The Kembs project: environmental integration of a large existing hydropower scheme

Abstract

The environment was a major issue for the Kembs relicensing process on the upper Rhin River. Since 1932, Kembs dam derives water from the Rhine River to the "Grand Canal d'Alsace" (GCA) which is equipped with four hydropower plants (max. diverted flow: 1400 m3/s, 630 MW, 3760 GWh/y). The Old Rhine River downstream of the dam is 50 km long and has been strongly affected by works (dikes) since the 19th century for flood protection and navigation, and then by the construction of the dam. Successive engineering works induced morphological simplification and stabilization of the channel pattern from a formerly braided form to a single incised channel, generating ecological alterations. As the Kembs hydroelectric scheme concerns three countries (France, Germany and Switzerland) with various regulations and views on how to manage with environment, EDF undertook an integrated environmental approach instead of a strict "impact/mitigation" balance that took 10 years to develop. Therefore, the project simultaneously acts on complementary compartments of the aquatic, riparian and terrestrial environment, to benefit from the synergies that exist between them ; a new powerplant (8,5 MW, 28 GWh/y) is built to limit the energetic losses and to ensure various functions thereby increasing the overall environmental gain.