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Snow is a crucial component of the hydrological cycle in the Western Himalaya. Water from snowmelt is used in various sectors in downstream regions, thus playing a critical role in securing the livelihoods of millions of people. In this study, we investigated the future evolution of snow cover and snowmelt in the Panjshir catchment of Afghanistan, a sub-basin of the Indus, in the Western Himalaya. We applied a three-step approach to select a few global climate model (GCM) simulations from CMIP5 climate datasets for RCP4.5 and RCP8.5, which showed reasonable performance with ERA5-Land dataset for the chosen historical period (1981–2010). The selected model simulations were then segregated into two groups: those projecting a cold-wet climate and those projecting a warm-dry climate by the end of the 21st century (2071–2100). These GCMs were downscaled to a higher resolution using empirical statistical downscaling. To simulate the snow processes, we used the distributed cryospheric-hydrological J2000 model. The results indicate that the model captures well the snow cover dynamics for the historical period when compared with the daily MODIS-derived snow cover. The J2000 model was then forced by climate projections from the selected GCMs to quantify future changes in snow cover area, snow storage and snowmelt. While a 10–18% reduction in annual snow cover area is projected in the cold-wet models, a 22–36% reduction is projected in the warm-dry models. Similarly, the snow cover area is projected to decrease in all elevation bands under climate change. At the seasonal scale, across all models and scenarios, the snow cover in the autumn and spring seasons are projected to reduce by as much as 25%, with an increase in winter and spring snowmelt and a decrease in summer snowmelt. The projected changes in the seasonal availability of snowmelt-driven water resources are likely to have direct implications for water-dependent sectors in the region and call for a better understanding of water usage and future adaptation practices.

Estimating the hydrological regime of ungauged catchments in the Himalayan region is challenging due to a lack of sufficient monitoring stations. In this paper, the spatial transferability of the model parameters of the process-oriented J2000 hydrological model was investigated in two glaciated sub-catchments of the Koshi river basin in eastern Nepal. The basins has a high degree of similarity with respect to their static landscape features. The model was first calibrated (1986–1991) and validated (1992–1997) in the Dudh Koshi sub-catchment. The calibrated and validated model parameters were then transferred to the nearby Tamor catchment (2001–2009). Sensitivity and uncertainty analyses were carried out for both sub-catchments to discover the sensitivity range of the parameters in the two catchments. The model represented the overall hydrograph well in both sub-catchments, including baseflow, rising and falling limbs; however, the peak flows were underestimated. The efficiency results according to both Nash-Sutcliffe (ENS) and the coefficient of determination (r2) were above 0.84 in both catchments (1986-1997 in Dudh Koshi and 2001-2009 in Tamor). The ranking of the parameters in respect to their sensitivity matched well for both catchments while taking ENS and Log Nash-Sutcliffe (LNS) efficiencies into account. However, there were some differences in sensitivity to ENS and LNS for moderate and low sensitive parameters, although the majority (13 out of 16 for ENS and 16 out of 16 for LNS) had a sensitivity response in a similar range. The generalized uncertainty likelihood estimation (GLUE) results suggest that the parameter uncertainty are most of the time within the range and the ensemble mean matches very good (ENS: 0.84) with observed discharge. The results indicate that transfer of the J2000 parameters to a neighboring catchment in the Himalayan region with similar physiographic landscape characteristics is viable. This indicates the possibility of applying calibrated process-based J2000 model to other ungauged catchments in the Himalayan region, which could provide important insights into the hydrological system dynamics and provide much needed information to support water resources planning and management.

The contrasting patterns of lake-level fluctuations across the Tibetan Plateau (TP) are indicators of differences in the water balance over the TP. However, little is known about the key hydrological factors controlling this variability. The purpose of this study is to contribute to a more quantitative understanding of these factors for four selected lakes in the southern-central part of the TP: Nam Co and Tangra Yumco (increasing water levels), and Mapam Yumco and Paiku Co (stable or slightly decreasing water levels). We present the results of an integrated approach combining hydrological modeling, atmospheric-model output and remote-sensing data. The J2000g hydrological model was adapted and extended according to the specific characteristics of closed-lake basins on the TP and driven with High Asia Refined analysis (HAR) data at 10 km resolution for the period 2001–2010. Differences in the mean annual water balances among the four basins are primarily related to higher precipitation totals and attributed runoff generation in the Nam Co and Tangra Yumco basins. Precipitation and associated runoff are the main driving forces for inter-annual lake variations. The glacier-meltwater contribution to the total basin runoff volume (between 14 and 30 % averaged over the 10-year period) plays a less important role compared to runoff generation from rainfall and snowmelt in non-glacierized land areas. Nevertheless, using a hypothetical ice-free scenario in the hydrological model, we indicate that ice-melt water constitutes an important water-supply component for Mapam Yumco and Paiku Co, in order to maintain a state close to equilibrium, whereas the water balance in the Nam Co and Tangra Yumco basins remains positive under ice-free conditions. These results highlight the benefits of linking hydrological modeling with atmospheric-model output and satellite-derived data, and the presented approach can be readily transferred to other data-scarce closed lake basins, opening new directions of research. Future work should go towards a better assessment of the model-chain uncertainties, especially in this region where observation data are scarce.

The Guarani Aquifer System (GAS) is the largest transboundary aquifer system in South America. One great challenge of managing the GAS is determining the effect of its exploitation for urban, industrial and agricultural use. The fully distributed, process-oriented hydrological model J2000 implemented in the Jena Adaptable Modelling System (JAMS) was used in this study to simulate the water balance in the Ribeirao da Onca (Onca Creek) watershed, because this is an outcrop zone of the Guarani Aquifer System (GAS). The J2000 model proved to be a flexible and easy-to-use tool. The constructed model was effective in predicting the hydrological response of the basin, showing a Nash-Sutcliffe coefficient of 0.76 and 0.81 during periods of model calibration and validation, respectively. The model adequately predicted the discharge volume, presenting percent biases of −0.66 and −2.80 % and root mean square error of 0.14 and 0.18 m3 s−1 for the two periods. The historical reconstruction of the flow series demonstrated that baseflow represents 86–98 % of the total annual discharge and 24–30 % of the total rainfall volume in the Ribeirao da Onca watershed. These estimates can be used to estimate the groundwater recharge rate, in order to establish quantitative targets to prevent overexploitation in the GAS water management. Additionally, the model can be used for further studies to determine the effects of land use and climate change on the hydrologic cycle of the basin.

In this paper, a method is presented to estimate excess nitrogen on large scales considering single field processes. The approach was implemented by using the physically based model J2000-S to simulate the nitrogen balance as well as the hydrological dynamics within meso-scale test catchments. The model input data, the parameterization, the results and a detailed system understanding were used to generate the regression tree models with GUIDE (Loh, 2002). For each landscape type in the federal state of Thuringia a regression tree was calibrated and validated using the model data and results of excess nitrogen from the test catchments. Hydrological parameters such as precipitation and evapotranspiration were also used to predict excess nitrogen by the regression tree model. Hence they had to be calculated and regionalized as well for the state of Thuringia. Here the model J2000g was used to simulate the water balance on the macro scale. With the regression trees the excess nitrogen was regionalized for each landscape type of Thuringia. The approach allows calculating the potential nitrogen input into the streams of the drainage area. The results show that the applied methodology was able to transfer the detailed model results of the meso-scale catchments to the entire state of Thuringia by low computing time without losing the detailed knowledge from the nitrogen transport modeling. This was validated with modeling results from Fink (2004) in a catchment lying in the regionalization area. The regionalized and modeled excess nitrogen correspond with 94%. The study was conducted within the framework of a project in collaboration with the Thuringian Environmental Ministry, whose overall aim was to assess the effect of agro-environmental measures regarding load reduction in the water bodies of Thuringia to fulfill the requirements of the European Water Framework Directive (Bäse et al., 2007; Fink, 2006; Fink et al., 2007).

Summary A key factor for sustainable management of groundwater systems is the accurate estimation of groundwater recharge. Hydrological models are common tools for such estimations and widely used. As such models need to be calibrated against measured values, the absence of adequate data can be problematic. We present a nested multi-response calibration approach for a semi-distributed hydrological model in the semi-arid catchment of Wadi al Arab in Jordan, with sparsely available runoff data. The basic idea of the calibration approach is to use diverse observations in a nested strategy, in which sub-parts of the model are calibrated to various observation data types in a consecutive manner. First, the available different data sources have to be screened for information content of processes, e.g. if data sources contain information on mean values, spatial or temporal variability etc. for the entire catchment or only sub-catchments. In a second step, the information content has to be mapped to relevant model components, which represent these processes. Then the data source is used to calibrate the respective subset of model parameters, while the remaining model parameters remain unchanged. This mapping is repeated for other available data sources. In that study the gauged spring discharge (GSD) method, flash flood observations and data from the chloride mass balance (CMB) are used to derive plausible parameter ranges for the conceptual hydrological model J2000g. The water table fluctuation (WTF) method is used to validate the model. Results from modelling using a priori parameter values from literature as a benchmark are compared. The estimated recharge rates of the calibrated model deviate less than ±10% from the estimates derived from WTF method. Larger differences are visible in the years with high uncertainties in rainfall input data. The performance of the calibrated model during validation produces better results than applying the model with only a priori parameter values. The model with a priori parameter values from literature tends to overestimate recharge rates with up to 30%, particular in the wet winter of 1991/1992. An overestimation of groundwater recharge and hence available water resources clearly endangers reliable water resource managing in water scarce region. The proposed nested multi-response approach may help to better predict water resources despite data scarcity.

The purpose of this paper is to estimate the water balance in a semi-arid environment with limited in situ data using a remote sensing approach. We focus on the Lake Manyara catchment, located within the East African Rift of northern Tanzania. We use a distributed conceptual hydrological model driven by remote sensing data to study the spatial and temporal variability of water balance parameters within the catchment. Satellite gravimetry GRACE data is used to verify the trends of the inferred lake level changes. The results show that the lake undergoes high spatial and temporal variations, characteristic of a semi-arid climate with high evaporation and low rainfall. We observe that the Lake Manyara water balance and GRACE equivalent water depth show comparable trends; a decrease after 2002 followed by a sharp increase in 2006–2007. Our modeling confirms the importance of the 2006–2007 Indian Ocean Dipole fluctuation in replenishing the groundwater reservoirs of East Africa. We thus demonstrate that water balance modeling can be performed successfully using remote sensing data even in complex climatic settings. Despite the small size of Lake Manyara, GRACE data showed great potential for hydrological research on smaller un-gauged lakes and catchments in similar semi-arid environments worldwide. The water balance information can be used for further analysis of lake variations in relation to soil erosion, climate and land cover/land use change as well as different lake management and conservation scenarios.

This paper provides the results of hydrological modelling in a mesoscale glaciated alpine catchment of the Himalayan region. In the context of global climate change, the hydrological regime of an alpine mountain is likely to be affected, which might produce serious implications for downstream water availability. The main objective of this study was to understand the hydrological system dynamics of a glaciated catchment, the Dudh Kosi River basin, in Nepal, using the J2000 hydrological model and thereby understand how the rise in air temperature will affect the hydrological processes. The model is able to reproduce the overall hydrological dynamics quite well with an efficiency result of Nash–Sutcliffe (0.85), logarithm Nash–Sutcliffe (0.93) and coefficient of determination (0.85) for the study period. The average contribution from glacier areas to total streamflow is estimated to be 17%, and snowmelt (other than from glacier areas) accounts for another 17%. This indicates the significance of the snow and glacier runoff in the Himalayan region. The hypothetical rise in temperature scenarios at a rate of +2 and +4 °C indicated that the snowmelt process might be largely affected. An increase in snowmelt volume is noted during the premonsoon period, whereas the contribution during the monsoon season is significantly decreased. This occurs mainly because the rise in temperature will shift the snowline up to areas of higher altitude and thereby reduce the snow storage capacity of the basin. This indicates that the region is particularly vulnerable to global climate change and the associated risk of decreasing water availability to downstream areas. Under the assumed warming scenarios, it is likely that in the future, the river might shift from a ‘melt-dominated river’ to a ‘rain-dominated river’. The J2000 model should be considered a promising tool to better understand the hydrological dynamics in alpine mountain catchments of the Himalayan region. This understanding will be quite useful for further analysis of ‘what-if scenarios’ in the context of global climate and land-use changes and ultimately for sustainable Integrated Water Resources Management in the Himalayan region. Copyright © 2012 John Wiley & Sons, Ltd.

Waterlogging and secondary salinisation have become serious problems in canal irrigated areas of arid and semi-arid regions. This study examined hydrology and estimated the seasonal net groundwater recharge of an irrigated semi-arid region located in the Haryana State of India where about 500 000 ha area are waterlogged and unproductive, and the size of the waterlogged area is increasing, causing a threat to agricultural sustainability. Groundwater recharge analysis during the study period (1989– 2010) revealed that percolation from irrigated fields was the main recharge component, with 48% contributing to total recharge. An annual groundwater table rise of 0.198 m was estimated for the study area. Since the groundwater table had been rising continuously, suitable water management strategies such as as conjunctive use of groundwater and canal water and changes in crop patterns by reducing rice crop areas against of other low-water crops such as sorghum are suggested to bring the groundwater table down to a safe limit and prevent further rise of the groundwater table. Copyright © 2012 John Wiley & Sons, Ltd.

This study reports on the integration of the J2K model (an object-oriented, hydrological system for fully distributed simulation of the water balance in large watersheds) under the Object Modeling System (OMS) environmental modeling framework and subsequent evaluation of OMS-J2K performance in the Cedar Creek watershed (CCW) in northeastern Indiana. The CCW is one of 14 benchmark watersheds in the USDA-ARS Conservation Effects Assessment Project (CEAP) watershed assessment study. Two input parameter sets were developed for OMS-J2K evaluation: (1) a "base parameter set" with parameter values taken from previous simulation studies where J2K was applied to watersheds with characteristics similar to the CCW, and (2) an "adjusted parameter set" with modifications to input parameters related to evapotranspiration, soil water storage, and soil water lateral flow. Comparisons of daily, average monthly, and annual average simulated and observed flows for the 1997-2005 simulation period using the base parameter set resulted in Nash-Sutcliffe efficiency (E NS ), root mean square deviation (RMSD), and relative error (PBIAS) coefficients of 0.34 to 0.48 for E NS , 1.50 to 8.79 m 3 s -1 for RMSD, and -18.43% for PBIAS. All statistical evaluation coefficients improved for the adjusted parameter set (e.g., 0.44 to 0.59 for E NS , 0.87 to 7.73 m 3 s -1 for RMSD, and -8.59% for PBIAS). The ranges of E NS and PBIAS values for uncalibrated or manually adjusted streamflow predictions in this study (using both parameter sets) were similar to others reported in the literature for various watershed models. This study represents the first attempt to develop and apply a complex natural resource system model under the OMS. The results indicate that the OMS-J2K watershed model was able to reproduce the hydrological dynamics of the CCW and should serve as a foundation on which to build a more comprehensive model to better quantify water quantity and quality at the watershed scale. In particular, the topological routing scheme employed by OMS-J2K (thus allowing the simulation of lateral processes vital for the modeling of runoff concentration dynamics) is much more robust than the quasi-distributed routing schemes used by other watershed-scale natural resource models and represents a noteworthy advancement in hydrological modeling toward deriving suitable conservation management scenarios.

In this paper, the application of a fully distributed hydrological model J2000 with limited hydrological data was investigated in an alpine small and glacierized catchment, the Qugaqie (55 km2 with 7.3% glacier area), in the central Tibetan Plateau (TP). The J2000 was examined to investigate the influence on model performance, as well as on data, parameters and sensitivities. The model was calibrated with time series of discharge at the basin outlet for the summers of 2006 and 2007 and validated for the summer of 2008 by examining multiple objective functions. The model coefficients of determination were 0.62 and 0.91 for the calibration periods in 2006 and 2007, respectively, and 0.56 for the validation period in 2008. Simulated discharge was generally less than the observed values for the calibration and validation periods. The sensitivity to alteration in meteorological parameter has revealed that a change in air temperature would cause a dramatic increase of discharge in the Qugaqie catchment. Hypothetical climate scenario experiments showed that the increase of air temperature by 1°C resulted in 14% increase in runoff, whereas 20% increase in precipitation caused 9% increase in runoff but 12% reduction in glacier melt.

The sustainability of the rice–wheat cropping system in an irrigated semi-arid area of Haryana State (India) is under threat due to the continuous rise in the poor quality groundwater table, which is caused by the geo-hydrological condition and poor irrigation water management. About 500,000 ha in the State are waterlogged and unproductive and the size of the waterlogged area is increasing. We analyse the hydrology and estimate seasonal net groundwater recharge in the study area. Rainfall is quite variable, particularly in the monsoon season, and the mean monthly reference evapotranspiration shows a high inter-annual variation, with values between 2.45 and 8.47 mm/day in December and May. Groundwater recharge analysis during the study period (1989–2008) reveals that percolation from irrigated fields is the main recharge component with 57% contribution to the total recharge. An annual groundwater table rise of 0.137 m has been estimated for the study area. As the water table has been rising continuously, suitable water management strategies such as increasing groundwater abstraction by installing more tubewells, using the groundwater conjunctively with good quality canal water, changes in cropping patterns, adoption of salt tolerant crops, changes in water-pricing policy, and matching water supply more closely with demand, are suggested to bring the water table down to a safe limit and to prevent further rising of the water table.

In this paper the J2000, a new modelling system for the distributed simulation of the water balance in large river basins, will be introduced and described briefly. The introduction comprises an overview of the model's purpose and concept, the simulated hydrological processes, the distribution concept for the spatial subdivision of the catchment as well as the methods for regionalisation of climate data from point sources. As an example for the model's capabilities simulation results of a large catchment in Germany are shown. The model description is complemented by the presentation of results of two land use change scenarios to prove the model's ability to be used for the spatial quantification of the impact of land use changes on the water balance.

Complex climatic interactions control hydrological processes in high mountains that in their turn regulate the erosive forces shaping the relief. To unravel the hydrological cycle of a glaciated watershed (Gunt River) considered representative of the Pamirs' hydrologic regime we developed a remote sensing-based approach. At the boundary between two distinct climatic zones dominated by Westerlies and Indian summer monsoon, the Pamir is poorly instrumented and only a few in situ meteorological and hydrological data are available. We adapted a suitable conceptual distributed hydrological model (J2000g). Interpolations of the few available in situ data are inadequate due to strong, relief induced, spatial heterogeneities. Instead we use raster data, preferably from remote sensing sources depending on availability and validation. We evaluate remote sensing-based precipitation and temperature products. MODIS MOD11 surface temperatures show good agreement with in situ data, perform better than other products and represent a good proxy for air temperatures. For precipitation we tested remote sensing products as well as the HAR10 climate model data and the interpolation-based APHRODITE dataset. All products show substantial differences both in intensity and seasonal distribution with in-situ data. Despite low resolutions, the datasets are able to sustain high model efficiencies (NSE ≥0.85). In contrast to neighbouring regions in the Himalayas or the Hindukush, discharge is dominantly the product of snow and glacier melt and thus temperature is the essential controlling factor. 80% of annual precipitation is provided as snow in winter and spring contrasting peak discharges during summer. Hence, precipitation and discharge are negatively correlated and display complex hysteresis effects that allow to infer the effect of inter-annual climatic variability on river flow. We infer the existence of two subsurface reservoirs. The groundwater reservoir (providing 40% of annual discharge) recharges in spring and summer and releases slowly during fall and winter. A not fully constrained shallow reservoir with very rapid retention times buffers melt waters during spring and summer. This study highlights the importance of a better understanding of the hydrologic cycle to constrain natural hazards such as floods and landslides as well as water availability in the downstream areas. The negative glacier mass balance (−0.6 m w.e. yr−1) indicates glacier retreat, that will effect the currently 30% contribution of glacier melt to stream flow.

[Departement_IRSTEA]Eaux [TR1_IRSTEA]ARCEAU; International audience; This paper addresses the impact of the source and processing method of land use information for hydrological simulations on the long-term water balance of the Yzeron peri-urban catchment (150 km 2), located near Lyon, France. A customised version of the distributed hydrological model J2000 was used to perform simulations at a daily time step. Five land use data sets obtained from aerial photographs BDOrtho@IGN and satellites Quickbird and Spot for the year 2008 are compared. The paper presents the methodology for model setup and the simulation results for the main water balance components of the catchment: total runoff at several gauging stations, runoff components, evapotranspiration and soil moisture. The model evaluation against discharge measurements at six locations shows a reasonable agreement between simulated and observed values, in particular for general seasonal variations, low flow periods and simulation of runoff components (surface runoff, interflow and base flow), with Nash–Sutc-liffe efficiencies ranging from 0.25 to 0.51 at the daily time step and 0.46–0.82 at the monthly time step. The comparison of the model outputs for the various land use maps shows that the total discharge is not very sensitive to the data set used (À4.88% to 4.65% at the catchment outlet), except in a small and more densely urbanised sub-catchment for which a significant impact of image resolution on simulated flow is detected (+25.81%). For all gauges, the results also highlight the sensitivity of the modelled flow components , in particular regarding the amount and seasonal dynamics of surface runoff generation (8–44% of total flow at the catchment outlet depending on the data set used). As a conclusion, land use information should be selected and processed with care, with respect to the objectives of a given study, and the sizes and urbanisation rates of the target sub-catchments.

Accurate and up to date information on the status and trends of water balance is needed to develop strategies for conservation and the sustainable management of water resources. The purpose of this research is to estimate water balance in a semi-arid environment with limited in-situ data by using a remote sensing approach. We focus on the Lake Manyara catchment, located within the East African Rift of northern Tanzania. We use remote sensing and a semi-distributed hydrological model to study the spatial and temporal variability of water balance parameters within Manyara catchment. Satellite gravimetry GRACE data is used to verify the trend of the water balance result. The results show high spatial and temporal variations and characteristics of a semi-arid climate with high evaporation and low rainfall. We observe that the Lake Manyara water balance and GRACE equivalent water depth show comparable trends a decrease after 2002 followed by a sharp increase in 2006–2007. Despite the small size of Lake Manyara, GRACE data are useful and show great potential for hydrological research on smaller un-gauged lakes and catchments in semi-arid environments. Our modelling confirms the importance of the 2006–2007 Indian Ocean Dipole fluctuation in replenishing the groundwater reservoirs of East Africa. The water balance information can be used for further analysis of lake variations in relation to soil erosion, climate and land cover/land use change as well as different lake management and conservation scenarios. We demonstrate that water balance modelling can be performed accurately using remote sensing data even in complex climatic settings.

The scientific sound definition of measures to achieve the goals of the EU water framework directive (WFD) acquires spatially distributed analyses of the water and substance dynamics in meso- to macro-scale catchments. For this purpose, modelling tools or systems are needed which are robust and fast enough to be applied on such scales, but which are also able to simulate the impact of changes on single fields or small areas of a specific land use in the catchment. To face these challenges, we combined the fully-distributed hydrological model J2000 with the nitrogen transport routines of the Soil Water Assessment Tool SWAT model, which are normally applied in a semi-distributive approach. With this combination, we could extend the quantitative focus of J2000 with qualitative processes and could overcome the semi-distributed limitation of SWAT. For the implementation and combination of the components, we used the Jena Adaptable Modelling System JAMS (Kralisch and Krause, 2006) which helped tremendously in the relatively rapid and easy development of the new resultant model J2000-S (J2000-Substance). The modelling system was applied in the upper Gera watershed, located in Thuringia, Germany. The catchment has an area of 844 km2 and includes three of the typical landscape forms of Thuringia. The application showed, that the new modelling system was able to reproduce the daily hydrological as well as the nitrogen dynamics with a sufficient quality. The paper will describe the results of the new model and compare them with the results obtained with the original semi-distributed application of SWAT.