Evaluation of groundwater mineralization processes and seawater intrusion extension in the coastal aquifer of Oualidia, Morocco: hydrochemical and geophysical approach

Abstract

Oualidia city is located on the Moroccan Atlantic coast. Groundwater is the only resource for agriculture irrigation in this area. This operation is done by intensive pumping mainly in the coastal fringe. In this study, hydrochemical and geophysical methods were conducted to evaluate both composition and processes which control groundwater mineralization in Oualidia. For this purpose, 19 samples of groundwater were analyzed in major ions. The results showed that the mineralization is mainly due to sea water intrusion, especially in the first kilometer over the ocean, with abundance of Na + (651.3 mg/l on average) and Cl − ions (1,425 mg/l on average). Beyond this fringe, 1 km, the mineralization is low, with an abundance of calcium (190.4 mg/l on average) and bicarbonate (241.1 mg/l on average) indicating the rock nature effect. Data interpretation from six profiles of electrical resistivity tomography (ERT), performed in the region, has led to detect seawater intrusion extension. The level assigned to the marine effect is characterized by a resistivity lower than 30 Ω m. Moreover, hydrochemical and geophysical studies were provided information on the mineralization extension in the aquifer of this zone, which is limited to 1 km from the ocean.

Groundwater Quality Forecasting Using Machine Learning Algorithms: Case Study Berrechid Aquifer, Central Morocco

“…Groundwater depletion is a significant problem in Morocco and is of particular concern to water managers. Rapid declines in groundwater levels (0.5 to 2 m per year on average) is generally caused by low groundwater recharge, marine intrusion, and excessive expansion of agricultural activities (Fadili et al, 2015;Najib et al, 2016;Ait Kadi and Ziyad, 2018;Alabjah et al, 2018;Mountadar et al, 2018;Bilali et al, 2021;Moukhliss et al, 2021;Zeynolabedin et al, 2021). Studied areas represent typical cases and are strongly impacted by climate variability, anthropogenic activity, and marine intrusion.…”

Groundwater Geochemistry and Saltwater Intrusion in the Dakar Coastal Area, Senegal

“…Especially, coastal groundwater systems are prone to quality changes induced by seawater intrusion caused by over-exploitation or rising sea-level (Roy & Bithin, 2018;Lal & Bithin, 2019), paleo salinity, and changes of climatic conditions leading to health risks for the populations in coastal zones (Faye et al, 2005;Werner et al, 2017;Kumari et al, 2018;Chidambaram et al, 2018;Balamurugan et al, 2020;Prakash et al, 2020). Over the past several decades, deterioration of coastal groundwater quality due to over-exploitation has been studied widely (e.g., Revelle, 1941;Narayana & Suresh, 1989;Ramesh et al, 1995;Pulido-Leboeuf, 2004;Walraevens & Van Camp, 2005;Bahir et al, 2018;Eissa et al, 2018) and geochemical indicator methods were applied to understand the dynamic behavior of coastal aquifer chemistry (Pascual & Custodio, 1990;Dixon & Chiswell, 1992;Appelo & Postma, 2005;De Montety et al, 2008;Fadili et al, 2015;Maman Hassan, 2022;Bauer et al, 2022;Daniele et al, 2022).…”

Contribution of geophysics to geometric characterization of freshwater–saltwater interface in the Maâmoura region (NE Tunisia)

“…This overexploitation has significantly affected water quality mainly through marine intrusion and has resulted in the abandonment of wells that are close to the sea coast. In addition, industrial and domestic discharges, and also the use of pesticides and chemical fertilizers in this area has significantly affected the quality of water (Daskalaki and Voudouris 2008; Kazakis et al 2016;Giambastiani et al 2013;Fadili et al 2015;Najib et al 2016Najib et al , 2017Besser et al 2017;Ben Alaya et al 2009;El Mandour et al 2007;Lambrakis et al 1997;Ferrara and Pappalardo 2004).…”