Runoff and Sediment Characteristics of Slope Land in Karst Areas of Guizhou Province

Soil erosion and rocky desertification strongly affect local sustainable development in karst area.In order to prevent and control efficiently soil erosion in karst area of Guizhou Province,runoff and sediment characteristics of different types of slope land were studied by means of runoff plots observation.Five types of runoff plots were set including commercial forest(pear trees),water conservation forest(Cinnamomum camphora),water conservation forest(cypress),slope farmland(crops) and bare slope land.The results showed that when the slope gradient was 13°,the slope land covered with crops and pear trees were good in protecting soil erosion,which could reduce runoff by 47.5% and 25.8%,respectively,and sediment yield by 78.5% and 58.9%,respectively.The slope land covered with Cinnamomum camphora and cypress were not significant in runoff reduction,while they could reduce sediment yield by 44.7% and 79.3%,respectively.When the slope gradient was 18°,the slope land covered with pear trees,Cinnamomum camphora,cypress and crops could reduce runoff by 45.8%,4.9%,3.8% and 16.6%,respectively,and sediment yield by 91.3%,81.1%,77.4% and 61.6%,respectively.When the slope gradients was 25°,sediment yield of the slope farmland was almost eight times more than that of the bare slope farmland.Runoff and sediment yield had power function relationship with rainfall(P),maximum rainfall intensity of 30 min(I30) and slope gradients(s).The sediment yield of slope land met linear function with the runoff of slope land.