Based on the data of Guojialiang test site

we built up soil erosion and sediment yield models and erosion control models of the hedgerow. The study produced water and sediment transport networks of the catchment from digital elevation model (DEM) and brought them to the models. The combination of GIS and models simulated the influence of upper runoff to the blower slope and the spatial process of runoff and sediment transport in a catchment. The result of the simulation from 1995 to 1999 showed that the cultivated slope land

bare slope land and natural grass land with low vegetative cover have the highest erosion modulus in Qingbiankohe catchment

and they are the important regions for erosion control. We simulated the system of the hedgerow crops in these regions whose areaonly has 18.2% of the whole catchment. The results shows that the control effect for runoff is between 8% and 46% and the control effect for sediment is between 42% and 50%. The simulation results of nutrient loss showed that the loss of the organic matter is severe on the current conditions. However

it is a efficient method to control the nutrient loss on the condition of hedgerow crops system.