ISSN 1000-3665 CN 11-2202/P

    层状非均质性影响下河流对地下水的补给过程研究

    Influence of stratified heterogeneity on the recharge from surface water to groundwater

    • 摘要: 河流对地下水的补给过程研究是科学认识水循环规律及地下水资源可持续管理的基础。河床沉积层与其下伏潜水含水层岩性差异是河流下伏含水层的主要结构特征,也是控制河流对地下水补给过程的主要因素。为揭示含水介质分层结构特征影响下河流对地下水的补给过程,基于黄河干流河南段野外试验结果,建立了地表水地下水相互作用概念模型,并以地下水流路径为对象,精细刻画了地表水地下水的相互作用过程。结果表明:(1)河流对地下水的补给量主要受河床沉积层渗透性影响,河床沉积层厚度变化对河流向地下水的补给量影响不大。即:河床低渗透性沉积物的存在是河流向地下水补给量降低的主要原因,当河床沉积层与其下伏含水层厚度比(HS/H)由0增大为0.125时,河流向地下水补给量的减小幅度达72%。(2)与均质条件相比,河床沉积层渗透性及其厚度变化均明显改变了河水向地下水补给的水流路径及径流时间。随着河床沉积物与下伏含水层渗透系数比KU/KL的增大,河水向地下水补给的水流路径穿透深度增大,径流时间延长。(3)河流对地下水的补给量及地下水径流时间对低渗透性河床沉积层渗透系数的敏感性随渗透系数的减小而增大,同时,地下水径流时间对低渗透性河床沉积层的厚度变化较为敏感,且随着厚度的增大,敏感性增强。研究成果可为地下水资源管理及可持续开发提供参考依据。

       

      Abstract: Knowledge of the recharge from surface water to groundwater is the basement of the scientific understanding of water cycle and the sustainable management of groundwater resources. Meanwhile, the layered heterogeneity is the main structural feature of riverbed sediments (i.e., the lithologic difference between riverbed sediments and the underlying aquifer) and the main factor that controlling the recharge from surface water to groundwater. To reveal the influence mechanism of layered structure of pore media on the recharge from surface water to groundwater, a conceptual model of surface water and groundwater interaction is established based on the field test results of Henan reaches of the Yellow River, and the process of the recharge from surface water to groundwater interaction is described using flow path as the object. The results show that the exchange flux of surface water and groundwater is mainly affected by hydraulic conductivity of riverbed sediments, and the change of the thickness of riverbed sediments has little effect on the exchange flux between surface water and groundwater. That is, the increase of the ratio of the thickness of the sediments to that of the underlying aquifer (HS/H) from 0 to 0.125 leads to the interaction flux decreased by 72%, indicating that the existence of the low permeability layer is the main reason that decreases the interaction flux between surface water and groundwater. The change of the permeability and the thickness of riverbed sediments has obviously changed the flow path from surface water to groundwater and the travel time. Specifically, the increase in KU/KL leads to a lager penetration depth of groundwater flow and lager travel times. The sensitivity of exchange flux between surface water and groundwater and groundwater travel time to the hydraulic conductivity of riverbed sediments increases with the decreasing hydraulic conductivity. At the same time, the groundwater travel time is more sensitive to the change of the thickness of the low permeability riverbed sediments, and the sensitivity increases with the increasing thickness. The research results can provide reference for groundwater resource management and sustainable development.

       

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