Abstract:This study aimed to quantitatively evaluate the effect of tillage erosion on runoff yield, sediment yield as well as hydraulic characteristics in the hilly croplands in the Dry-hot Valley Region by the simulated tillage and scouring experiments. Two forms of tillage erosion were adopted that one was the simulated tillage duration (10-, 20-, 30-, 35-, 40-year tillage) which caused the attenuation of soil thickness at the upper slope positions, and the other was the simulated soil flux (0, 12, 21 kg/m) which occurred in rills at the lower slope positions. Results showed that under the influence of tillage duration, both runoff yield and soil detachment rate displayed an increasing trend with the increase of tillage duration. Runoff stayed in the pattern of rapid laminar-flow for the treatment of 40-year tillage, while the slow laminar-flow for the other treatments. The drag coefficient and shear stress exhibited a decreasing and increasing trend as the tillage duration increased, respectively. Under the influence of soil flux, runoff yield rate was in a decreasing trend with the increase of soil flux while soil detachment rate was in an increasing trend. Runoff changed from the pattern of rapid laminar-flow to slow laminar-flow when the soil flux reached 21 kg/m. As the soil flux increased, drag coefficient presented an increasing trend and shear stress was in a decreasing trend. Reynolds number was the best hydrodynamic parameter which could explain the characteristics of hydraulic erosion under the influence of tillage erosion by correlation analysis. These results could provide scientific guidance for the exploration of soil erosion mechanism and treatment methods in the hilly croplands of Dry-hot Valley Region.