基于LAWSTAC模型的植物生长条件下层状土壤水盐运移的数值模拟

Numerical Simulation of Water and Salt Transport in Subsoil Under Plant Growth Conditions Based on LAWSTAC Model

为研究层状土壤对水盐运移以及植被生长的影响,进一步了解植物水分的有效利用情况,以植物生长条件下的室内层状(上层为壤土,下层为河砂)一维土柱水盐运移试验为基础,利用课题组开发的层状土壤水盐运移模型(Layered soil water solute transport and crop growth model,LAWSTAC)进行了相应的模拟和分析。研究结果表明:①LAWSTAC模型可以较好的模拟入渗过程中均质壤土的水盐运移,模型相关参数可以直接用于层状土土柱的模型中。②LAWSTAC模型可以较好地模拟入渗条件下上细下粗型层状土的水盐运移情况,但是对于蒸发过程来说,由于下层河砂参数选取的误差、亦或由于目前水盐运移理论在有优先流存在的层状土中适用性不好,导致蒸发过程模拟效果不佳。③粗质土覆盖细质土能有效减小蒸发量及蒸腾量,上层粗质土对水分运动和盐分运移均有抑制作用。上粗下细型层状结构土壤的蒸发失水主要来自上层粗质土,而上细下粗型层状结构土壤的蒸发失水主要来自下层粗质土,且其累积蒸发量远大于上粗下细型层状土。因此,LAWSTAC模型可为研究自然界中土壤质地差异较大的农田的盐碱化防治以及灌溉水的高效利用提供数据支持。

To study the effect of layered soil on water and salt transport and vegetation growth,and further understand the effective utilization of plant water,based on the water and salt transport test of indoor one-dimensional soil column with layer(loam in the upper layer and river sand in the lower layer)under the condition of plant growth,the Layered soil water solute transport and crop growth model(Layered soil water solute transport and crop growth model,LAWSTAC)developed by the research group was used for the corresponding simulation and analysis.The results show that:①The LAWSTAC model can well simulate the water and salt migration of homogeneous loam during infiltration,and relevant parameters of the model can be directly used in the model of the layered soil column.②The LAWSTAC model can well simulate the water and salt migration in the fine-upper and coarser layered soil under infiltration conditions.However,for the evaporation process,due to the error in the selection of the parameters of the lower river sand,or the poor applicability of the current water and salt migration theory in the layered soil with preferential flow,the simulation effect of the evaporation process is not good.③Covering fine soil with coarse soil can effectively reduce evaporation and transpiration,the upper coarse soil can inhibit water movement and salt migration.The evaporation and water loss of the upper coarse-lower fine layered soil is mainly from the upper coarse-grained soil,The evaporation and water loss of the upper fine layer soil and the lower coarse layer soil mainly came from the lower coarse soil,And the cumulative evaporation is much larger than that of the upper coarse and lower fine layered soil.As a result,the LAWSTAC model can provide data support for the study of salinization control and efficient utilization of irrigation water in farmland with large differences in soil texture in nature.