The area of soil and water loss in Dingxi Municipality is 6726.6km²,accounting for 83.2% of the total land. In the region of soil and water loss,two hundreds and thirty.seven lager and medium sediment trapping dams with the total capacity of 71.9612 million cubic meters had been established by the end of 2003. These dams play significantroles in trapping sediment,controlling floods,reducing hazards and facilitating the conversion of slope farmland to forestor grass land,improving the transportation and supplying drinking water for local resident sand livestock as well.