大型灌区土壤水盐运移模拟研究进展

Research progress on simulation of soil water-salt transport in large-scale irrigation districts

土壤盐渍化是一种由自然和人类活动综合作用引起的土地退化现象,灌区人类活动频繁,影响土壤盐渍化的因素多样,深入理解土壤水盐运移过程将有助于灌区的土壤盐渍化防治。在对灌区土壤水盐运移的影响因素、国内外水盐模型特点和应用研究梳理的基础上,提出了灌区水盐运移模拟的可能发展方向。灌区盐渍化的形成与气候干旱、地形、土壤季节性冻融、地下水含盐量和成土母质等自然因素,以及不合理的灌溉管理措施、耕作方式和施肥制度等人为因素密切相关。水盐运移模型是研究土壤水盐运移过程的有效工具,目前常用的水盐运移模型包括水盐平衡模型、物理模型和统计模型。由于模型率定和验证所需的土壤水盐运移过程、作物生长过程观测资料较难获取,水盐运移模型多用于田间尺度的节水控盐策略和灌排管理措施优化研究,在区域应用较为有限。现代大型灌区的快速发展导致灌区土壤水盐运移时空分布规律变化较大,对模型的不断改进以及计算机技术的快速发展为探究大型灌区水盐运移时空演变机制提供了可能性。未来应加强基于生态安全的灌区土壤水盐运移机制研究,构建耦合气候模式或经济模型的多过程水盐运移模型。

Soil salinization is a manifestation of land degradation caused by the combined effect of natural processes and human activities.This issue is particularly common in irrigation districts,where various factors exacerbated by frequent human interventions influence soil salinity.To prevent soil salinization,it is essential to have a comprehensive understanding of soil water-salt transport mechanisms in irrigation districts with frequent human activities.After reviewing the factors that influence soil water-salt transport in irrigation districts and the characteristics and applications of water-salt transport model,we propose a potential direction for simulating water-salt transport in irrigation areas.The formation of salinization in irrigation areas is closely related to natural factors such as climatic aridity,terrain,seasonal soil freeze-thaw cycles,groundwater salinity,and parent material of soils,as well as anthropogenic factors such as irrational irrigation practices,agricultural methodologies,and fertilization regimes.To understand the process of water-salt transport,soil water-salt transport models are effective tools.The commonly used models for water-salt transport include water-salt balance models,physical models,and statistical models.They are mainly used to optimize irrigation water-saving regimes and drainage management for salinity control at the field scale.However,applying these models at the regional scale presents challenges due to the difficulty of obtaining observational data to calibrate and validate models that involve soil water-salt transport processes and crop growth.The rapid development of modern large-scale irrigation districts has changed the spatiotemporal distribution of soil water-salt transport.However,the continuous improvements of the model and the rapid development of computer technology have provided possibilities for investigating the spatiotemporal evolution mechanisms of water-salt transport in large-scale irrigation districts.Future models should focus on strengthening the soil water-salt transport mechanisms based on ecological safety.It is recommended to develop a multi-process water-salt transport model that is coupled with a climate model or an economic model.