Silting land and sediment blocking benefit of check damin hilly and gully region on the Loess Plateau

On the basis of investigation data of check dams in small watersheds in hilly and gully region of Huangpuchuan, Kuyehe, Jialuhe,Tuweihe and Dalihe rivers on the Loess Plateau, the velocity of silting, sediment blocking index and sediment blocking benefit of single check dam, and the relationships between them and its effect factors were analyzed. The annual average silting volume of check dam was 0.9～2.1×10⁴ m³, and the annual average silting land of check dam was 0.14～0.45 hm²; They are positively related to the height and control area of check dam, erosive sediment modulus and the size of sediment particles in the control area of check dam. The sediment blocking index varied from 500×10⁴ t/km² to 760×10⁴ t/km², and has positive relationship with the height of check dam, and negative relationship with the size of sediment particles. The sediment blocking benefit of check dam ranged from 23.3% to 52.9%, and has positive relationship with check dam height, negative relationship with the control area of check dam and the modulus of coarse sediment(d＞0.05 mm) in the control area of check dam. It was considered that the comprehensive control should be carried out to produce a marked effect of each of soil-water conservation measures, to promote converting slope field into forest or grasses cultivation, and to restore the forest and grasses and bring the soil erosion preventing function of forest and grasses into full play in the early period of ecological environment construction.