Advance in research on groundwater vulnerability: A review

Groundwater vulnerability research has great significance for water environment protection and sustainable groundwater resource utilization. In this review, the formation and development of "groundwater vulnerability" concept, including intrinsic vulnerability and specific vulnerability, were introduced. The recent advance in groundwater vulnerability studies were also summarized with an emphasis on the evaluation methods as well as their advantages and disadvantages. It is important and urgent to set up new groundwater vulnerability models capable of evaluating both primary contamination resistance abilities of vadose zone and characteristics of pollutants relevant to their migration and transformation in aquifer. The credibility and uncertainty of groundwater vulnerability evaluation results has attracted more and more attentions of government agencies and researchers and is becoming a hot topic.