Structural measures for flood mitigation mpact the river ecosystems and functions.Therefore, projects need authorizations and are expertized. Ideally, ecology experts should be involved earlier, throughout the design process; practically collaboration is laborious between specialists with different background and objectives. The authors therefore adapted “riverscapes” to facilitate discussions. Biologists defi ne riverscapes by a cross-section, a list of features including artifi cialization, and describe the resulting expected processes and biodiversity. Riverscapes are ranked, with an explanation of the factors differentiating the levels. Then, to select the most relevant technical solutions, the local effects are measured by the loss of riverscape levels induced. Our method was tested for dry dam design in mountainous rivers, and the riverscape hierarchy closely followed the imperviousness gradient. We present here the prerequisites for a generalization to various contexts. The riverscape should be understood as a reach, rather than defined by just one typical cross section, and extended sideways to include at least the riparian vegetation, and possibly floodplain features. Descriptors should be added, for instance sediment descriptors or functional units. Finally, the ranking method should be refi ned to promote the diversity of sub-types, for instance by replacing the absolute rank by a relative rank to the local natural situation. Finally, to be operational, the methodology must be confronted to the criteria used by the authorities in charge of validating projects; we shall therefore list there requirements, mainly derived in Europe from the WFD and make sure they are taken into account through the process.