Influence of Recharge Change on the Increasing Trend of Groundwater Salinity in the Funnel Area of Hufu Plain in North China

In the past 50 years, groundwater salinity in the funnel area ofHufu Plain in North China keeps growing and locally exceeds the groundwater quality Class III water standard (1000 mg/L).Rechargechange is an important factor affecting the increasingtrendofgroundwater salinity in the funnel area ofHufu Plain in North China. In this paper, using geo-mathematical statistical methods, Durov diagrams, Gibbs diagrams, and ionratio coefficient methods, evolution characteristics of groundwater rechargeand salinity in the funnel area ofHufu Plain in North China are analyzed for the past 50 years, and the effects of rechargechangeon increasing groundwater salinity in the funnel area ofHufu Plain in North China are discussed. The results show that: in addition to endogenous mechanism, the increasing groundwater salinity in the funnel area ofHufu Plain in North China is also closely related to the scale of the groundwaterrecharge from the upstream. The salinity increase is small in the years with ample flow and great groundwaterrecharge.Otherwise, the salinity tends to increase more. Thegroundwater recharge from the upstream plays a role in diluting and mitigating groundwater salinity in the funnel area, and the effect is weakened due to significant decreased groundwater recharge in the final stage.