基于旱排控盐模型的沿黄灌区不同地类间水盐运移与平衡分析

Water and Salt Transport Pattern and Balance Analysis among Different Land Classes in Yellow River Irrigation Area Based on Dry Drainage Salt Control Model

在地下水埋深较浅的干旱半干旱地区,耕荒地分布较为分散破碎,旱排控盐是减轻土壤盐渍化的重要管理手段。旱排控盐使不灌溉的盐荒地成为蒸发盐汇区域,接收邻近灌溉农田的水分和盐分。本研究以河套灌区一个典型的旱排单元(盐荒地和相邻的不同作物农田)为例,利用Darcy定律计算并揭示了盐荒地与相邻农田之间的水盐分布及迁移规律。结果表明:不同农田类型腾发量(ET)存在较大差异,玉米农田平均ET比葵花农田和盐荒地分别高23.47%和88.97%,葵花农田ET较盐荒地高53.06%;不同作物根区土壤(0~100 cm)盐分存在明显差异,葵花农田含盐量为玉米农田的2.10~2.47倍,盐荒地平均土壤含盐量为耕地的2.81~6.95倍。此外,在春灌和作物生长阶段,灌溉和降水使农田地下水埋深最大上升157 cm,从而促使水盐从农田向未灌溉的盐荒地迁移,减轻了耕地作物根系的盐分,维持了作物生长;在春灌时期,葵花地灌溉水渗漏并快速排泄到未灌溉地类,导致水盐通量达到最大值,水分迁移量平均为0.045 cm/d,盐分迁移量为0.013 mg/(d·cm^(2))。盐荒地作为耕地的排泄区域,具有维持水盐平衡的功能,该研究量化分析了耕荒地间水盐的迁移规律,可为干旱区水盐平衡规律提供理论依据。

In arid and semi-arid areas with shallow groundwater depths,where the distribution of cultivated and wasteland is more dispersed and broken,dry drainage and salt control are important management tool for reducing soil salinization.Dry drainage salt control makes the non-irrigated wasteland an evaporative salt sink area,receiving water and salt from neighboring irrigated farmland.A typical dry drainage unit(wasteland and adjacent cultivated land of different crops)in Hetao Irrigation District was used as an example,and Darcy’s law was utilized to calculate and reveal the water and salt distribution and migration law between the wasteland and adjacent cultivated land.The results showed that there were significant differences in ET among different farmland types,and the average ET of corn farmland was 23.47%and 88.97%higher than that of sunflower farmland and wasteland,respectively,and the ET of sunflower farmland was 53.06%higher than that of wasteland;there were obvious differences in the salinity of soil in the root zone(0~100 cm)of different crops.The salinity in sunflower farmland was 2.10~2.47 times higher than that of corn farmland,and the average soil salinity of wasteland was 2.81~6.95 times that of cultivated land.In addition,during the spring irrigation and crop growth stages,irrigation and precipitation caused the groundwater depth of farmland to rise maximum of 157 cm,which promoted the migration of water and salts from the farmland to unirrigated wasteland,alleviating the salinity in the root system of the cultivated land,and sustaining the growth of the crop.During the spring irrigation period,the irrigation water of the sunflower field leaked and quickly drained to the unirrigated land,resulting in the maximum water and salt fluxes,with the average water transport amount of 0.045 cm/d and salt transport of 0.013 mg/(d·cm^(2)).Wasteland,as the drainage area of cultivated land,had the function of maintaining water-salt balance,and the water-salt transport law among cultivated and wasteland was quantitatively analyzed,which can provide a theoretical basis for the water-salt balance law in arid areas.