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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.

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).

The neighbouring river systems Cubango and Cuito drain the southeastern part of the Angolan Highlands and form the Okavango River after their confluence, thus providing 95% of the Okavango River discharge. Although they are characterised by similar environmental conditions, runoff records indicate remarkable differences regarding the hydrological dynamics. The Cubango River is known for rapid discharges with high peaks and low baseflow whereas the Cuito runoff appears more balanced. These differences are mainly caused by heterogeneous geological conditions or terrain features. The Cubango headwaters are dominated by crystalline bedrock and steeper, v-shaped valleys while the Cuito system is characterised by wide, swampy valleys and thick sand layers, thus attenuating runoff. This study presents model exercises which have been performed to assess and quantify these effects by applying the distributive model J2000g for each sub-basin. The models provide reasonable results representing the spatio-temporal runoff pattern, although some peaks are over- or underestimated, particularly in the Cuito catchment. This is explained by the scarce information on extent and structure of storages, such as aquifers or swamps, in the Cuito system. However, the model results aid understanding of the differences of both tributaries in runoff generation and underpin the importance of floodplains regarding the control of runoff peaks and low flows in the Cuito system. Model exercises reveal that basin heterogeneity needs to be taken into account and must be parameterised appropriately for reliable modelling and assessment of the entire Okavango River basin for managing the water resources of the transboundary Okavango River in a harmonious way.

Integrated Water Resources Management (IWRM) is a process which strives towards the sustainable management of water resources in river basins. The approach integrates insights and knowledge from various scientific disciplines comprising natural, socio-economic, and engineering sciences. These three pillars of sustainability are important components of this approach integrating the environmental, economic and social dimension. In the ideal IWRM case planning is based on the river basin scale and therefore is comparatively discussed herein for the two twinning BRAHMATWINN river basins, i.e. the Upper Danube River Basin (UDRB) in Europe and the Upper Brahmaputra River Basin (UBRB) in South Asia. In this chapter major challenges for the implementation of the IWRM process towards a sustainable management of water resources in the two UDRB and UBRB twinning river basins of the BRAHMATWINN project are analysed. The study revealed that in the UDRB the IWRM approach is already part of water management planning and the implementation of the EU Water Framework Directive (WFD) is a good example in this regard. Contrary in the UBRB the implementation of IWRM is just at the beginning phase, only recently is being discussed in the riparian states but has not been implemented in any way so far on the basin scale.

In this study, land cover changes between 1972 and 2013 were investigated in the Binah River watershed (North of Togo and Benin) using remote sensing and geographic information system technologies. Multitemporal satellite images—Landsat MSS (1972), TM (1987), and OLI-TIRS (2013)—were processed using object-based image analysis and post–classification comparison methods including landscape metrics and changes trajectories analysis. Land cover maps referring to five main land cover classes, namely, agricultural land, forest land, savannah, settlements, and water bodies, were produced for each acquisition date. The overall accuracies were 76.64% (1972), 83.52% (1987), and 88.84% (2013) with respective Kappa statistics of 0.69, 0.78, and 0.86. The assessment of the spatiotemporal pattern of land cover changes indicates that savannah, the main vegetation type, has undergone the most dominant change, decreasing from 67% of the basin area in 1972 to 56% in 1987 and 33% in 2013. At the same time, agricultural land has significantly increased from 15% in 1972 to 24% in 1987 and 43% in 2013, while some proportions of agricultural land were converted to savannah relating to fallow agriculture. In total, more than 55% of the landscape experienced changes between 1972 and 2013. These changes are primarily due to human activities and population growth. In addition, agricultural activities significantly contributed to the increase in the number of patches, degree of division, and splitting index of forest and savannah vegetations and the decrease in their effective mesh sizes. These results indicate further fragmentation of forest and savannah vegetations between 1972 and 2013. Further research is needed to quantitatively evaluate the influences of individual factors of human activities and to separate these from the impacts of climate change-driven disturbances.

This paper summarizes some of the climate (change) impact modeling activities conducted in the Land use and Climate Change interactions in Central Vietnam (LUCCi) project. The study area is the Vu Gia-Thu Bon (VGTB) river basin in Central Vietnam, which is characterized by recurrent floods during the rainy season, but also water shortages during the dry season. The impact modeling activities, such as the validation of the models are hindered by the scarcity of hydrometeorological data and an unfavorable distribution of the observation network, i.e., station data is available only for the lowlands. In total, two different process-based and distributed hydrological models are applied in concert with climate change and land use projections. Based on that, the magnitudes and return periods of extreme flows are estimated. The modeling results suggest increases of extreme high flows due to climate change. A multi-objective agro-economical model was developed for a typical irrigation scheme in the region in order to optimize the area for cropping, irrigation-techniques and schedules. The model results suggest the irrigation technique Alternate Wetting and Drying, which has the potential to increase the benefits for the farmers and help to mitigate greenhouse gases at the same time. In addition, the regional-scale crop model GLAM is applied for groundnut under rainfed conditions, which is capable to identify regions suitable for cropping in the future. The paper further synthesizes recommendations for local stakeholders in Central Vietnam.

A process-oriented hydrological model J2000 was employed on daily and monthly time steps for run-off simulation under Indian condition for the years 2003–2010. Further, a validated model was used for water balance assessment of the basin under both present scenario and hypothetical variations in precipitation and temperature. The regional sensitivity analysis (RSA) approach was employed for sensitivity analysis to determine the critical input parameter of the study area. It is inferred that recession coefficient for overland flow (soilConcRD1) is the most sensitive parameter, followed by recession coefficient for interflow (soilConcRD2) and linear reduction coefficient for AET (soilLinRed). Four evaluation criteria, i.e. coefficient of correlation (R), Nash-Sutcliffe efficiency (NSE), percent bias (PBIAS) and root-mean-square error (RMSE) observation standard deviation ratio (RSR), were adopted, for judging the model’s performance. For daily time steps, the PBIAS, R, NSE and RSR were found to be 4.73, 0.85, 0.67 and 0.45, respectively, during calibration and −1.50, 0.92, 0.85 and 0.29, respectively, during validation of the model. For monthly time steps, the PBIAS, R, NSE and RSR were found to be 4.73, 0.88, 0.7 and 0.43, respectively, during calibration and −1.50, 0.94, 0.89 and 0.26, respectively, during validation of the model. Further, model-simulated run-off components are overland flow (RD1), model’s interflow components (RD2 and RG1) and baseflow component (RG2), and the percent contribution was found to be 43.1 %, 35.8 % and 21.1 %, respectively. The water balance analysis carried out in the study demonstrated that the annual average precipitation in the basin is about 1,388 mm, out of which about 21 % flows out as run-off, 22 % as groundwater and about 56 % as evapotranspiration. The higher value of evaluation criteria indicates that the model is efficient in imitating the hydrological phenomenon of the Kopili River basin fairly well and can be cogitated as a promising tool to understand the constantly changing hydrological processes of Northeast (NE) India. Moreover, the hypothetical temperature increases due to the lowest emission scenario (1.1–2.9 °C), and the highest emission scenario (2.4–6.4 °C) of the IPCC (Climate change 2007: the physical science basis. Contribution of working group I. In: Solomon S, Qin D, Manning M, Chen Z, Marquis M, Averyt KB, Tignor M, Miller HL (eds) Fourth assessment report of the intergovernmental panel on climate change. Cambridge University Press, Cambridge, UK, 2007) indicates that the higher evapotranspiration is mainly resulting in low surface run-off and groundwater contribution. The run-off fluctuations resulting from ±10 % variation in precipitation were also analysed and were found to be approx. ±18 % deviation from simulated run-off. This analysis will be useful to understand the verge of hydrological processes in anticipation of global climate change (CC) and finally for sustainable water resource management in the NE region of India.

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.

The EC-project BRAHMATWINN was carrying out a harmonised integrated water resources management (IWRM) approach as addressed by the European Water Initiative (EWI) in headwater river systems of alpine mountain massifs of the twinning Upper Danube River Basin (UDRB) and the Upper Brahmaputra River Basins (UBRB) in Europe and Southeast Asia respectively. Social and natural scientists in cooperation with water law experts and local stakeholders produced the project outcomes presented in Chapter 2 till Chapter 10 of this publication. BRAHMATWINN applied a holistic approach towards IWRM comprising climate modelling, socio-economic and governance analysis and concepts together with methods and integrated tools of applied Geoinformatics. A detailed description of the deliverables produced by the BRAHMATWINN project is published on the project homepage http://www.brahmatwinn.uni-jena.de.

A comprehensive understanding of the interplay between the natural environment and the human dimension is one of the prerequisites to successful and sustaining IWRM practises in large river basins such as the Upper Brahmaputra river basin or the Upper Danube river basin. These interactions, their dynamics and changes, and the likely future scenarios were investigated in the BRAHMATWINN project with a series of tools from remote sensing and geoinformatics. An integrated assessment of main components of the natural environment in the two river basins as well as in five reference catchments within those basins, has led to the delineation of hydrological response units (HRUs). HRUs are spatial units bearing a uniform behaviour in terms of the hydrological response regime, as a function of physical parameters land use, soil type, water, vegetation cover and climate. Besides the delineated HRUs which are available in a spatially exhaustive manner for all reference catchments, the following information were provided as spatial layers: (1) uniform digital surface models of both the twinned basins and the reference catchments; (2) glacier areas and the magnitude of glacier loss; (3) mountain permafrost distribution and identification of areas particularly affected by permafrost thaw; (4) a consistent land use/land cover information in all reference catchments; and (5) the vulnerabilities of wetlands and groundwater in terms of anthropogenic impact and climate change.

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.

Modelling of ground water recharge-potential in hard-rock areas principally aims at water-resource evaluation. Various techniques are available to assess recharge-potential, and their capability in estimating recharge is also variable. However, the water level fluctuation method is found capable in computing actual ground water recharge. Demarcation of ground water recharge-potential zones in arid and semi-arid regions is of great importance for human survival and sustainable development. Remote sensing and geographic information systems (GIS) techniques have been widely used by numerous researchers for qualitative assessment of ground water potential of a basin or terrain. In the present study, a GIS-based water table fluctuation method has been attempted for quantitative modelling of ground water recharge of the hard-rock Aravalli terrain. This GIS-based model is further used to evaluate recharge-potential of the terrain by integrated assessment of infiltration capacity, normal rainfall, and its cumulative frequency.

Diffuse nitrogen pollution caused by irrigated agriculture is quantified for the Pocochay stream located in the Aconcagua watershed in the Valparaiso region, Chile. The study area has an extent of 93 km 2 with 36 km 2 under irrigation. It is representative for the central part of Chile where intensive irrigation is prevailing and predominantly taking place in the alluvial plains of river systems with water sources from the Andes Mountains. Water quality and discharge were monitored biweekly at several points of the Pocochay main stream from December 2003 to June 2006. The study was supported by an agricultural survey and remote imagery interpretation in order to retrieve data on cropping pattern and actual fertilizer uses in the sub-watersheds. Nitrate – N concentration in the Pocochay stream ranged from 1.3 to 10.1 mg L −1 with a mean of 4.8 mg L −1 . Other nitrogen species showed very low concentrations. At average, around 52 kg N ha −1 a −1 are drained from the study area as compared to 167 kg Nh a −1 a −1 applied as fertilizer to the fields. Even though nitrate concentrations in the Pocochay do not reach alarming levels yet, the impact of irrigated agriculture on surface water quality is obvious and makes a case for introducing best management practices to avoid aggravation of contamination.

The impact of large scale land use changes such as afforestation on the hydrological system behaviour of river basins is of major interest to water resources managers. Particularly in semi-arid areas, where water is strongly limited, the continuous assessment and monitoring of the hydrological system components are necessary. Their analysis and prognostic hydrological modelling requires both the determination of updated land use patterns and an estimation of their spatial dynamics over time. In this study optical remote sensing data were used in order to provide such hydrological model input parameters at different scales. Therefore, Landsat TM data from 1995 to 1999 have been utilized for various scale depended land use maps within the semi-arid Umzimvubu catchment, South Africa. The classification results were compared due to the temporal changes as a consequence thereof the afforestation. Based on an complex accuracy estimation during all processing steps, significant changes of the land use patterns could be quantified. In addition, the Leaf Area Index (LAI) distribution has been calculated for the Mooi river subcatchment based on the transformation of the normalized difference vegetation index derived from Landsat TM data to LAI utilizing an empiric equation.

Interflow is of major importance for runoff generation and groundwater recharge in mountainous and hilly catchments. However, integrated process studies and model simulation of the hydrological dynamics of hillslope drainage by interflow are still scarce. Therefore, such a study has been carried out on the Kiefer-Hang test hillslope in the catchment of the Sieg River, located in the middle mountain range of the Rheinische Schiefergebirge in Germany. The overall objective was to analyse and to simulate soil moisture, interflow and groundwater recharge with a high resolution in time and space. For the simulation study the two-dimensional HILLS numerical hillslope model was selected, parameterized and calibrated by detailed field surveys. The simulations were undertaken using measured hydro–meteorological data with 5-minute intervals. The process analyses of the study revealed the hydrological dynamics of the test slope, and the results of the simulations proved the ability of the HILLS model to simulate interflow. However, some extreme storms and dry weather periods were simulated poorly because: (i) the soil-physics is simplified in the model as compared to the complex structure of the test slope, and (ii) HILLS in its present version does not account for feedback from the level of the adjacent Breidenbach Creek.

The concept of hydrological response units (HRUs) and their delineation and application to the Brol catchment ( A =216 km 2 ) in Germany is presented. HRUs are object orientated physiographic entities and can be used as model entities within the MMS/PRMS hydrological catchment model. Applying the HRU concept to the Brol catchment altogether 23 different HRUs were delineated from a DEM (50×50 m grid size), three classified pedo-topo-geological associations and four dominant land-use classes by means of GIS-overlay analyses. MMS/PRMS was then run with these HRUs using a 20-year daily data hydrometeorological time series. The model parameterization was carried out in such a way that rainfall input not consumed by evapotranspiration was routed to a common conceptual subsurface storage. The latter was drained by interflow laterally towards the shallow groundwater aquifer in the valley floors, which in turn seeped into the drainage channel network. The model fit between simulated and observed discharge was good ( r =0.91) and it was found that the model was sensitive to parameters related to the land-use controlling evapotranspiration and direct overland flow. Future research activities will concentrate on applying the HRU concept and MMS/PRMS model in drainage basins of different climates in an object oriented way. Special attention will be given to integrating the spatial distributed precipitation into the HRU delineation and the flow routing linkages of the HRU subcells within the catchment which must be included in the present holistic approach.

A modified concept of hydrological response units (HRUs) for regional modelling of river basins using the PRMS/ MMS model is presented. The HRUs are delineated by geographical information system (GIS) analysis from physiographic basin properties such as topography, soils, geology, rainfall and land use using a thorough hydrological systems analysis. The HRUs, once classified by GIS analysis, preserve the three-dimensional heterogeneity of the drainage basin. The River Brol basin (A = 216km 2 ), Rheinisches Schiefergebirge, Germany was selected to apply the concept. In total, 23 HRUs were delineated and tested with the PRMS/MMS model using a 20-year hydrometeorological daily database. The hydrological systems analysis revealed that interflow is the dominant flow process through the basin's slopes and the major contribution to groundwater recharge and river runoff. This was accounted for by parameterizing the HRUs in the model control file to drain their surplus water not used for satisfying the demand of evapotranspiration to a common conceptual subsurface storage. This storage was simulated by interflow drainage to the groundwater aquifer in the valley floor, which in turn drained to the channel network. The PRMS/MMS model simulated the observed daily discharge very well and the fit was described by a daily correlation coefficient of r = 0.91. The NASIM and HSPF models using different means to represent the basin's physiographic heterogeneity were applied to the Brol basin as well, but did not achieve this correlation. The HRU concept was found to be a reliable method for regional hydrological basin modelling and allows spatial up- and downscaling. Future research on this concept will focus on incorporating the variable precipitation distribution into the classification of HRUs and on the hydrodynamic routing of the modelled discharge. Additionally, satellite imagery must be used for classifying land use in macroscale drainage basins.

River salination due to dryland agriculture was studied between 1985 and 1986 in the 150-km2 large catchment of the Sandspruit river, a tributary of the Berg river in the semi-arid Western Cape Province of South Africa. The study included investigations of all major water bodies within the catchment and aimed to identify and quantify their salinity dynamics. The following results can be presented: 1) The mean annual rainfall is about 400 mm, and has a salt concentration from the ocean of 37 mg/L. 2) Groundwater recharge of the shale aquifer only occurred during the winter season when salts from the soil and the weathered shale were transported into the groundwater. 3) The main salt output occurred between July and September and is associated with floods. A linear regression model was established to estimate salt output from the catchment by using the water level measured at the gauging station. 4) The total salt output in 1986 was 8052 Mg (tons), but bulk atmospheric deposition accounted only for a third of this amount. The remainder salt output was delivered by groundwater and interflow from the weathered shale and the soils within the catchment.

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.