Abstract:

A large-scale rainfall experiment was carried out to investigate the rules of rainfall infiltration and runoff erosion of vegetated slopes with different gradients. The parameters such as slope water content and soil and water loss were monitored in real-time. The effects of slope gradient on rainwater infiltration, slope runoff and soil erosion were quantitatively analyzed. The results show that under a continuous rainfall condition of 4 h and 60 mm/h, the cumulative rainwater infiltration of bare soil slopes with 1:2, 1:1.75, and 1:1.5 are 70.6%, 80.4%, and 92.3% those of vegetated slopes with the same slope gradient. Vegetation cover will accelerate the rainwater infiltration rate and increase the cumulative rainwater infiltration of the slope. The smaller the slope gradient of the vegetated slopes, the faster the rainwater infiltration rate and the greater the cumulative rainwater infiltration, while the bare soil slopes are the opposite. Vegetation cover can effectively reduce runoff rate and cumulative runoff. The smaller the slope gradient, the more significant the effect of reducing runoff. Compared with the bare soil slopes with the same gradient, the vegetated slopes of 1:2, 1:1.75, and 1:1.5 reduce runoff by 53.11%, 32.56%, and 17.73%, respectively. The sediment content of soil and water loss in vegetated slopes is less than 0.1%. Vegetation cover can effectively restrain soil erosion on the slope. The larger the bare soil gradient is, the more serious the slope erosion is. The soil erosion unit areas of 1:2, 1:1.75 and 1:1.5 bare soil slope are 3.623, 5.710, and 11.295 kg/m², and the sediment contents of soil and water loss are 3.06%, 4.29%, and 7.34%, respectively. Based on the test results, the relationship between the total amount of mud and sediment yield of bare soil slope y and slope gradient x and rainfall duration t is y=0.0028_t^-0.67x^4.11t0.0647  .

Key words: slope gradient, vegetated slope, rainfall infiltration, slope runoff, soil erosion