Loess Slope Land Infiltration

Based on the theory and method of soil water-dynamics and soil erosion, using the simulated rainfall and double-ring methods, the author systematically studied the soil infiltration law in the slope land of loess plateau. The primarily results were displayed as follows:1 .According to research for linear slope in the different slope gradient and different rainfall intensity, soil steady infiltration rates between water-pressure and no water-pressure have a linear relation while there is the same soil properties, soil steady infiltration rates in gully areas of loess plateau is between 1.8 times and 3.0 times, between 2.1 times and 3.2 times in hilly areas of loess plateau.2.On the basis of analyzing experimental data for slope land of loess plateau in different slope gradient and rain intensity and soil and water conservation tillage measures, using curve-fitting techniques, a soil infiltration rates model was woke out, the accuracy of the model is tested by a series of experiment data, the result of these indicate that the soil infiltration rates model is accurate and has good stability for slope land of loess plateau.3.Using soil infiltration rates and runoff time and wetting frontal surface depth of soil infiltration reflect effect of factor affecting soil infiltration rates. On the basis of analyzing factor (soil particle composition, soil bulk density, water stable aggregate content, antecedent soil moisture, slope gradient, rain intensity, accumulation depth and soil crust, soil and water conservation tillage measures) affecting soil infiltration rates, several relation models was obtained; Analyzed in detail different soil and water conservation tillage measures intensifying infiltration rates, while there have the same rainfall condition, the increasing infiltration rates of contour tillage and artificial digging and artificial hoeing in gully areas of loess plateau are 67% and 41% and 29%; the increasing infiltration rates in hilly areas of loess plateau is 45% and 22% and 14%. On the basis of analyzing infiltration process to different soil and water conservation tillage measures type, a increasing infiltration rates model for different soil and water conservation tillage measures type by using water balance equation is woke out.4.Accumulation depth and soil crust have a better affect to soil initial stage infiltration rates and a little affect to soil stable infiltration rates. Accumulation depth is 5cm and 3cm, soil stable infiltration rates in gully area of loess plateau is 0.57mm/min and 0.56mm/min, in hilly area of loess plateau is 0.94mm/min and 0.93mm/min.5.Study on silt-laden water in different sediment content, we may obtain that silt-laden water steady infiltration rates have an increase tread with increase sediment content, sediment content is 0% and 10% and 20% and 30% and 40%, soil steady infiltration rates in gully areas of loess plateau is 0.48mm/min and 0.28mm/min and 0.24mm/min and 0.21mm/min and 0.20mm/min; soil steady infiltration rates in hilly areas of loess plateau is 0.53mm/min and 0.35mm/min and 0.32mm/min and 0.30mm/min and 0.29mm/min,they have an index relation. The more the soil clay index is, the less the soil steady infiltration rates is, the soil clay index is 53.51% and 56.09% and 59.4%, soil steady infiltration rates in gully areas of loess plateau is 0.32mm/min and 0.28rnm/min and 0.27mm/min, the soil clay index is 35.23% and 38.48% and 42.25%, soil steady infiltration rates in hilly areas of loess plateau is 0.38mm/min and 0.30mm/min and 0.29mm/min, they have an power function relation.