Application of groundwater functional zoning to coastal groundwater management: a case study in the plain area of Weifang City, China

Abstract

As a useful index-based evaluation framework, groundwater functional zoning (GWFZ) presents a very positive effect on groundwater management at a regional scale due to its concise results. Currently, the GWFZ lacks definition and detailed processes, hence requiring a systematic structure to offer more knowledge bases to the methodology. A typical study area (Weifang City) characterized by a coastal zone and relying on groundwater supply, as well as the occurrence of groundwater-derived geo-environmental issues, was chosen. We provided a detailed index-based GWFZ method by focusing on the assessment of the resource supply function (RSF) and geo-environment stability function (GSF), with a good understanding of the hydrogeological conditions in the selected area. The RSF was assessed by delineating the potential area of groundwater exploitation, while the GSF was evaluated by identifying the vulnerability of geo-environmental issues. By integrating the RSF and GSF into the GIS environment, the study area was finally divided into five functional sub-areas: concentrated groundwater supply area (1.08%), decentralized groundwater supply area (18.36%), vulnerable geo-environment area (11.78%), unsuitable to exploit groundwater area (14.11%), and recharge protection area (54.67%). Seven groundwater exploitation boreholes in the plain area were validated to be unreasonable with regard to mining scale, which indicates a connection with the inland saltwater intrusion boundary in recent years. With simple data acquisition methods and concise results, GWFZ is of great benefit to groundwater management and can be further applied in other regional studies.