The project "RIVERTWIN" financed by the European Community aims to adjust, test and implement an integrated regional model for the strategic planning of water resources management in "twinned river basins" (similar river basins in different parts of the world) under contrasting ecological, social and economic conditions. The regional model will take into account the impacts of demographic trends, economic and technological development, and the effects of global climate and land use change on the availability and quality of water bodies in humid temperate, sub humid tropical as well as semiarid regions. The existing integration framework will first be tested in the Neckar river basin with high data availability and data density. The transferability of the model to other regions with a different economic level, ecological standards and with low data availability will be jointly tested by the project team and river basin organisations in the Oueme river basin in Benin (West Africa) and the Chirchik river basin in Uzbekistan (part of the Aral Sea basin). Here, the problem of adequate human resources and the uncertainties of input data for the implementation of computer-based decision-support tools will be addressed. The twinning of river basins will promote mutual transfer of know-how and technology between European and Third countries. Based on the results, river basin management plans can be prepared. Through its holistic basin wide approach, the project contributes to the EU Water Framework Directive, the Millennium Goals defined by the WSSD and the EU water initiative for Africa and Newly Independent States. The YSW contributes a groundwater flow model of the Neckar basin to the integrated model.