贵阳市岩溶地下水水化学特征及水质评价

Hydrochemical Characteristics and Water Quality Evaluation of Karst Groundwater in Guiyang

贵阳市是典型的岩溶盆地地貌,地下水系统十分复杂,具有特殊的水文地球化学特征。为查明贵阳市主城区及周边地区地下水水化学特征及水质状况,运用数理统计、piper三线图、Schoeller图对该研究区60个地下水监测点枯、丰两季的水化学指标进行分析,采用基于GRA-AHP的地下水水质评价模型对研究区的水质进行评价,结果表明:研究区地下水中各水化学指标满足生活饮用水标准,地下水化学参数除K+、Fe^3+变异性较强外,其他含量均相对稳定,水化学成分中优势阳离子为Ca^2+、Mg^2+,优势阴离子为HCO^3-、SO4^2-,地下水水化学类型以HCO^3-.SO4^2--Ca型、HCO3^--Ca.Mg型和HCO3^--Ca型为主;相关关系分析表明地下水表现出高Ca^2+、Mg^2+、SO4^2-特征是来自该研究区石灰岩、白云岩、石膏中不同造岩矿物的溶解;利用基于GRA-AHP的地下水水质评价模型对研究区的水质进行综合评价,结果显示该研究区岩溶地下水丰水期质量优于枯水期质量,丰水期Ⅱ类水占33%,Ⅲ类水占63%,枯水期Ⅱ类水占16%,Ⅲ类水占75%。该研究结果对贵阳市的水-岩-生态-环境的保护提供依据。

Guiyang is a typical karst basin landform,the groundwater system is very complex and has unique hydrogeological and geochemical characteristics.In order to ascertain the groundwater chemical characteristics and water quality of the main urban area and surrounding areas of Guiyang City,the monitoring data of 60 groundwater samples in the area were analyzed,the hydrochemicl characteristics of the area were analyzed by mathematical statistics,piper three-line diagram and Schoeller diagram,and the GRA-AHP based groundwater quality assessment model was used for water quality evaluation.The results show that:the hydrochemical indicators in the groundwater of the study area meet the drinking water standards;except the strong variability of K+and Fe^3+,the groundwater chemical parameters are relatively stable,the dominant cations in hydrochemical composition are Ca^2+ and Mg^2+,and the dominant anions are HCO3^-,SO4^2-,the groundwater chemical type is mainly HCO3^-.SO42^--Ca type,、HCO3--Ca.Mg type and HCO3--Ca type.Correlation analysis shows that the groundwater shows high Ca^2+,Mg^2+,SO4^2- characteristics from the dissolution of different rock-forming minerals in limestone,dolomite and gypsum in the study area.The results of water quality evaluation by using GRA-AHP model based on index scale in study area show that the quality of kars groundwater in rainy season in this study area is better than that in dry season.In flood season,typeⅡ water accounts for 33%,typeⅢ water accounts for 63%,while in dry season,typeⅡwater accounts for 16%,and typeⅢ water accounts for 75%.The results of this study provide a basis for the protection of water-rock-ecological-environment in Guiyang City.