bluuebunny/crossref_metadata_2025 huggingface dataset:
Aspects of seasonality and flood generating circulation patterns in a mountainous catchment in south-eastern Germany
Authors: Petrow T. , Merz B. , Lindenschmidt K.-E. , Thieken A. H.
Published: April 2010

Abstract. Analyses of discharge series, precipitation fields and flood producing atmospheric circulation patterns reveal that two governing flood regimes exist in the Mulde catchment in south-eastern Germany: frequent floods during the winter and less frequent but sometimes extreme floods during the summer. Differences in the statistical parameters skewness and coefficient of variation of the discharge data can be found from west to east and are discussed in the context of landscape parameters that influence the discharge. Annual maximum discharge series were assigned to the triggering Großwetterlage in order to evaluate which circulation patterns are likely to produce large floods. It can be shown that the cyclone Vb-weather regime generates the most extreme flood events in the Mulde catchment, whereas westerly winds produce frequently small floods. Vb-weather regimes do not always trigger large flood events in the study area, but large floods are mostly generated by these weather patterns. Based on these findings, it is necessary to revise the traditional flood frequency analysis approach and develop new approaches which can handle different flood triggering processes within the dataset.
Inferring the flood frequency distribution for an ungauged basin using a spatially distributed rainfall-runoff model
Authors: Moretti G. , Montanari A.
Published: April 2010

Abstract. The estimation of the peak river flow for ungauged river sections is a topical issue in applied hydrology. Spatially distributed rainfall-runoff models can be a useful tool to this end, since they are potentially able to simulate the river flow at any location of the watershed drainage network. However, it is not fully clear to what extent these models can provide reliable simulations over a wide range of spatial scales. This issue is investigated here by applying a spatially distributed, continuous simulation rainfall-runoff model to infer the flood frequency distribution of the Riarbero Torrent. This is an ungauged mountain creek located in northern Italy, whose drainage area is 17 km2. The results were checked by using estimates of the peak river flow obtained by applying a classical procedure based on hydrological similarity principles. The analysis highlights interesting perspectives for the application of spatially distributed models to ungauged catchments.
Dye staining and excavation of a lateral preferential flow network
Authors: Anderson A. E. , Weiler M. , Alila Y. , Hudson R. O.
Published: April 2010

Abstract. Preferential flow features have been found to be important for runoff generation, solute transport, and slope stability in many areas around the world. Although many studies have identified the particular characteristics of individual features and measured the runoff generation and solute transport within hillslopes, no studies have determined how individual features are hydraulically connected at a hillslope scale. In this study, we used dye staining and excavation to determine the morphology and spatial pattern of a preferential flow network over a large scale (30 m). We explore the feasibility of extending small-scale dye staining techniques to the hillslope scale. We determine the lateral preferential flow features that are active during the steady state flow conditions and their interaction with the surrounding soil matrix. We also calculate the velocities of the flow through each cross-section of the hillslope and compare them to hillslope scale applied tracer measurements. Finally, we investigate the relationship between the contributing area and the characteristics of the preferential features. The experiment revealed that larger contributing areas coincided with highly developed and hydraulically connected preferential features that had flow with little interaction with the surrounding soil matrix. We found evidence of subsurface erosion and deposition of soil and organic material laterally and vertically within the soil. These results are important because they add to the understanding of the runoff generation, solute transport, and slope stability of these types of hillslopes.
Relations between topography, wetlands, vegetation cover and stream water chemistry in boreal headwater catchments in Sweden
Authors: Andersson J.-O. , Nyberg L.
Published: April 2010

Abstract. A large part of the spatial variation of stream water chemistry is found in headwater streams and small catchments. To understand the dominant processes, taking place in small and heterogeneous catchments, spatial and temporal data with high resolution is needed. In most cases available map data has too low quality and resolution to successfully be used in environmental assessments and modelling. In this study 18 forested catchments (1–4 km2) were selected within a 120×50 km area in the county of Värmland in western Sweden. The aim was to test if topographic and vegetation variables derived from official datasets were correlated to stream water chemistry, represented by DOC, Al, Fe and Si content. A GIS was used to analyse the elevation characteristics, generate topographic indices and calculate the percentage of wetlands and a number of vegetation classes. The results clearly show that the topography has a major influence on the occurrence of wetlands, which has a major influence on stream water chemistry. There were very strong correlations between mean slope and percentage wetland, percentage wetland and DOC, mean slope and DOC and mean topographic wetness index and DOC. The conclusion was that official topographic data, despite uncertain or low quality and resolution, could be useful in the prediction of headwater chemistry in boreal forested catchments.
Impacts of ditch cleaning on hydrological processes in a drained peatland forest
Authors: Koivusalo H. , Ahti E. , Laurén A. , Kokkonen T. , Karvonen T. , Nevalainen R. , Finér L.
Published: April 2010

Abstract. One fourth (5.5 Mha) of forests in Finland are growing on peatlands that have been drained to improve forest growth. Forestry operations such as cuttings and ditch network maintenance in these areas may increase export of suspended solids and nutrients, and deteriorate water quality in receiving lakes and rivers. Mitigation of the deterioration calls for understanding how forest management operations affect peatland hydrology. A process-based simulation model FEMMA was applied to quantify the effects of ditch network maintenance on peatland water balance. The model has separate computation routines for evapotranspiration in tree stand and understorey vegetation, snow accumulation and melt, water movement in unsaturated and saturated soil, and drainage. Hydraulic characteristics of peat, as well as different drainage designs can be parameterised in the model. The model was applied in artificially delineated research catchments in northern Finland, where the ditch network was maintained by cleaning and digging the ditches deeper. The simulation results indicated that ditch cleaning affected the water balance slightly and the effect was dependent on stand characteristics and soil structure. When the growing stock volume was low and poorly conductive soil extended close to the soil surface, ditch cleaning increased evapotranspiration. In stands with a high stock volume and a thick topmost layer of highly conductive soil, evapotranspiration was less affected. In the study catchments, the effect of ditch cleaning on runoff was small compared to the error between measured and modelled runoff.
Anomaly in the rainfall-runoff behaviour of the Meuse catchment. Climate, land use, or land use management?
Authors: Fenicia F. , Savenije H. H. G. , Avdeeva Y.
Published: April 2010

Abstract. An anomaly has been found in the rainfall runoff behaviour of the Meuse. Ninety years of rainfall-runoff simulations show a consistent underestimation of the runoff in the period between 1930 and 1965. Different authors have debated possible causes for the anomaly, including climatic variability, land use change and data errors. None of the authors considered the way in which the land is used by for instance agricultural and forestry practises. This paper focuses on the possible effects of land use and land use management on the hydrological response of the Meuse catchment. In absence of detailed information on land use over the observation period, we adopted a fully "top-down" approach to the problem. The approach consists of a dynamic evaluation of a conceptual hydrological model and the interpretation of the temporal trends of model parameters. It appears that land use has had a considerable impact on the hydrological behaviour of the Meuse catchment. The time lag of the catchment has reduced markedly over time, possibly related to more intensive drainage and river training works. Moreover we hypothesise that forest rotation has had a significant impact on the evaporation of the catchment. These results contrast with previous studies, where the effect of land use change on the hydrological behaviour of the Meuse catchment was considered negligible, mainly because there was not sufficient change in land cover to account for it. Here we hypothesise that in the Meuse it was not the change of land cover that was responsible for hydrological change, but rather the way the land was managed.
Controls on the temporal and spatial variability of soil moisture in a mountainous landscape: the signatures of snow and complex terrain
Authors: Williams C. J. , McNamara J. P. , Chandler D. G.
Published: April 2010

Abstract. The controls on the spatial distribution of soil moisture include static and dynamic variables. The superposition of static and dynamic controls can lead to different soil moisture patterns for a given catchment during wetting, draining, and drying periods. These relationships can be further complicated in snow-dominated mountain regions where soil water input by precipitation is largely dictated by the spatial variability of snow accumulation and melt. In this study, we assess controls on spatial and temporal soil moisture variability in a small (0.02 km2), snow-dominated, semi-arid catchment by evaluating spatial correlations between soil moisture and site characteristics through different hydrologic seasons. We assess the relative importance of snow with respect to other catchment properties on the spatial variability of soil moisture and track the temporal persistence of those controls. Spatial distribution of snow, distance from divide, soil texture, and soil depth exerted significant control on the spatial variability of moisture content throughout most of the hydrologic year. These relationships were strongest during the wettest period and degraded during the dry period. As the catchment cycled through wet and dry periods, the relative spatial variability of soil moisture tended to remain unchanged. We suggest that the static properties in complex terrain (slope, aspect, soils) impose first order controls on the spatial variability of snow and consequent soil moisture, and that the interaction of dynamic (timing of water input) and static properties propagate that relative constant spatial variability through the hydrologic year. The results demonstrate snow exerts significant influence on how water is retained within mid-elevation semi-arid catchments throughout the year and infer that reductions in annual snowpacks associated with changing climate regimes may strongly influence spatial and temporal soil moisture patterns and catchment physical and biological processes.
Sensitivity of the West African hydrological cycle in ORCHIDEE to infiltration processes
Authors: d'Orgeval T. , Polcher J. , de Rosnay P.
Published: April 2010

Abstract. The aim of this article is to test the sensitivity of the Land Surface Model (LSM) ORCHIDEE to infiltration processes in the West African region, and to validate the resulting version of ORCHIDEE against African river discharges. The parameterizations to take into account the effects of flat areas, ponds and floodplains on surface infiltration, and the effect of roots and deep-soil compactness on infiltration are first described. It is shown that the surface infiltration processes have a stronger impact in the soudano-sahelian region and more generally in semi-arid African basins, whereas the rootzone and deep-soil infiltration also play a role in the guinean region and in the intermediate basins between arid and humid ones. In the equatorial region and the semi-humid basins, infiltration processes generally play a minor role. The infiltration parameterizations may explain part of the difference between simulated and observed river discharge in semi-arid and intermediate basins. So ORCHIDEE could be recalibrated to reduce the discharge errors. However, different sources of uncertainty might also explain part of the error. Indeed, the precipitation forcing in the whole West African region, the long-term storage in the soudano-sahelian region, the soil types in the guinean region and the vegetation types in the equatorial region are significant sources of errors. Therefore, a denser monitoring of the hydrological cycle at different scales in West Africa would ensure the reliability of future calibrations for the infiltration parameterizations.
Topographic control of snow distribution in an alpine watershed of western Canada inferred from spatially-filtered MODIS snow products
Authors: Tong J. , Déry S. J. , Jackson P. L.
Published: April 2010

Abstract. A spatial filter (SF) is used to reduce cloud coverage in MODIS 8-day maximum snow cover extent products (MOD10A2) from 2000–2007 to assess the topographic control on snow cover fraction (SCF) and snow cover duration (SCD) in the Quesnel River Basin (QRB) of British Columbia, Canada. Results show that the SF reduces cloud coverage and improves by 2% the accuracy of snow mapping in the QRB. The SF shows larger SCF and longer SCD than MOD10A2, with higher altitudes experiencing longer snow cover and perennial snow above 2500 m. The gradient of SCF with elevation (d(SCF)/d(elevation)) during the snowmelt season is 8% (100 m)−1. The average melt rates of SCF are similar for different 100 m elevation bands at about 5.5% (8 days)−1 for altitudes <1500 m with decreasing values with elevation to near 0% (8 days)−1 for altitudes >2500 m. Different combinations of slopes and aspects also affect the SCF with a maximum difference of 20.9% at a given time. Correlation coefficients between SCD and elevation attain 0.96 (p<0.001). Mean gradients of SCD with elevation are 3.8, 4.3, and 11.6 days (100 m)−1 for the snow onset, snowmelt, and entire year, respectively. The SF decreases the standard deviations of SCDs compared to MOD10A2 with a maximum difference near 0.63 days, 0.89 days, and 1.04 days for the snow onset, snowmelt and entire year, respectively.
Geostatistical modeling of spatial variability of water retention curves
Authors: Saito H. , Seki K. , Šimůnek J.
Published: April 2010

Abstract. This study compares the performance of two geostatistical approaches, parametric and non-parametric, to evaluate the spatial distribution of water retention curves. Data used in this study were obtained from the Las Cruces trench site database that contains water retention data for 448 soil samples. In a commonly used parametric approach, three standard water retention models, i.e. Brooks and Corey (BC), van Genuchten (VG), and log-normal (LN), were first fitted to each data set. For each model, a cross validation procedure was used to estimate parameters at each sampling location, allowing computation of prediction errors. In a rarely used non-parametric approach, a cross validation procedure was first used to directly estimate water content values for eleven pressure heads at each sampling location and then the three water retention models were fitted using the same automated procedure to compute prediction errors. The results show that the non-parametric approach significantly lowered prediction errors for the VG model, while moderately reducing them also for the LN and BC models.
A modelling approach to assess the hydrological response of small Mediterranean catchments to the variability of soil characteristics in a context of extreme events
Authors: Manus C. , Anquetin S. , Braud I. , Vandervaere J.-P. , Creutin J.-D. , Viallet P. , Gaume E.
Published: April 2010

Abstract. This paper presents a modeling study aiming at quantifying the possible impact of soil characteristics on the hydrological response of small ungauged catchments in a context of extreme events. The study focuses on the September 2002 event in the Gard region (South-Eastern France), which led to catastrophic flash-floods. The proposed modeling approach is able to take into account rainfall variability and soil profiles variability. Its spatial discretization is determined using Digital Elevation Model (DEM) and a soil map. The model computes infiltration, ponding and vertical soil water distribution, as well as river discharge. The model is set up without any calibration and the soil parameter specification is based on an existing soil database. To perform the simulations, radar rainfall estimations are used at a 1 km2 and 5 min resolution. To specify the soil hydraulic properties, two types of pedotransfer function (PTF) are compared. It is shown that the PTF including information about soil structure reflects better the spatial variability that can be encountered in the field. The study is focused on four small ungauged catchments of less than 10 km2, which experienced casualties. Simulated specific peak discharges are found to be in agreement with estimations from a post-event in situ investigation. Examining the dynamics of simulated infiltration and saturation degrees, two different behaviors are shown which correspond to different runoff production mechanisms that could be encountered within catchments of less than 10 km2. They produce simulated runoff coefficients that evolve in time and highlight the variability of the infiltration capacity of the various soil types. Therefore, we propose a cartography distinguishing between areas prone to saturation excess and areas prone only to infiltration excess mechanisms. The questions raised by this modeling study will be useful to improve field observations, aiming at better understanding runoff generation for these extreme events and examine the possibility for early warning, even in very small ungauged catchments.
Food consumption patterns and their effect on water requirement in China
Authors: Liu J. , Savenije H. H. G.
Published: April 2010

Abstract. It is widely recognized that food consumption patterns significantly impact water requirements. The aim of this paper is to quantify how food consumption patterns influence water requirements in China. The findings show that per capita water requirement for food (CWRF) has increased from 250 m3 cap−1 y−1 in 1961 to 780 m3 cap−1 y−1 in 2003, largely due to an increase in the consumption of animal products in recent decades. Although steadily increasing, the CWRF of China is still much lower than that of many developed countries. The total water requirement for food (TWRF) has been determined as 1023 km3 y−1 in 2003. Three scenarios are proposed to project future TWRF, representing low, medium, and high levels of modernization (S1, S2, and S3, respectively). Analysis of these three scenarios indicates that TWRF will reach a maximum between 2020 and 2025, after which it is expected to decline. According to S2, the shift in food consumption patterns together with population growth may lead to an additional amount of required water of 114 km3 y−1 in 2025, even after taking technological advances into consideration. This will undoubtedly put high pressure on China's already scarce water resources. China needs to strengthen "green water" management and to take advantage of "virtual water" import to meet the additional TWRF.
On the relationship between large-scale climate modes and regional synoptic patterns that drive Victorian rainfall
Authors: Verdon-Kidd D. , Kiem A. S.
Published: April 2010

Abstract. In this paper regional (synoptic) and large-scale climate drivers of rainfall are investigated for Victoria, Australia. A non-linear classification methodology known as self-organizing maps (SOM) is used to identify 20 key regional synoptic patterns, which are shown to capture a range of significant synoptic features known to influence the climate of the region. Rainfall distributions are assigned to each of the 20 patterns for nine rainfall stations located across Victoria, resulting in a clear distinction between wet and dry synoptic types at each station. The influence of large-scale climate modes on the frequency and timing of the regional synoptic patterns is also investigated. This analysis revealed that phase changes in the El Niño Southern Oscillation (ENSO), the Southern Annular Mode (SAM) and/or Indian Ocean Dipole (IOD) are associated with a shift in the relative frequency of wet and dry synoptic types. Importantly, these results highlight the potential to utilise the link between the regional synoptic patterns derived in this study and large-scale climate modes to improve rainfall forecasting for Victoria, both in the short- (i.e. seasonal) and long-term (i.e. decadal/multi-decadal scale). In addition, the regional and large-scale climate drivers identified in this study provide a benchmark by which the performance of Global Climate Models (GCMs) may be assessed.
A social-economic-engineering combined framework for decision making in water resources planning
Authors: Chung E. S. , Lee K. S.
Published: April 2010

Abstract. This study presents a new methodology not only to evaluate willingness to pays (WTPs) for the improvement of hydrological vulnerability using a choice experiment (CE) method but also to do a cost-benefit analysis (CBA) of some feasible alternatives combing the derived WTPs with an alternative evaluation index (AEI). The hydrological vulnerability consists of potential streamflow depletion (PSD), and potential water quality deterioration (PWQD) and can be quantified using a multi-criteria decision making technique and pressure-state-response (PSR) framework. PSD and PWQD not only provide survey respondents with sufficient site-specific information to avoid scope sensitivity in a choice experiment but also support the standard of dividing the study watershed into six sub-regions for site-fitted management. Therefore CE was applied to six regions one after the other, in order to determine WTPs for improvements on hydrological vulnerability considering the characteristics which are vulnerability, location, and preferences with regard to management objectives. The AEI was developed to prioritize the feasible alternatives using a continuous water quantity/quality simulation model as well as multi-criteria decision making techniques. All criteria for alternative performance were selected based on a driver-pressures-state-impact-response (DPSIR) framework, and their weights were estimated using an Analytic Hierarchy Process (AHP). In addition, the AEI that reflects on residents' preference with regard to management objectives was proposed in order to incite the stakeholder to participate in the decision making process. Finally, the economic values of each alternative are estimated by a newly developed method which combines the WTPs for improvements on hydrologic vulnerability with the AEI. This social-economic-engineering combined framework can provide the decision makers with more specific information as well as decrease the uncertainty of the CBA.
HESS Opinions "Climate, hydrology, energy, water: recognizing uncertainty and seeking sustainability"
Authors: Koutsoyiannis D. , Makropoulos C. , Langousis A. , Baki S. , Efstratiadis A. , Christofides A. , Karavokiros G. , Mamassis N.
Published: April 2010

Abstract. Since 1990 extensive funds have been spent on research in climate change. Although Earth Sciences, including climatology and hydrology, have benefited significantly, progress has proved incommensurate with the effort and funds, perhaps because these disciplines were perceived as "tools" subservient to the needs of the climate change enterprise rather than autonomous sciences. At the same time, research was misleadingly focused more on the "symptom", i.e. the emission of greenhouse gases, than on the "illness", i.e. the unsustainability of fossil fuel-based energy production. There is a real risk of severe socioeconomic crisis in the not-too-distant future, unless energy saving and use of renewables become the norm. A framework for drastic change is needed, in which water plays a central role, due to its unique link to all forms of renewable energy, from production (hydro, wave) to storage (for time-varying wind and solar sources), to biofuel production (irrigation). The expanded role of water should be considered in parallel to usual roles in domestic, agricultural and industrial use. Hydrology, the science of water on Earth, must reinvent itself within this new paradigm and radically rethink its fundaments, which are unjustifiably trapped in the 19th-century myths of deterministic theories and the zeal to eliminate uncertainty. Guidance is offered by modern statistical and quantum physics, revealing the intrinsic character of uncertainty/entropy in nature, thus advancing towards a new understanding and modelling of physical processes, which is fundamental for the effective use of renewable energy and water resources.
Bayesian objective classification of extreme UK daily rainfall for flood risk applications
Authors: Little M. A. , Rodda H. J. E. , McSharry P. E.
Published: April 2010

Abstract. In this study we describe an objective classification scheme for extreme UK daily precipitation to be used in flood risk analysis applications. We create a simplified representation of the spatial layout of extreme events based on a new digital archive of UK rainfall. This simplification allows a Bayesian clustering algorithm to compress these representations down to eight prototypical patterns of extreme falls. These patterns are then verified against a five-class, manual, subjective typing scheme, produced independently using known meteorological mechanisms, isohyetal maps and additional descriptive text from the archive. Compared against the manual scheme, the new objective scheme can reproduce the known meteorological conditions, both in terms of spatial layout and seasonal timing, and is shown to be of hydrological relevance when matched to several notable flooding events in the past century. Furthermore, it is computationally simple and straightforward to apply in classifying future extreme rainfall events. We discuss the practical use of this new typing scheme in flood simulations and climate change applications.
Analysing the temporal dynamics of model performance for hydrological models
Authors: Reusser D. E. , Blume T. , Schaefli B. , Zehe E.
Published: April 2010

Abstract. The temporal dynamics of hydrological model performance gives insights into errors that cannot be obtained from global performance measures assigning a single number to the fit of a simulated time series to an observed reference series. These errors can include errors in data, model parameters, or model structure. Dealing with a set of performance measures evaluated at a high temporal resolution implies analyzing and interpreting a high dimensional data set. This paper presents a method for such a hydrological model performance assessment with a high temporal resolution and illustrates its application for two very different rainfall-runoff modeling case studies. The first is the Wilde Weisseritz case study, a headwater catchment in the eastern Ore Mountains, simulated with the conceptual model WaSiM-ETH. The second is the Malalcahuello case study, a headwater catchment in the Chilean Andes, simulated with the physics-based model Catflow. The proposed time-resolved performance assessment starts with the computation of a large set of classically used performance measures for a moving window. The key of the developed approach is a data-reduction method based on self-organizing maps (SOMs) and cluster analysis to classify the high-dimensional performance matrix. Synthetic peak errors are used to interpret the resulting error classes. The final outcome of the proposed method is a time series of the occurrence of dominant error types. For the two case studies analyzed here, 6 such error types have been identified. They show clear temporal patterns which can lead to the identification of model structural errors.
Modeling for transboundary water resources planning and allocation
Authors: Juízo D. , Lidén R.
Published: April 2010

Abstract. International water resources agreements for transboundary rivers in southern Africa are based on system analysis models for water planning and allocation. The Water Resources Yield Model (WRYM) developed in South Africa has so far been the only model applied in official joint water resources studies aimed to form water-sharing agreements. The continuous discussion around the model performance and growing distress over it being South African, where it was originally developed, while South Africa is one of the interested parties in the process, results in an increased controversy over the system analysis results that are often only meant to guide in selecting the options for water resources management in a given set of scenarios. The objective of this study was therefore to assess the model performance of two other models; WAFLEX and WEAP21 in the Umbeluzi River Basin system where the WRYM was previously applied as part of a Joint River Basin Study. A set of basin development scenarios was equally tested in the three models and the results compared. The results show that the three models all are possible tools for system analysis of river basins in southern Africa, although the structure and complexity of the models are different. The obtained level of satisfaction for specific water users could, however, vary depending on which model was used, which causes uncertainties. The reason for the diverse results is the structurally different ways of describing allocation and prioritization of water in the three models. However, the large degrees of freedom in all system models cause even larger uncertainty in the results since the model user can, intentionally or unintentionally, direct the results to favor certain water users. The conclusion of this study is therefore that the choice of model does not per se affect the decision of best water allocation and infrastructure layout of a shared river basin. The chosen allocation and prioritization principles for the specific river basin and the model user's experience and integrity are more important factors to find the optimal and equitable allocation.
Influence of hydropedology on viticulture and oenology of Sangiovese vine in the Chianti area (Central Italy)
Authors: Costantini E. A. C. , Pellegrini S. , Bucelli P. , Storchi P. , Vignozzi N. , Barbetti R. , Campagnolo S.
Published: April 2010

Abstract. The adoption of precision agriculture in viticulture requires the knowledge of the spatial and temporal variability of available soil water. A three-years trial was carried out in Chianti (central Italy) on Sangiovese vine to test the prediction capacity of selected hydropedological models for two soil series cultivated with grape and for delineating hydrological functional units within two vineyards. The soils of the vineyards differentiated in structure, porosity and related hydropedological characteristics, as well as in salinity. Soils were mapped with a geophysical survey and six plots were selected in different morphological positions: summit, backslope and footslope. Water content, redox processes and temperature were monitored, and yield, phenological phases, and chemical analysis of grapes were determined. The isotopic ratio δ13C was measured in the wine ethanol upon harvesting to evaluate the degree of water stress suffered by vines. The grapes in each plot were collected for wine making in small barrels. The wines obtained were analysed and submitted to a blind organoleptic testing. The results demonstrated that the tested hydropedological models can be used for the prevision of the moisture status of soils cultivated with grape during summertime in Mediterranean climate. As foreseen by the models, the amount of mean daily transpirable soil water differed considerably between the vineyards and increased significantly along the three positions on slope in both vineyards and in every year, even during the very dry 2006. However, both the response of Sangiovese to water stress and the quality of wine were influenced by the interaction between transpirable water and salinity. The installation of IRIS tubes allowed confirmation of the occurrence of redox processes, although discoloration was influenced more by soil temperature, rather than by moisture. The map produced by once only geophysical survey mirrored only partially the seasonal hydropedology of these heavily tilled soils on slope.
Daily reservoir inflow forecasting combining QPF into ANNs model
Authors:   Jun Zhang,   Chun-tian Cheng,   Sheng-li Liao,   Xin-yu Wu,   Jian-jian Shen
Published: April 2010

Abstract. Daily reservoir inflow predictions with lead-times of several days are essential to the operational planning and scheduling of hydroelectric power system. The demand for quantitative precipitation forecasting (QPF) is increasing in hydropower operation with the dramatic advances in the numerical weather prediction (NWP) models. This paper presents a simple and an effective algorithm for daily reservoir inflow predictions which solicits the observed precipitation, forecasted precipitation from QPF as predictors and discharges in following 1 to 6 days as predicted targets for multilayer perceptron artificial neural networks (MLP-ANNs) modeling. An improved error back-propagation algorithm with self-adaptive learning rate and self-adaptive momentum coefficient is used to make the supervised training procedure more efficient in both time saving and search optimization. Several commonly used error measures are employed to evaluate the performance of the proposed model and the results, compared with that of ARIMA model, show that the proposed model is capable of obtaining satisfactory forecasting not only in goodness of fit but also in generalization. Furthermore, the presented algorithm is integrated into a practical software system which has been severed for daily inflow predictions with lead-times varying from 1 to 6 days of more than twenty reservoirs operated by the Fujian Province Grid Company, China.
Intensity-Duration-Frequency and spatial analysis of droughts using the Standardized Precipitation Index
Authors: Mohseni Saravi M. , Safdari A. A. , Malekian A.
Published: April 2010

Abstract. Precipitation deficit and its daily, seasonal and annual oscillations are inherent characteristics of Iran's climate. Droughts are generally characterized by a prolonged and abnormal moisture deficiency. In drought studies it is important to characterize the start and end of a drought as well as its intensity, duration, frequency and magnitude. The objective of this study was to analyze drought characteristics and to develop drought maps in the Karoon river basin, Iran. The Standardized Precipitation Index (SPI) was used in drought analysis based on the data for meteorological stations located inside or adjacent to the study area and three time scales including the 3-, 6- and 12-month SPI were evaluated. After determining the dry and wet periods, historical characteristics of droughts were identified and spatial distribution maps of droughts were plotted using GIS. Based on frequency distributions, drought durations and magnitudes were computed corresponding to 5, 10, 20, 50 and 100-year return periods. The Time scale-Duration-Frequency (TDF) and Time scale-Magnitude-Frequency (TMF) relationships were also developed, which constitute an essential tool for water resource design purposes. Drought spatial distribution maps show that extreme conditions dominate the southeastern regions of the basin. The efficiency of the SPI is determined by monitoring the drought of 1999.
Estimating spatially distributed monthly evapotranspiration rates by linear transformations of MODIS daytime land surface temperature data
Authors: Szilagyi J. , Jozsa J.
Published: April 2010

Abstract. Under simplifying conditions catchment-scale vapor pressure at the drying land surface can be calculated as a function of its watershed-representative temperature () by the wet-surface equation (WSE, similar to the wet-bulb equation in meteorology for calculating the dry-bulb thermometer vapor pressure) of the complementary relationship of evaporation. The corresponding watershed ET rate, , is obtained from the Bowen ratio with the help of air temperature, humidity and percent possible sunshine data. The resulting (, ) pair together with the wet-environment surface temperature () and ET rate (ETw), obtained by the Priestley-Taylor equation, define a linear transformation on a monthly basis by which spatially distributed ET rates can be estimated as a sole function of MODIS daytime land surface temperature, Ts, values within the watershed. The linear transformation preserves the mean which is highly desirable. , in the lack of significant open water surfaces within the study watershed (Elkhorn, Nebraska), was obtained as the mean of the smallest MODIS Ts values each month. The resulting period-averaged (2000–2007) catchment-scale ET rate of 624 mm/yr is very close to the water-balance derived ET rate of about 617 mm/yr. The latter is a somewhat uncertain value due to the effects of (a) observed groundwater depletion of about 1m over the study period caused by extensive irrigation, and; (b) the uncertain rate of net regional groundwater supply toward the watershed. The spatially distributed ET rates correspond well with soil/aquifer properties and the resulting land use type (i.e., rangeland versus center-pivot irrigated crops).
Connecting ecohydrology and hydropedology in desert shrubs: stemflow as a source of preferential flow in soils
Authors: Li X.-Y. , Yang Z.-P. , Li Y.-T. , Lin H.
Published: April 2010

Abstract. Ecohydrology and hydropedology are two emerging fields that are interconnected. In this study, we demonstrate stemflow hydrology and preferential water flow along roots in two desert shrubs (H. scoparium and S. psammophila) in the south fringe of Mu Us sandy land in North China. Stemflow generation and subsequent movement within soil-root system were investigated during the growing seasons from 2006 to 2008. The results indicated that the amount of stemflow in H. scoparium averaged 3.4% of incident gross rainfall with a range of 2.3–7.0%, and in S. psammophila stemflow averaged 6.3% with a range of 0.2–14.2%. Stemflow was produced from rainfall events more than 1 mm for both shrubs. The average funneling ratio (the ratio of rainfall amount delivered to the base of the tree to the rainfall that would have reached the ground should the tree were not present) was 77.8 and 48.7 for H. scoparium and S. psammophila, respectively, indicating that branches and stems were fully contributing to stemflow generation and thereby provided considerable amount of water to deep soil layer. Analysis of rhodamine-B dye distribution under the shrubs showed that stemflow entered the soil preferentially along root channels contributing to deep storage and that the depth of stemflow infiltrated increased with increasing incident rainfall amount. Distribution of soil water content under the shrubs with and without stemflow ascertained that stemflow was conducive to concentrate and store water in deep layers in the soil profiles, creating favorable soil water conditions for plant growth under arid conditions. Accordingly there is a clear linkage between aboveground ecohydrology and belowground hydropedology in the desert shrubs, whereby an increase in stemflow would result in an increase in soil hydrological heterogeneity.
Improvement of surface albedo parameterization within a regional climate model (RegCM3)
Authors: Bao Y. , Lü S.
Published: April 2010

Abstract. A parameterization for calculating surface albedo of Solar Zenith Angel (SZA) dependence with coefficient for each vegetation type determined on the Moderate Resolution Imaging Spectro-radiometer (MODIS) reformed by the Bidirectional Reflectance Distribution Function (BRDF) is incorporated within the latest Abdus Salam International Centre for Theoretical Physics (ICTP) Regional Climate Model (RegCM3), and evaluated with a high resolution one-way nesting simulation in China using the Climate Research Unit (CRU) data and the observations from the Field Experiment on Interaction between Land and Atmosphere in Arid Region of Northwest China (NWC-ALIEX). The performance of the SZA method modeling surface characteristic is investigated.Results indicate, RegCM with SZA method (RCM_SZA) considerably improve the cold bias of original RegCM (RCM_ORI) in air surface temperature in East Asia with 1.2 degree increased in summer due to the lower albedo produced by SZA method which makes more solar radiation absorbed by the surface and used for heating the atmosphere near to the surface. The simulated diurnal cycle of ground temperature conforms fairly well to the observation in the nesting simulation in Northwest China, especially during the noon time when the SZA has the lowest value. However, the modification can not obviously affect the East Asia summer monsoon precipitation simulation although RCM_SZA produce more evapo-transpiration in surface with more than 2 Wm−2 increases in simulated latent heat fluxes both in East Asia and in Northwest China compared to RCM_ORI.
Physical based retrieval of crop characteristics for improved water use estimates
Authors: Richter K. , Timmermans W. J.
Published: April 2010

Abstract. The increasing scarcity of water from local to global scales requires the efficient monitoring of this valuable resource, especially in the context of a sustainable management in irrigated agriculture. In this study, a two-source energy balance model (TSEB) was applied to the Barrax test site. The inputs of Leaf area index (LAI) and fractional vegetation cover (fCover), were estimated from CHRIS imagery by using the traditional scaled NDVI and a LUT inversion approach. The LUT was constructed using the well established SAILH+PROSPECT radiative transfer model. Simulated fluxes were compared with tower measurements and vegetation characteristics were evaluated with in situ LAI and fCover measurements of a range of crops from the SPARC campaign 2004. Results showed a better retrieval performance for the LUT approach for canopy parameters, affecting flux predictions that were related to land use.
A framework for assessing flood frequency based on climate projection information
Authors: Raff D. A. , Pruitt T. , Brekke L. D.
Published: April 2010

Abstract. Flood safety is of the utmost concern for water resources management agencies charged with operating and maintaining reservoir systems. Risk evaluations guide design of infrastructure alterations or lead to potential changes in operations. Changes in climate may change the risk due to floods and therefore decisions to alter infrastructure with a life span of decades or longer may benefit from the use of climate projections as opposed to use of only historical observations. This manuscript presents a set of methods meant to support flood frequency evaluation based on current downscaled climate projections and the potential implications of changing flood risk on how evaluations are made. Methods are demonstrated in four case study basins: the Boise River above Lucky Peak Dam, the San Joaquin River above Friant Dam, the James River above Jamestown Dam, and the Gunnison River above Blue Mesa Dam. The analytical design includes three core elements: (1) a rationale for selecting climate projections to represent available climate projections; (2) generation of runoff projections consistent with climate projections using a process-based hydrologic model and temporal disaggregation of monthly downscaled climate projections into 6-h weather forcings required by the hydrologic model; and (3) analysis of flood frequency distributions based on runoff projection results. In addition to demonstrating the methodology, this paper also presents method choices under each analytical element, and the resulting implications to how flood frequencies are evaluated.
Agricultural-to-hydropower water transfers: sharing water and benefits in hydropower-irrigation systems
Authors: Tilmant A. , Goor Q. , Pinte D.
Published: April 2010

Abstract. This paper presents a methodology to assess agricultural-to-hydropower water transfers in water resources systems where irrigation crop production and hydropower generation are the main economic activities. In many countries, water for crop irrigation is often considered as a static asset: irrigation water is usually allocated by a system of limited annual rights to use a prescribed volume of water. The opportunity cost (forgone benefits) of this static management approach may be important in river basins where large irrigation areas are present in the upstream reaches. Temporary reallocation of some (or all) of the irrigation water downstream to consumptive and/or non-consumptive users can increase the social benefits if the sum of the downstream productivities exceeds those of the upstream farmers whose entitlements are curtailed. However, such a dynamic allocation process will be socially acceptable if upstream farmers are compensated for increasing the availability of water downstream. This paper also presents a methodology to derive the individual contribution of downstream non-consumptive users, i.e. hydropower plants, to the financial compensation of upstream farmers. This dynamic management approach is illustrated with a cascade of multipurpose reservoirs in the Euphrates river basin. The analysis of simulation results reveals that, on average, the annual benefits obtained with the dynamic allocation process are 6% higher that those derived from a static allocation.
An inversion method based on multi-angular approaches for estimating bare soil surface parameters from RADARSAT-1
Authors: Sahebi M. R. , Angles J.
Published: April 2010

Abstract. The radar signal recorded by earth observation (EO) satellites is known to be sensitive to soil moisture and soil surface roughness, which influence the onset of runoff. This paper focuses on the inversion of these parameters using a multi-angular approach based on RADARSAT-1 data with incidence angles of 35° and 47° (in mode S3 and S7). This inversion was done based on three backscatter models: Geometrical Optics Model (GOM), Oh Model (OM) and Modified Dubois Model (MDM), which are compared in order to obtain the best configuration. For roughness expressed in rms of heights, mean absolute errors of 1.23 cm, 1.12 cm and 2.08 cm, and for dielectric constant, mean absolute errors of 2.46, 4.95 and 3.31 were obtained for the MDM, GOM and the OM simulation, respectively. This means that the MDM provided the best results with minimum errors. Based on these results, the latter inversion algorithm was applied on the images and the final results are presented in two different maps showing pixel and homogeneous zones for surface roughness and soil moisture.