Stable isotope evidences on sources and mechanisms of groundwater recharge in Hohhot basin, China

Abstract

It is extremely important for water resources management to understand the mechanisms of recharge to aquifer. Monitoring changes in stable isotopes (δ 2H and δ 18O) can be used to learn some information on groundwater recharge processes. In this study, the stable isotopes from precipitation and groundwater samples were employed to trace the recharge processes. In Hohhot area (inner Mongolia), the recharge of shallow groundwater is mainly due to precipitation from the eastern mountain area in eastern and southeastern parts and from the northern mountain area in the northern and southwestern parts. The recharge mechanisms for shallow groundwater are the infiltration of surface water in the piedmont area and lateral flow recharge. The source of deep groundwater in confined aquifer is probably from precipitation in high-altitude area or cold weather conditions, which perhaps have the same recharge source as shallow groundwater in the northern and southwestern parts. Compared with the previous data from Shao’s (Geotech Investig Surv 4:41–43, 1989) study, the variation of groundwater recharge for nearly 30 years in the study area was inferred: the recharge zone is the eastern and northern mountain areas. The recharge way to shallow groundwater has changed into lateral recharge from surface runoff in the mountain area and from surface runoff and vertical rainfall infiltration in the piedmont area. But the recharge mechanism for deep groundwater has a similar origin with the one for northern shallow groundwater, namely the lateral recharge.