Runoff and Sediment Yield Process on the Sand-covered Loess Slopes Under Simulated Runoff Conditions
ZHANG Yang;LI Zhanbin;NIU Wen;DUAN Jinxiao;Key Lab of Northwest Water Resources and Environment Ecology of Ministry of Education,Xi'an University of Technology;State Key Laboratory of Soil Erosion and Dryland Agriculture on the Loess Plateau,Institute of Soil and Water Conservation,Chinese Academy of Sciences and Ministry of Water Resources;CCCC First Highway Consultants Co.,LTD;
Runoff and sediment yield process on sand-covered loess slopes under simulated runoff conditions were studied through simulating wind-water complex erosion based on the controlled scouring experiments.This study set up three water flow rates(5,10,and 15L/min)and five sand-covered thicknesses(0,5,15,25 and 35mm).The results showed that the runoff yield time on the sand-covered slope was extended,and it extended with the increasing of sand-covered thickness.Under different water flow rate,the runoff yield time on sand-covered slopes(5,15,25,35mm)were 1.29~1.46 times,1.66~2.5times,2.5~3.76 times and 3.76~4.72 times,respectively,than those on the loss slope.Compared to the loess slope,sediment yield contribution rate was greater than runoff contribution rate on the sand-covered slope.Under the same water flow rate,the total amount of runoff on sand-covered slope was 1.05~1.8times of that on the loess slope,and the total amount of sediment yield was 1.6~7.5times.Under different water flow rates,the increase-rate of runoff rate on the sand-covered slope was significantly higher than that on the loess slope within 0~5min,and in the later 25 min of runoff,increase-rates of runoff rate on both two kinds of slopes were basically coincident.In the whole runoff,the fluctuation of runoff rate on sand-covered slope was significantly higher than that on loess slope.With the increasing of water flow rate,the initial sediment yield strength on sand-covered slope significantly increased.However,in the same water flow rate,the initialsediment yield strength did not increased significantly with the increasing of sand-covered thickness.Under different water flow rates and different sand-covered thicknesses,the sediment yield strength firstly increased dramatically,then decreased,and then gradually reached a steady state,and the fluctuation of sediment yield strength on the sand-covered slope was significantly higher than that on the loess slope.The results indicated that the sand-covered slope destroyed the stability of the water flow,and aggravated soil erosion at a certain extent.
【Key Words】： wind-water complex erosion scouring experiment sand-covered loess slopes erosion and sediment yield
【CateGory Index】： S157.1
【CateGory Index】： S157.1