Research On Irrigation Erosion On Slope Land Of Yili River Basin

Irrigation erosion has become one of the most serious environment problems in Ili River Basin, and it restricts soil resources development in newly exploitation zone. Therefore, understanding of irrigation erosion discipline is beneficial to know and evaluate soil loss accurately in soil and water resources development, and it also provides scientific theoretical basis to soil and water conservation. Based on field water scouring experiment of bear slope and soybean slope under different scouring discharge, characteristics of runoff and sediment production, hydraulic parameters of runoff (flow velocity, Reynolds number, Froude number, Darcy-Weisbach resistance coefficient) and rill development were system analyzed. The results showed that:(1)The hydraulic parameters characteristics of runoff on bear slope: runoff velocity, Reynolds number and Darcy-Weisbach resistance coefficient increased as scouring discharge increased, and Froude number decreased. The relation between runoff velocity and scouring discharge, Froude number and Reynolds number both presented power functions. The water flow presented a turbulent, rapid flow state. The effect degree of irrigation quota on hydraulic parameters was less clear than scouring sicharge.The hydraulic parameters characteristics of runoff on soybean slope: space and time variation existed in runoff velocity. The water flow changed from laminar flow to turbulent flow, and it also presented a rapid flow state. Runoff velocity, Reynolds number and Darcy-Weisbach resistance coefficient increased as scouring discharge increased, and Froude number decreased. Runoff velocity and scouring discharge, Darcy-Weisbach resistance coefficient and Reynolds number both could be well fitted by power laws. The hydraulic parameters presented different variation with the growth of soybean.(2)The characteristics of runoff and sediment production on bear slope: as scouring discharge increased, sediment transporting rate went up, and sediment concentration showed a high-low trend. As irrigation quota increased, sediment transporting rate and sediment concentration both decreased. The effect degree of irrigation quota on sediment transporting rate and sediment concentration was less clear than scouring discharge. Sediment yield and runoff went up with scouring discharge and irrigation quota increasing. The variation of sediment yield was much bigger than runoff.The characteristics of runoff and sediment production on soybean slope: runoff and sediment yiele took place the big variety with scouring discharge increasing of all growth stage, and it is discovered the power rules between runoff and sediment production. There was the same trend in sediment concentration, sediment transporting rate and runoff coefficient with scouring increasing. Sediment concentration varied in waves with scouring discharge increasing, and sediment transporting rate, runoff coefficient went up with scouring discharge increasing.(3)Time of runoff beginning related to scouring discharge and soybean growth. It is found that time delayed with soybean growing, and time advanced as scouring discharge increased.(4)The soybean slope had significant effects on runoff and sediment reduction compared to the control, and the function of runoff reduction was weaker than the sediment reduction. Soil infiltration rate went up with scouring discharge increasing in two slopes. The infiltration rate in soybean slope was higher by 20% compared to the control, and time of runoff beginning of soybean slope was later by 8min than the bear one.(5)The width of rill became wider when scouring discharge increased, and the depth became deeper at the same time. The morphologic characteristic of rill under different scouring discharge: the rill distributed in the lower slope and showed a net work of high scouring discharge, with less quantity, long length, deep depth and wide width; the rill distributed in the upper slope and showed a sectional distribution of low scouring discharge, with more quantity, short length, shallow depth and narrow width.