The surface of the Black Sea watershed amounts to about 2 mil. km2 with a population of 160 mil. Inhabitants over 25 countries. In light of the current and forthcoming climate, land cover and population changes in this region, it is becom- ing extremely important to better understand how the quantity and quality of waters will vary in the catchment over the coming decades. To model the hydrology of this catchment, three steps are needed: (1) a large transnational data collection effort, (2) adequate management and sharing processes of the environmental data in a dedicated Spatial Data Infrastructure, and (3) distributed computing in order to allow running a high-resolution model. The EU/FP7 enviroGRIDS project (running 2009–2013) is addressing these steps with a 30-partner consortium mainly located in the Black Sea region. In this paper we are discussing how enviroGRIDS is approaching the various data-related challenges of the project. We particularly address the important issue of sharing data through international initiative such as GEOSS, the specificity of the hydrological modeling tool SWAT (Soil and Water Assessment Tool), and the technical requirement for using Grid computing infra- structures to optimize computationally-intensive simulations.