Importance of soil surface characteristics on water erosion in a small grazed Sahelian catchment

摘要: This study concerns the problem of water erosion in Sahel. Surface and sediment yields (suspended matter bedload) were monitored for 3 years (1998–2000) at outlet a small grazed catchment (1Ð4 ha) northern part Burkina Faso. The consists about 64% sandy deposits (DRY soil surface type), which support most vegetation, 34% crusted bare soils (ERO type). annual solid-matter export is more than 90% suspended sediment, varying between 4Ð 0a nd 8 Ð 4th � 1 . bedload represents less 10% losses. In single flood event (10 year return period), yield can reach 2th During period studied, proportion (20 to 32%) floods was thus responsible large (80%) solid transport. Seasonal variation suspended-matter content also observed: high mean values (9 g l ) June, decreasing July stabilizing August (between 2 4 ). behaviour may be consequence reorganization surfaces that have been destroyed by trampling animals during previous long dry season, vegetation growth (increase protecting effect herbaceous cover) and, lesser extent, particle-supply limitation (exhaustion dust July). particle-size distribution collected 60% made up clay: fraction <2 µm. contribution this clay maximum when rises its kaolinite/quartz ratio then close ERO-type surfaces. indicates these are main source within catchment. Copyright  2003 John Wiley & Sons, Ltd.