantly. A focus was given for the modulation of ENSO over the inter annual variations in the hydrological budget over Amazon. During El Niño events, the contribution from NA increases from June/year 0 to January/year 1 slightly and the contribution from SA is enhanced during Austral Autumn/year 1. Enhanced transport from Amazon towards Southeastern South America prevails during an El Niño episode.
    Print ISSN: 1812-2108
    Electronic ISSN: 1812-2116
    Topics: Geography , Geosciences
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    Cover Page (2014)
    Oxford University Press
    Details
    Publication Date: 2014-01-23
    Print ISSN: 0258-6770
    Electronic ISSN: 1564-698X
    Topics: Economics
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