Semiquantitative Risk Assessment Method for Groundwater Source Protection Using a Process-based Interdisciplinary Approach

Abstract

Potable groundwater resources are at risk as a result of industrial development and an increase in fertilizer use. Protection of the groundwater supply may require the establishment of groundwater source protection zones (GSPZs) to allow the implementation of protective measures. The aim of this study was to develop a new approach to groundwater source risk assessment (GSRA). The risk was defined as the highest of the risks identified for individual potential sources of contamination (PSCs). The risk resulting from a given PSC is the combination of its adverse impact on groundwater, unwanted event probability, and adverse effect and annoyance to the population. A multicriteria assessment method was designed to estimate indices of the potential groundwater impact of industrial facilities and noninert waste landfills with the range and weight method. Application of the proposed approach was tested considering an idealized model and three scenarios involving various industrial PSCs and fertilization practices. The overall nitrogen load was compared to the maximum effective nitrogen load for the crops in question. Sensitivity analysis of this methodology revealed that the main factors influencing the risk to the water supply include the nonreactive contaminant mass load in PSC leachate and the ratio of the groundwater volume abstracted from wells to the amount of water flowing from PSCs into wells, which determines the dilution degree of the contaminant mass. This proposed interdisciplinary approach to GSRA provides a robust basis to reach decisions on GSPZ establishment and the development of a groundwater risk analysis methodology.