Spatial Heterogeneity Of Soil Physieal-chemical Properties In Typical Grass Slope Of Inner Mongolia

As for actual condition, the distribution of the precipitation in a year is not symmetrical in the typical steppe of Inner Mongolia, and the precipitation that has high intensity mostly appears with one of the few times. In the typical steppe of Inner Mongolia, the typical grass slope surface is the main study object, using the research methods which combine field experiments with lab analysis, to study the spatial heterogeneity of soil physical and chemical properties and the adaptability of the WEPP model in the typical grass slope surface. It is of great significance that studying the transfer mechanism of soil nutrient and Managing moisture of hillside fields in the typical grass slope surface. The conclusions could be drawn as follows:1、Slope position has affection to the spatial heterogeneity of soil properties in the natural grass slope surface.(1) Moisture content in bottom is the lowest, but changing range is the largest, furthermore, the more close to gully mouth, the lower moisture content.(2) That slope position impact on volume weight of soil related with location of slope surface in channel, volume weight of soil is obvious higher than other slope positions in the bottom.(3) For organic matter and total nitrogen, slope positions have the same affection to them. Their content are the largest on the top-slope, the least on the mid-slope; changing range is the largest on the ditch mouth, the least on the ditch head; the higher content is, the closer to the ditch mouth. Slope positions have the different affection to total phosphorus and total potassium. Slope position has affection to total phosphorus which shows that content is the largest on the top-slope, the least on the mid-slope; changing range is the largest on the ditch mouth, the least on the middle of ditch; the higher content is, the closer to the ditch mouth. That slope position has affection to total potassium are related to the position of slope surface which located at the position of the channel; content is the largest on the mid-slope, the least on the top-slope; changing range is the largest on the ditch head, the least on the ditch mouth; on the top-slope, the higher content is, the closer to the ditch mouth.2、The parameter sensitivity analysis about the WEPP model. conductivity affect the simulation results of the runoff with the WEPP model; In addition to soil albedo. Rill and soil critical shear forces outside, the other three of the parameters influence the simulation results of the sediment. In the four CLIGEN climate model parameters, the simulation value of runoff and sediment with storm amount and maximum rainfall intensity increases; the simulation value of runoff and sediment with the increase of storm duration presents the first decreased and then increased; the simulation value of runoff and sediment with the increase of ratio which achieving maximum rainfall intensity of time, and the ratio of storm duration, presenting the first decreased and then increased, the simulation value of Sediment than the extent of change of runoff.3、The reseach on the simulation with the WEPP model of slope surface versionIn30°、5°and8°the three different slope under the condition of simulated tests, predicted runoff by WEPP was poor under the condition of Single rainfall, only on3°simulation results are good, and the greater the slope is, the value of runoff simulation is poor;predicted sediment by WEPP was good under the condition of Single rainfall, on the whole, predicted on the small slope is better than on the large slope. Under the condition of different slope, two rainfall characteristics parameters that the maximum rainfall intensity and rainfall duration have important affections on predicted by WEPP model, the simulation results of rainfall events has large deviation, that the maximum rainfall intensity is big, however, the predicted runoff that the maximum rainfall intensity is big has large deviation.