| The WEPP model, as an extensive soil erosion model currently, which is a detailed description of physical process related to the soil erosion. This model have a large number of applied study in many area of China,such as purple soil in Southwest, loess soil in loess plateau area and black soil in northeast district. However, the adaptability of the red soil of slope orchard is still need to be studied. Therefore, this study chooses three different measures of the runoff plots in Fuzhou City Fujian province, Jinshan Water and soil conservation scientific education park. By collecting erosion data of single rainfall and some relevant data which include soil, topography and crop management information, we could get simulate runoff and erosion by running the WEPP model. We can check the adaptability of WEPP model in red soil orchard district of south China by using such indexes as coefficient of efficiency of the model (ME) and absolute value of relative error, and study the degree of influence of runoff and erosion by the rainfall parameters through path analysis, and study the affection of runoff and erosion by soil parameters through sensitivity analysis. The main conclusions are as follows:1. Through absolute value of relative error and coefficient of efficiency of the model, we can see that, the simulating effect of WEPP model is relative well in the No.115°fallow area, but the simulating effect in the No. Ⅱ and No. Ⅲ orchards measures district is poor. This show that the WEPP model comes with the parameters can be applied in the Southern Red fallow district, but its adaptability is very poor in the orchards measures area. Comparatively speaking, The forecast accuracy of the runoff yield is well than the forecast accuracy of sediment yield, and the results obtained by model comes through the manual calculation of input parameters is better than through the establishing method after choose different soil parameters input mode.2. Among the five rainfall parameters, the function of Maximum rainfall intensity is the largest, and the duration of rainfall is less important. For the fallow runoff plots, the rainfall and maximum rainfall intensity have great effect on the runoff yields and erosion yields, and the effect of other rainfall parameters is relatively small. For the different orchards measures runoff plots, the maximum rainfall intensity and average rainfall intensity have great effect on runoff and erosion yields.3. Among the five soil parameters, from the study of three runoff plots we could find that, initial saturated hydraulic conductivity and effective hydraulic conductivity are performance for the highly sensitive for the runoff yields and erosion yields of single rainfall, and the initial saturated hydraulic conductivity was expressed as positive correlation, the effective hydraulic conductivity was expressed as negative correlation. From the determinants of soil parameters, we also know that the three Characteristic parameters, Soil moisture content before the rainfall, Sand content and cation exchange capacity have very important on the single storm, soil albedo, rill erodibility, interrill erodibility and critical shear, as four soil parameters have relatively small effects on runoff and runoff. Among them, the sensitivity values of soil albedo and rill erodibility are equal to zero. So, for this study we could not consider about soil albedo and rill erodibility. |
