The operation of the “Bassée pilot site” consists of the study of a temporary flood retention area on the Bassée sector and the implementation of ecological enhancement measures for the Wetlands of Bassée, a Natura 2000 area of national importance. This large-scale project will reduce flood levels from the Seine-Yonne confluence to the Seine-Oise confluence. The pilot site with a retention volume of 8.8 M. m³ is bounded by a 7.8 km earth dam and pumped at a flow of 34 m³/s. The project also incorporates ecological recovery measures in the downstream Bassée sector (remediation of hydro-ecological continuity, restoration of wetlands, creation of hydraulic annexes, reprofiling of banks). This request for assistance concerns in particular the studies necessary for the design of the project.