济南市玉符河岩溶含水层多水源回灌补源水量优化方案

Water quantity optimal schemes of the karst aquifer recharge with multi-source water at the Yufuhe river,Ji'nan

随着济南市城区不断南扩,岩溶地下水补给受到严重影响。将地表水转化成地下水是解决济南市保泉和供水安全这一矛盾的现实途径,玉符河流域在其中发挥着关键作用。在玉符河已建成3个地下水回灌工程的基础上,确定合理的玉符河回灌放水流量和放水时间,使地表水能够有效地回灌到岩溶含水层中,减少第四系孔隙水无效补给以及地表水出境排泄显得尤为重要。本文选取济南泉域西部玉符河上游寨而头至南北大桥河段为研究区,结合水文地质条件和地层、岩性等资料,将研究区划分为4个子河段。利用Hydrus-2D对各个子河段的垂直以及侧向渗流进行数值模拟,模拟验证显示拟合效果良好后,继续对地下水位埋深最大、最小以及水位埋深处于两者之间三种情景进行模拟,得出回灌补源水量优化方案:当以约28万m3~·d^(-1)的小流量放水时,地下水位埋深较大的情况下,持续放水19.5d;在地下水位埋深较小的情况下,持续放水10.5d;在地下水位埋深位于最大和最小之间时,持续放水12.7d。

With steady expansion of the urban area of Ji＇nan City,the supply of karst groundwater has been seriously affected.Under the current background,it is a practical way and important measure to transform surface water into groundwater for solving the contradiction between the protection of springs and the security of water supply,in which the Yufuhe river basin in the west of Ji＇nan plays a key role.On the basis of three groundwater recharge projects built on the Yufuhe river,it is vital to determine the reasonable recharge volume and recharge time to ensure the limestone karst water recharge and reducing the invalid quaternary pore water recharge and the discharge of surface water.This work selected the section from Zhai＇ertou to South-North Bridge upstream of the Yufuhe river as the target.Combining the hydrogeological conditions and other data of strata and lithology,this section was divided into 4 sub-reaches.Using Hydrus-2 Dto this work numerically simulated the vertical and lateral seepages of each sub-reach,yielding good results.Then we made further simulations on three scenarios with the maximum,medium and minimum groundwater depth,respectively.The modeling permitted to establish the optimal schemes of water quantity for recharge,which suggest that when the flow is about 280,000 m^3·d^（-1）,a continuous discharge should be for 19.5 days,10.5 days and 12.7 days in the cases of maximum,medium and minimum groundwater depth,respectively.