盐分再分配条件下河套灌区冲洗水量的数值模拟

该文旨在探讨干旱缺水地区长期灌溉条件下,合理解决节水灌溉与冲洗灌溉间矛盾的途径,为在该地区实施节水灌溉战略提供理论依据。采用修正的对流扩散模型(SOTR)及特征有限元方法对中国内蒙古河套灌区冲洗—蒸发条件下的冲洗定额进行数值模拟研究。并用γ射线测定土柱土壤水盐运移结果标定了数值模拟结果。重点分析了基于土壤水动力学与溶质动力学原理,再灌溉冲洗与再分配条件下,均质垂直剖面上溶质运移过程;长期灌溉条件下,干旱地区土壤盐分布与冲洗定额、初始土壤盐分含量、地下水位埋深及地下水矿化度间的内在联系;在此基础上,确定节水灌溉条件下河套灌区最优的冲洗定额。该成果对于促进该地区农业可持续发展具有一定的指导意义

Simulation of Leaching Requirement for Hetao Irrigation District Considering Salt Redistribution After Irrigation

The leaching requirement for the Hetao Irrigation District of Inner Mongolia Autonomous Region, China, was estimated by numerical simulation. To simulate the salt transfer under leaching evaporation conditions, a modified solute transport model, Second Order model compared with Two Region model(SOTR), was employed. An advanced numerical method, the characteristics method combined with the finite element(CMCFE) scheme, was used. The simulation was verified by experiment of soil water transport in the soil column using a Gamma ray method. The salt transport processes were investigated when solutes leach and redistribute through a vertical homogeneous soil based on the soil water and solute dynamics. The relationship between the dynamic long term distributions of soil salt content and the leaching requirement, ground water depth, ground water salt concentration and initial soil salt content distribution in an arid area was discussed and analysed. And the optimum leaching requirement for the Hetao Irrigation District was determined.