Rates of fluvial erosion in basins with a Mediterranean type climate

Rates of erosion in mediterranean type climate areas are variable and they depend on climatic, physiographic and human factors. Available data from four mediterranean climatic areas are analysed, in order to find a relationship between sediment yield trends and precipitation values within each area and to compare trends along different areas. It may be inferred that there is a decrease in sediment yield with increasing precipitation; two distinctive curves are noticed: one for Israel and Spain, with a sediment peak at 300 mm of annual precipitation and a decreasing rate of 50 t/km^-2/yr^-1 for 100 mm of increasing annual rainfall, and the other for the Pacific coast areas - California and Chile - with a sediment peak at 400 mm and a faster decreasing rate of 100 t/km^-2/yr^-1 every 100 mm increase of rainfall. Non climatic factors, such as relief and human impact, may explain the higher rate of sediment yield for the Pacific coastal areas. The general trend of the "Langbein-Schumm curve", determining an established correlation between mean annual precipitation and sediment yield, is valid for the analysed areas.