Current status and future challenges of groundwater vulnerability assessment: A bibliometric analysis

Groundwater is the main source of drinking and irrigation on earth because of its large quantity and worldly distribution, albeit unequally. However, it is presently being threatened by over-consumption and contamina-tion. Groundwater vulnerability (GV) is to assess the aquifer sustainability under a contaminant load for an area, which plays a significant part in sustainable groundwater management in practice. In the last several decades, the studies of GV have increased exponentially over the entire globe, and there is currently no statistical review in GV by using bibliometric analysis with the increasing publications. In this review, a global bibliometric analysis was conducted to analyze and visualize the current status and determine future challenges of GV research by considering a total of 949 articles based on Web of Science core collection database. Nine different aspects, including trend, related disciplines, journals, author productivity, countries or regions, institutions, ci-tations, keywords and practical implementation were visualized and analyzed by CiteSpace 5.8 R3, Microsoft's Excel and Tableau. By in-depth analysis, this review clearly showed the major contribution members and the evolutionary process of GV, as well as identified four research frontiers (model development, modification and optimization, climate change impacts, human activity impacts and sustainable groundwater management) and four future challenges (unequal research development, insufficient cooperation, response to climate change and human activities, and SDGs in groundwater management). Finally, the corresponding suggestions for overcoming the challenges were proposed to achieve sustainable groundwater management.