武汉市地表水-地下水交互带识别与变化模拟

Identification and Variation Simulation of Surface Water and Groundwater Hyporheic Zone in Wuhan City

地表水-地下水交互带是地表水与地下水混合交换的重要区域,该混合特性也是识别其范围的难点。为确定地表水-地下水交互带的识别方法与变化特征,选取地表水-地下水相互作用明显的武汉市汉江-府河河间地块冲湖积平原为研究区,构建了研究区内的地下水数值模型,得到了研究区内地下水流场轨迹,分析了研究区区域和局部的水流系统,总结了地表水-地下水交互作用模式,并结合MODPATH模块追踪地下水流运动轨迹,识别地表水-地下水交互带及其变化特征。结果表明:研究区地表水-地下水完全混合交互带的范围在汉江顺流方向由40 m不断拓宽至180 m,沿长江流向地表水-地下水交互带范围整体缩小但保持在70~100 m范围内;粒子运动轨迹分析结果显示,影响地表水-地下水交互带范围与交互作用强度的因素主要有地形、地表水形态、含水层水文地质条件。该研究结果可为确认地表水-地下水交互带范围及其动态变化特征提供依据。

The hyporheic zone is an important area for the mixing and exchange of surface water and groundwater,and the mixing characteristics are also the difficulty to identify its scope.In order to identify the hyporheic zone and det ermine dynamic characteristics,a groundwater numerical model is established based on the alluvial lacustrine plain of Hanjiang River-Fuhe River interfluvial lands in Wuhan City,where there is clearly interaction between groundwater and surface water.The trajectory of groundwater flow field in the study area is obtained through the groundwater numerical simulation,the regional and the local water flow system in the study area is analyzed,the form of the int eraction bet ween groundwater and surface water is obtained,the groundwater flow trace in the hyporheic zone is tracked by MODPATH,and the surface water and groundwater hyporheic zone and its variation characteristics are identified.The results show that the range of surface water and groundwater fully mixed hyporheic zone in the study area is continuously widened from 40 m to the maximum range of 180 m in the downstream direction of the Hanjiang River,and it is generally reduced but kept at 70-100 m along the Yangtze River;the analysis results o£the particle trajectory show that the factors affecting the range and intensity o£the hyporheic zone include topography,surface water morphology,and hydrogeological conditions of aquifers.The research results can provide a basis for confirming the range and dynamic change characteristics of the surface water and groundwater hyporheic zone.