Research On The Soil Moisture Infiltration And Redistribution Characteristics In Collapsing Hill

Collapsing hill erosion is one of the most serious type of water loss and earth erosion in South China. Soil moisture is the power and premise of collapsing hill. Field investigation and laboratory test were used to compare the applicability of three different methods for soil infiltration in collapsing hill, study on the infiltration characteristics and mechanical components of different soil layers, analysis the characteristics of moisture migration profile of different soil layers by monitoring, Results showed that:(1)Infiltration ability was poor in collapsing hill, three different methods could simulate the relationship between Infiltration rate and infiltration time, they had a power function relationship:y=ax"n. The automatic measurement system had the best result in fitting effect. For the three different methods, effect factors were different. The main influence factors are organic matter and soil mechanical composition for soil infiltration in collapsing hill erosion.(2)Look from the effects of the experiments, although the structure of the double-ring was simple and the result were representative, it was easy to damage of soil and could not be used for the soil infiltration rate in sloping fields; Metal cylinder method was poor in representation and its coefficient of variation was high; Automatic measurement system was convenient to use and the computational procedures were simple, it was controlled by computer, so it could overcome the subjective judgment of the experimenter. It could keep the soil properties. The results were more accurate and saving time. But Further research was needed on the effects of the intensity of water supply to soil infiltration.(3)Collapsed hill had a poor water-holding capacity. In the horizontal direction, the red soil layer was the most sensitive to water. To be stable, red soil layer’s water-holding capacity were better other two layers. For the same soil layer, the response of 5cm and 10cm of soil moisture were the most significant, and the moisture content of 40cm in the experimental period did not change significantly. When stop the water, the soil water content decreased, but at same time, moisture content was not reduced to the content before the experiment, the dehydration process lasted far higher than the water absorption process. Comparing the water characteristic curve of three layers:water characteristic curve of red soil layer was relatively smooth. Under the same suction, red soil layers’ had a higher water content than that of other two layers. With the increase of soil depth, soil water characteristic curve showed a overall trend of more and more relaxed.