王格, 郭欣伟, 党素珍. 采煤扰动下潜水位及包气带水分变化特征[J]. 农业工程学报, 2022, 38(6): 105-112. DOI: 10.11975/j.issn.1002-6819.2022.06.012
    引用本文: 王格, 郭欣伟, 党素珍. 采煤扰动下潜水位及包气带水分变化特征[J]. 农业工程学报, 2022, 38(6): 105-112. DOI: 10.11975/j.issn.1002-6819.2022.06.012
    Wang Ge, Guo Xinwei, Dang Suzhen. Variation characteristics of water table and water content in vadose zone under disturbance of coal mining[J]. Transactions of the Chinese Society of Agricultural Engineering (Transactions of the CSAE), 2022, 38(6): 105-112. DOI: 10.11975/j.issn.1002-6819.2022.06.012
    Citation: Wang Ge, Guo Xinwei, Dang Suzhen. Variation characteristics of water table and water content in vadose zone under disturbance of coal mining[J]. Transactions of the Chinese Society of Agricultural Engineering (Transactions of the CSAE), 2022, 38(6): 105-112. DOI: 10.11975/j.issn.1002-6819.2022.06.012

    采煤扰动下潜水位及包气带水分变化特征

    Variation characteristics of water table and water content in vadose zone under disturbance of coal mining

    • 摘要: 为更好地了解采煤扰动下潜水位及包气带水分变化规律,在陕北典型矿区开展了降雨、潜水位、包气带土壤含水率等水循环要素的野外原位观测试验,基于观测数据,采用Spearman秩相关系数检验、小波分析等方法,分析了未开采区及采空区潜水位和包气带水分的变化特征。结果表明:未开采区地下水位对于降水的响应明显且时间上存在4、5个月的滞后,采煤扰动后,地下潜水位持续下降,与降水响应关系微弱;在垂向上,未开采区较大降水可对100 cm以下埋深的土壤含水率产生影响,采空区土壤含水率总体减小,且同降水的响应程度不显著,含水率最大值相对于未开采区出现时间提前,50 cm以下埋深的土壤含水率对小强度降水无响应。采煤扰动潜水位下降后造成包气带增厚,包气带损耗的水量增加,随之造成降雨入渗补给地下水减少,进一步加剧了潜水位下降。

       

      Abstract: Abstract: Human activities commonly dominate the water source, such as moisture conditions, even for the surface subsidence, fissure zone, more severe groundwater exploitation, and complex precipitation in the semi-arid areas. This study aims to determine the variation of groundwater level and water content in the vadose zone in typical mining areas of Northern Shaanxi Province in China. The relationship between precipitation and groundwater was established by in-situ observation, statistical and wavelet analysis from the perspective of the water cycle. Some parameters were also measured, including the precipitation, groundwater table and soil moisture content in the vadose zone under the disturbance of coal mining. Particularly, the vadose zone dominated the infiltration, evapotranspiration, groundwater recharge and discharge in the water cycle. The interaction mechanism was also proposed for the response of groundwater level and water content to the changes in precipitation in both unmined areas and mining areas. The self-test system, groundwater observation wells and sensors were used to evaluate the rainfall, phreatic water level, soil moisture, and water potential in the mining areas. The soil water movement was monitored in the depths of about 10, 20, 30, 40, 50, 80, 100, and 150 cm in the unmined areas and in the depths of about 10, 20, 30, and 50 cm in the mining areas. After that, an evaluation was made on the variation of groundwater level under the disturbance of coal mining, the trend of soil moisture content with the depth, and the relationship between soil moisture content and rainfall response before and after coal mining. The results show that there was an outstanding response of groundwater level to precipitation in the unmined areas, where the absolute value of correlation coefficient reached more than 0.7. There was also a lag of about four or five months. There was no effect of small intensity of precipitation (like 50 mm) on the soil water content near the depth below 100 cm in the unmined area, but the larger precipitation (60 mm) infiltrated the depth below 100 cm. The groundwater level continued to decline, indicating the weak relationship between groundwater level and precipitation after the disturbance of coal mining for about several years. The moisture decreased with the increase of depth in the vadose zone, indicating the gentle fluctuation range of dynamic change. The soil moisture was less vulnerable to the external influence, as the farther away from the ground. There was an outstandingly different trend of soil moisture content with the rainfall at different depths, although no significant response of water content to precipitation at the same depth. In addition, the maximum soil moisture content in the mining area occurred earlier than that in the unmined area, indicating a reduced range overall. In particular, the precipitation increased significantly in July and August. The reason was that the fissures caused by coal mining shortened the precipitation time to recharge the shallow groundwater. There was no response at the depth below 50 cm to the small intensity of precipitation (like 30 mm). In general, the coal mining caused the drop in water level, resulting in the thickening of the vadose zone, whereas, the loss of water increased in the vadose zone, resulting in the rainfall infiltration of groundwater recharge decreased, further aggravating the drop of water level. Accordingly, the findings can provide theoretical support for the water cycle mechanism under coal mining.

       

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