[Regional Evolution and Control Factors of Karst Groundwater in Liulin Spring Catchment].

Abstract

The Liulin Spring is one of the ten most famous karst springs in the Shanxi province. The abundant karst groundwater resources support the economic and social development in the Luliang Prefecture. Therefore, the study of evolution and control factors of karst groundwater is of great significance to the sustainable utilization of water resources in the watershed. For revealing the evolution and control factors of karst groundwater in the Liulin Spring area, the main ion components of 29 karst groundwater samples from spring supply area, runoff area, discharge area, and deep buried area were analyzed. The results showed that the temperature and Na+, Ca2+, Mg2+, Cl-, HCO3-, and SO42- concentrations increased continuously along the runoff route, from the recharge area to the runoff area, to the discharge area, and then to the deep burial area. K+, Na+, and Cl- mainly come from salt rock dissolution, and Ca2+, Mg2+, HCO3-, and SO42- mainly come from the dissolution of calcite, dolomite, and gypsum. Because they are controlled by the continuous dissolution of salt rock and gypsum, the concentration of Na+, Cl-, and SO42- in groundwater has increased greatly, with the maximum value being 50 times, 80 times, and 32 times of the minimum value, respectively. Under the influence of dedolomitization, the concentration of Ca2+ and HCO3- in groundwater does not change significantly, the maximum is 2-3 times of the minimum. In the recharge area and runoff area, Na+ and Cl- amounts are lower, and Ca2+ and HCO3- are the main cations and anions in the groundwater. However, in the discharge area and deep buried area, Cl- and Na+ exceed HCO3-, Ca2+, and Mg2+ and become the main anions and cations in the groundwater. The hydrochemical type changes from HCO3-Ca·Mg in the supply area to HCO3·SO4-Ca·Mg in the runoff area, to HCO3·SO4-Ca·Na·Mg in the recharge area, and finally to Cl·HCO3-Na·Ca, Cl·HCO3-Na, and Cl-Na·Ca in the deep burial area.