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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.

Understanding hydrological process dynamics is a crucial requirement for river basin management and environmental planning. Possible future climate changes raise questions about their impact on human livelihoods, which strongly depend on water availability and quality, soil fertility, and other ecosystem services. This chapter presents a physically based, spatially distributed ecohydrological model that was applied within three meso- to macroscale watersheds in the hinterland of Rio de Janeiro. While an increasing population and a fast-growing industrial sector create a high demand for water supply, the study region faces serious problems of forest fragmentation, overexploitation, and soil degradation, which create increasing pressures on water resources. This situation is further intensified by the climate conditions with distinct wet and dry periods that can cause floods and landslides in the rainy season and water shortages during dry periods, especially affecting the agricultural and domestic supply sectors. Recent water shortages raise questions how future climate changes will impact the hydrological dynamics and if river basin management needs to take appropriate counteractions. The results show that the developed models allow simulating hydrological processes at a high spatiotemporal resolution. Given the fact that their process representation is physically based, these models can help answer questions about hydrological dynamics under changing environmental conditions.

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.

A prerequisite for integrated land and water resources management (ILWRM) is a holistic river basin assessment. The latter requires information and data from different scientific disciplines but also appropriate data management systems to store and manage historical and real time data, set up protocols that facilitate data and information access and sharing among different stakeholders, and triggering further collaboration among different institutions in support of watershed-based assessment, management and planning. In West Africa in general and especially in the transboundary Volta River basin where different environmental data are collected and managed by different agencies in different countries and also where data access and dissemination are very challenging and difficult tasks, comprehensive river basin information systems are required. This paper presents the Oti River Basin Information System (OtiRBIS), a web-based data storage, management andanalysis platform that addresses these needs and facilitates ILWRM implementation in the Kara river basin., 13 pages, 6 figures

Spatial precipitation is a major input to distributed hydrological models, and the accuracy of runoff predictions greatly depends on its accuracy. Satellite-based precipitation products are expected to offer an alternative to ground-based rainfall estimates in the present and the foreseeable future. In the present study, the suitability of tropical rainfall measuring mission (TRMM) multisatellite precipitation analysis (TMPA) rainfall in driving a distributed hydrological model for runoff prediction was evaluated. For this purpose, a hydrological model from the literature was calibrated and validated using raingauge data on daily time step for simulation of runoff in Kopili River basin (=7,198 km2) during 2003–2010. The calibrated model was then used for simulation of runoff employing specialized software and compared with the observed discharge at Kherunighat gauging site. Evaluation criteria, i.e., coefficient of correlation (CC), Nash-Sutcliffe coefficient (NSE), percent bias (PBIAS) and root ...

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.

Methodological aspects of scale-related impact assessment from changing land use/land cover (LULC) management and climate on river basin water resources and their management are discussed. Both control the interactive hydrological process dynamics that transfer precipitation input on the landscape to the different surface and subsurface water resources components and ultimately to river runoff draining the river basin. As the integrated water resources management (IWRM) concept does not sufficiently account for the landscape-related process dynamics associated with LULC management, it is enhanced to the integrated land and water resources management (ILWRM) approach. The latter requires, firstly, a consistent methodological concept and, secondly, a toolset for its implementation. The DPSIR (D = Drivers, P = Pressures, S = State, I = Impacts, R = Responses) approach is a suitable analysis concept in this regard and is enhanced by a Decision Information Knowledge System (DIKS). Both are implemented by means of the integrated land management system (ILMS) toolset developed at the University of Jena, Germany, and tested in numerous research projects in Africa, Asia, Australia, Europe and South America. The majority of river catchment studies focus on a particular scale. Upscaling and downscaling of the hydrological knowledge they generate requires the separation of the generic knowledge components from their modifying local specifications. The interdisciplinary ILWRM applications presented in this paper from two projects in South Africa and SE Asia address this challenge by applying a multi-scale nested catchment approach (NCA) and respective upscaling and downscaling techniques to regionalize hydrological knowledge between scales.

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.

Based on daily maximum and minimum surface air temperature and precipitation records at 303 meteorological stations in China, the spatial and temporal distributions of indices of climate extremes are analyzed during 1961–2003. Twelve indices of extreme temperature and six of extreme precipitation are studied. Temperature extremes have high correlations with the annual mean temperature, which shows a significant warming of 0.27°C/decade, indicating that changes in temperature extremes reflect the consistent warming. Stations in northeastern, northern, northwestern China have larger trend magnitudes, which are accordance with the more rapid mean warming in these regions. Countrywide, the mean trends for cold days and cold nights have decreased by −0.47 and −2.06 days/decade respectively, and warm days and warm nights have increased by 0.62 and 1.75 days/decade, respectively. Over the same period, the number of frost days shows a statistically significant decreasing trend of −3.37 days/decade. The length of the growing season and the number of summer days exhibit significant increasing trends at rates of 3.04 and 1.18 days/decade, respectively. The diurnal temperature range has decreased by −0.18°C/decade. Both the annual extreme lowest and highest temperatures exhibit significant warming trends, the former warming faster than the latter. For precipitation indices, regional annual total precipitation shows an increasing trend and most other precipitation indices are strongly correlated with annual total precipitation. Average wet day precipitation, maximum 1-day and 5-day precipitation, and heavy precipitation days show increasing trends, but only the last is statistically significant. A decreasing trend is found for consecutive dry days. For all precipitation indices, stations in the Yangtze River basin, southeastern and northwestern China have the largest positive trend magnitudes, while stations in the Yellow River basin and in northern China have the largest negative magnitudes. This is inconsistent with changes of water vapor flux calculated from NCEP/NCAR reanalysis. Large scale atmospheric circulation changes derived from NCEP/NCAR reanalysis grids show that a strengthening anticyclonic circulation, increasing geopotential height and rapid warming over the Eurasian continent have contributed to the changes in climate extremes in China.

Prediction of the sediment generated within a catchment basin is a crucial input in the management and design of water resources projects. Due to the unavailability and complexity of the precipitation and hydrological process, reliable sediment concentration is hardly predicted by applying linear and nonlinear regression methods. In the present study, an attempt has been made to explore the use of Tropical Rainfall Measuring Mission (TRMM-3B42) dataset for modeling suspended sediment using neural networks (NNs) with different training functions, i.e., Levenberg-Marquardt (LM), scaled conjugated gradient (SCG), and Bayesian regulation (BR) for the Kopili River basin, India. The input vector to the various models using different algorithms were derived considering the statistical properties such as autocorrelation function, partial autocorrelation function, and cross-correlation function of the time series. The daily rainfall data from 2000 to 2010 (4,018 days) were considered for the training (70%)...

The BRAHMATWINN project was funded by the European Community (EC contract no. 036952) and was carried out between June 2006 and December 2009. Its overall objective was to provide a comprehensive impact assessment of climate change to the hydrological dynamics and integrated land and water resources management (ILWRM) in alpine mountain massifs.

Water resources management is an important issue in southern African countries. With respect to water quality problems, the understanding of the dynamics of integrated soil erosion processes in river basins is of crucial importance. This study is on the delineation of response units (RUs) in the Mkomazi River catchment (KwaZulu/Natal; South Africa). It was carried out within the framework of an interdisciplinary EU-funded project aimed at developing an integrated water resources management system for water resources analyses and prognostic scenario planning in semi-arid catchments of southern Africa. Within this more general framework, particular attention was focused on the identification of sediment source areas. For this purpose, the RUs concept was applied to delineate erosion RUs (ERUs). The ERUs were subsequently used to identify heterogeneously distributed areas within a river catchment characterized by specific hydrological and erosion dynamics and features. Therefore, they can be applied as modelling entities in physically based hydrological and erosion models. Spatially distributed input data from the catchment were derived by remote sensing techniques and geographical information systems analyses. Taking into account the high amount of sediments produced by gully erosion, not considered in USLE-type models, special attention was focused on gully erosion using a dynamic gully erosion model. The example from southern Africa shows that the methods applied are able to identify areas affected by gully erosion. Furthermore, it was possible to estimate the entire amount of soil loss, including gully erosion. Copyright © 2003 John Wiley & Sons, Ltd.

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.

Understanding the upstream-downstream linkages in hydrological processes is essential for water resources planning in river basins. Although there are many studies of individual aspects of these processes in the Himalayan region, studies along the length of the basins are limited. This study summarizes the present state of knowledge about linkages in hydrological processes between upstream and downstream areas of river basins in the Himalayan region based on a literature review. The paper studies the linkages between the changes in the physical environment of upstream areas (land use, snow storage, and soil erosion) and of climate change on the downstream water availability, flood and dry season flow, and erosion and sedimentation. It is argued that these linkages are complex due to the extreme altitudinal range associated with the young and fragile geology, extreme seasonal and spatial variation in rainfall, and diversity of anthropogenic processes. Based on the findings, the paper concludes that integrated systems analysis is required to understand the holistic complexity of upstream-downstream linkages of hydrological processes in the river basin context. The integrated land and water resources management (ILWRM) approach can be instrumental in developing adaptive solutions to problems and can also enable stakeholders of upstream and downstream areas with various interests and needs to work together for the better utilization and management of land and water resources. As a part of this, the specific circumstances of the upstream communities, who live in fragile and inaccessible mountain areas with limited resource opportunities, should be taken into account so that incentive mechanisms can be established to encourage and acknowledge their contribution.

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.