Analysis of the role of agricultural abandoned terraces on the hydrology and sediment dynamics in a small mountainous basin. (High Llobregat, eastern Pyrenees)

Abstract

The results show the preservative role of the agricultural terraces, characterized by a high water retention capacity and a very low sediment yield, in spite of significant amounts of sediment which are transferred within the basin but do not reach the outlet. During rainy periods the partial saturation of terraces produces important runoff volumes quickly drained by the man made network of ditches, generating sharp runoff peaks. These ditches are shown therefore to be the elements of major hydrological and linear erosion risks. Nowadays the lack of drainage network maintenance, as a result of land abandonment, has caused disorganization which may have some important hydro-geomorphological and land conservation consequences. -from Authors