Measurements of suspended load in the Durance river over 150 years (1857-2007): links with the operations of ecological restoration at the scale of the catchment and the river

Abstract

The aim of this paper is to make a review of suspended sediment load in the Durance river for 150 years, trying to relate evolutions to changes in the basin and in hydroclimatology. This work illustrates the difficulty of isolating the factors of each others because the feedback loops between processes are numerous. Essential for erosion, forest cover, for example, has been significantly increased to approximately 40 % of the basin today. Before 1948, this increase is mainly due to reforestation of eroded mountains (260 000 ha). After that date, the processes of natural recolonization of degraded land is fundamental. On marly small experimental basins near Digne, in the Bleone sub-basin, we now measure specific annual production of sediments 220 times less important in a catchment with a vegetation coverage of 87 % that a catchment with a vegetation coverage of 32 %. To analyze the data during more than a century, it is also necessary to understand the "relationship to the object of study" that scientists from different periods have because their motivations directly affect the datas and papers that they leave to us. This should make us think on those we will leave to future generations.