Quantitative study on influences of terraced field construction and check-dam siltation on soil erosion

To study the influences of terraced field construction and check-dam siltation on soil erosion of a watershed, we built a simplified watershed model for the Loess Plateau hilly-gully region including terraced fields, slope farmlands, steep-slope grasslands, and dam farmlands, and defined three states of watershed (i.e., pioneer, intermediate, and climax stages, respectively). Then, the watershed soil erosion moduli at various stages were studied by using a revised universal soil loss equation. Our results show that the pioneer and climax stages are the extreme states of watershed soil-and-water conservation and control; in the pioneer stage, the soil erosion modulus was 299.56 t center dot ha(-1)center dot a(-1) above the edge of gully, 136.64 t center dot ha(-1)center dot a(-1) below the edge of gully, and 229.74 t center dot ha(-1)center dot a(-1) on average; in the climax stage, the soil erosion modulus was 39.10 t center dot ha(-1)center dot a(-1) above the edge of gully, 1.10 t center dot ha(-1)center dot a(-1) below the edge of gully, and 22.81 t center dot ha(-1)center dot a(-1) on average; in the intermediate stage, the soil erosion modulus above the edge of gully exhibited an exponential decline along with the increase in terraced field area percentage, while the soil erosion modulus below the edge of gully exhibited a linear decline along with the increase in siltation height.