Enhanced Groundwater Protection and Management Using Gravity and Geoelectrical Data (Valls Basin, Spain)

Abstract

The basis for the protection and prevention of groundwater pollution lies in the accurate assessment of vulnerability in terms of the exposure of groundwater bodies to contaminants before they are potentially discharged into the environment. The vulnerability assessment consists of calculating the ease with which pollutants can reach the aquifer from the surface through the vadose zone, which effectively reduces the pollutant load when the transit time is long. Index methods are mostly used, as they are based on input data that are readily available, easy to implement and interpret, and which are simple and practical. However, there are also limitations, as some methods are somewhat subjective and provide only a qualitative approximation. This case study aims to develop a methodology that can quantitively estimate the hydrogeological parameters of the aquifer formations of the Valls basin using geophysical methods and the Dar Zarrouk parameters. The specific treatment carried out on data from gravity stations and vertical electric soundings, supported by the available well data, allows for the delineation of the most favourable areas for the exploitation of groundwater resources (higher hydraulic transmissivity) and the areas most susceptible to pollution (with a shorter transit time) on a regional scale. Geophysical methods have proved useful, sustainably providing valuable information without the need to drill new boreholes that could act as preferential pathways for pollutants into the aquifer.

Keywords

• vulnerability mapping
• groundwater protection
• hydrogeophysics
• electrical resistivity methods
• gravity survey
• aquifer transmissivity