不同沉陷应力区土壤水分和溶质运移的模拟试验

doi:10.12118/j.issn.1000-6060.2022.615

摘要/Abstract

摘要：

中国山西-陕西-内蒙古交界地开采沉陷对地表土壤扰动强烈，引起地表生态损伤。为了揭示开采沉陷对土壤水盐运移的影响机制，通过建立土壤沉陷物理模型，利用沉陷剖面不同应力区土壤容重数据建立HYDRUS-2D水盐模型，研究土壤蒸发过程中，土壤水分、总盐分、不同溶质离子在不同沉陷应力区随土壤深度和运移时间的变化规律。结果表明：（1） 0~40 cm深度，沉陷拉张作用显著增强土壤蒸发作用，造成挤压区土壤含水率显著大于拉张区，土壤含水率随时间变化曲线呈现典型的蒸发过程“三阶段”模式。（2）沉陷组各应力区土壤总含盐量不但随深度呈现强烈变异，具体表现为20~40 cm、60~80 cm土壤总含盐量相对积聚；而且右侧拉张区总含盐量积聚深度有向下迁移的趋势。（3）沉陷拉张区Ca²⁺、SO₄^2-、Mg²⁺、Cl^-离子积聚浓度大于挤压区。Ca²⁺、SO₄^2-、CO₃^2-土壤离子浓度随深度呈单峰积聚，沉陷拉张区积聚深度均显著下移。（4） HYDRUS-2D水盐模型可以较好地模拟开采沉陷土壤剖面中的土壤水盐运移。土壤含盐量、含水率的实测值与模拟值率定结果为平均相对误差（ME）≤0.5，均方根误差（RMSE）≤0.5，决定系数（R²）>0.95，模拟精度满足试验要求。研究结果可为科学开展开采沉陷区生态修复工程、提高生态自修复能力提供重要理论依据。

关键词: 开采沉陷, 土壤水分运移, 土壤溶质运移, HYDRUS-2D

Abstract:

Mining subsidence in the Shanxi-Shaanxi-Inner Mongolia border region of northwestern China has caused ecological damage by strongly disturbing the surface soil. To explore the mechanism by which mining subsidence influences soil water and salt transport, physical soil subsidence and numerical soil-water and salt-transport models were established in the HYDRUS-2D water-salt model using soil bulk density data from different stress areas of the subsidence profile. The variation in soil moisture, total salt, and different solute-ion content with soil depth and migration time in different subsidence stress regions during soil evaporation was studied. The results showed that: (1) At 0-40 cm depth, the effect of subsidence and tension significantly enhanced soil evaporation, resulting in soil water content in the extrusion zone significantly higher than the tension zone. (2) The total soil salt content in each subsidence stress region varied strongly with depth, and salt accumulation was observed in the 20-40 cm and 60-80 cm soil layers. Moreover, the salt accumulation depth in the right tensile area showed a downward migration trend. (3) The accumulation concentrations of Ca²⁺, SO₄^2-, Mg²⁺, and Cl^- in the subsidence tensile zone were greater than the extrusion zone. The concentrations of Ca²⁺, SO₄^2-, and CO₃^2- showed a single peak of accumulation with depth and a significant decrease in accumulation depth in the subsidence and extension areas. (4) The HYDRUS-2D water-salt model can accurately simulate soil water and salt transport in mining subsidence soil profiles. Compared with the measured soil salt and water content values, the average relative error, root mean square error, and coefficient of determination of the simulated values were respectively as follows: ≤0.5, ≤0.5, and >0.95. In the mining subsidence areas of the Shanxi-Shaanxi-Inner Mongolia border region, salt migration through the subsidence tensile stress area of the soil can greatly alleviate the problem of land salinization caused by strong evaporation. This study thus provides an important theoretical basis for implementing science-based ecological restoration projects in mining subsidence areas, for establishing differentiated ecological restoration models, and for accelerating ecological self-healing capabilities.

Key words: mining subsidence, soil moisture migration, soil solute transport, HYDRUS-2D

温欣, 尚海丽, 黄显武, 李建伟, 李依临, 杨宏宇. 不同沉陷应力区土壤水分和溶质运移的模拟试验[J]. 干旱区地理, 2023, 46(9): 1481-1492.

WEN Xin, SHANG Haili, HUANG Xianwu, LI Jianwei, LI Yilin, YANG Hongyu. Simulation experiment on soil moisture and solute transport in different subsidence stress regions[J]. Arid Land Geography, 2023, 46(9): 1481-1492.

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测试项目	粒径占比/%
测试项目	粗砂（497~2000 μm）	中砂（240~497 μm）	细砂（72~240 μm）	黏土（<72 μm）
矿区土壤	16.35	23.98	42.03	17.64
供试土壤	16.50	29.06	43.34	11.10

处理组	θ_r/cm³·cm^-3	θ_s/cm³·cm^-3	α	n	K_s/cm·d^-1
左侧边缘区	0.0436	0.3956	0.0363	1.6585	96.68
拉张B区	0.0415	0.3607	0.0395	1.6303	61.54
挤压C区	0.0413	0.3579	0.0396	1.6243	59.24
拉张D区	0.0368	0.2802	0.0498	1.4600	17.38
右侧边缘区	0.0405	0.3468	0.0414	1.5969	50.64
对照组	0.0375	0.3364	0.0469	1.6164	53.80

处理组	土层深度/cm	土壤含水率			土壤含盐量
处理组	土层深度/cm	RMSE	ME	R²	RMSE	ME	R²
试验组	0~20	0.03	0.01	0.99	0.04	-0.01	0.95
	20~40	0.03	0.01	0.99	0.04	-0.04	0.96
	40~60	0.02	-0.01	0.98	0.03	0.01	0.95
	60~80	0.05	0.05	0.93	0.03	0.01	0.94
	80~100	0.02	0.04	0.94	0.04	-0.01	0.96
对照组	0~20	0.02	-0.02	0.95	0.03	0.04	0.96
	20~40	0.03	-0.02	0.94	0.04	0.03	0.97
	40~60	0.01	0.01	0.92	0.01	0.03	0.96
	60~80	0.02	-0.02	0.96	0.01	0.03	0.95
	80~100	0.03	-0.03	0.97	0.01	0.02	0.97