The Mediterranean basin is characterised by a strong heterogeneity of cultures, economies and societies which often implied problematic interactions. It is one of the areas where water resource scarcity and conflicts between different water users are more dramatic. The need and relevance for sustainable integrated water management strategies is therefore clear. DSS tools have an enormous potential for the identification of water management regimes in different environmental situations. They can help manage socio-political conflicts over competing demands for water uses. Yet, their potential is often not exploited for various reasons, as lack of communication between scientists and policy makers. A need for reorientation of science to support policy making an d for the adoption of multisectoral and multidisciplinary approaches integrating socio-economic and environmental considerations is evident. NOSTRUM-DSS will address this gap by fostering mediation between policy makers and scientists and between policy ob jectives and scientific knowledge to create an enabling environment for a more equitable and efficient water resource management in the basin.