Besides the major flooding of main rivers, significant damage is caused by flooding of smaller tributaries. Thus flood protection measures implemented through large engineering projects must - to make them efficient as possible - be complemented by integrated river catchment management, implying the active involvement of farmers, foresters, and residents, since changing both user habits and land use will have an impact on water retention and run-off. This technical water project, led by the German Research Institute for Forest Ecology and forestry (Rheinland-Pfalz), which brings together a total of 11 partners from Germany, France, Luxembourg and Switzerland over 4½ years, looks at preventative water retention measures implemented across the NWE. The economic, ecological and managerial efficiency of different measures will be assessed by calculating their effects across different landscape structure, meteorological situations and types of land use in the Member States involved. WaReLa will use GISbased systems and open programme-controlled systems (and promote training in them) to test individual flood scenarios, compile a comprehensive overview and elaborate a regional planning framework/decision support system for transnational river basin management. The transnational network of partners consists of expertise from hydroclimatological analysts, flood experts, decision-makers, farmers and local water authorities, who will all benefit from a transfer of knowledge within the partnership.