The objective of the SWATCH21 project is to improve our understanding of eco-hydrologic services at the catchment level, and biodiversity at the river scale. Six research questions are proposed: (i) How can we improve the access to input data for hydrological and ecological modeling? (ii) What is the role of glacier and snow in modifying the hydrological services? (iii) How can we best assess hydrologic services supplies and demands with the available data and tools? (iv) What will be the impact of the main hydrologic changes on species diversity in rivers? (v) Can we meet the targets of multi-sectorial river-related policies under different climate and landuse forecasting scenarios? (vi) How detailed do ES data and models need to be to answer relevant policy questions? The above questions are tackled through an integrated framework to access, share, process, model, and deliberate on hydrologic ecosystems services. State-of-the-art models have been selected, and will be compared and improved to model different ecosystems and their services. Initial results from a first SWAT model of Switzerland and Species Distribution Models are presented. Expected outputs from various climate and land use change scenarios include rivers’ hydrology, predicted biodiversity, and the assessment of ecosystem services in terms of provisioning services (e.g. water resources), regulating services (e.g. nutrient, sediment and flood water retention), and cultural services (e.g. biodiversity, recreation). The expected outcome of the project is to improve integrated evidence-based water policy in the future through the analysis of tradeoffs and synergies between services.