Feature And Mathematical Model Of The Soil Solute Transport With Runoff On Loess Slope

Serious water and soil loss cause the soil quality degratation and serious agricautural non-point polution. The feature and mathematical model of the soil solute transfer with surface runoff on loess slope were studied in order to provide some guidance for soil, water and nutrient loss control through the experiment, theoritical analyses and mthe model. The main results are as following.1 Soil solute transfer with runoff is a complex physical-chemical prosess. The effects of the features of the soil, rainfall, slope degree and length, applying fertileizer approach, vegetation and supplying water from lower part of the soil on the soil solute transfer with runoff were analyzed based on the experimental data indoor and in field, and the mechanism of the soil solute transport with runoff was studied in order to lay a solid foundation of establishing the mathematical model describing the soil solute transport with runoff.2 The feature of soil water movement during rainfall and Philip equation, Green-ampt equation and one-dimensional algbric infiltration model were analyzed based on the physical processes of soil water movement. Three physical-basis models describing rainfall-infiltration and runoff formation were established, and the parameters in the three models were analyzed. The three models were evaluated based on the experimental data, and the results indicate that three model can describe the processes of rainfall-infiltration-runoff formation.3 The completed mixing model, partial completed mixing model and equalvelent advence transfer model decribing soil solute transfer into runoff on loess slope were established, and the features of the three models and relevent parameters in the three models were analyzed. The three models were evaluated based on the experimentl data, and the reesults indicate that the equalvelent advence transfer model fits the eperimental data very well. The partial completed mixing model fits the exprimental data better than the completed mixing model, but the completed mixing model is simple the mathematical express and the relevant parameters are easy to be obtained.4 The field plot experimental results indicate the the runoff amount, soil and solute loss amount first increses then decrease as the slope degree increases, and the the runoff amount, soil and solute loss amount decrease as the vegetation converage degree increases. The role of grass land for increasing infltration and reducing soil, water and solute loss is better than the trees. The results also indicates the the equalvelent advence transfer model can fit the field experimental data well.5 The features of soil and nutrients loss in small watershed and the role of complehensive control methods of soil and water loss were analyzed, the determination method of the dam height of the silt.