干旱区绿洲棉田土壤水盐运动数值模拟

本文中利用预报校正法求解土壤水分运动的ｈ型Ｒｉｃｈａｒｄｓ方程。同时利用具有二阶高精度的差分法求解土壤盐分运移的对流扩散方程，此格式可避免利用一般差分格式时出现的数值弥散问题。最后，将上述数学模型对干旱区绿洲棉田，在蒸发条件下土壤水分运动和土壤盐分向上运动积累过程进行数值模拟，计算结果与测量值吻合较好。可为预报土壤盐碱化提供科学依据。

NUMERICAL SIMULATION OF MOISTURE-SALT TRANSPORT IN COTTON FIELD SOIL IN THE OASES,ARID AREAS

The research on soil moisture-salt transport has a great economic value for improving saline-alkaline land. According to the primary statistical results, the total area of saline-alkaline land in China is about 26. 7 million ha., in which the area of cultivated saline-alkaline land occupies about 6. 7 million ha. It is the main subject for improving saline-alkaline land to research the transport features of moisture-salt in surface soil layer. However, the available research results of moisture-salt transport in unsaturated soil are far inferior to solving the practical problems in agricultural production. In this paper, forecast-correction method is applied to salve the h form of Richards equation for soil moisture transport, and quadratic differential method is used to solve the convection-diffusion equation for salt transport in soil. Which can avoid the numerical dispersion. Finally, this mathematical model is used to simulate moisture-salt transport in cotton field soil in the oases, arid areas under the condition of evaporation. There is a good agreement between the calculated results and the measured data. The equation of soil moisture-salt transport and the differential pattern can ideally reflect the practical situation, and can be used for forecasting the transport law of moisture-salt in cotton field soil in arid areas.