黑河中游盆地南部山区地下水对平原区侧向径流补给量的估算

山区地下水对平原区的侧向径流补给量是一个长期争议且悬而未决的难题，这个量在西北内陆干旱盆地，被估算得或很小或很大。在总结前人研究的基础上，采用地质水文地质调查、物探、钻探、抽水试验、地下水动态观测、水化学测试、盆地地下水水位统测和综合研究等技术方法，查明了黑河中游盆地南部山盆交接带的地质构造接触关系、地层岩性接触关系及梨园河口白垩系风化壳含水层结构和水文地质参数。通过山区不同流域等级的地表水与地下水转化关系分析，将山区地下水对平原区侧向径流补给带划分为大中型河流河谷补给段和小微型河流或冲沟群流域构成的浅山带补给段。河谷补给段勘探资料较为丰富，多用达西断面流方法计算；针对浅山带补给段极为缺乏勘探资料的实际，以梨园河口断面径流量为参照，构建了浅山带岩性、汇水区面积、降水量等3 个变量的山区地下水对平原区侧向径流补给量的估算方法。估算出黑河中游盆地南部山区浅山带地下水对平原的侧向径流补给量为0.40×108 m3/a，河谷段基岩侧向补给量为0.07×108 m3/a；推算出河谷段第四系地下水补给量为0.30×108 m3/a；3 项补给量之和为0.77×108 m3/a，占盆地地下水资源量的3.0%。该研究为西北内陆干旱盆地山区地下水对平原区侧向径流补给量的估算提供了一个可供借鉴的实例。

Estimation of groundwater lateral flow in the southern mountainous area of the middle Heihe River Basin

The quantity of recharge of groundwater lateral flow from mountainous areas to plain areas is a long-term controversial and unresolved problem, which is always estimated to be too small or too large in arid inland basins in northwest China. Based on previous studies, this paper uses the technical methods of geological and hydrogeological investigation, geophysical exploration, drilling, pumping test, groundwater dynamic observation, hydrochemical test, basin groundwater level measurement and comprehensive study to identify the geological structure contact relationship, stratigraphic lithology contact relationship at the southern mountain-basin transition zone of the middle reaches of the Heihe River Basin, and the Cretaceous weathering crust aquifer structure and hydrogeological parameters at the Liyuan estuary. Through the analysis of the surface water and groundwater transformation relationships of different watershed levels in the mountainous areas, the recharge zones of groundwater lateral flow from the mountainous areas to the plain areas are divided into the large and medium-sized river valley recharge sections and shallow mountain recharge sections composed of small and micro rivers and gully groups. The exploration data of the river valley recharge sections are abundant, and the Darcy section flow method is used to calculate the recharge quantity. In view of the fact that the recharge section of the shallow mountain belt extremely lacks the exploration data, the runoff of the Liyuan estuary section is used as a reference. The estimation method of recharge of the groundwater lateral flow from the mountainous areas in the shallow mountain belt to the plain area is constructed with three variables of lithology, catchment area and precipitation. The results show that the quantity of recharge of groundwater lateral flow from the southern mountainous area to the plain area in the shallow mountain zone of the middle reaches of the Heihe River Basin is 0.40 × 108 m3/a, and that of bedrock in the valley sections is 0.07 × 108 m3/a. The quantity of recharge of groundwater of the Quaternary sediments in the valley sections is 0.30 × 108 m3/a. The sum of the three recharges is 0.77 × 108 m3/a, accounting for 3.0 % of the basin groundwater resources. This method provides an example for the estimation of the recharge of groundwater lateral flow from the mountainous areas to the plain areas in the northwest inland arid basins.