利用GIS水化学和同位素方法判断灵水来源

尝试利用多种方法确定南宁市武鸣县灵水岩溶泉的补给来源和汇水范围。获取了可能在其汇水范围内的岩溶泉、钻孔、表层岩溶泉枯季及雨季水化学资料,在CaCO3-CO2-H2O平衡体系中区分不同出露形式的岩溶水的水化学成因,发现CO2分压、地下水赋存条件和污染等因素影响此化学平衡体系。灵水的钙离子浓度和CO2分压在岩溶泉中较高,体现了灵水为区域地下水流系统的排泄点。环境同位素分析表明,当地雨水的δ2H和δ18O同位素存在季节效应和高程效应,地下水中同位素的变化被混合作用削弱,其平均值接近于夏季雨水的同位素组成,表明该地区的降雨入渗补给主要发生在夏季。利用GIS技术划分地表水流域,以此作为地下水流域识别的依据。得到灵水汇水面积为697km2,其中约126km2属于埋藏型岩溶,其余为覆盖型岩溶。

Source identification of Lingshui Spring using GIS-based hydrochemistry and environmental isotopic methods

Multiple methods were used in this study in an attempt to identify the boundary and source of the Lingshui Spring, a karst spring in Wuming County of Nanning City. Hydro chemical data from the karst springs, boreholes, and epikarst springs possibly distributed in the Lingshui drainage area were collected in dry and rainy seasons. The hydro- chemical causes for different karst water were distinguished in the CaCOs-CO2-H20 equilibrium system. It was discovered that the chemical equilibrium system was influenced by CO2 partial pressures, pollution, and the existing conditions of groundwater. The analysis of the environmental isotope indicates that the isotopes δ^2H and δ^18O in the rainwater of the study area were affected by season and altitude. The variation of isotopes in groundwater was weakened by the mixed process in the aquifer. The average contents of δ^2H and δ18O were almost equal to those of rainfall in summer, indicating that the rainfall infiltration recharge mostly occurred in summer. The GIS technique was used to divide the watersheds of the surface water system, based on which the groundwater drainage area was identified. The drainage area of the Lingshui Spring was found to be 697 km^2, of which 126 km^2were buried karst and the rest were covered karst.