Combining of MASW and GPR Imaging and Hydrogeological Surveys for the Groundwater Resource Evaluation in a Coastal Urban Area in Southern Spain

Francisco Javier Alcalá,Jaruselsky Pérez-Cuevas,Maria Catarina Paz,Francisco Domingo,Manuel Navarro,Pedro Martínez-Pagán

doi:10.3390/app11073154

Abstract

This paper conceptualizes and evaluates the groundwater resource in a coastal urban area hydrologically influenced by peri-urban irrigation agriculture. Adra town in southern Spain was the case study chosen to evaluate the groundwater resource contributed from the northern steep urban sector (NSUS) to the southern flat urban sector (SFUS), which belongs to the Adra River Delta Groundwater Body (ARDGB). The methodology included (1) geological and hydrogeological data compilation; (2) thirteen Multichannel Analysis of Surface Waves (MASW), and eight Ground Penetrating Radar (GPR) profiles to define shallow geological structures and some hydrogeological features; (3) hydrogeological surveys for aquifer hydraulic definition; (4) conceptualization of the hydrogeological functioning; and (5) the NSUS groundwater resource evaluation. All findings were integrated to prepare a 1:5000 scale hydrogeological map and cross-sections. Ten hydrogeological formations were defined, four of them (Paleozoic weathered bedrock, Pleistocene littoral facies, Holocene colluvial, and anthropogenic filling) in the NSUS contributing to the SFUS. The NSUS groundwater discharge and recharge are, respectively, around 0.28 Mm3 year−1 and 0.31 Mm3 year−1, and the actual groundwater storage is around 0.47 Mm3. The groundwater renewability is high enough to guarantee a durable small exploitation for specific current and future urban water uses which can alleviate the pressure on the ARDGB.

Highlights

Water scarcity in many coastal drylands with limited surface water resources has propitiated high groundwater abstraction rates to supply the increasing urban, tourism, industrial, and agriculture demands [1]
This paper is aimed at developing the above two first general stages in deep, whilst the third one evaluates the groundwater resource contributed from the northern steep urban sector (NSUS) to the southern flat urban sector (SFUS), which belongs to the Adra River Delta Groundwater Body (ARDGB)
The Multichannel Analysis of Surface Waves (MASW) survey covered all the geological formations defined in Adra town

Summary

Introduction

Water scarcity in many coastal drylands with limited surface water resources has propitiated high groundwater abstraction rates to supply the increasing urban, tourism, industrial, and agriculture demands [1] This is the case in some coastal areas in Spain where aquifers play a critical role in sustaining the economy and the environment [2,3,4]. On favorable topographic and hydrogeological conditions, for instance when steep topography and low-permeability bedrock exist, urban and irrigation returns can be identified in water quantity and quality changes of local springs These mechanisms are well known, the groundwater resource in most medium-sized urban and peri-urban areas is unknown because they are typically ungauged settings. These evaluations may serve to conceptualize the groundwater resource generated in neighboring towns having similar habits for water consumption, but a flat topography that prevents direct groundwater observations

Objectives

Methods

Results

Discussion

Conclusion