基于MODFLOW的贺江岩溶流域地下水资源评价

Evaluation of groundwater resources based on MODFLOW in Hejiang karst basin

运用地下水模拟软件MODFLOW构建了贺江上游岩溶流域的数值模型,在地下河发育部位,采用Drain模块刻画查明的地下河岩溶管道,利用区域地下水监测数据和枯水期地下河实测流量进行模型校正。该模型能较好地反映区域地下水位动态变化及不同类型含水层间水资源的补排关系,以及地下河枯季流量。模拟结果显示,降水量偏少时段,区内地下水处于亏损状态,丰水期获得大气降水补给后逐渐盈余。模拟期内,降水对地下水的补给量为3.54×108 m3,地下水排泄量为3.41×108 m3。区内岩溶含水层的主要补给来源为大气降水,年均贡献率66.0%;其次为花岗岩裂隙水,年均贡献量14.3%;碎屑岩裂隙水对岩溶水的补给贡献量仅为7.9%。花岗岩风化裂隙含水层具有良好的调蓄能力,其在枯水期对岩溶含水层的补给贡献大于大气降水。

Visual numerical simulation is an important method for groundwater resource evaluation.The numerical model of karst watershed in the upper reaches of Hejiang River is established by using groundwater simulation software MODFLOW.In this model,the karst conduit network is conceptualized by Drain module.The groundwater level data and discharge of the subterranean river in dry months are used for the model calibration.The simulation result shows the established model can finely reproduce the groundwater dynamic,the recharge and drainage relationship among different types of aquifers,and the discharge in dry months.The groundwater in simulation region is under deficit during the low rainfall period and replenished in wet season.During the simulation period,the total groundwater recharge is 3.54×108 m3 and discharge is 3.41×108 m3.The precipitation is the main recharge source of karst aquifer accounting for 66.0%of the total recharge.The granite fissure water and clastic-rock fissure water are the second and third recharge resource of karst aquifer with the contribution proportion of 14.3%and 7.9%,respectively.Due to the fine storage of the granite fissure aquifer,the contribution of water in granite fissure aquifer to recharge karst aquifer is larger than the precipitation in dry season.