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Rapid land use and land-cover changes strongly affect water resources. Particularly in regions that experience seasonal water scarcity, land use scenario assessments provide a valuable basis for the evaluation of possible future water shortages. The objective of this study is to dynamically integrate land use model projections with a hydrologic model to analyze potential future impacts of land use change on the water resources of a rapidly developing catchment upstream of Pune, India. For the first time projections from the urban growth and land use change model SLEUTH are employed as a dynamic input to the hydrologic model SWAT. By this means, impacts of land use changes on the water balance components are assessed for the near future (2009-2028) employing four different climate conditions (baseline, IPCC A1B, dry, wet). The land use change modeling results in an increase of urban area by +23.1% at the fringes of Pune and by +12.2% in the upper catchment, whereas agricultural land (-14.0% and -0.3%, respectively) and semi-natural area (-9.1% and -11.9%, respectively) decrease between 2009 and 2028. Under baseline climate conditions, these land use changes induce seasonal changes in the water balance components. Water yield particularly increases at the onset of monsoon (up to +11.0mm per month) due to increased impervious area, whereas evapotranspiration decreases in the dry season (up to -15.1mm per month) as a result of the loss of irrigated agricultural area. As the projections are made for the near future (2009-2028) land use change impacts are similar under IPCC A1B climate conditions. Only if more extreme dry years occur, an exacerbation of the land use change impacts can be expected. Particularly in rapidly changing environments an implementation of both dynamic land use change and climate change seems favorable to assess seasonal and gradual changes in the water balance.

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The Upper Bhima River Basin is facing both episodic and chronic water shortages due to intensive irrigation development. The main objective of this study was to characterize the hydrologic processes of the Upper Bhima River Basin and assess crop water productivity using the distributed hydrologic model, SWAT. Rainfall within the basin varies from 450 to 5000 mm in a period of 3-4 months. The basin has an average rainfall of 711 mm (32 400 Mm 3 (million cubic metres)) in a normal year, of which 12.8% (4150 Mm ) ruissellent, et le reste (63%) est prélevé pour l'évapotranspiration. La productivité de l'eau agricole dans le bassin pour la canne à sucre, le sorgho et le mil ont été estimés à 2.90, 0.51 et 0.30 kg m¯3, ce qui est significativement plus faible que le potentiel maximal habituellement rencontré dans le monde. Il y a donc des marges de progrès qu'il convient d'explorer. Différents scénarios impliquant différents itinéraires techniques ont été testés dans le but d'accroître la valeur économique de la productivité de l'eau dans le système d'irrigation d'Ujjani. L'analyse suggère que la maximisation de la superficie grâce à la fourniture d'irrigation d'appoint pour les zones pluviales, ainsi que le recours à des pratiques agricoles de gestion plus économes en eau, peuvent offrir des possibilités pour améliorer la productivité de l'eau.

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