ALBERT

Beschreibung: Landfast ice thickness in the Canadian Arctic Archipelago from observations and models Stephen E. L. Howell, Frédéric Laliberté, Ron Kwok, Chris Derksen, and Joshua King The Cryosphere, 10, 1463-1475, doi:10.5194/tc-10-1463-2016, 2016 The Canadian Ice Service record of observed landfast ice and snow thickness represents one of the longest in the Arctic that spans over 5 decades. We analyze this record to report on long-term trends and variability of ice and snow thickness within the Canadian Arctic Archipelago (CAA). Results indicate a thinning of ice at several sites in the CAA. State-of-the-art climate models still have difficultly capturing observed ice thickness values in the CAA and should be used with caution.

Beschreibung: Coastal dynamics and submarine permafrost in shallow water of the central Laptev Sea, East Siberia Pier Paul Overduin, Sebastian Wetterich, Frank Günther, Mikhail N. Grigoriev, Guido Grosse, Lutz Schirrmeister, Hans-Wolfgang Hubberten, and Aleksandr Makarov The Cryosphere, 10, 1449-1462, doi:10.5194/tc-10-1449-2016, 2016 How fast does permafrost warm up and thaw after it is covered by the sea? Ice-rich permafrost in the Laptev Sea, Siberia, is rapidly eroded by warm air and waves. We used a floating electrical technique to measure the depth of permafrost thaw below the sea, and compared it to 60 years of coastline retreat and permafrost depths from drilling 30 years ago. Thaw is rapid right after flooding of the land and slows over time. The depth of permafrost is related to how fast the coast retreats.

Beschreibung: Age of the Mt. Ortles ice cores, the Tyrolean Iceman and glaciation of the highest summit of South Tyrol since the Northern Hemisphere Climatic Optimum Paolo Gabrielli, Carlo Barbante, Giuliano Bertagna, Michele Bertó, Daniel Binder, Alberto Carton, Luca Carturan, Federico Cazorzi, Giulio Cozzi, Giancarlo Dalla Fontana, Mary Davis, Fabrizio De Blasi, Roberto Dinale, Gianfranco Dragà, Giuliano Dreossi, Daniela Festi, Massimo Frezzotti, Jacopo Gabrieli, Stephan Galos, Patrick Ginot, Petra Heidenwolf, Theo M. Jenk, Natalie Kehrwald, Donald Kenny, Olivier Magand, Volkmar Mair, Vladimir Mikhalenko, Ping Nan Lin, Klaus Oeggl, Gianni Piffer, Mirko Rinaldi, Ulrich Schotterer, Margit Schwikowski, Roberto Seppi, Andrea Spolaor, Barbara Stenni, Davdi Tonidandel, CChiara Uglietti, Victor Zagorodnov, Thomas Zanoner, and Piero Zennaro The Cryosphere Discuss., doi:10.5194/tc-2016-159,2016 Manuscript under review for TC (discussion: open, 0 comments) New ice cores were extracted from Alto dell'Ortles, the highest glacier of South Tyrol in the Italian Alps, to check whether prehistoric ice, that is coeval to the famous 5200 years old Tyrolean Iceman, is still preserved in this region. Dating of the ice cores confirms the hypothesis and indicates that the drilling site was glaciated since the end of the Northern Hemisphere Climatic Optimum (7000 BP). We also infer that an unprecedented acceleration of the glacier flow has just recently begun.

Beschreibung: Combined diurnal variations of discharge and hydrochemistry of the Isunnguata Sermia outlet of the Greenland Ice Sheet give in sight on sub glacial conditions Joseph Graly, Joel Harrington, and Neil Humphrey The Cryosphere Discuss., doi:10.5194/tc-2016-137,2016 Manuscript under review for TC (discussion: open, 0 comments) At a major outlet of the Greenland Ice Sheet in West Greenland, we find that the chemical solutes is the emerging subglacial waters are out of phase with water discharge and can spike in concentration during waning flow. This suggests that the subglacial waters are spreading out across a large area of the glacial bed throughout the day, stimulating chemical weathering beyond the major water distribution channels.

Beschreibung: Increased nitrate and decreased δ 15 N–NO 3 − in the Greenland Arctic after 1940 attributed to North American oil burning Nathan J. Chellman, Meredith G. Hastings, and Joseph R. McConnell The Cryosphere Discuss., doi:10.5194/tc-2016-163,2016 Manuscript under review for TC (discussion: open, 0 comments) This manuscript analyzes the changing sources of nitrate deposition to Greenland since 1760 CE using a dataset consisting of sub-seasonally resolved nitrogen isotopes of nitrate and source tracers. Correlations amongst ion concentration, source tracers, and the δ 15 N–NO 3 − provide evidence of the impact of biomass burning and fossil fuel combustion emissions of nitrogen oxides and suggest that oil combustion is the likely driver of increased nitrate concentration in Greenland ice since 1940 CE.

Beschreibung: Inversion of geothermal heat flux in a thermomechanically coupled nonlinear Stokes ice sheet model Hongyu Zhu, Noemi Petra, Georg Stadler, Tobin Isaac, Thomas J. R. Hughes, and Omar Ghattas The Cryosphere, 10, 1477-1494, doi:10.5194/tc-10-1477-2016, 2016 We study how well the basal geothermal heat flux can be inferred from surface velocity observations using a thermomechanically coupled nonlinear Stokes ice sheet model. The prospects and limitations of this inversion is studied in two and three dimensional model problems. We also argue that a one-way coupled approach for the adjoint equations motivated by staggered solvers for forward multiphysics problems can lead to an incorrect gradient and premature termination of the optimization iteration.

Beschreibung: Increased nitrate and decreased δ 15 N–NO 3 − in the Greenland Arctic after 1940 attributed to North American oil burning Nathan J. Chellman, Meredith G. Hastings, and Joseph R. McConnell The Cryosphere Discuss., doi:10.5194/tc-2016-163,2016 Manuscript under review for TC (discussion: open, 0 comments) This manuscript analyzes the changing sources of nitrate deposition to Greenland since 1760 CE using a dataset consisting of sub-seasonally resolved nitrogen isotopes of nitrate and source tracers. Correlations amongst ion concentration, source tracers, and the δ 15 N–NO 3 − provide evidence of the impact of biomass burning and fossil fuel combustion emissions of nitrogen oxides and suggest that oil combustion is the likely driver of increased nitrate concentration in Greenland ice since 1940 CE.

Beschreibung: Response of seasonal soil freeze depth to climate change across China Xiaoqing Peng, Oliver W. Frauenfeld, Tingjun Zhang, Kang Wang, Bin Cao, Xinyue Zhong, Hang Su, and Cuicui Mu The Cryosphere Discuss., doi:10.5194/tc-2016-129,2016 Manuscript under review for TC (discussion: open, 0 comments) Previous researches paid more attention on the permafrost, e.g. active layer thickness, soil temperature, permafrost area extent, and associated with permafrost degradation leading other changes. However, seasonally frozen ground, vast area extent, did not focus by so much attention. Here, we combined more than 800 observation station data and gridded data to investigate soil freeze depth across China. The results indicate that soil freeze depth increase with climate warming.

Beschreibung: Slight glacier reduction over the northwestern Tibetan Plateau despite significant recent warming Yetang Wang, Shugui Hou, Wenling An, Hongxi Pang, and Yaping Liu The Cryosphere Discuss., doi:10.5194/tc-2016-165,2016 Manuscript under review for TC (discussion: open, 0 comments) This study further confirms "Pamir–Karakoram–Western-Kunlun-Mountain (northwestern Tibetan Plateau) Glacier Anomaly". Slight glacier reduction over the northwestern Tibetan Plateau may result from more accumulation from increased precipitation in winter which to great extent protects it from mass reductions under climate warming during 1961–2000. Warming slowdown since 2000 happening at this region may further mitigate glacier mass reduction.

Beschreibung: Response of seasonal soil freeze depth to climate change across China Xiaoqing Peng, Oliver W. Frauenfeld, Tingjun Zhang, Kang Wang, Bin Cao, Xinyue Zhong, Hang Su, and Cuicui Mu The Cryosphere Discuss., doi:10.5194/tc-2016-129,2016 Manuscript under review for TC (discussion: open, 0 comments) Previous researches paid more attention on the permafrost, e.g. active layer thickness, soil temperature, permafrost area extent, and associated with permafrost degradation leading other changes. However, seasonally frozen ground, vast area extent, did not focus by so much attention. Here, we combined more than 800 observation station data and gridded data to investigate soil freeze depth across China. The results indicate that soil freeze depth increase with climate warming.

Beschreibung: Effects of Multiple Doppler Radar data assimilation on the numerical simulation of a Flash Flood Event during the HyMeX campaign Ida Maiello, Sabrina Gentile, Rossella Ferretti, Luca Baldini, Nicoletta Roberto, Errico Picciotti, Pier Paolo Alberoni, and Frank S. Marzano Hydrol. Earth Syst. Sci. Discuss., doi:10.5194/hess-2016-320,2016 Manuscript under review for HESS (discussion: open, 0 comments) An analysis to evaluate the impact of assimilating multiple radar data with a three dimensional variational (3D-Var) system on a heavy precipitation event is presented. The main goal is to establish a general methodology to quantitatively assess the performance of flash-flood numerical weather prediction at mesoscale. In this respect, during the first Special Observation Period (SOP1) of HyMeX (Hydrological cycle in the Mediterranean Experiment) campaign several Intensive Observing Periods (IOPs) were launched and nine occurred in Italy. Among them IOP4 is chosen for this study because of its low predictability. This event hit central Italy on 14 September 2012 producing heavy precipitation and causing several damages. Data taken from three C-band radars running operationally during the event are assimilated to improve high resolution initial conditions. In order to evaluate the impact of the assimilation procedure at different horizontal resolution and to assess the impact of assimilating multiple radars data, several experiments using Weather Research and Forecasting (WRF) model are performed. Finally, the statistical indexes as accuracy, equitable threat score, false alarm ratio and frequency bias are used to objectively compare the experiments, using rain gauges data as benchmark.

Beschreibung: Model-based study of the role of rainfall and land use–land cover in the changes in the occurrence and intensity of Niger red floods in Niamey between 1953 and 2012 Claire Casse, Marielle Gosset, Théo Vischel, Guillaume Quantin, and Bachir Alkali Tanimoun Hydrol. Earth Syst. Sci., 20, 2841-2859, doi:10.5194/hess-20-2841-2016, 2016 Since 1950, the Niger River basin has overcome drastic changes. In Niamey city, the highest river levels and the longest flooded period ever recorded occurred in 2003, 2010, 2012 and 2013, with heavy casualties and property damage. The reasons for these changes, and the relative role of climate versus Land Use Land Cover changes are still debated and are investigated in this paper using observations and modelling. We conclude on the successive role of cover and then rainfall variability.

Beschreibung: Upscaling instantaneous to daily evapotranspiration using modelled daily shortwave radiation for remote sensing applications: an Artificial Neural Network approach Loise Wandera, Kaninska Mallick, Gerard Kiely, Olivier Roupsard, Matthias Peichl, and Vicenzo Magliulo Hydrol. Earth Syst. Sci. Discuss., doi:10.5194/hess-2016-344,2016 Manuscript under review for HESS (discussion: open, 0 comments) Upscaling instantaneous to daily evapotranspiration (ET i to ET d ) is one of the central challenge in regional vegetation water use mapping using polar orbiting satellites. Here we developed a robust ET i upscaling for global studies using the ratio between daily and instantaneous global radiation (R Sd /R Si ). Using data from 126 FLUXNET tower sites this study demonstrated R Sd /R si ratio to be the most robust factor explaining ET d /ET i variability across variable sky conditions and multiple biomes.

Beschreibung: Characteristics of an avalanche-feeding and partially debris-covered glacier and its response to atmospheric warming in Mt. Tomor, Tian Shan, China Puyu Wang, Zhongqin Li, and Huilin Li The Cryosphere Discuss., doi:10.5194/tc-2016-138,2016 Manuscript under review for TC (discussion: open, 0 comments) A cirque-valley glacier with complex topography and partially debris-covered area was investigated in the Mt. Tomor, Tian Shan. The glacier is analogous to temperate one on movement and temperature regimes. The strongest ablation and most significant terminus retreat and area reduction occurred at the end of last century and the beginning of this century. Since inhibition of debris cover to melting, it is expected to keep shrinkage in the coming decades, but the terminus retreat is to be slower.

Beschreibung: Development of high-resolution multi-scale modelling system for simulation of coastal-fluvial urban flooding Agnieszka Indiana Olbert, Joanne Comer, Stephen Nash, and Michael Hartnett Nat. Hazards Earth Syst. Sci. Discuss., doi:10.5194/nhess-2016-238,2016 Manuscript under review for NHESS (discussion: open, 0 comments) A novel nested flood model (MSN_Flood) is applied to simulate complex coastal-fluvial urban flooding in order to critically examine the model's capability to forecast evolution of urban inundation. The model demonstrates high accuracy of outputs without incurring the computational expense of high spatial resolution over the entire model domain. MSN_Flood provides full characteristics of water levels and flow regimes necessary for flood hazard identification and flood risk assessment.

Beschreibung: Development of high-resolution multi-scale modelling system for simulation of coastal-fluvial urban flooding Agnieszka Indiana Olbert, Joanne Comer, Stephen Nash, and Michael Hartnett Nat. Hazards Earth Syst. Sci. Discuss., doi:10.5194/nhess-2016-238,2016 Manuscript under review for NHESS (discussion: open, 0 comments) A novel nested flood model (MSN_Flood) is applied to simulate complex coastal-fluvial urban flooding in order to critically examine the model's capability to forecast evolution of urban inundation. The model demonstrates high accuracy of outputs without incurring the computational expense of high spatial resolution over the entire model domain. MSN_Flood provides full characteristics of water levels and flow regimes necessary for flood hazard identification and flood risk assessment.

Beschreibung: On the propagation of diel signals in river networks using analytic solutions of flow equations Morgan Fonley, Ricardo Mantilla, Scott J. Small, and Rodica Curtu Hydrol. Earth Syst. Sci., 20, 2899-2912, doi:10.5194/hess-20-2899-2016, 2016 We design and implement a theoretical experiment to show that, under low-flow conditions, observed streamflow discrepancies between early and late summer can be attributed to different flow velocities in the river network. By developing an analytic solution to represent flow along a given river network, we emphasize the dependence of streamflow amplitude and time delay on the geomorphology of the network. We also simulate using a realistic river network to highlight the effects of scale.

Beschreibung: On the propagation of diel signals in river networks using analytic solutions of flow equations Morgan Fonley, Ricardo Mantilla, Scott J. Small, and Rodica Curtu Hydrol. Earth Syst. Sci., 20, 2899-2912, doi:10.5194/hess-20-2899-2016, 2016 We design and implement a theoretical experiment to show that, under low-flow conditions, observed streamflow discrepancies between early and late summer can be attributed to different flow velocities in the river network. By developing an analytic solution to represent flow along a given river network, we emphasize the dependence of streamflow amplitude and time delay on the geomorphology of the network. We also simulate using a realistic river network to highlight the effects of scale.

Beschreibung: Simultaneous calibration of hydrological models in geographical space András Bárdossy, Yingchun Huang, and Thorsten Wagener Hydrol. Earth Syst. Sci., 20, 2913-2928, doi:10.5194/hess-20-2913-2016, 2016 This paper explores the simultaneous calibration method to transfer model parameters from gauged to ungauged catchments. It is hypothesized that the model parameters can be separated into two categories: one reflecting the dynamic behavior and the other representing the long-term water balance. The results of three numerical experiments indicate that a good parameter transfer to ungauged catchments can be achieved through simultaneous calibration of models for a number of catchments.

Beschreibung: Looking beyond general metrics for model comparison – lessons from an international model intercomparison study Tanja de Boer-Euser, Laurène Bouaziz, Jan De Niel, Claudia Brauer, Benjamin Dewals, Gilles Drogue, Fabrizio Fenicia, Benjamin Grelier, Jiri Nossent, Fernando Pereira, Hubert Savenije, Guillaume Thirel, and Patrick Willems Hydrol. Earth Syst. Sci. Discuss., doi:10.5194/hess-2016-339,2016 Manuscript under review for HESS (discussion: open, 0 comments) In this study the rainfall–runoff models of eight international research groups were compared for a set of subcatchments of the Meuse basin to investigate the influence of certain model components on the modelled discharge. Although the models showed similar performances based on general metrics, clear differences could be observed for specific events. The differences during drier conditions could indeed be linked back to differences in model structures.

Beschreibung: Comparison and validation of global and regional ocean forecasting systems for the South China Sea Xueming Zhu, Hui Wang, Guimei Liu, Charly Régnier, Xiaodi Kuang, Dakui Wang, Shihe Ren, Zhiyou Jing, and Marie Drévillon Nat. Hazards Earth Syst. Sci., 16, 1639-1655, doi:10.5194/nhess-16-1639-2016, 2016 This paper examined the performances of two operational ocean forecasting systems, Mercator Océan in France and SCSOFS in China, based on observed satellite and in situ data obtained in 2012. The comparison and validation are focused on the ocean circulations, the structures of temperature and salinity, and some mesoscale activities in the South China Sea. Finally, some recommendations have been proposed for both systems to improve their performances in the near future.

Beschreibung: An ice-sheet-wide framework for englacial attenuation from ice-penetrating radar data T. M. Jordan, J. L. Bamber, C. N. Williams, J. D. Paden, M. J. Siegert, P. Huybrechts, O. Gagliardini, and F. Gillet-Chaulet The Cryosphere, 10, 1547-1570, doi:10.5194/tc-10-1547-2016, 2016 Ice penetrating radar enables determination of the basal properties of ice sheets. Existing algorithms assume stationarity in the attenuation rate, which is not justifiable at an ice sheet scale. We introduce the first ice-sheet-wide algorithm for radar attenuation that incorporates spatial variability, using the temperature field from a numerical model as an initial guess. The study is a step toward ice-sheet-wide data products for basal properties and evaluation of model temperature fields.

Beschreibung: Improving together: better science writing through peer learning Mathew A. Stiller-Reeve, Céline Heuzé, William T. Ball, Rachel H. White, Gabriele Messori, Karin van der Wiel, Iselin Medhaug, Annemarie H. Eckes, Amee O'Callaghan, Mike J. Newland, Sian R. Williams, Matthew Kasoar, Hella Elisa Wittmeier, and Valerie Kumer Hydrol. Earth Syst. Sci., 20, 2965-2973, doi:10.5194/hess-20-2965-2016, 2016 Scientific writing must improve and the key to long-term improvement of scientific writing lies with the early-career scientist (ECS). We introduce the ClimateSnack project, which aims to motivate ECSs to start writing groups around the world to improve their skills together. Writing groups offer many benefits but can be a challenge to keep going. Several ClimateSnack writing groups formed, and this paper examines why some of the groups flourished and others dissolved.

Beschreibung: River water quality changes in New Zealand over 26 years (1989–2014): Response to land use and land disturbance Jason P. Julian, Kirsten M. de Beurs, Braden Owsley, Robert J. Davies-Colley, and Anne-Gaelle E. Ausseil Hydrol. Earth Syst. Sci. Discuss., doi:10.5194/hess-2016-323,2016 Manuscript under review for HESS (discussion: open, 0 comments) New Zealand (NZ) is a natural laboratory for investigating water quality responses to land use change because its landscape is managed intensively. We interpreted water quality state and trends (1989–2014) of 77 river sites across NZ. We show that the greatest long-term impacts on river water quality in NZ have been densely stocked pastures (due to high nutrient inputs), followed by plantation forestry (due to sediment/nutrient runoff during harvesting).

Beschreibung: A post-wildfire response in cave dripwater chemistry Gurinder Nagra, Pauline C. Treble, Martin S. Andersen, Ian J. Fairchild, Katie Coleborn, and Andy Baker Hydrol. Earth Syst. Sci., 20, 2745-2758, doi:10.5194/hess-20-2745-2016, 2016 Our current understanding of wildfires on Earth is filled with knowledge gaps. One reason for this is our poor record of fire in natural archives. We open the possibility for speleothems to be "a missing piece to the fire-puzzle". We find by effecting surface evaporation and transpiration rates, wildfires can have a multi-year impact on speleothem, forming dripwater hydrology and chemistry. We open a new avenue for speleothems as potential palaeo-fire archives.

Beschreibung: Improving together: better science writing through peer learning Mathew A. Stiller-Reeve, Céline Heuzé, William T. Ball, Rachel H. White, Gabriele Messori, Karin van der Wiel, Iselin Medhaug, Annemarie H. Eckes, Amee O'Callaghan, Mike J. Newland, Sian R. Williams, Matthew Kasoar, Hella Elisa Wittmeier, and Valerie Kumer Hydrol. Earth Syst. Sci., 20, 2965-2973, doi:10.5194/hess-20-2965-2016, 2016 Scientific writing must improve and the key to long-term improvement of scientific writing lies with the early-career scientist (ECS). We introduce the ClimateSnack project, which aims to motivate ECSs to start writing groups around the world to improve their skills together. Writing groups offer many benefits but can be a challenge to keep going. Several ClimateSnack writing groups formed, and this paper examines why some of the groups flourished and others dissolved.

Beschreibung: Circumpolar polynya regions and ice production in the Arctic: Results from MODIS thermal infrared imagery for 2002/2003 to 2014/2015 with a regional focus on the Laptev Sea Andreas Preußer, Günther Heinemann, Sascha Willmes, and Stephan Paul The Cryosphere Discuss., doi:10.5194/tc-2016-133,2016 Manuscript under review for TC (discussion: open, 0 comments) Our study presents spatial and temporal characteristics of 16 prominent polynya regions over the entire Arctic basin. By using an energy balance model, we are able to derive daily thin-ice thickness distributions from satellite and atmospheric reanalysis data. All polynyas combined yield an average ice production of about 1444 km 3 per winter. Interestingly, we find distinct regional differences in calculated trends over the last 13 years. Finally, we set a special focus on the Laptev Sea region.

Beschreibung: Circumpolar polynya regions and ice production in the Arctic: Results from MODIS thermal infrared imagery for 2002/2003 to 2014/2015 with a regional focus on the Laptev Sea Andreas Preußer, Günther Heinemann, Sascha Willmes, and Stephan Paul The Cryosphere Discuss., doi:10.5194/tc-2016-133,2016 Manuscript under review for TC (discussion: open, 0 comments) Our study presents spatial and temporal characteristics of 16 prominent polynya regions over the entire Arctic basin. By using an energy balance model, we are able to derive daily thin-ice thickness distributions from satellite and atmospheric reanalysis data. All polynyas combined yield an average ice production of about 1444 km 3 per winter. Interestingly, we find distinct regional differences in calculated trends over the last 13 years. Finally, we set a special focus on the Laptev Sea region.

Beschreibung: Using video games for volcanic hazard education and communication: an assessment of the method and preliminary results Lara Mani, Paul D. Cole, and Iain Stewart Nat. Hazards Earth Syst. Sci., 16, 1673-1689, doi:10.5194/nhess-16-1673-2016, 2016 Here, we aim to better understand the potential for using video games in volcanic hazard education with at-risk communities. A study using a bespoke-designed video game – St. Vincent's Volcano – was trialled on the Caribbean island of St. Vincent in 2015. Preliminary data analysis demonstrates 94 % of study participants had an improved knowledge of volcanic hazards after playing the game, leading us to conclude that video games could be a logical progression for education and outreach activities.

Beschreibung: Debris flow impact estimation on a rigid barrier Federico Vagnon and Andrea Segalini Nat. Hazards Earth Syst. Sci., 16, 1691-1697, doi:10.5194/nhess-16-1691-2016, 2016 This study has the aim of reviewing the dynamics of debris flow impact against rigid structures and providing a new simple formulation to predict peak thrust. The proposed equation differs from other formulations because it takes into account flow characteristics, material properties, and barrier dimensions. The developed model is sufficiently capable of predicting measured force during the laboratory tests.

Beschreibung: Validation of Terrestrial Water Storage Variations as Simulated by Different Global Numerical Models with GRACE Satellite Observations Liangjing Zhang, Henryk Dobslaw, Tobias Stacke, Andreas Güntner, Robert Dill, and Maik Thomas Hydrol. Earth Syst. Sci. Discuss., doi:10.5194/hess-2016-330,2016 Manuscript under review for HESS (discussion: open, 0 comments) Global numerical models perform differently as has been found in some model intercomparison studies, which mainly focused on components as evapotranspiration, soil moisture or runoff. We have applied terrestrial water storage that is estimated from state-of-art post-processing method to validate four global numerical models and try to identify the advantages and deficiencies of a certain model. GRACE based TWS demonstrates its additional benefits to improve models in future.

Beschreibung: A practical approach to lake water density from electrical conductivity and temperature Santiago Moreira, Martin Schultze, Karsten Rahn, and Bertram Boehrer Hydrol. Earth Syst. Sci., 20, 2975-2986, doi:10.5194/hess-20-2975-2016, 2016 Density calculations in lakes are essential in the study of stability, stratification and numerical modelling. However, density equations which use fixed constant coefficients are still common in use, despite their limitations. We present a practical approach which can specifically include the effect of dissolved substances by fitting two coefficients. The method has been tested against density equations and density measurements in lakes.

Beschreibung: Validation of Terrestrial Water Storage Variations as Simulated by Different Global Numerical Models with GRACE Satellite Observations Liangjing Zhang, Henryk Dobslaw, Tobias Stacke, Andreas Güntner, Robert Dill, and Maik Thomas Hydrol. Earth Syst. Sci. Discuss., doi:10.5194/hess-2016-330,2016 Manuscript under review for HESS (discussion: open, 0 comments) Global numerical models perform differently as has been found in some model intercomparison studies, which mainly focused on components as evapotranspiration, soil moisture or runoff. We have applied terrestrial water storage that is estimated from state-of-art post-processing method to validate four global numerical models and try to identify the advantages and deficiencies of a certain model. GRACE based TWS demonstrates its additional benefits to improve models in future.

Beschreibung: Model Study on Potential Contributions of the Proposed Huangpu Gate to Flood Control in Taihu Lake Basin Hanghui Zhang, Shuguang Liu, Jianchun Ye, and Pat Yeh Hydrol. Earth Syst. Sci. Discuss., doi:10.5194/hess-2016-310,2016 Manuscript under review for HESS (discussion: open, 0 comments) The Taihu Lake basin is located in the hinterland of the Yangtze River Delta. Constructing a gate at the mouth of the Huangpu River is considered one of the effective solutions to the basin's flooding problems. The pattern of river flow changes from bi-directional to unidirectional flow when the estuary gate is operated. It is concluded that the Huangpu River with a proposed gate is more effective than a natural channel, and its beneficiaries include the lake and the related surrounding areas.

Beschreibung: Model Study on Potential Contributions of the Proposed Huangpu Gate to Flood Control in Taihu Lake Basin Hanghui Zhang, Shuguang Liu, Jianchun Ye, and Pat Yeh Hydrol. Earth Syst. Sci. Discuss., doi:10.5194/hess-2016-310,2016 Manuscript under review for HESS (discussion: open, 0 comments) The Taihu Lake basin is located in the hinterland of the Yangtze River Delta. Constructing a gate at the mouth of the Huangpu River is considered one of the effective solutions to the basin's flooding problems. The pattern of river flow changes from bi-directional to unidirectional flow when the estuary gate is operated. It is concluded that the Huangpu River with a proposed gate is more effective than a natural channel, and its beneficiaries include the lake and the related surrounding areas.

Beschreibung: Radiocarbon dating of glacier ice Chiara Uglietti, Alexander Zapf, Theo M. Jenk, Sönke Szidat, Gary Salazar, and Margit Schwikowski The Cryosphere Discuss., doi:10.5194/tc-2016-160,2016 Manuscript under review for TC (discussion: open, 0 comments) A meaningful interpretation of the climatic history contained in ice cores requires a precise chronology. For dating the older and deeper part of the glaciers, radiocarbon analysis can be used, when organic matter such as plant or insect fragments is found in the ice. Since this happens rarely, a complementary dating tool is based on radiocarbon dating of the insoluble fraction of carbonaceous aerosols entrapped in the ice, allowing dating ice with ages between 200 and more than 10 000 years.

Beschreibung: Hydrological modeling in glacierized catchments of Central Asia: status and challenges Yaning Chen, Weihong Li, Gonghuan Fang, and Zhi Li Hydrol. Earth Syst. Sci. Discuss., doi:10.5194/hess-2016-325,2016 Manuscript under review for HESS (discussion: open, 0 comments) This paper reviews the status of hydrological modeling in the mountainous region of Central Asia, discussing the limitations of the available models and shedding light on future directions. We conclude that the main sources of uncertainty in hydrological modeling are the input uncertainty and lack of understanding of the hydrological regimes. Future focuses should be on the use of multi-source of input data combined with multi-objective calibration and validation.

Beschreibung: Consequences and mitigation of saltwater intrusion induced by short-circuiting during aquifer storage and recovery (ASR) in a coastal subsurface Koen Gerardus Zuurbier and Pieter Jan Stuyfzand Hydrol. Earth Syst. Sci. Discuss., doi:10.5194/hess-2016-343,2016 Manuscript under review for HESS (discussion: open, 0 comments) The subsurface is increasingly perforated for exploitation of water and energy. This has increased the risk of leakage between originally separated aquifers. It is shown how this leakage can have a very negative impact on the recovery of freshwater during aquifer storage and recovery (ASR) in brackish-saline aquifers. Deep interception of intruding brackish-saline water can mitigate the negative effects and buoyancy of freshwater to some extent, but not completely.

Beschreibung: Monitoring surface water quality using social media in the context of citizen science Hang Zheng, Hong Yang, Di Long, and Hua Jing Hydrol. Earth Syst. Sci. Discuss., doi:10.5194/hess-2016-359,2016 Manuscript under review for HESS (discussion: open, 0 comments) Do you feel angry if the river in your living place is polluted by industries? Do you want to do something to save your environment? Just log in http://www.thuhjjc.com and use the Tsinghua Environment Monitoring Platform (TEMP) to photograph the water pollution actives and make your report. This study established a social media platform to monitor and report surface water quality. The effectiveness of the platform was demonstrated by the 265 water quality reports across 29 provinces in China.

Beschreibung: Consequences and mitigation of saltwater intrusion induced by short-circuiting during aquifer storage and recovery (ASR) in a coastal subsurface Koen Gerardus Zuurbier and Pieter Jan Stuyfzand Hydrol. Earth Syst. Sci. Discuss., doi:10.5194/hess-2016-343,2016 Manuscript under review for HESS (discussion: open, 0 comments) The subsurface is increasingly perforated for exploitation of water and energy. This has increased the risk of leakage between originally separated aquifers. It is shown how this leakage can have a very negative impact on the recovery of freshwater during aquifer storage and recovery (ASR) in brackish-saline aquifers. Deep interception of intruding brackish-saline water can mitigate the negative effects and buoyancy of freshwater to some extent, but not completely.

Beschreibung: Wave climate in the Arctic 1992–2014: seasonality and trends Justin E. Stopa, Fabrice Ardhuin, and Fanny Girard-Ardhuin The Cryosphere, 10, 1605-1629, doi:10.5194/tc-10-1605-2016, 2016 Satellite observations show the Arctic sea ice has decreased the last 30 years. From our wave model hindcast and satellite altimeter datasets we observe profound increasing wave heights, which are caused by the loss of sea ice and not the driving winds. If ice-free conditions persist later into fall, then regions like the Beaufort–Chukchi Sea will be prone to developing larger waves since the driving winds are strong this time of year.

Beschreibung: Microstructure representation of snow in coupled snowpack and microwave emission models Melody Sandells, Richard Essery, Nick Rutter, Leanne Wake, Leena Leppänen, and Juha Lemmetyinen The Cryosphere Discuss., doi:10.5194/tc-2016-181,2016 Manuscript under review for TC (discussion: open, 0 comments) This study looks at a wide range of options for simulating sensor signals for satellite monitoring of water stored as snow, though an ensemble of 1323 coupled snow evolution and microwave scattering models. The greatest improvements will be made with better computer simulations of how the snow microstructure changes, followed by how the microstructure scatters radiation at microwave frequencies. Snow compaction should also be considered in systems to monitor snow mass from space.

Beschreibung: Brief communication: Organochlorine pesticides in an archived firn core from Law Dome, East Antarctica Marie Bigot, Mark A. J. Curran, Andrew D. Moy, Derek C. G. Muir, Darryl W. Hawker, Roger Cropp, Camilla F. Teixeira, and Susan Bengtson Nash The Cryosphere Discuss., doi:10.5194/tc-2016-178,2016 Manuscript under review for TC (discussion: open, 0 comments) Organochlorine pesticides (OCPs) were, for the first time, quantified in archived firn cores from the East Antarctic ice sheet representative of 1945–1957 C.E. and 1958–1967 C.E. The core sections were melted under high purity nitrogen atmosphere and the melt water analysed. Methods allowed quantification of hexachlorocyclohexanes, heptachlor, trans-chlordane, dieldrin and endrin. While the core presented evidence of nominal modern-use chemical contamination, indicating handling and/or storage contamination, legacy OCP concentrations and deposition rates reported are orders of magnitude lower than those from Arctic regions, lending support for their validity. The study further provides a description of equipment used and suggests adapted methods to overcome logistical challenges associated with trace organic contaminant detection in Polar Regions.

Beschreibung: The European 2015 drought from a hydrological perspective Gregor Laaha, Tobias Gauster, Lena M. Tallaksen, Jean-Philippe Vidal, Kerstin Stahl, Christel Prudhomme, Benedikt Heudorfer, Radek Vlnas, Monica Ionita, Henny A. J. Van Lanen, Mary-Jeanne Adler, Laurie Caillouet, Claire Delus, Miriam Fendekova, Sebastien Gailliez, Jamie Hannaford, Daniel Kingston, Anne F. Van Loon, Luis Mediero, Marzena Osuch, Renata Romanowicz, Eric Sauquet, James H. Stagge, and Wai K. Wong Hydrol. Earth Syst. Sci. Discuss., doi:10.5194/hess-2016-366,2016 Manuscript under review for HESS (discussion: open, 0 comments) In 2015 large parts of Europe were affected by a drought. In terms of low flow magnitude, a region around the Czech Republic was most affected with annual low flows that exhibited return intervals of 100 years and more. In terms of deficit volumes, the geographical centre of the event was in the area of Southern Germany where the drought lasted particularly long. For an assessment of drought impacts on water resources hydrological data is required in addition to the hydro-meteorological indices.

Beschreibung: Hydrological threats for riparian wetlands of international importance – a global quantitative and qualitative analysis Christof Schneider, Martina Flörke, Lucia De Stefano, and Jacob D. Petersen-Perlman Hydrol. Earth Syst. Sci. Discuss., doi:10.5194/hess-2016-350,2016 Manuscript under review for HESS (discussion: open, 0 comments) Riparian wetlands are disappearing worldwide due to altered river hydrology. The WaterGAP3 model is used to compare modified to natural flow regimes at 93 Ramsar sites. Results show that water resource management seriously impairs inundation patterns at 29 % of the sites. New dam initiatives are likely to affect especially wetlands located in South America, Africa, Asia and the Balkan Peninsula. Hotspots for climate change impacts could be Eastern Europe and South America.

Beschreibung: Response of water temperatures and stratification to changing climate in three lakes with different morphometry Madeline R. Magee and Chin H. Wu Hydrol. Earth Syst. Sci. Discuss., doi:10.5194/hess-2016-262,2016 Manuscript under review for HESS (discussion: open, 0 comments) Water temperatures and stratification in three morphometrically different lakes over the century are examined. It is found that surface temperatures increased, bottom temperatures decreased, and duration of the stratified increased. Abrupt changes in latent heat flux appear to be independent of morphometry, indicating that the timing of change is driven by climate. Increasing air temperature warmed bottom waters while decreasing wind speed cooled bottom waters, suggesting that the change of bott

Beschreibung: The European 2015 drought from a hydrological perspective Gregor Laaha, Tobias Gauster, Lena M. Tallaksen, Jean-Philippe Vidal, Kerstin Stahl, Christel Prudhomme, Benedikt Heudorfer, Radek Vlnas, Monica Ionita, Henny A. J. Van Lanen, Mary-Jeanne Adler, Laurie Caillouet, Claire Delus, Miriam Fendekova, Sebastien Gailliez, Jamie Hannaford, Daniel Kingston, Anne F. Van Loon, Luis Mediero, Marzena Osuch, Renata Romanowicz, Eric Sauquet, James H. Stagge, and Wai K. Wong Hydrol. Earth Syst. Sci. Discuss., doi:10.5194/hess-2016-366,2016 Manuscript under review for HESS (discussion: open, 0 comments) In 2015 large parts of Europe were affected by a drought. In terms of low flow magnitude, a region around the Czech Republic was most affected with annual low flows that exhibited return intervals of 100 years and more. In terms of deficit volumes, the geographical centre of the event was in the area of Southern Germany where the drought lasted particularly long. For an assessment of drought impacts on water resources hydrological data is required in addition to the hydro-meteorological indices.

Beschreibung: Insights into the water mean transit time in a high-elevation tropical ecosystem Giovanny M. Mosquera, Catalina Segura, Kellie B. Vaché, David Windhorst, Lutz Breuer, and Patricio Crespo Hydrol. Earth Syst. Sci., 20, 2987-3004, doi:10.5194/hess-20-2987-2016, 2016 This study focuses on the investigation of baseflow mean transit times (MTTs) in a high-elevation tropical ecosystem (páramo) using stable water isotopes. Results showed short MTTs (

Beschreibung: Leaf-scale experiments reveal important omission in the Penman-Monteith equation Stanislaus J. Schymanski and Dani Or Hydrol. Earth Syst. Sci. Discuss., doi:10.5194/hess-2016-363,2016 Manuscript under review for HESS (discussion: open, 0 comments) Most of the rain falling on land is returned to the atmosphere by plant leaves, which release water vapour (transpire) through tiny pores. To better understand this process, we used artificial leaves in a special wind tunnel and discovered major problems with an established approach (PM equation), widely used to quantify transpiration and its sensitivity to climate change. We present an improved set of equations, consistent with experiments and displaying more realistic climate sensitivity.

Beschreibung: Identifying water deficit and vegetation response during the 2009/10 drought over North China: Implications for the South-to-North Water Diversion project Bowen Zhu, Xianhong Xie, and Kang Zhang Hydrol. Earth Syst. Sci. Discuss., doi:10.5194/hess-2016-313,2016 Manuscript under review for HESS (discussion: open, 0 comments) This study attempts to identify water deficit using GRACE data and vegetation response during the 2009/10 drought over North China. There was a decling trend in total water storage for the past decade based on GRACE data, and the regional deficit of water storage was approximately 25 km 3 in 2009/10. This drought event has led to suppression of vegetation growth in North China. The SNWD project may ease the water storage deficit in North China for this level of drought intensity.

Beschreibung: Hydrological threats for riparian wetlands of international importance – a global quantitative and qualitative analysis Christof Schneider, Martina Flörke, Lucia De Stefano, and Jacob D. Petersen-Perlman Hydrol. Earth Syst. Sci. Discuss., doi:10.5194/hess-2016-350,2016 Manuscript under review for HESS (discussion: open, 0 comments) Riparian wetlands are disappearing worldwide due to altered river hydrology. The WaterGAP3 model is used to compare modified to natural flow regimes at 93 Ramsar sites. Results show that water resource management seriously impairs inundation patterns at 29 % of the sites. New dam initiatives are likely to affect especially wetlands located in South America, Africa, Asia and the Balkan Peninsula. Hotspots for climate change impacts could be Eastern Europe and South America.

Beschreibung: Assessment of land use impact on hydraulic threshold conditions for gully head cut initiation Aliakbar Nazari Samani, Qiuwen Chen, Shahram Khalighi, Robert James Wasson, and Mohammad Reza Rahdari Hydrol. Earth Syst. Sci., 20, 3005-3012, doi:10.5194/hess-20-3005-2016, 2016 We hypothesized that land use had important effects on hydraulic threshold conditions for gully head cut initiation. We investigated the effects using an experimental plot. The results indicated that the use of a threshold value of τ cr  = 35  dyne cm −2 and ω u  = 0.4 Cm S −1 in physically based soil erosion models is susceptible to high uncertainty when assessing gully erosion.

Beschreibung: Numerical Solution and Application of Time-Space Fractional Governing Equations of One-Dimensional Unsteady Open Channel Flow Process Ali Ercan and M. Levent Kavvas Hydrol. Earth Syst. Sci. Discuss., doi:10.5194/hess-2016-364,2016 Manuscript under review for HESS (discussion: open, 0 comments) A finite difference numerical approach is proposed to solve the time-space fractional governing equations of one-dimensional unsteady/non-uniform open channel flow process. Numerical simulations showed that flow discharge and water depth can exhibit heavier tails in downstream locations as space and time fractional derivative powers decrease from 1. The fractional governing equations under consideration are generalizations of the well-known Saint Venant equations.

Beschreibung: Vegetative impacts upon bedload transport capacity and channel stability for differing alluvial planforms in the Yellow River source zone Zhi Wei Li, Guo An Yu, Gary Brierley, and Zhao Yin Wang Hydrol. Earth Syst. Sci., 20, 3013-3025, doi:10.5194/hess-20-3013-2016, 2016 Influence of vegetation upon bedload transport and channel morphodynamics is examined along a channel stability gradient ranging from meandering to anabranching to anabranching–braided to fully braided planform conditions along trunk and tributary reaches of the Yellow River source zone in western China. This innovative work reveals complex interactions between channel planform, bedload transport capacity, sediment supply in the flood season, and the hydraulic role of vegetation.

Beschreibung: Mekong River flow and hydrological extremes under climate change Long Phi Hoang, Hannu Lauri, Matti Kummu, Jorma Koponen, Michelle T. H. van Vliet, Iwan Supit, Rik Leemans, Pavel Kabat, and Fulco Ludwig Hydrol. Earth Syst. Sci., 20, 3027-3041, doi:10.5194/hess-20-3027-2016, 2016 We modelled hydrological changes under climate change in the Mekong River, focusing on extreme events. The scenario ensemble shows an intensification of the hydrological cycle under climate change. Annual river flow increases between 5 and 16 % depending on locations. Extreme high flows increase substantially in both magnitude and frequency, posing threats to flood safety in the basin. Extreme low-flow events are projected to reduce as a result of increased river flow during the dry season.

Beschreibung: On the non-stationarity of hydrological response in anthropogenically unaffected catchments: An Australian perspective Hoori Ajami, Ashish sharma, Lawrence E. Band, Jason P. Evans, Narendra K. Tuteja, G. E. Amirthanathan, and Mohammed A. Bari Hydrol. Earth Syst. Sci. Discuss., doi:10.5194/hess-2016-353,2016 Manuscript under review for HESS (discussion: open, 0 comments) We present the first data-based framework for explaining why catchments behave in a non-stationary manner, even when they are unaffected by deforestation or urbanization. The role of vegetation dynamics on stream flow are indicated by similar or greater sensitivity of annual runoff ratio to annual fractional vegetation cover. We formulated a novel ecohydrologic catchment classification framework that incorporates the role of vegetation dynamics on catchment scale water partitioning.

Beschreibung: Using rainfall thresholds and ensemble precipitation forecasts to issue and improve urban inundation alerts Tsun-Hu Yang, Gong-Do Hwang, Chin-Cheng Tsai, and Jui-Yi Ho Hydrol. Earth Syst. Sci. Discuss., doi:10.5194/hess-2016-340,2016 Manuscript under review for HESS (discussion: open, 0 comments) Taiwan continues to suffer from floods. This study proposes the integration of rainfall thresholds and ensemble precipitation forecasts to provide probabilistic urban inundation forecasts. Utilization of ensemble precipitation forecasts can extend forecast lead times to 72%thinsp;h, preceding peak flows and allowing response agencies to take necessary preparatory measures. This study also develops a hybrid of real-time observation and rainfall forecasts to improve the first 24-h inundation forecasts.

Beschreibung: Statistical indicators of Arctic sea-ice stability – prospects and limitations Sebastian Bathiany, Bregje van der Bolt, Mark S. Williamson, Timothy M. Lenton, Marten Scheffer, Egbert H. van Nes, and Dirk Notz The Cryosphere, 10, 1631-1645, doi:10.5194/tc-10-1631-2016, 2016 We examine if a potential "tipping point" in Arctic sea ice, causing abrupt and irreversible sea-ice loss, could be foreseen with statistical early warning signals. We assess this idea by using several models of different complexity. We find robust and consistent trends in variability that are not specific to the existence of a tipping point. While this makes an early warning impossible, it allows to estimate sea-ice variability from only short observational records or reconstructions.

Beschreibung: Statistical indicators of Arctic sea-ice stability – prospects and limitations Sebastian Bathiany, Bregje van der Bolt, Mark S. Williamson, Timothy M. Lenton, Marten Scheffer, Egbert H. van Nes, and Dirk Notz The Cryosphere, 10, 1631-1645, doi:10.5194/tc-10-1631-2016, 2016 We examine if a potential "tipping point" in Arctic sea ice, causing abrupt and irreversible sea-ice loss, could be foreseen with statistical early warning signals. We assess this idea by using several models of different complexity. We find robust and consistent trends in variability that are not specific to the existence of a tipping point. While this makes an early warning impossible, it allows to estimate sea-ice variability from only short observational records or reconstructions.

Beschreibung: Enhancing local action planning through quantitative flood risk analysis: a case study in Spain Jesica Tamara Castillo-Rodríguez, Ignacio Escuder-Bueno, Sara Perales-Momparler, and Juan Ramón Porta-Sancho Nat. Hazards Earth Syst. Sci., 16, 1699-1718, doi:10.5194/nhess-16-1699-2016, 2016 This article presents a method to incorporate and promote quantitative flood risk analysis to support local action planning against flooding. The conducted research work aims at providing a framework for local flood risk analysis and to support risk-informed decision-making (e.g. urban planning and development, flood risk management, civil protection). This article shows the added value of a risk-informed perspective, applied to a real case study in Spain.

Beschreibung: Meteorological factors driven glacial till changing and the associated periglacial debris flows in Tianmo Valley, southeast Tibetan Plateau Mingfeng Deng, Ningsheng Chen, and Mei Liu Nat. Hazards Earth Syst. Sci. Discuss., doi:10.5194/nhess-2016-251,2016 Manuscript under review for NHESS (discussion: open, 0 comments) Initiation of deris flows in Tianmo valley shows annual temperature spiked and glacier retreat quickly before the three debris flows, while they did not occur when glacier retreat is sharpest, resulting from the bared glacial till is frozen as the melting of internal ice lags behind glacial retreat. The activity of the glacial till can be enhanced by prolonged high air temperature. Finally, either rainfall or continuous percolation of ice ablation water flows can generate periglacial debris flows.

Beschreibung: Meteorological factors driven glacial till changing and the associated periglacial debris flows in Tianmo Valley, southeast Tibetan Plateau Mingfeng Deng, Ningsheng Chen, and Mei Liu Nat. Hazards Earth Syst. Sci. Discuss., doi:10.5194/nhess-2016-251,2016 Manuscript under review for NHESS (discussion: open, 0 comments) Initiation of deris flows in Tianmo valley shows annual temperature spiked and glacier retreat quickly before the three debris flows, while they did not occur when glacier retreat is sharpest, resulting from the bared glacial till is frozen as the melting of internal ice lags behind glacial retreat. The activity of the glacial till can be enhanced by prolonged high air temperature. Finally, either rainfall or continuous percolation of ice ablation water flows can generate periglacial debris flows.

Beschreibung: Analysis of slope processes in the Vallcebre landslide (Eastern Pyrenees, Spain) by means of Cross Correlation Function applied to high frequency monitoring data Marco Mulas, Jordi Corominas, Alessandro Corsini, and Jose Moya Nat. Hazards Earth Syst. Sci. Discuss., doi:10.5194/nhess-2016-253,2016 Manuscript under review for NHESS (discussion: open, 0 comments) In this work, the Cross-Correlation Function is used in order to quantitatively investigate the time-lagged correlation between high frequency monitoring data on rainfall, piezometric and displacement with the objective to evidence hydro-mechanical processes in the Vallcebre landslide (Eastern Pyrenees, Spain). The analysis highlighted and constrained in time a dual triggering mechanism in which factors controlling movement change from the upper to the lower part of the landslide.

Beschreibung: Analysis of slope processes in the Vallcebre landslide (Eastern Pyrenees, Spain) by means of Cross Correlation Function applied to high frequency monitoring data Marco Mulas, Jordi Corominas, Alessandro Corsini, and Jose Moya Nat. Hazards Earth Syst. Sci. Discuss., doi:10.5194/nhess-2016-253,2016 Manuscript under review for NHESS (discussion: open, 0 comments) In this work, the Cross-Correlation Function is used in order to quantitatively investigate the time-lagged correlation between high frequency monitoring data on rainfall, piezometric and displacement with the objective to evidence hydro-mechanical processes in the Vallcebre landslide (Eastern Pyrenees, Spain). The analysis highlighted and constrained in time a dual triggering mechanism in which factors controlling movement change from the upper to the lower part of the landslide.

Beschreibung: Enhancing local action planning through quantitative flood risk analysis: a case study in Spain Jesica Tamara Castillo-Rodríguez, Ignacio Escuder-Bueno, Sara Perales-Momparler, and Juan Ramón Porta-Sancho Nat. Hazards Earth Syst. Sci., 16, 1699-1718, doi:10.5194/nhess-16-1699-2016, 2016 This article presents a method to incorporate and promote quantitative flood risk analysis to support local action planning against flooding. The conducted research work aims at providing a framework for local flood risk analysis and to support risk-informed decision-making (e.g. urban planning and development, flood risk management, civil protection). This article shows the added value of a risk-informed perspective, applied to a real case study in Spain.

Beschreibung: Contrasting transit times of water from peatlands and eucalypt forests in the Australian Alps determined by tritium: implications for vulnerability and the source of water in upland catchments I. Cartwright and U. Morgenstern Hydrol. Earth Syst. Sci. Discuss., doi:10.5194/hess-2016-361,2016 Manuscript under review for HESS (discussion: open, 0 comments) This research determines timescales over which water is stored in peatlands and adjacent eucalyptus forest catchments in upland river systems in southeast Australia using tritium. The mean transit times in the peatland catchments were in many cases less than one year which contrasts with the longer transit times (years to decades) in the eucalyptus catchments. The results indicate that the peat is susceptible to drying which renders it vulnerable to degradation and bushfire.

Beschreibung: Effect of restoration vegetation on the stochasticity of soil erosion in a semi-arid environment Ji Zhou, Bojie Fu, Guangyao Gao, Yihe Lü, and Shuai Wang Hydrol. Earth Syst. Sci. Discuss., doi:10.5194/hess-2016-386,2016 Manuscript under review for HESS (discussion: open, 0 comments) By monitoring soil erosion in the Loess Plateau, we constructed an integrated analysis system to quantify the stochasticity of environment, found that the morphological structures in vegetation types are the source of different stochasticities of soil erosion, and proved that Poisson model is fit for predicting erosion stochasticity at larger temporal scale. This study could be meaningful for the selection of restoration vegetation for conserving soil and water resources in the Loess Plateau.

Beschreibung: Signature of Arctic first-year ice melt pond fraction in X-band SAR imagery Ane S. Fors, Dmitry V. Divine, Anthony P. Doulgeris, Angelika H. H. Renner, and Sebastian Gerland The Cryosphere Discuss., doi:10.5194/tc-2016-125,2016 Manuscript under review for TC (discussion: open, 0 comments) This paper investigates the signature of melt ponds in satellite borne synthetic aperture radar (SAR) imagery. The study shows that polarimetric X-band SAR can be used to extract melt pond fraction from drifting first-year sea ice, and discusses the influence of factors like wind speed, SAR incidence angle and instrument noise floor. Melt ponds strongly influence the Arctic sea ice energy budget, and the results imply prospective opportunities for expanded monitoring of melt ponds from space.

Beschreibung: Sustainability of water uses in managed hydrosystems: human- and climate-induced changes for the mid-21st century Julie Fabre, Denis Ruelland, Alain Dezetter, and Benjamin Grouillet Hydrol. Earth Syst. Sci., 20, 3129-3147, doi:10.5194/hess-20-3129-2016, 2016 We assess the sustainability of planned water uses in complex mesoscale river basins by modeling water demand and availability under climatic and anthropogenic changes. We present an analysis through indicators that relate to water management goals. The impacts of climate projections on both water availability and demand question the water allocations and environmental constraints currently planned for the coming decades. This work brings an essential long-term perspective to water sharing plans.

Beschreibung: Greenland annual accumulation along the EGIG line, 1959–2004, from ASIRAS airborne radar and neutron-probe density measurements Thomas B. Overly, Robert L. Hawley, Veit Helm, Elizabeth M. Morris, and Rohan N. Chaudhary The Cryosphere, 10, 1679-1694, doi:10.5194/tc-10-1679-2016, 2016 We demonstrate that snow accumulation rates across the Greenland Ice Sheet, determined from RADAR layers and modeled snow density profiles, are identical to ground-based measurements of snow accumulation. Three regional climate models underestimate snow accumulation compared to RADAR layer estimates. Using RADAR increases spatial coverage and improves accuracy of snow accumulation estimates. Incorporating our results into climate models may reduce uncertainty of sea-level rise estimates.

Beschreibung: Greenland annual accumulation along the EGIG line, 1959–2004, from ASIRAS airborne radar and neutron-probe density measurements Thomas B. Overly, Robert L. Hawley, Veit Helm, Elizabeth M. Morris, and Rohan N. Chaudhary The Cryosphere, 10, 1679-1694, doi:10.5194/tc-10-1679-2016, 2016 We demonstrate that snow accumulation rates across the Greenland Ice Sheet, determined from RADAR layers and modeled snow density profiles, are identical to ground-based measurements of snow accumulation. Three regional climate models underestimate snow accumulation compared to RADAR layer estimates. Using RADAR increases spatial coverage and improves accuracy of snow accumulation estimates. Incorporating our results into climate models may reduce uncertainty of sea-level rise estimates.

Beschreibung: Lightning risk assessment at a high spatial resolution using the resident sub-district scale: A case study in Beijing metropolitan areas Hai Bo Hu and Jing Xiao Li Nat. Hazards Earth Syst. Sci. Discuss., doi:10.5194/nhess-2016-231,2016 Manuscript under review for NHESS (discussion: open, 0 comments) Lightning risk indexes identifying the potential number of dangerous lightning events (NDLEs) and ground sensitivity to lightning in resident sub-districts of Beijing metropolitan areas have been unprecedentedly estimated on a 5 m resolution grid. The gridded cloud to ground (CG) lightning stroke density was used in the NDLE calculation, on account of multiple contacts formed by CG lightning flash multiplicity. Meanwhile, in the NDLE estimates, the critical CG stroke gridded densities derived from the lightning location system (LLS) data were corrected for network detection efficiency (DE). This case study on resident sub-district indicates that the site-specific sensitivity to lightning, which is determined by the terrain factors related to lightning attachment, as well as lightning rod effects induced by nearby structures, differs greatly across types of underlying ground areas. The discrepancy of the NDLE which is the numerical product of sensitivity and CG stroke density, is predominated by the sensitivity on account of the relatively stationary CG stroke density in a resident sub-district scale. Conclusively, the visualization of lightning risk sensitivity and NDLE discrepancy in parts of a resident sub-district at high spatial resolution makes it convenient in risk reduction and risk control for lightning risk management.

Beschreibung: Modeling liquid water transport in snow under rain-on-snow conditions – considering preferential flow Sebastian Würzer, Nander Wever, Roman Juras, Michael Lehning, and Tobias Jonas Hydrol. Earth Syst. Sci. Discuss., doi:10.5194/hess-2016-351,2016 Manuscript under review for HESS (discussion: open, 0 comments) We discuss a dual-domain water transport model in a physics based snowpack model to account for preferential flow (PF) in addition to matrix flow. Yet so far no operationally used snow model was explicitly accounting for PF. The new approach is compared to existing water transport models and validated against in-situ data from sprinkling and natural rain-on-snow (ROS) events. Our work demonstrates the benefit of considering PF in modeling hourly snowpack runoff, especially during ROS conditions.

Beschreibung: Modeling liquid water transport in snow under rain-on-snow conditions – considering preferential flow Sebastian Würzer, Nander Wever, Roman Juras, Michael Lehning, and Tobias Jonas Hydrol. Earth Syst. Sci. Discuss., doi:10.5194/hess-2016-351,2016 Manuscript under review for HESS (discussion: open, 0 comments) We discuss a dual-domain water transport model in a physics based snowpack model to account for preferential flow (PF) in addition to matrix flow. Yet so far no operationally used snow model was explicitly accounting for PF. The new approach is compared to existing water transport models and validated against in-situ data from sprinkling and natural rain-on-snow (ROS) events. Our work demonstrates the benefit of considering PF in modeling hourly snowpack runoff, especially during ROS conditions.

Beschreibung: Vulnerability curves vs. vulnerability indicators: application of an indicator-based methodology for debris-flow hazards Maria Papathoma-Köhle Nat. Hazards Earth Syst. Sci., 16, 1771-1790, doi:10.5194/nhess-16-1771-2016, 2016 Two established methods for assessing the physical vulnerability of buildings to natural hazards (vulnerability indicators and vulnerability curves) are compared after beind applied at the same case study. The case study area is located in South Tyrol (Italy) and it is subject to debris flow hazard. The results indicate that both methods have advantages and disadvantages and should be used in combination rather than in isolation by practitioners.

Beschreibung: VISIR: technological infrastructure of an operational service for safe and efficient navigation in the Mediterranean Sea Gianandrea Mannarini, Giuseppe Turrisi, Alessandro D'Anca, Mario Scalas, Nadia Pinardi, Giovanni Coppini, Francesco Palermo, Ivano Carluccio, Matteo Scuro, Sergio Cretì, Rita Lecci, Paola Nassisi, and Luca Tedesco Nat. Hazards Earth Syst. Sci., 16, 1791-1806, doi:10.5194/nhess-16-1791-2016, 2016 Safety and efficiency of navigation can be enhanced through a better situational awareness at sea. We designed and realized an operational infrastructure for providing the navigators with optimal routes through various devices: PC, tablets, and smartphones. Sea-state and wind forecasts are used as inputs. Both motor- and sailboat routes are addressed by VISIR.

Beschreibung: What if the 25 October 2011 event that struck Cinque Terre (Liguria) had happened in Genoa, Italy? Flooding scenarios, hazard mapping and damage estimation Francesco Silvestro, Nicola Rebora, Lauro Rossi, Daniele Dolia, Simone Gabellani, Flavio Pignone, Eva Trasforini, Roberto Rudari, Silvia De Angeli, and Cristiano Masciulli Nat. Hazards Earth Syst. Sci., 16, 1737-1753, doi:10.5194/nhess-16-1737-2016, 2016 During the autumn of 2011 two catastrophic, very intense rainfall events affected two different parts of the Liguria Region of Italy causing various flash floods. The first occurred in October and the second at the beginning of November. Both the events were characterized by very high rainfall intensities (〉 100 mm h −1 ) that persisted on a small portion of territory causing local huge rainfall accumulations (〉 400 mm 6 h −1 ). Two main considerations were made in order to set up this work. The first consideration is that various studies demonstrated that the two events had a similar genesis and similar triggering elements. The second very evident and coarse concern is that two main elements are needed to have a flash flood: a very intense and localized rainfall event and a catchment (or a group of catchments) to be affected. Starting from these assumptions we did the exercise of mixing the two flash flood ingredients by putting the rainfall field of the first event on the main catchment struck by the second event, which has its mouth in the biggest city of the Liguria Region: Genoa. A complete framework was set up to quantitatively carry out a “what if” experiment with the aim of evaluating the possible damages associated with this event. A probabilistic rainfall downscaling model was used to generate possible rainfall scenarios maintaining the main characteristics of the observed rainfall fields while a hydrological model transformed these rainfall scenarios in streamflow scenarios. A subset of streamflow scenarios is then used as input to a 2-D hydraulic model to estimate the hazard maps, and finally a proper methodology is applied for damage estimation. This leads to the estimation of the potential economic losses and of the risk level for the people that stay in the affected area. The results are interesting, surprising and in a way worrying: a rare but not impossible event (it occurred about 50 km away from Genoa) would have caused huge damages estimated between 120 and EUR 230 million for the affected part of the city of Genoa, Italy, and more than 17 000 potentially affected people.

Beschreibung: The unrest of the San Miguel volcano (El Salvador, Central America): installation of the monitoring network and observed volcano-tectonic ground deformation Alessandro Bonforte, Douglas Antonio Hernandez, Eduardo Gutiérrez, Louis Handal, Cecilia Polío, Salvatore Rapisarda, and Piergiorgio Scarlato Nat. Hazards Earth Syst. Sci., 16, 1755-1769, doi:10.5194/nhess-16-1755-2016, 2016 In this paper, we present the work done during an international cooperation between Italy and El Salvador, for implementing the multiparametric monitoring of the San Miguel volcano in El Salvador after its sudden unrest. In particular, the aim of this paper is to show and describe the installed geodetic network and to show, comment and interpret the very first detailed ground deformation data obtained on this volcano during an unrest period, useful for characterizing its unknown dynamics.

Beschreibung: Vulnerability curves vs. vulnerability indicators: application of an indicator-based methodology for debris-flow hazards Maria Papathoma-Köhle Nat. Hazards Earth Syst. Sci., 16, 1771-1790, doi:10.5194/nhess-16-1771-2016, 2016 Two established methods for assessing the physical vulnerability of buildings to natural hazards (vulnerability indicators and vulnerability curves) are compared after beind applied at the same case study. The case study area is located in South Tyrol (Italy) and it is subject to debris flow hazard. The results indicate that both methods have advantages and disadvantages and should be used in combination rather than in isolation by practitioners.

Beschreibung: VISIR: technological infrastructure of an operational service for safe and efficient navigation in the Mediterranean Sea Gianandrea Mannarini, Giuseppe Turrisi, Alessandro D'Anca, Mario Scalas, Nadia Pinardi, Giovanni Coppini, Francesco Palermo, Ivano Carluccio, Matteo Scuro, Sergio Cretì, Rita Lecci, Paola Nassisi, and Luca Tedesco Nat. Hazards Earth Syst. Sci., 16, 1791-1806, doi:10.5194/nhess-16-1791-2016, 2016 Safety and efficiency of navigation can be enhanced through a better situational awareness at sea. We designed and realized an operational infrastructure for providing the navigators with optimal routes through various devices: PC, tablets, and smartphones. Sea-state and wind forecasts are used as inputs. Both motor- and sailboat routes are addressed by VISIR.

Beschreibung: Can integrative catchment management mitigate future water quality issues caused by climate change and socio-economic development? Mark Honti, Nele Schuwirth, Jörg Rieckermann, and Christian Stamm Hydrol. Earth Syst. Sci. Discuss., doi:10.5194/hess-2016-297,2016 Manuscript under review for HESS (discussion: open, 0 comments) Catchments are complex systems where water quantity, quality and the provided ecological services are determined by interacting physical, chemical, biological, economic, and social factors. The awareness of these interactions led to the prevailing catchment management paradigm of Integrated Water Resources Management. The design and evaluation of solutions for integrated water resources management requires to predict changes of local or regional water quality, which requires integrated approach for modeling too. On one hand, integrated models have to be comprehensive enough to cover the aspects relevant for management decisions, allow for mapping of global change processes – as climate change, population growth, migration, and socio-economic development – to the regional and local contexts. On the other hand, models have to be sufficiently simple and fast enough to apply proper methods of uncertainty analysis, which can consider model structure deficits and propagate errors through the chain of submodels. Here, we present an integrated catchment model satisfying both objectives. The conceptual "iWaQa" model was developed to support the integrated management of small streams. It can predict both traditional water quality parameters like nutrients and a wide set of organic micropollutants originating from plant and material protection products. Due to the model's simplicity, it allows for a full, propagative analysis of predictive uncertainty, including certain structural and input errors. The usefulness of the model is demonstrated by predicting future water quality in a small catchment with mixed land use in the Swiss Plateau. The focus of our study is the change of water quality over the next decades driven by climate change, population growth or decline, socio-economic development and the implementation of management strategies for improving water quality. Our results indicate that input and model structure uncertainties are the most influential factors on certain water quality parameters and in these cases the uncertainty of modeling is already very high for the present conditions. Nevertheless, a proper quantification of today's uncertainty can make the management fairly robust for the foreseen range of possible evolution into the next decades. With a time-horizon of 2050, it seems that human land use and management decisions have a larger influence on water quality than climate change. However, the analysis of single climate model chains indicates that the importance of climate grows when a certain climate prediction is considered instead of the ensemble forecast.

Beschreibung: Can integrative catchment management mitigate future water quality issues caused by climate change and socio-economic development? Mark Honti, Nele Schuwirth, Jörg Rieckermann, and Christian Stamm Hydrol. Earth Syst. Sci. Discuss., doi:10.5194/hess-2016-297,2016 Manuscript under review for HESS (discussion: open, 0 comments) Catchments are complex systems where water quantity, quality and the provided ecological services are determined by interacting physical, chemical, biological, economic, and social factors. The awareness of these interactions led to the prevailing catchment management paradigm of Integrated Water Resources Management. The design and evaluation of solutions for integrated water resources management requires to predict changes of local or regional water quality, which requires integrated approach for modeling too. On one hand, integrated models have to be comprehensive enough to cover the aspects relevant for management decisions, allow for mapping of global change processes – as climate change, population growth, migration, and socio-economic development – to the regional and local contexts. On the other hand, models have to be sufficiently simple and fast enough to apply proper methods of uncertainty analysis, which can consider model structure deficits and propagate errors through the chain of submodels. Here, we present an integrated catchment model satisfying both objectives. The conceptual "iWaQa" model was developed to support the integrated management of small streams. It can predict both traditional water quality parameters like nutrients and a wide set of organic micropollutants originating from plant and material protection products. Due to the model's simplicity, it allows for a full, propagative analysis of predictive uncertainty, including certain structural and input errors. The usefulness of the model is demonstrated by predicting future water quality in a small catchment with mixed land use in the Swiss Plateau. The focus of our study is the change of water quality over the next decades driven by climate change, population growth or decline, socio-economic development and the implementation of management strategies for improving water quality. Our results indicate that input and model structure uncertainties are the most influential factors on certain water quality parameters and in these cases the uncertainty of modeling is already very high for the present conditions. Nevertheless, a proper quantification of today's uncertainty can make the management fairly robust for the foreseen range of possible evolution into the next decades. With a time-horizon of 2050, it seems that human land use and management decisions have a larger influence on water quality than climate change. However, the analysis of single climate model chains indicates that the importance of climate grows when a certain climate prediction is considered instead of the ensemble forecast.

Beschreibung: CFSv2-based sub-seasonal precipitation and temperature forecast skill over the contiguous United States Di Tian, Eric F. Wood, and Xing Yuan Hydrol. Earth Syst. Sci. Discuss., doi:10.5194/hess-2016-376,2016 Manuscript under review for HESS (discussion: open, 0 comments) Forecasts from global seasonal climate forecast models can be potentially exploited for sub-seasonal forecasts of precipitation and 2-m temperature. The probabilistic sub-seasonal forecast skill of ten precipitation and temperature indices is investigated using the 28-years’ hindcasts of the Climate Forecast System version 2 (CFSv2) over the contiguous United States (CONUS). The forecast skill is highly dependent on the forecast indices, regions, seasons, leads, and methods. Indices characterizing mean precipitation and temperature as well as measuring frequency or duration of precipitation and temperature extremes for 7-, 14-, and 30-day forecasts were skillful depending on seasons, regions, and forecast leads. Forecasts for 7- and 14-day temperature indices showed skill even at weeks 3 and 4, and generally more skillful than precipitation indices. Overall, temperature indices showed higher skill than precipitation indices over the entire CONUS region. While the forecast skill related to mean precipitation indices were low in summer over the CONUS, the number of rainy days, number of consecutive rainy days, and the number of consecutive dry days showed considerable high skill for the west coast region. The 30-day forecasts of precipitation and temperature indices calculated from the downscaled monthly CFSv2 forecasts are less skillful than those calculated from the daily CFSv2 forecasts, suggesting the potential usefulness of the CFSv2 daily forecasts for hydrological applications relative to the temporally disaggregated CFSv2 monthly forecasts. While the presence of active Madden-Julian Oscillation (MJO) events improves CFSv2 weekly mean precipitation forecast skill over major areas of CONUS, MJO or El Niño Southern Oscillation did not have same strong effects on weekly mean temperature forecasts.

Beschreibung: Thermal impacts of engineering activities and vegetation layer on permafrost in different alpine ecosystems of the Qinghai–Tibet Plateau, China Qingbai Wu, Zhongqiong Zhang, Siru Gao, and Wei Ma The Cryosphere, 10, 1695-1706, doi:10.5194/tc-10-1695-2016, 2016 Climate warming and engineering activities have various impacts on the thermal regime of permafrost in alpine ecosystems of the Qinghai–Tibet Plateau. Using recent observations of permafrost thermal regimes along the Qinghai–Tibet highway and railway, the changes of such regimes beneath embankments constructed in alpine meadows and steppes are studied. The results show that alpine meadows on the Qinghai–Tibet Plateau can have a controlling role among engineering construction effects on permafrost beneath embankments. As before railway construction, the artificial permafrost table (APT) beneath embankments is not only affected by climate change and engineering activities but is also controlled by alpine ecosystems. However, the change rate of APT is not dependent on ecosystem type, which is predominantly affected by climate change and engineering activities. Instead, the rate is mainly related to cooling effects of railway ballast and heat absorption effects of asphalt pavement. No large difference between alpine and steppe can be identified regarding the variation of soil temperature beneath embankments, but this difference is readily identified in the variation of mean annual soil temperature with depth. The vegetation layer in alpine meadows has an insulation role among engineering activity effects on permafrost beneath embankments, but this insulation gradually disappears because the layer decays and compresses over time. On the whole, this layer is advantageous for alleviating permafrost temperature rise in the short term, but its effect gradually weakens in the long term.

Beschreibung: Thermal impacts of engineering activities and vegetation layer on permafrost in different alpine ecosystems of the Qinghai–Tibet Plateau, China Qingbai Wu, Zhongqiong Zhang, Siru Gao, and Wei Ma The Cryosphere, 10, 1695-1706, doi:10.5194/tc-10-1695-2016, 2016 Climate warming and engineering activities have various impacts on the thermal regime of permafrost in alpine ecosystems of the Qinghai–Tibet Plateau. Using recent observations of permafrost thermal regimes along the Qinghai–Tibet highway and railway, the changes of such regimes beneath embankments constructed in alpine meadows and steppes are studied. The results show that alpine meadows on the Qinghai–Tibet Plateau can have a controlling role among engineering construction effects on permafrost beneath embankments. As before railway construction, the artificial permafrost table (APT) beneath embankments is not only affected by climate change and engineering activities but is also controlled by alpine ecosystems. However, the change rate of APT is not dependent on ecosystem type, which is predominantly affected by climate change and engineering activities. Instead, the rate is mainly related to cooling effects of railway ballast and heat absorption effects of asphalt pavement. No large difference between alpine and steppe can be identified regarding the variation of soil temperature beneath embankments, but this difference is readily identified in the variation of mean annual soil temperature with depth. The vegetation layer in alpine meadows has an insulation role among engineering activity effects on permafrost beneath embankments, but this insulation gradually disappears because the layer decays and compresses over time. On the whole, this layer is advantageous for alleviating permafrost temperature rise in the short term, but its effect gradually weakens in the long term.

Beschreibung: Mekong River flow and hydrological extremes under climate change Long Phi Hoang, Hannu Lauri, Matti Kummu, Jorma Koponen, Michelle T. H. van Vliet, Iwan Supit, Rik Leemans, Pavel Kabat, and Fulco Ludwig Hydrol. Earth Syst. Sci., 20, 3027-3041, doi:10.5194/hess-20-3027-2016, 2016 We modelled hydrological changes under climate change in the Mekong River, focusing on extreme events. The scenario ensemble shows an intensification of the hydrological cycle under climate change. Annual river flow increases between 5 and 16 % depending on locations. Extreme high flows increase substantially in both magnitude and frequency, posing threats to flood safety in the basin. Extreme low-flow events are projected to reduce as a result of increased river flow during the dry season.

Beschreibung: Improved large-scale hydrological modelling through the assimilation of streamflow and downscaled satellite soil moisture observations Patricia López López, Niko Wanders, Jaap Schellekens, Luigi J. Renzullo, Edwin H. Sutanudjaja, and Marc F. P. Bierkens Hydrol. Earth Syst. Sci., 20, 3059-3076, doi:10.5194/hess-20-3059-2016, 2016 We perform a joint assimilation experiment of high-resolution satellite soil moisture and discharge observations in the Murrumbidgee River basin with a large-scale hydrological model. Additionally, we study the impact of high- and low-resolution meteorological forcing on the model performance. We show that the assimilation of high-resolution satellite soil moisture and discharge observations has a significant impact on discharge simulations and can bring them closer to locally calibrated models.

Beschreibung: Application of tritium in precipitation and baseflow in Japan: a case study of groundwater transit times and storage in Hokkaido watersheds Maksym A. Gusyev, Uwe Morgenstern, Michael K. Stewart, Yusuke Yamazaki, Kazuhisa Kashiwaya, Terumasa Nishihara, Daisuke Kuribayashi, Hisaya Sawano, and Yoichi Iwami Hydrol. Earth Syst. Sci., 20, 3043-3058, doi:10.5194/hess-20-3043-2016, 2016 Tritium-estimated groundwater mean transit times (MTTs) and storage volumes provide useful information for water resources management especially during droughts. In Hokkaido, we find that (1) one tritium measurement at baseflow is already sufficient to estimate MTT for some catchments, (2) the hydrogeological settings control tritium transit times of subsurface groundwater storage at baseflow, and (3) in future, one tritium measurement will be sufficient to estimate MTT in most Japanese catchments.

Beschreibung: Technical note: Inference in hydrology from entropy balance considerations Stefan J. Kollet Hydrol. Earth Syst. Sci., 20, 2801-2809, doi:10.5194/hess-20-2801-2016, 2016 In this study, the method of inference of macroscale thermodynamic potentials, forces, and exchange coefficients for variably saturated groundwater flow is outlined based on the entropy balance. The theoretical basis of the method of inference is the explicit calculation of the internal entropy production from microscale, thermodynamic flux–force relationships using, e.g., hyper-resolution variably saturated groundwater flow models. Emphasis is placed on the two-scale nature of the entropy balance equation that allows simultaneously incorporating movement equations at the micro- and macroscale. The method is illustrated with simple hydrologic cross sections at steady state and periodic sources/sinks at dynamic equilibrium, and provides a thermodynamic point of view of upscaling in variably saturated groundwater flow. The current limitations in the connection with observable variables and predictive capabilities are discussed, and some perspectives for future research are provided.

Beschreibung: Redox controls on methane formation, migration and fate in shallow aquifers Pauline Humez, Bernhard Mayer, Michael Nightingale, Veith Becker, Andrew Kingston, Stephen Taylor, Guy Bayegnak, Romain Millot, and Wolfram Kloppmann Hydrol. Earth Syst. Sci., 20, 2759-2777, doi:10.5194/hess-20-2759-2016, 2016 Development of unconventional energy resources if often associated with public concerns regarding potential contamination of shallow groundwater due to methane leakage. We combined chemical and isotopic analyses of gas and water samples obtained from shallow aquifers in Alberta (Canada) to assess baseline methane sources and found that 〉 67 % of the samples contained biogenic methane formed in situ in the aquifers. There was no evidence of deep thermogenic methane migration into shallow aquifers.

Beschreibung: Evaluating uncertainty in estimates of soil moisture memory with a reverse ensemble approach Dave MacLeod, Hannah Cloke, Florian Pappenberger, and Antje Weisheimer Hydrol. Earth Syst. Sci., 20, 2737-2743, doi:10.5194/hess-20-2737-2016, 2016 Soil moisture memory is a key aspect of seasonal climate predictions, through feedback between the land surface and the atmosphere. Estimates have been made of the length of soil moisture memory; however, we show here how estimates of memory show large variation with uncertain model parameters. Explicit representation of model uncertainty may then improve the realism of simulations and seasonal climate forecasts.

Beschreibung: Spatial and Temporal Variability in Baseflow in the Mattole River Headwaters, California, USA Nathan Queener and Andrew P. Stubblefield Hydrol. Earth Syst. Sci. Discuss., doi:10.5194/hess-2016-300,2016 Manuscript under review for HESS (discussion: open, 0 comments) Understanding controls on stream low flow is critical for managing aquatic resources. Baseflows in small river basins in northern California, USA were found to be quite divergent. The difference in water yield was much greater than the difference in precipitation. Steep, high elevation areas, dissected by many channels, had the highest baseflow. The positive correlation between basin steepness and flow is thought to result from greater basin storage capacity in thick weathered bedrock layers.

Beschreibung: Estimating drought risk across Europe from reported drought impacts, drought indices, and vulnerability factors Veit Blauhut, Kerstin Stahl, James Howard Stagge, Lena M. Tallaksen, Lucia De Stefano, and Jürgen Vogt Hydrol. Earth Syst. Sci., 20, 2779-2800, doi:10.5194/hess-20-2779-2016, 2016 Drought is one of the most costly natural hazards in Europe. Due to its complexity, drought risk, meant as the combination of the natural hazard and societal vulnerability, is difficult to define and challenging to detect and predict, as the impacts of drought are very diverse, covering the breadth of socioeconomic and environmental systems. Pan-European maps of drought risk could inform the elaboration of guidelines and policies to address its documented severity and impact across borders. This work tests the capability of commonly applied drought indices and vulnerability factors to predict annual drought impact occurrence for different sectors and macro regions in Europe and combines information on past drought impacts, drought indices, and vulnerability factors into estimates of drought risk at the pan-European scale. This hybrid approach bridges the gap between traditional vulnerability assessment and probabilistic impact prediction in a statistical modelling framework. Multivariable logistic regression was applied to predict the likelihood of impact occurrence on an annual basis for particular impact categories and European macro regions. The results indicate sector- and macro-region-specific sensitivities of drought indices, with the Standardized Precipitation Evapotranspiration Index (SPEI) for a 12-month accumulation period as the overall best hazard predictor. Vulnerability factors have only limited ability to predict drought impacts as single predictors, with information about land use and water resources being the best vulnerability-based predictors. The application of the hybrid approach revealed strong regional and sector-specific differences in drought risk across Europe. The majority of the best predictor combinations rely on a combination of SPEI for shorter and longer accumulation periods, and a combination of information on land use and water resources. The added value of integrating regional vulnerability information with drought risk prediction could be proven. Thus, the study contributes to the overall understanding of drivers of drought impacts, appropriateness of drought indices selection for specific applications, and drought risk assessment.

Beschreibung: Redox controls on methane formation, migration and fate in shallow aquifers Pauline Humez, Bernhard Mayer, Michael Nightingale, Veith Becker, Andrew Kingston, Stephen Taylor, Guy Bayegnak, Romain Millot, and Wolfram Kloppmann Hydrol. Earth Syst. Sci., 20, 2759-2777, doi:10.5194/hess-20-2759-2016, 2016 Development of unconventional energy resources if often associated with public concerns regarding potential contamination of shallow groundwater due to methane leakage. We combined chemical and isotopic analyses of gas and water samples obtained from shallow aquifers in Alberta (Canada) to assess baseline methane sources and found that 〉 67 % of the samples contained biogenic methane formed in situ in the aquifers. There was no evidence of deep thermogenic methane migration into shallow aquifers.

Beschreibung: Ordinary kriging as a tool to estimate historical daily streamflow records William H. Farmer Hydrol. Earth Syst. Sci., 20, 2721-2735, doi:10.5194/hess-20-2721-2016, 2016 The potential of geostatistical tools, leveraging the spatial structure and dependency of correlated time series, for the prediction of daily streamflow time series at unmonitored locations is explored. Simple geostatistical tools improve on traditional estimates of daily streamflow. The temporal evolution of spatial structure, including seasonal fluctuations, is also explored. The proposed method is contrasted with more advanced geostatistical methods and shown to be comparable.

Beschreibung: Spatial and Temporal Variability in Baseflow in the Mattole River Headwaters, California, USA Nathan Queener and Andrew P. Stubblefield Hydrol. Earth Syst. Sci. Discuss., doi:10.5194/hess-2016-300,2016 Manuscript under review for HESS (discussion: open, 0 comments) Understanding controls on stream low flow is critical for managing aquatic resources. Baseflows in small river basins in northern California, USA were found to be quite divergent. The difference in water yield was much greater than the difference in precipitation. Steep, high elevation areas, dissected by many channels, had the highest baseflow. The positive correlation between basin steepness and flow is thought to result from greater basin storage capacity in thick weathered bedrock layers.

Beschreibung: Combined diurnal variations of discharge and hydrochemistry of the Isunnguata Sermia outlet of the Greenland Ice Sheet give in sight on sub glacial conditions Joseph Graly, Joel Harrington, and Neil Humphrey The Cryosphere Discuss., doi:10.5194/tc-2016-137,2016 Manuscript under review for TC (discussion: open, 0 comments) At a major outlet of the Greenland Ice Sheet in West Greenland, we find that the chemical solutes is the emerging subglacial waters are out of phase with water discharge and can spike in concentration during waning flow. This suggests that the subglacial waters are spreading out across a large area of the glacial bed throughout the day, stimulating chemical weathering beyond the major water distribution channels.

Beschreibung: An examination of land use impacts of sea level rise induced flooding Jie Song, Xinyu Fu, Yue Gu, Yujun Deng, and Zhong-Ren Peng Nat. Hazards Earth Syst. Sci. Discuss., doi:10.5194/nhess-2016-157,2016 Manuscript under review for NHESS (discussion: open, 0 comments) We present a joint model which couples urban growth dynamics with coastal hazards. We use the SLEUTH platform to investigate three urban growth scenarios under different land use policies. We found that compact development may contribute to the region's vulnerability to sea level rise induced flooding, and that strict land development regulations may greatly mitigate such vulnerability. The findings highlight the importance of land use simulations in formulating coastal management plans.

Beschreibung: Domestic drones: the politics of verticality and the surveillance industrial complex Ciara Bracken-Roche Geogr. Helv., 71, 167-172, doi:10.5194/gh-71-167-2016, 2016 Drones are being introduced as innovative and cost-effective technologies for civil, commercial, and recreational purposes in the domestic realm. While the presence of these technologies is increasing, regulations are being introduced in order to ensure their safe and responsible use. As drones are adopted for a number of purposes, the “de facto practices settle around it, rendering change much more difficult” (Gersher, 2014), and so the policy debates must consider all contingencies and unintended consequences of their use. This paper discusses the background of unmanned aerial vehicles (UAVs), their role as surveillance technologies, and how they reinforce asymmetries in power and visibility that contribute to a politics of verticality, ultimately arguing that surveillance concerns must become part of the discussion at the policy and regulatory level in order to mitigate any harms. Where drones are already used for care and control as technologies of surveillance, privileged use of drones by public and police agencies could further reinforce a politics of verticality (Weizman, 2002), resulting in specific types of space, risk, and population management.

Beschreibung: Impact of Icebergs on Net Primary Productivity in the Southern Ocean Shuang-Ye Wu and Shugui Hou The Cryosphere Discuss., doi:10.5194/tc-2016-166,2016 Manuscript under review for TC (discussion: open, 0 comments) The primary productivity in the Southern Ocean (SO) is limited by the amount of iron available for biological activities. Recent studies show that icebergs could be a main source of iron to the SO. Based on remote sensing data, our study shows that iceberg presence has a small, yet statistically significant, positive impact on productivity. As iceberg quantity increases, their positive influence on productivity also increases. This impact could serve as a negative feedback to the climate system.