膜下滴灌条件下绿洲棉田土壤水分运动数值模拟

Numerical Simulation of Soil Water Movement in Oasis Cotton Field with Drip Irrigation under Mulch

应用非饱和土壤水运动理论，建立膜下滴灌条件下土壤水分运动二维数值模拟模型，研究了田间层状土壤在膜下滴灌条件下土壤水分运动特征。应用不同小区不同灌水处理的实测值与模拟值进行对比，同时对模型做了精度分析，结果表明符合精度要求，这说明所建立的模型能客观地反映实际土壤条件下的水分运动情况。研究结果表明：土壤剖面30-40cm粘土层使土壤水分运动具有很大的差异，0～30cm变化明显，而40cm以下土壤水分运动的变化较小。膜下滴灌应该采取灌水量小，频度大的灌溉模式。

Based on the theory of the movement of unsaturated soil-water, a two dimensional vertical plane model was developed to simulate soil water movement under drip irrigation under mulch. The soil water movement of stratified soil in the experimental field was calculated under the condition of drip irrigation under mulch. The field test was carried out in Aksu water balance experiment station to verify the numerical simulation results of soil water content in different test field with different irrigation treatment. The result indicated that they had better conformity. Comparing the soil water content of 0- 10 cm depth in different time and different location observed by PTM-48（Photosynthesis Transpiration Monitor） with numerical simulation results, it can be found that the numerical simulation results was less than the value of field test, but the changing tendency was agreeable. So the numerical simulation model of soil water movement under the condition of drip irrigation under mulch is acceptable. From the research result , it can be found that the soil water movement was explicitly various in different depth for the clay stratification in 30-40 cm depth. The obvious difference can be seen in 0-30 cm of soil profile, while there is no sharp change below the 40 cm depth. So the irrigation water quantity should be reduced and the irrigation frequency should be increased to enhance the water use efficiency.