Characteristics Of Rainfall Runoff And Soil Erosion On Sloping Farmland In The Gentle Hilly Region Of Western Of Heilongrang Province

The area of western Heilongjiang province, has rich land resources, is an important grain production base in China. Because protection work of economic development and ecological environment disjointed, water and soil loss was more serious. Aiming at the problems of serious soil and water loss on the sloping farmland in the gentle hilly region of the western Heilongjiang province, five technology modes of mole drain (SD), the combination of mole drain and subsurface pipe (SA), furrow damming (LQ), the combination of mole drain and furrow damming (SQ), the combination of mole drain and subsurface pipe and furrow damming (SAQ) were selected in2010and2011. The paper studied on comprehensive technique model with the first combination of engineering technology and tillage technology under natural rainfall condition. Compared with comparison plot--conventional tillage (CK), it revealed characteristics of rainfall runoff and soil erosion on sloping farmland in the gentle hilly region of western of Heilongjiang province. And surface runoff and soil erosion process of different soil and water conservation measures were simulated respectively by using kinematic wave equation and universal soil loss equation. The results as following:1. Characteristics of surface runoff of different treatments:There were obvious hysteretic nature between runoff process and rainfall process of different treatments, individual rainfall runoff process changed with rainfall intensity. The treatment which had obvious hysteretic nature, had better water soil, and it was affected little by rainfall intensity. Annual runoff and individual runoff had the same result that was:SAQ whose annual runoff was0.053mm, had the best effect on reducing runoff.2. Characteristics of soil erosion of different treatments:Changes of sediment yield process of different measures with runoff process had the same trend. Compared with runoff process, sediment yield process was affected obviously by the change of rainfall intensity, soil erosion of different measures showed an uneven season distribution, it concentrated on July and August that had abundant precipitation. The annual erosion of SAQ was least, the value was0.005t/hm2. The annual erosion of other measures were in the range of soil loss torelance in Heilongjiang province.3. In this paper, a numerical model of runoff generation on sloping land in Heilongjiang province was established with the combination of kinematic wave theory and the Green-Ampt infiltration model, and under the conditions of nature rainfall, and compared with the Measured runoff processes.The result presented that the precision was not high. The reason was that kinematic wave equation was established for plane slope, the simulation effect was not ideal in slope field ridge tillage. In order to improve the precision, further comparative study on runoff model in this place was needed.4. Based on soil test method, organic matter, nitrogen, phosphorus, potassium, available nitrogen, available phosphorus, available potassium content in the erosion sediment samples of different plots were determined. The results showed that the largest loss amount was organic matter, the second was the erosion of total nutrient, the loss of available nutrients was relatively less. The order of the loss of nutrient from big to small was CK>LQ>SD>SA>SQ>SAQ, which was consistent with the arrangement regulation of sediment yield.5.Soil erosion of plots were simulated by soil loss equation in this paper. According to the observation data about rainfall and plots in2010and2011and other study on soil erosion in Heilongjiang province, this paper determined each factor in USLE and then stimulated. Though the errors between calculated values and measured values were large, USLE model could stimulate soil erosion well based on increasing test year.In a word, compared with CK, runoff and soil erosion of SAQ were least, the order of runoff and sediment amount from big to small was LQ>SD>SA>SQ>SAQ. The result showed that runoff and sediment reduction effect of comprehensive technique model was better than that of single technique model. The precision in slope field ridge tillage in Heilongjiang province using kinematic wave equation was not high, we need to seek model that precision was higher in further researches. Soil loss equation was established according to experimental data, but errors between simulation values and measured values were little high. It was affected by test years, we would carried out more test to improving the precision of model.