A study on groundwater recharge in the Anyanghe River alluvial fan,North China Plain,based on hydrochemistry,stable isotopes and tritium

Studies on groundwater recharge are essential for sustainable exploitation of groundwater resources, especially in areas of extensive groundwater exploitation such as the Anyanghe River alluvial fan (ARAF) in the North China Plain (NCP). However, the recharge sources and processes and the contribution of each recharge flow component remain unclear. This study used hydrochemistry, stable isotopes, and tritium to investigate sources and underlying processes of groundwater recharge, along with the steady flow Mixing Cell Model (MCMsf) to quantify the proportion of each source flow for the shallow confined groundwater system in the medial fan. The results showed that groundwater mainly originates from precipitation occurring on the eastern Taihang Mountain area with average elevation estimated at 700–1,000 m above sea level during the East Asia summer monsoon period since 1952. Recharge mechanisms are: (1) river water seepage for the unconfined aquifers of the proximal and medial fan; (2) lateral flow for the confined aquifers of the medial and distal fan; and (3) precipitation infiltration for the phreatic water system. The MCMsf simulation showed that the shallow confined groundwater system in the central zone of the medial fan mainly recharged by the lateral flow from the proximal fan, a constant and considerable recharge flow from the southwestern and southern hills, and river water seepage in the medial fan; the lateral recharge flow from the Zhanghe alluvial aquifer was insignificant by comparison. The results of this study can act as a valuable reference for sustainable groundwater management in the ARAF.