Difference of runoff and sediment yield under various experimental conditions for the Huaibei area based on artificial rainfall simulations

Aiming at the problems of soil and water losing in the Huaibei area,the difference of runoff and sediment yielding from the Lime Concretion Black soil (LCBS) slope and the Fluvo-aquic Yellow soil (FYS) slope with gradients of 5°,10°,15° under different rainfall intensities (40 mm/h,60 mm/h,80 mm/h) was experimentally investigated. The results show that the initial runoff yielding time from the LCBS slope is longer than that from the FYS slope while the total runoff yield is relatively smaller for the LCBS slope. The initial flow sediment concentration from LCBS slope tends to decrease once slope rills appearing and eventually to a stable level. However,the flow sediment concentration from the FYS slope exhibits a fluctuating change. Sediment yield from the LCBS slope is less than that from the FYS slope under the various experimental conditions with exception of the combining situations of slope gradient 10° and rainfall intensity of 60 mm/h or 80 mm/h. The rills were well developed to an interconnected dendritic structure on the LCBS slope surface with a higher density rills occurring in the middle and lower part of the slope. Relatively,the rill density on the FYS slope surface is smaller. The runoff,sediment yield highly correlated to the slope gradient,rain intensity with multivariate linear and multivariate power relationships respectively for the both soil type slopes. The rainfall intensity gains a higher effect on runoff and sediment yield than slope gradient does.