Identifying and assessing human activity impacts on groundwater quality through hydrogeochemical anomalies and NO3-, NH4+, and COD contamination: a case study of the Liujiang River Basin, Hebei Province, PR China

In the face of rapid economic development and increasing human activity, the deterioration of groundwater quality has seriously affected the safety of the groundwater supply in eastern China. Identifying and assessing the impact of human activities is key to finding solutions to this problem. This study is an effort to scientifically and systematically identify and assess the influence of human activities on groundwater based on irregularities in hydrochemical properties and water contamination, which are considered to directly result from anthropogenic activity. The combination of the hydrochemical anomaly identification (HAI) and the contaminant identification (CI) was proposed to identify the influence of human activities on groundwater quality. And the degree of abnormality was quantified by the background threshold value. The principal component analysis (PCA) and land use map were used to verify the reliability of the identification result. The final result show that the strong influence areas mainly distributed in the south of the basin and the affected indicators contained the major elements and NO3-, NH4+, COD. Impacts from anthropogenic activities can be divided into two types: mine drainage that disrupts natural water-rock interaction processes, agricultural cultivation, and sewage emissions that contribute to nitrate pollution.