[Analysis of Groundwater Hydrochemical Variation and Its Source During the Low Water Level Period in the Southern Oasis Area of Gaochang District, Turpan City].

To explore the changes in groundwater hydrochemistry and its source influence in the low water level period of the southern oasis area of Gaochang District, Turpan City before and after the management of groundwater overexploitation, based on 12 groups of water samples in 2016 （three groups of unconfined water, nine groups of confined water） and 18 groups of water samples in 2023 （five groups of unconfined water, thirteen groups of confined water）, mathematical statistics, hydrochemical diagraph, hydrogen and oxygen isotope means, and an absolute principle component-multiple linear regression （APCS-MLR） model were used to analyze the changes and sources of groundwater hydrochemistry. The results showed that due to the dynamic conditions of groundwater, the dominant cation changed from Na to Ca, and the anion changed from HCO to SO. The dominant cation of confined water changed from Ca to Na, and the dominant anion remained unchanged as SO. The main supply source of both unconfined water and confined water was atmospheric precipitation, which was affected by evaporation, and the effect of evaporation of unconfined water was greater than that of confined water. The chemical composition of groundwater was mainly controlled by rock weathering and cation exchange. Na, Ca, and Mg were mainly derived from the dissolution of evaporative salt rock and silicate salt rock. NO was mainly derived from agricultural fertilizers, human and animal manure, and domestic sewage. Leaching and enrichment （F1）, agricultural activity and primary geological activity （F2）, and industrial activity （F3） were the main factors affecting groundwater chemistry in the study area, and the contribution rates were 58.41%, 18.12%, and 9.12%, respectively.