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  • 1
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    Long-term CO2 fertilization increases vegetation productivity but has little effect on hydrological partitioning in tropical rainforests (2016)
    Wiley
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    Publication Date: 2016-07-27
    Description: Understanding how tropical rainforests respond to elevated atmospheric CO 2 concentration (eCO 2 ) is essential for predicting Earth's carbon, water and energy budgets under future climate change. Here we use long-term (1982-2010) precipitation ( P ) and runoff ( Q ) measurements to infer runoff coefficient ( Q / P ) and evapotranspiration ( E ) trends across 18 unimpaired tropical rainforest catchments. We complement that analysis by using satellite observations coupled with ecosystem process modelling (using both ‘top-down’ and ‘bottom-up’ perspectives) to examine trends in carbon uptake and relate that to the observed changes in Q / P and E . Our results show there have been only minor changes in the satellite-observed canopy leaf area over 1982-2010, suggesting that eCO 2 has not increased vegetation leaf area in tropical rainforests and therefore any plant response to eCO 2 occurs at the leaf-level. Meanwhile, observed Q / P and E also remained relatively constant in the 18 catchments, implying an unchanged hydrological partitioning and thus approximately conserved transpiration under eCO 2 . For the same period, using a ‘top-down’ model based on gas-exchange theory, we predict increases in plant assimilation ( A ) and light-use efficiency ( ε ) at the leaf-level under eCO 2 , the magnitude of which is essentially that of eCO 2 ( i.e ., ~12% over 1982-2010). Simulations from ten state-of-the-art ‘bottom-up’ ecosystem models over the same catchments also show the direct effect of eCO 2 is to mostly increase A and ε with little impact on E . Our findings add to the current limited pool of knowledge regarding the long-term eCO 2 impacts in tropical rainforests.
    Print ISSN: 0148-0227
    Topics: Biology , Geosciences
    Published by Wiley on behalf of American Geophysical Union (AGU).
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  • 2
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    The millennium drought in southeast Australia (2001–2009): Natural and human causes and implications for water resources, ecosystems, economy and society (2013)
    Wiley
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    Publication Date: 2013-02-07
    Description: The ‘Millennium Drought’ (2001–2009) can be described as the worst drought on record for southeast Australia. Adaptation to future severe droughts requires insight into the drivers of the drought and its impacts. These were analyzed using climate, water, economic and remote sensing data combined with biophysical modeling. Prevailing El Niño conditions explained about two-thirds of rainfall deficit in east Australia. Results for south Australia were inconclusive; a contribution from global climate change remains plausible but unproven. Natural processes changed the timing and magnitude of soil moisture, streamflow and groundwater deficits by up to several years, and caused the amplification of rainfall declines in streamflow to be greater than in normal dry years. By design, river management avoided impacts on some categories of water users, but did so by exacerbating the impacts on annual irrigation agriculture and, in particular, river ecosystems. Relative rainfall reductions were amplified 1.5–1.7 times in dryland wheat yields, but the impact was offset by steady increases in cropping area and crop water use efficiency (perhaps partly due to CO2 fertilization). Impacts beyond the agricultural sector occurred (e.g., forestry, tourism, utilities) but were often diffuse and not well quantified. Key causative pathways from physical drought to the degradation of ecological, economic and social health remain poorly understood and quantified. Combined with the multiple dimensions of multi-year droughts and the specter of climate change, this means future droughts may well break records in ever new ways and not necessarily be managed better than past ones.
    Print ISSN: 0043-1397
    Electronic ISSN: 1944-7973
    Topics: Architecture, Civil Engineering, Surveying , Geography
    Published by Wiley on behalf of American Geophysical Union (AGU).
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  • 3
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    Global-scale regionalization of hydrologic model parameters (2016)
    Wiley
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    Publication Date: 2016-04-21
    Description: Current state-of-the-art models typically applied at continental to global scales (hereafter called macro-scale) tend to use a priori parameters, resulting in suboptimal streamflow ( Q ) simulation. For the first time, a scheme for regionalization of model parameters at the global scale was developed. We used data from a diverse set of 1787 small-to-medium sized catchments (10-10000 km 2 ) and the simple conceptual HBV model to set up and test the scheme. Each catchment was calibrated against observed daily Q , after which 674 catchments with high calibration and validation scores, and thus presumably good-quality observed Q and forcing data, were selected to serve as donor catchments. The calibrated parameter sets for the donors were subsequently transferred to 0.5° grid cells with similar climatic and physiographic characteristics, resulting in parameter maps for HBV with global coverage. For each grid cell, we used the ten most similar donor catchments, rather than the single most similar donor, and averaged the resulting simulated Q , which enhanced model performance. The 1113 catchments not used as donors were used to independently evaluate the scheme. The regionalized parameters outperformed spatially-uniform (i.e., averaged calibrated) parameters for 79% of the evaluation catchments. Substantial improvements were evident for all major Köppen-Geiger climate types and even for evaluation catchments 〉 5000 km distant from the donors. The median improvement was about half of the performance increase achieved through calibration. HBV with regionalized parameters outperformed nine state-of-the-art macro-scale models, suggesting these might also benefit from the new regionalization scheme. The produced HBV parameter maps including ancillary data are available via http://water.jrc.ec.europa.eu/HBV/ . This article is protected by copyright. All rights reserved.
    Print ISSN: 0043-1397
    Electronic ISSN: 1944-7973
    Topics: Architecture, Civil Engineering, Surveying , Geography
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  • 4
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    Global analysis of seasonal streamflow predictability using an ensemble prediction system and observations from 6192 small catchments worldwide (2013)
    Wiley
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    Publication Date: 2013-04-18
    Description: Ideally, a seasonal streamflow forecasting system would ingest skilful climate forecasts and propagate these through calibrated hydrological models initialised with observed catchment conditions. At global scale, practical problems exist in each of these aspects. For the first time, we analysed theoretical and actual skill in bimonthly streamflow forecasts from a global Ensemble Streamflow Prediction (ESP) system. Forecasts were generated six times per year for 1979–2008 by an initialised hydrological model and an ensemble of 1º resolution daily climate estimates for the preceding 30 years. A post-ESP conditional sampling method was applied to 2.6% of forecasts, based on predictive relationships between precipitation and one of 21 climate indices prior to the forecast date. Theoretical skill was assessed against a reference run with historic forcing. Actual skill was assessed against streamflow records for 6192 small (〈10,000 km 2 ) catchments worldwide. The results show that initial catchment conditions provide the main source of skill. Post-ESP sampling enhanced skill in equatorial South America and Southeast Asia, particularly in terms of tercile probability skill, due to the persistence and influence of the El Niño Southern Oscillation. Actual skill was on average 54% of theoretical skill but considerably more for selected regions and times of year. The realized fraction of the theoretical skill probably depended primarily on the quality of precipitation estimates. Forecast skill could be predicted as the product of theoretical skill and historic model performance. Increases in seasonal forecast skill are likely to require improvement in the observation of precipitation and initial hydrological conditions.
    Print ISSN: 0043-1397
    Electronic ISSN: 1944-7973
    Topics: Architecture, Civil Engineering, Surveying , Geography
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  • 5
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    Global patterns in baseflow index and recession based on streamflow observations from 3394 catchments (2013)
    Wiley
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    Publication Date: 2013-11-06
    Description: Numerous previous studies have constructed models to estimate baseflow characteristics from climatic and physiographic characteristics of catch- ments and applied these to ungauged regions. However, these studies generally used streamflow observations from a relatively small number of catchments ( 〈 200) located in small, homogeneous study areas, which may have led to less reliable models with limited applicability elsewhere. Here, we use streamflow observations from a highly heterogeneous set of 3394 catchments ( 〈 10000 km2) worldwide to construct reliable, widely applicable models based on 18 climatic and physiographic characteristics to estimate two important baseflow characteristics: (1) the baseflow index (BFI), defined as the ratio of long-term mean baseflow to total streamflow; and (2) the baseflow recession constant ( k ), defined as the rate of baseflow decay. Regression analysis results revealed that BFI and k were related to several climatic and physiographic characteristics, notably mean annual potential evaporation, mean snow-water equivalent depth, and abundance of surface-water bodies. Ensembles of Artificial Neural Networks (ANNs; obtained by sub-sampling the original set of catchments) were trained to estimate the baseflow characteristics from climatic and physiographic data. The catchment-scale estimation of the baseflow characteristics demonstrated encouraging performance with R 2 values of 0.82 for BFI and 0.72 for k . The connection weights of the trained ANNs indicated that climatic characteristics were more important for estimating k than BFI. Global maps of estimated BFI and k were obtained using global climatic and physiographic data as input to the derived mod- The resulting global maps are available for free download at http://www.hydrology-amsterdam.nl .
    Print ISSN: 0043-1397
    Electronic ISSN: 1944-7973
    Topics: Architecture, Civil Engineering, Surveying , Geography
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  • 6
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    Global reconstruction of naturalized river flows at 2.94 million reaches (2019)
    Wiley
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    Publication Date: 2019
    Description: Abstract Spatio‐temporally continuous global river discharge estimates across the full spectrum of stream orders are vital to a range of hydrologic applications, yet they remain poorly constrained. Here we present a carefully‐designed modeling effort (VIC land surface model and RAPID river routing model) to estimate global river discharge at very high resolutions. The precipitation forcing is from a recently published 0.1° global product that optimally merged gauge‐, reanalysis‐, and satellite‐based data. To constrain runoff simulations, we use a set of machine learning‐derived, global runoff characteristics maps (i.e., runoff at various exceedance probability percentiles) for grid‐by‐grid model calibration and bias correction. To support spaceborne discharge studies, the river flowlines are defined at their true geometry and location as much as possible – approximately 2.94 million vector flowlines (median length 6.8 km) and unit catchments are derived from a high‐accuracy global DEM at 3 arc‐second resolution (~90 m), which serves as the underlying hydrography for river routing. Our 35‐year daily and monthly model simulations are evaluated against over 14,000 gauges globally. Among them, 35% (64%) have a percentage bias within ±20% (±50%), and 29% (62%) have a monthly Kling‐Gupta Efficiency ≥0.6 (0.2), showing data robustness at the scale the model is assessed. This reconstructed discharge record can be used as a priori information for the Surface Water and Ocean Topography (SWOT) satellite mission's discharge product, thus named “Global Reach‐level A priori Discharge Estimates for SWOT (GRADES)”. It can also be used in other hydrologic applications requiring spatially‐explicit estimates of global river flows.
    Print ISSN: 0043-1397
    Electronic ISSN: 1944-7973
    Topics: Architecture, Civil Engineering, Surveying , Geography
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  • 7
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    River gauging at global scale using optical and passive microwave remote sensing (2016)
    Wiley
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    Publication Date: 2016-08-06
    Description: Recent discharge observations are lacking for most rivers globally. Discharge can be estimated from remotely sensed floodplain and channel inundation area, but there is currently no method that can be automatically extended to many rivers. We examined whether automated monitoring is feasible by statistically relating inundation estimates from moderate to coarse (〉0.05°) resolution remote sensing to monthly station discharge records. Inundation extents were derived from optical MODIS data and passive microwave sensors, and compared to monthly discharge records from over 8000 gauging stations and satellite altimetry observations for 442 reaches of large rivers. An automated statistical method selected grid cells to construct ‘satellite gauging reaches' (SGRs). MODIS SGRs were generally more accurate than passive microwave SGRs, but there were complementary strengths. The rivers widely varied in size, regime and morphology. As expected performance was low ( R 〈0.7) for many (86%), often small or regulated, rivers, but 1263 successful SGRs remained. High monthly discharge variability enhanced performance: a standard deviation of 100-1000 m 3 s −1 yielded ca. 50% chance of R 〉0.6. The best results ( R 〉0.9) were obtained for large unregulated lowland rivers, particularly in tropical and boreal regions. Relatively poor results were obtained in arid regions, where flow pulses are few and recede rapidly, and in temperate regions, where many rivers are modified and contained. Where discharge variations produce clear changes in inundated area and gauge records are available for part of the satellite record, SGRs can retrieve monthly river discharge values back to around 1998 and up to present. This article is protected by copyright. All rights reserved.
    Print ISSN: 0043-1397
    Electronic ISSN: 1944-7973
    Topics: Architecture, Civil Engineering, Surveying , Geography
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  • 8
    Electronic Resource
    Electronic Resource
    Eni naturwissenschaftliches Literaturkarussell. Biologie (1993)
    Weinheim : Wiley-Blackwell
    Chemie in unserer Zeit 27 (1993), S. III 
    Details
    ISSN: 0009-2851
    Keywords: Chemistry ; Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ciuz.19930270209
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  • 9
    Electronic Resource
    Electronic Resource
    Disproportionierung der Sulfinsäuren und die Struktur der Sulfinsäureanhydride (1958)
    Weinheim : Wiley-Blackwell
    Zeitschrift für die chemische Industrie 70 (1958), S. 268-269 
    Details
    ISSN: 0044-8249
    Keywords: Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ange.19580700904
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  • 10
    Electronic Resource
    Electronic Resource
    Synthesis and properties of a cellulose exchanger with the crown ether diaminodibenzo-17-crown-5 as anchor group (1995)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 227 (1995), S. 101-110 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Ein Cellulose- Austauscher wurde aus “o-Aminophenol-Cellulose” durch Diazotieren und Kuppeln mit Diaminodibenzo-17-krone-5 hergestellt. Die Verteilungskoeffizienten für Ca2+, Sr2+, Ba2+, Na+ und K+ wurden in Wasser/Methanol-Mischungen als Funktion des Wassergehaltes bestimmt. Die Trennung von Ca2+, Na+ und K+ und die Fraktionierung der Calciumisotope 48Ca und 40Ca wurde untersucht. Der Anreicherungsfaktor ε = 4.9 · 10-3 für 48Ca2+ ist merklich größer als der für Kationenaustauscher mit SO3H-Gruppen gefundene, aber niedriger als der in der Literatur für bestimmte Kryptanden angegebene Wert.
    Notes: A new cellulose exchanger was synthesized from “o-aminophenolcellulose” by diazotation and coupling with diaminodibenzo-17-crown-5. The distribution coefficients for Ca2+, Sr2+, Ba2+, Na+ and K+ were determined in water/methanol mixtures as a function of the water content. Separation of Ca2+, Na+ and K+ and fractionation of the calcium isotopes 48Ca and 40Ca were investigated. The enrichment factor ε = 4.9 · 10-3 for 48Ca2+ is appreciably higher than that found for cation exchange resins with —SO3H groups, but lower than that reported for certain cryptands.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/apmc.1995.052270110
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