滹沱河超采区地下水回补的水化学效应研究

Hydrochemical Effect of Groundwater Recharge in Over-Exploited Area of Hutuo River Basin

由于长期超采地下水,导致滹沱河冲洪积平原地下水位持续下降,水质恶化,为缓解滹沱河超采区水资源矛盾,2018年开始实施了河道回补工程,回补水源为黄壁庄水库水和“南水北调”水.为了研究回补后地下水化学效应变化,应用水文地球化学、水文学和统计学等理论方法,开展了现场动态监测、地下水化学检测工作.结果表明:①实施滹沱河补水后地下水位上升显著,滹沱河沿线地下水位平均回升5.83 m;2019年较2015年滹沱河超采区地下水位平均回升5.93 m,地下水漏斗形状发生改变,地下水向漏斗中心汇集已不明显.②滹沱河多年受上游高硫酸盐水源补给的影响,滹沱河沿岸分布HCO 3·SO 4-Ca·Mg型地下水,并在HCO 3·SO 4-Ca·Mg型水两侧形成了条带状的HCO 3·SO 4·Cl-Ca·Mg型水.与2015年相比,2019年HCO 3-Ca·Mg型水的面积减少了20.6%,HCO 3·SO 4·Cl-Ca·Mg型水和HCO 3·SO 4-Ca·Mg型水的面积增加了13.6%.③河道补给有效缓解了地下水环境恶化,区域地下水中硫酸盐平均含量基本持平,氯化物浓度、TDS(溶解性总固体)浓度、总硬度呈下降趋势;受上游黄壁庄水库补水影响,滹沱河沿岸附近地下水中硫酸盐的浓度升高,高浓度的硫酸盐主要分布在滹沱河、石津灌渠及黄壁庄水库副坝附近,随着补水的不断推进,水位持续回升,在水动力作用下,其有向下游扩散的趋势.研究显示,科学合理地选择补水水源与回补方式是减缓该地区地下水硫酸盐污染及保持地下水可持续利用的有效方式.

Due to long-term over-exploitation of groundwater,the groundwater level in the Hutuo River alluvial plain continued to decline,and the water quality deteriorated.In order to alleviate the contradiction of water resources in this area,a river replenishment project was implemented in 2018.The water source for replenishment was contributed by Huangbizhuang Reservoir and the water originated from the‘South-to-North Water Diversion Project’.In order to study the changes in groundwater chemistry after replenishment,on-site monitoring and groundwater chemical testing were carried out,and further joint analysis was carried out through hydrogeochemistry,hydrology,statistics and other theoretical methods.The results showed that:(1)After the Hutuo River water replenishment was implemented,the groundwater level increased significantly.The average groundwater level along the Hutuo River rose by 5.83 m.Regionally,compared with 2015,the groundwater level in 2019 increased by an average of 5.93 m.The shape of the groundwater funnel also changed,and it no longer clearly showed that the groundwater converged towards the center of the funnel.(2)Affected by the long-term supply of high sulfate brine sources in the upper stream of the Hutuo River,the groundwater along the watercourse was dominated by the water type of HCO 3·SO 4-Ca·Mg,and strip-shaped HCO 3·SO 4·Cl-Ca·Mg water was distributed further along both sides.However,compared with year of 2015,HCO 3-Ca·Mg water area decreased by 20.6%in 2019,while HCO 3·SO 4·Cl-Ca·Mg water and HCO 3·SO 4-Ca·Mg water increased by 13.6%.(3)The river replenishment effectively alleviated the deterioration of the groundwater environment.The regional groundwater sulfate level remained relatively constant,while the chloride,TDS,and total hardness showed a downward trend.Affected by the water replenishment of Huangbizhuang reservoir,high-concentration sulfates are mainly distributed near the Hutuo River,Shijin Irrigation Canal and the auxiliary dam of Huangbizhuang Reservoir.With the continuous advancement of water replenishment,the water level continued to rise,and under the action of hydrodynamics,there was a tendency to diffuse downstream.The studies have shown that scientifically and rationally selecting water replenishment sources and replenishment methods is an effective way to mitigate the sulfate pollution of groundwater in this area and maintain the sustainable use of groundwater.