Effects of antecedent soil moisture on hillslope runoff-generation and soil erosion over red soil-mantled landscapes

The effect of antecedent soil moisture on hillslpoe infiltration processes,runoff generations and soil erosions was investigated through artificial rainfall experiments at two sites with different types of red soil-mantled landscapes.The results show that the higher the level of antecedent soil moisture,the lower the accumulated infiltration is,the smaller the soil absorption is,the more quickly the runoff generation is,and the shorter the duration of runoff and infiltration steady is.The rainfall duration is found to be linearly correlated with both runoff coefficient and infiltration rate at the two sites under low initial soil moisture conditions.The state of equilibrium will not be reached within 60 minutes of the artificial rainfall.Under high initial soil moisture conditions,the Boltzmann equation can be used to describe the relationships between the rainfall duration and the runoff coefficient,the infiltration rate,as well as the soil erosion rate.Low or even invariable soil erosion rates are observed from the quaternary red clay under the slightly dry condition and from the red sandstone under the dry condition during the entire periods of artificial rainfalls.Interestingly,noted that the soil erosion rates at the two sites will increase linearly if the initial soil moisture conditions are swapped among the two cases.