Global warming and groundwater from semi-arid areas : Essaouira region (Morocco) as an example

Climate change is undoubtedly becoming a subject of great concern for public authorities in all regions of the globe, in particular, the regions under Saharan, arid, and semi-arid climate. In this regard, this study aims to assess the effect of climate change on groundwater from semi-arid environments, taking the Essaouira basin as an example. The climate approach shows a downward trend in precipitation from 12 to 16% and an increase in temperature from 1.2 to 2.3 degrees C, and this during the last three decades. A continuous decline in the piezometric level exceeding 12 m for the Cenomanian-Turonian aquifer and 17 m for the Plio-Quaternary aquifer has been observed. The groundwater mineralization is controlled by the dissolution of evaporate and carbonate minerals, by the bases exchange phenomenon, and by the marine intrusion, especially in Plio-Quaternary aquifer. Also, the groundwater quality in the study area deteriorates gradually over time and space. However, the results of this study confirm that the groundwater from Essaouira basin is vulnerable to the global warming

The use of GIS and water quality index to assess groundwater quality of krimat aquifer (Essaouira ; Morocco)

The aim of this present study was to evaluate groundwater quality in the upstream part of the Essaouira basin. A detailed geochemical study of groundwater region is described, and the origin of the chemical composition of groundwater has been qualitatively evaluated, using multivariate statistical methods (PCA, HCA), and Water Quality Index (WQI) was used to determine the suitability of water for drinking. To attempt this investigation, 38 samples were analysed for various physicochemical parameters such as temperature, pH, TDS, Na, NO3, K, Ca, HCO3, Cl, Mg, and SO4. The results obtained showed that the facies characterizing the study area was a combination of Ca-SO4 and mixed Ca-Mg-Cl. Hydrochemical approach based on the bivariate diagrams of major ions indicates that the origins of groundwater mineralization are the result of (I) evaporite dissolution; (II) cation-exchange reactions; and (III) evaporation processes. The WQI values range from 82.3 to 390.9, and therefore the water samples can be categorized into five groups: excellent water to water unsuitable for drinking. In global, 61% of the groundwater sampled had poor water quality, 18% were very poor water quality, 16% are unsuitable for drinking, and just 6% represent a good quality. However, the results of this paper indicate that most water is not safe for drinking and needs further treatment

Surface and groundwater characteristics within a semi-arid environment using hydrochemical and remote sensing techniques

The understanding of hydro systems is of great importance in monitoring quantitative and qualitative changes in water resources. The Essaouira region at the edge of the Moroccan Atlantic Ocean is subject to a semi-arid climate. The decrease in rainfall as a result of climate change and the increase in the exploitation of surface and groundwater have disrupted the stability of these resources and threaten the socio-economic and environmental balance in the area under investigation. Climate scenarios estimate that precipitation will decrease by 10-20% while warming increases by 3 degrees C over the next 30 years. The physico-chemical parameters studied show that the evolution of the pH and temperature of the groundwater remained stable with a neutral (pH approximate to 7) and a hypothermal character (T < 30 degrees C). For the electrical conductivity, it showed an increasing trend from 2017 to 2020. A hydrochemical approach showed that the groundwater mineralization was controlled by the dissolution of evaporites and carbonates, by cation exchange processes, and by seawater contamination. A groundwater assessment for drinking use was made by comparing the concentrations of the chemical elements with the standards set by the World Health Organization. The results obtained show that the groundwater from the aquifers studied requires treatment before being consumed, in particular for Cl- and SO42-. Furthermore, the groundwater quality for irrigation was evaluated based on the parameters Na% and Sodium Adsorption Ratio (SAR). The results showed that the groundwater was adequate for agricultural purposes, especially for the plants that adapt to high salinity. The monitoring of surface water by processing the satellite images via the calculation of the normalized difference water index (NDWI) showed an increase in water surface areas in the region following the commissioning of two large dams (Zerrar and Igouzoullene). Despite the installation of these hydraulic structures, a drop of 4.85 km(2) in water surface area was observed beyond 2016. This situation requires intervention in order to preserve this vital resource