Characteristics of slope runoff and sediment yield under individual rainfall events in southern red soil region
Huang Jun, Kang Qing, Jin Pingwei, Jiang Xuebing, Li Le, Wei Congmou, Liu Bin, Kou Xinyue, Xu Zhou
1. Pearl River Hydraulic Research Institute, Pearl River Water Resources Commission, Ministry of Water Resources, 510611, Guangzhou, China;
2. Soil and Water Conservation Monitoring Center of Pearl River Basin, Pearl River Water Resources Commission, Ministry of Water Resources,510611, Guangzhou, China;
3. Key Laboratory of Soil and Water Loss Process and Control on the Loess Plateau, Ministry of Water Resources,450003, Zhengzhou, China
[Background] It is significant for slope soil loss control, soil and water resources utilization and management to study slope soil infiltration, runoff and sediment yield characteristics at slope scales. [Methods] Based on the field artificial runoff plots in the Promotion Test Station of Wuhua County in Guangdong Province, the characteristics of soil infiltration and runoff and sediment yield were investigated and analyzed with the natural rainfall events of 2014. The experimental treatment includes: the natural abandoned land (NAL), artificial forest (AF), as well as shrubs and grass land (SGL). [Results] There was a significant correlation (P < 0.05,R2 = 0.95) between infiltration amount (Inf ) and the surface vegetation cover (Lsvc). Inf increased firstly and then decreased with the rainfall intensity (Rai ) increasing. There was a critical Rai which induced the largest infiltration amount. The critical Rai for the AF and SGL ranged from 19.9 to 27.8 mm/ h, both were larger than that under the NAL. There are significant negative correlations ( P < 0.05) between runoff depth, soil loss and Lsvc with all the correlation coefficients over 0.9. Erosion rate was positively related to runoff coefficient by a power function, the sediment concentration increased with runoff coefficient and rainfall erosivity increasing by logarithmic functions, soil loss increased with both rainfall erosivity and runoff depth increasing by linear functions. [Conclusions] The runoff depth of 20 mm was an inflection point for soil loss, the soil loss rate was high when the runoff depth was over 20 mm. Compared with the NAL, the AF and SGL obviously improved soil infiltration and reduced runoff and sediment yield.