旱区地下水文与生态效应研究现状与展望

为了探究寒旱露天煤矿区土壤水分运移规律及其生态效应，以位于蒙东草原的露天煤矿为研究区，开展了长时间段土壤水分观测原位试验。研究结果表明：非冻结期浅层土壤含水率主要受降水影响，冻结期土壤含水率受土壤温度影响明显；50 cm以上土壤饱和渗透系数大于150 cm/d，50 cm以下土壤饱和渗透系数仅为20 cm/d左右，表现为土壤饱和渗透系数随土壤深度的增加呈减小趋势，降水入渗形成的土壤水主要滞留在50 cm以上的植被根系作用层；区内地下水位埋深(>10 m)远超地下水补给植被的临界埋深(3.52 m)，植被指数与年降水量呈正相关关系，表明土壤水是维持区内植被需水的最关键水源；冻融期土壤含水率可恢复甚至超过非冻结期的含水率水平，同时特殊的土层结构造成植被根系区的土壤持水性较好，以上2个因素对植被生长具有积极意义。研究结果可为寒旱露天煤矿区的生态环境保护与修复提供借鉴。

Research status and prospect of the subsurface hydrology and ecological effect in arid regions

In order to explore the soil moisture migration mechanism and its ecological effect in the cold and arid open-pit coal mining area, a long-term in-situ test was carried out to observe the soil moisture, taking the open-pit coal mine in eastern Mongolia grassland area as the study area. The results show that: The shallow soil moisture content is mainly affected by rainfall in non-freezing period, while the soil moisture content is significantly affected by soil temperature in freezing period. Besides, the saturated permeability coefficient of soil in depth less than 50 cm is greater than 150 cm/d, but that of soil in depth greater than 50 cm is only about 20 cm/d, which indicates that the saturated permeability coefficient of soil decreases with the increase of soil depth, and then the soil moisture formed by rainfall infiltration mainly remains in the root action layer within 50 cm depth. The groundwater depth in the study aera (>10 m) is much greater than the critical depth of groundwater recharging to the vegetation (3.52 m). Meanwhile, the vegetation index is positively correlated with the annual rainfall, which indicates that the soil moisture is the most important water source for maintaining the water consumption of vegetation in the region. Moreover, the soil moisture content in freezing-thawing period is recoverable or even higher than that in the non-freezing-thawing period, and the vegetation root zone presents a good soil moisture holding capacity due to the special soil layer structure. Both of the two factors are of positive significance for vegetation growth. The research results could provide reference for the ecological environment protection and restoration in cold and arid open-pit coal mining area.