Numerical Simulation And Movement Regularity Of Soil Water And Salt In Typical Experimentation Area Of Yanqi Basin, Xingjiang

This research takes typical experiment area as an example, discusses the dynamic variation characteristics of the soil salt and water on the condition of shallow water table, analyzes the variation law of the soil water and some influencing factors of the soil salt. On this basis, sets up the two-dimensional numerical model for the movement of soil water and salt in typical area, and makes use of this model, compare with the various irrigation programs, consider the soil water and the salt synthetically , gained the irrigation program adapt to this area. The main conclusions of are as follow:1. The variety of the groundwater level in typical area is subjected to the irrigation function, relatively great fore-and-aft irrigation; It's not obviously change if have no irrigation, because the supply of phreatic water. The mineralized degree of deep groundwater is not changed too much in typical area, interannual variations is between 0.575-0.717g/L, the shallow groundwater is relatively great, the maximum is 7.38 g/ L, the minimum is 3.76 g/ L. But the total trend is desalt.2. Under the influence of irrigation, the variety of soil water content in typical area farmland is bigger than in the peripheral wasteland. The variable coefficient of the soil water content at depth of 10cm in farmland soil is up to 0.59, but is only 0.05 in the wasteland. Moreover, after irrigation, the soil water content is distributed over again in typical area, the soil water above 20cm soil doesn't change greatly; but at depth of 20cm, the amount of soil water content become saturated, past a few days after irrigation, the soil water minimizes gradually, nearing to the remain soil water content. The soil water content is tends stabile at depth of 150cm, the variable coefficient is between 0.04 and 0.01.3. The peak value for many year of the soil salt above depth of 30cm appears in June or July in typical area, stabile comparatively in September. Below 30cm depth, soil salt is more stabile near the groundwater level.4. Making use of the information statistic method discusses the relation between the soil salt and the groundwater level, the result shows that: when the depth is 0-100cm, the surface soil salt between 0-30cm is influenced most with groundwater depth; The mineralized degree of soil water between 60-220cm depth is influenced biggest with the groundwater depth when the depth is placed at 100-130cm.5. By the thought of multivariate statistics, making use of correlation analysis model in the SPSS software, analyzes the effect of soil salt by the soil compositions, the result indicates: the Pearson's correlation coefficient is -0.263 between the sand and the soil salt, the silt is 0.38, the clay is 0.507, 2-tailed significant examines is 0.015, 0.000, 0.000, all passed the significant examination.All these show that the soil salt is influenced by the clay mainly in typical area.6. Making used of the regression analysis method, sets up the relational expression between soil salt Y and mineralized degree X: Y=0.1873X-0.1856, the related coefficient is 0.837, significant examines is 0.001. 7. From microcosms, using the method of correlation analysis, analyzes the relation between the soil salt and the ions, the result shows the relativity of soil salt is great with Cl^-,SO₄^2-,(K⁺+Na⁺),Mg²⁺ these four ions, on the depth is slight variety.8. Sets up the two-dimensional numerical model for the soil water and salt movement in typical area, and adopts the measured data to contrast and verify the model, the date is between the 15^th,April,2001 and 30^th,December,add up to 260 days, the result shows that the model is creditable.9. Take wheat as an example, considers crop's water requirement, the practical irrigation program and irrigation program in model, changes irrigation quantity, partition and of times, draws up three kinds of irrigation program, compares the water and salt by this model, gets the irrigation program adopt the typical area, is the irrigation program comprehensive consider the crop water requirement and winter irrigation for wash soil salt.10. The irrigation scheme that suitable for the region was calculated, contrast with the other three schemes on irrigation amount,crop water requirement and soil salt ,knows the superiority of this scheme.This research provides theory basis and flat roof for better reveal the order of groundwater-soil water and salt movement. It is significance for agriculture yield, environments improvement and economy development in Yanqi Basin.The features of my paper are: from the water and salt transport features, sets up the two-dimensional numerical model for the soil water and salt movement in this area, and by this model, calculates the irrigation scheme ,considering irrigation amount,crop water requirement and soil salt, gets the irrigation program that suitable for the region. Therefore it provides the theoretical basis for the development of agricultural production and irrigation water in this area.