河道硬化对傍河地下水源补给结构及范围的影响

为研究傍河地下水的水均衡状况，以及傍河水源井群补给范围受河道硬化的影响，选取张家口盆地的Y傍河地下水源地为研究对象.采用数值模拟法建立研究区地下水数值模型，通过水均衡分析探究河道硬化对傍河地下水水均衡状况造成的影响；利用MODPATH对水源井群进行质点反向示踪模拟，获得井口质点向前追踪1 000 d的补给范围，对比水源井群补给范围并结合历史与近期水质数据分析河道硬化造成的影响.结果表明:①傍河地下水水均衡情况显示，主要的补给项为边界流入和降雨入渗，二者补给量分别为208.04×103与35.91×103 m3/d，占比分别为82.88%与14.31%；主要的排泄项为边界流出与地下水开采，二者排泄量分别为152.12×103与95.40×103 m3/d，占比分别为60.60%与38.01%.②河道硬化对傍河地下水水均衡的影响表现为河水对地下水的入渗量减少了46.79×103 m3/d，入渗量减幅为86.91%，且地下水停止了对河水的排泄，补给范围地下水水位下降了2~6 m.③河道硬化对傍河水源井群补给范围的影响表现为井群1 000 d的补给范围沿河流方向上减少了271 m，垂直河流的最宽距离增加了210 m，面积增加了0.77 km2，补给区域向远离河岸的方向发生偏移.④河道硬化对傍河地下水水质影响表现为河道硬化后傍河地下水pH、总硬度、氨氮浓度等均下降，有效减少了地表水污染物的入渗，但地下水的化学环境发生改变，潜在风险增加.研究显示，河道硬化极大地阻碍了河流与地下水之间的相互作用，严重影响了傍河地下水源的补给量和补给范围，使水源井群的补给区域发生偏移，给傍河地下水水源安全带来新的潜在风险. 

Effects of River Hardening on Recharging Structure and Range of Riverside Groundwater Source Field

In order to study the flow budget of the riverside source field and the effects of river hardening on the recharge range of riverside source fields, the Y riverside well field in the Zhangjiakou Basin was selected as the study object. The results of the numerical simulation methods demonstrated the effects of river hardening on the flow budget of riverside field well by flow budget analysis. Moreover, the MODPATH module was used to conduct reverse particle tracer simulation for 1000 days to compare the change in the recharg range after river hardening and analyze the historical and recent water quality data. The study showed that the flow budget of the riverside source field: the main recharge was boundary inflow, and rainfall infiltration and recharge of groundwater are 208.04×10³ m³/d and 35.91×10³ m³/d, respectively, accounting for 82.88% and 14.31%. The main discharges were boundary outflow and groundwater extraction. The discharges of groundwater were 152.12×10³ m³/d and 95.40×10³ m³/d, accounting for 60.60% and 38.01%, respectively. The effects of river hardening on water flow budget was significant. The river infiltration of groundwater decreased by 86.91%, cutting down 46.79×10³ m³/d. In addition, the groundwater discharge into river was stopped, and the groundwater table in the recharge area decreased by 2-6 m. The effects of river hardening on recharge range of riverside field well was also investigated. The recharge range of 1000 days of the well group decreased by 271 m along the river flowing direction, and the widest distance of the vertical river flowing increased by 210 m, resulting in the recharging area increasing by 0.77 km², while the recharge area went away from the riverside. The pH, total hardness and ammonia nitrogen of groundwater were all decreased, reducing the infiltration of surface water pollutants, but the chemical environment of groundwater changed and the potential risk increased. The results showed that the river hardening significantly obstructed the interaction between the river and the groundwater, which affect the riverside water source recharge and recharge area.