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 ecosys tems of piedmont and mountain floodplains, since it regulates the dive rsity of habitats, species and vegetal units. A plan for managing this erosion was established for the Galaure River, a tributary of the Mid dle Rhone characterized by mobile meander dynamics. Geomorphological a nalysis provided grounds for sectioning the river on the basis of late ral instability and led to defining geomorphological trends over a per iod 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 ab andoning this policy is difficult in view of opposition to this from r iverside landowners. The management plan devised allows for continued bank protection of certain reaches where lateral erosion is moderate a nd the conditions merit such measures. In contrast, nature conservatio n measures are planned for the section characterized by actively mobil e meanders. An area of free channel evolution or streamway has been de fined within which all bank protection measures are prohibited. This a rrangement was made possible through a contract between managers and r iverside landowners, by which managers are to purchase conservation la nds while landowners receive indemnities for reduced usage rights. Con servation of fluvial dynamics is accompanied by forest corridor rehabi litation of lands 15 to 20 m from the active channel, where poplar sta nds are replaced by indigenous hygrophyte, species. (C) 1997 John Wile y & Sons, Ltd.