塔里木盆地绿洲农田土壤水盐运动动力学模式研究

本文采用改进型Ｐｉｃａｒｄ迭代差分法求解土壤水分运动的混鸽ｉｃｈａｒｄｓ方程,避免了采用Ｐｉｃａｒｄ迭代求解ｈ型Ｒｉｃｈａｒｄｓ方程所现的质量平衡误差问题。

STUDY ON MECHANICAL MODEL OF WATER-SALT MOVEMENT IN SOIL OF DASIS CROPLAND IN TARIM BASIN

To study the law of water-salt movement in soil has both theoretical and practical significances, especially for improving saline soil and controlling secondary salinization or alkalinization of farmland. The area of saline or alkaline wasteland is about 20 million hm"and that of farmland is about 6. 7 million hm2 including a part of secondary salinized land in China. Therefore, one of the urgent matters is to improve saline soil and control secondary salinization of farmland for rapid development of agriculture in China, especia1ly in north west China.In this paper, the modified Picard iteration method is applied to solve the mixed form of Richards equation for water movement in soil. The mass balance error in this algorithm is far less than that in traditional procedure in which the Picard iteration method is applied to soIve the capillary pressure in based form of Richards equation. Furthermore, the quadratic upstream interpolation difference method is used to solve the convection-diffu sion equation for salt movement in soil, it can avoid the munerical dispersion. Finally, this mechanical model is used to simulate water-salt movement in soil of oasis cropland in Tarim Basin under condition of permeance. The numerical results are in a good agreement with the experimental data. The model can provide scientific basis for improving saline soil.