Research of the soil erosion on the low-volume unpaved road in the Three Gorge Reservoir area

The road network plays a great role in altering the erosion processes and water quality. In this paper, two rural roads with different traffic load, which located in the Jieya watershed Three Gorge Reservoir area, were selected to discuss the road soil erosion and non-point source pollutants loss under the nature rainfall events. The results show that both the runoff rate and erosion rate were higher on the high traffic load roads than that on the low traffic load roads. The rainfall precipitation significantly affected the runoff generation and sediment yield, and the rainfall intensity and rain energy also played great role in affecting the sediment production. The rainfall type had a significant impact on the non-point source pollutants loss, the pollutants loss processes were almost simultaneous to the rainfall under pre-centralized rainfall event, and the first flush effect on the Total Nitrogen, NH₄-N, particulate phosphorus, and dissolved phosphorus were much stranger than that under the mid-centralized rainfall event. Slightly first flush effect happened on sediment and the appearance of pick concentration of the pollutants lost was much prior to the pick rainfall intensity when under mid-centralized rainfall event. The nitrogen was lost in the form of Total Nitrogen, which contained of 80% of the total quantity, most of the phosphorus was lost in the form of particulate phosphorus.