Influence of the Rainfall on Soil and Water Loss in the Dry-Hot Valleys of the Jinsha River

The dryhot valleys of the Jinsha River are one of the areas with worst ecological environment and most seriously of soil and water loss as well. Basing on the rainfall data in Panzhihua from 2010 to 2012 and combining with monitor data of water and soil loss about 9 runoff plots of slope farmland, the influence of the rainfall on soil and water loss in the dryhot valleys of the Jinsha River was analyzed. The results showed that the rain falls mainly occurred from June to October and the strong rainfall which accumulation precipitation account for 31%-36% of the annual total occurred from June to August. The soil and water loss were caused by strong rainfall, the erosive factor of rainfall was 33617（J·cm）/（m2·h） in this area. The runoff coefficient related to rainfall intensity, gradient, crop species and tillage methods, The runoff coefficient of crops on sloping lands was 008-012 and increased with the increase of intensity. The runoff coefficient in transforming slope into terrace, shrub forests (Fructus forsythiae), fishscale, plastic film mulching along the slope was respectively: 002-004, 002-004, 008, 028.