Bank erosion management based on geomorphological, ecological and economic criteria on the Galaure River, France

Bank erosion is a key geomorphological mechanism in the fluvial ecosystems of piedmont and mountain floodplains, since it regulates the diversity of habitats, species and vegetal units. A plan for managing this erosion was established for the Galaure River, a tributary of the Middle Rhône characterized by mobile meander dynamics. Geomorphological analysis provided grounds for sectioning the river on the basis of lateral instability and led to defining geomorphological trends over a period of 50 years. In parallel, riverside landowners were questioned in order to take their opinions into account during planning. It is shown that active bank protection is not financially worthwhile, whereas abandoning this policy is difficult in view of opposition to this from riverside landowners. The management plan devised allows for continued bank protection of certain reaches where lateral erosion is moderate and the conditions merit such measures. In contrast, nature conservation measures are planned for the section characterized by actively mobile meanders. An area of free channel evolution or streamway has been defined within which all bank protection measures are prohibited. This arrangement was made possible through a contract between managers and riverside landowners, by which managers are to purchase conservation lands while landowners receive indemnities for reduced usage rights. Conservation of fluvial dynamics is accompanied by forest corridor rehabilitation of lands 15 to 20 m from the active channel, where poplar stands are replaced by indigenous hygrophyte species. ©1997 John Wiley & Sons, Ltd