Quantifying recharge sources to groundwater to an oasis area: Implications for strengthening water resource management under changing environmental conditions

Abstract

AbstractIn order to implement sustainable management of water resources in the Desert Oasis, it is necessary to quantify the changes in the groundwater recharge process. Using the Cl−, stable hydrogen and oxygen isotope datasets extracted from 113 groundwater samples in the years of 2000 and 2020, and combining these with the MixSIAR model, changes in the groundwater recharge process and recharge source contributions in the Minqin Oasis (MO) in northwestern China area before and after ecological treatment were quantitatively analysed. Overall, confined groundwater was the greatest contributor to the recharge of shallow groundwater in the MO area in 2000. However, after 10 years of ecological rehabilitation, surface water has become the most important recharge source of shallow groundwater, with its contribution increasing by 10.6% between 2000 and 2020 ~ 2021. River water diversion projects have reversed falling groundwater levels in the MO area. Of these projects, that in the MO has seen groundwater levels rise at a rate of 0.09 m·year−1 from 2008 to 2019. This coincides with the increase in the contribution of surface water to groundwater recharge in 2020. In addition, insignificant changes were observed in the contributions made by lateral groundwater flow to groundwater recharge in the MO area in the years of 2000 and 2020 ~ 2021, indicating that groundwater in the upper and middle reaches of the MO area have contributed very little to the restoration of groundwater levels in the area's lower reaches. All these factors would appear to indicate that regional ecological management has had a lasting impact, and that the exploitation of groundwater in this desert oasis area in an inland river basin should be based upon rational planning and integrated, comprehensive management strategies.