基于水化学的南水北调中线干渠水与地下水水力联系指标识别

Indices Identification of Hydraulic Connection Between Groundwater and Canal Water in Middle Route of the South⁃to⁃North Water Diversion Project Based on Hydrochemistry

从一般水化学角度研究了南水北调中线源头地表水、干渠水及其周边地下水的差异。结果发现,钠离子在地下水与干渠水和源头地表水中的浓度差异最为明显,其次是总溶解固体(TDS)浓度,其他主要离子以及pH差异均不明显,说明钠离子浓度可作为识别南水北调中线干渠水及其周边地下水水力联系的备选指标。利用聚类分析和水化学类型的相似性,剔除了与干渠水可能存在水力联系的地下水样钠离子浓度,初步确定南水北调中线沿线与干渠水没有水力联系的地下水钠离子浓度大于9.8 mg/L,且该数值是干渠水钠离子浓度的1.6倍以上。因此,可将钠离子浓度及其参考范围用于快速判断南水北调干渠周边地下水与干渠水是否存在水力联系。

This paper investigated the differences of hydrochemistry indices between the source surface water,canal water,and its surrounding groundwater in the middle route of South⁃to⁃North Water Division Project.The results showed that the difference of sodium ion concentration be⁃tween groundwater and canal water as well as the source canal water was the most significant,followed by the concentration of total dissolved solids(TDS),while the concentration of other main ions and pH had no significant difference,indicating that sodium ion concentration could be used as an alternative indicator to identify the hydraulic connection between canal water and its surrounding groundwater in the middle route of South⁃to⁃North Water Division Project.Using the cluster analysis and the similarity of hydrochemical types,sodium concentration in groundwater samples that might have hydraulic connection with canal water were excluded.It was preliminarily delineated that the reference range of sodium concentration in the groundwater without hydraulic connection with the canal water along the middle route of South⁃to⁃North Water Division Project was over 9.8 mg/L,and the range value was more than 1.6 times as the range value of sodium concentration in the canal water.There⁃fore,the indicator of sodium ion and its concentration range could be used to quickly identify whether the groundwater around the main canal of South⁃to⁃North Water Division Project had hydraulic connection with the canal water.