Hydrogeochemical and statistical approach to characterize groundwater salinity in the Ghiss-Nekkor coastal aquifers in the Al Hoceima province, Morocco

Yousfi, Yassine El; Himi, Mahjoub; Ouarghi, Hossain El; Elgettafi, Mohammed; Benyoussef, Said; Gueddari, Hicham; Aqnouy, Mourad; Salhi, Adil; Alitane, Abdennabi

doi:10.1016/j.gsd.2022.100818

“…SWI was mainly detected in coastal areas: surrounding the Ghiss river and along the coast between the Nekor river and the village of Hdid. Our findings are consistent with those of Salhi (2008), Vroey (2012), Chafouq et al (2017), Ghalit et al (2017), Benabdelouahab et al (2019), andEl Yousfi et al (2022) in that the oceanfront areas east of the Nekor river have been affected by marine intrusion and extends in some areas two kilometers inward. In the present study, a marine intrusion phenomenon was also detected at the mouth of the Ghiss river.…”

Section: The Gis-based Overlay Analysissupporting

confidence: 93%

“…10). Many researchers have used solely the saltwater fraction (fsea) (Equation 1) to assess SWI (Daniele et al, 2022;El Yousfi et al, 2022;Slama et al, 2022;Sonkamble et al, 2014), however, this index may not be sufficient on its own due to its numerous flaws (Tomaszkiewicz et al, 2014). Alternatively, Tomaszkiewicz et al (2014) developed the Groundwater Quality Index specific to SWI (GQIswi) (Equation 2), which is based on both the GQI of the saltwater fraction (fsea) (Equation 3) and the GQIPiper(mix) (Equation 4).…”

Section: Simpson Ratio Contamination Degreementioning

confidence: 99%

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A geochemical approach in assessing seawater intrusion by integrating geospatial techniques: a case study of Ghiss-Nekor coastal aquifer, Central Rif of Morocco

BOURJILA

¹

,

Dimane

²

,

GHALIT³

et al. 2022

Preprint

2

0

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For effective coastal aquifers management, it is strongly required to effectively analyze seawater intrusion (SWI). This study used an integrated approach of hydrogeochemical, statistical, geological, and geospatial techniques to assess the extent of SWI in the Ghiss-Nekor aquifer by evaluating the physicochemical parameters of 52 groundwater samples. Two main groundwater facies were identified, Na-Cl (38%) and Ca-Mg-Cl-SO4 (62%). The correlation matrix and a principal component analysis (PCA) depicted that the high salinization in the study area is influenced by both geogenic and anthropogenic factors, including a potential mixing with seawater. A single indicator or a small number of techniques were insufficient to evaluate SWI owing to the multiple causes of salinization in the study area. As a result, we coupled various geochemical indicators with geospatial methods to assess this complicated phenomenon. Accordingly, several ionic ratios (Cl/HCO3, SO4/Cl, Na/Cl, and Mg/Mg+Ca) and SWI indices (GQIswi and SMI) were overlaid to generate the final map that highlights the regions prone to SWI. Most of the SWI spots were discovered within two kilometers or less from the coast. The saline water detected far from the coast was interpreted as the encroachment of seawater from the Souani area being trapped where the clay-marly substratum is deep. These results support the application of geospatial tools to manage groundwater resources in water-stressed areas with complex aquifer systems, by combining various ionic ratios and indices. These findings will assist decision-makers in the Al Hoceima region in developing suitable groundwater management plans and strategies.

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“…Such a drought limits the recharge of groundwater. Currently, several countries are experiencing a decline in the quantity and quality of coastal groundwater resources because of a combination of natural constraints (saline intrusion and climate change) and anthropological activities (overexploitation of water resources and increases in diffuse source pollution) (Yousfi et al, 2002;Gain et al, 2012;Hussain et al, 2019;Razack et al, 2019;Afsari et al, 2022;Wang et al, 2022;Wu et al, 2022). In Senegal, apart from regions with permanent surface water courses, the population's drinking water supply relies largely on the exploitation of groundwater.…”

Section: Introductionmentioning

confidence: 99%

Hydrogeochemical characterization of groundwater in a coastal area, central western Senegal

Ndoye

¹

,

Diedhiou

²

,

Celle

³

et al. 2023

Front. Water

5

0

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One of the most serious problems affecting coastal aquifers is seawater intrusion. Senegal is currently facing an increased demand for freshwater resources due to population growth and economic development in coastal areas. In areas affected by saltwater contamination, chloride concentrations as high as 8880 mg/L were measured in groundwater samples taken from wells near the coastal zone, indicating deterioration in water quality. Our study aims to identify the zones of degradation of the water quality by determining the chemical composition of groundwater and the geochemical processes controlling the chemical patterns. Hydrogeochemical (Piper and Chadha diagrams, chloroalkaline indices, normalized bivariate plots) and multivariate statistical (Hierarchical cluster analyses) techniques were used. Forty-two groundwater samples were collected and analyzed for concentrations of major and some minor ions, electrical conductivity (EC), total dissolved solids (TDS), temperature, and pH. From samples we were able to establish a diagnosis of the very heterogeneous quality of the groundwater in this area. The average pH of the groundwater is 7.6 and about 80% of the groundwater samples have a TDS below 1000 mg/L. On the other hand, the EC values are very heterogeneous with very high conductivities in coastal areas. Approximately, 80% of the groundwater samples have a TDS less than 1000 mg/L and EC values are very heterogeneous. The dominant water types in the study area are Na-Cl water type (less than 10% of the samples) characteristic of the spatial evolution of groundwater salinization from west to east, mixed Ca-Mg-Cl due to fresh water/salt water contact and Ca-Mg-HCO3 water-type (nearly 56% of the samples) to the east. A hydrogeochemical zonation of the aquifer, based on the presence of different water families allows us to visualize the highly degraded (west), mixed (center) and healthy (east) zones. Chloroalkaline indices and normalized bivariate plots show that the chemistry of groundwater is controlled mainly by water-rock interaction and evaporation processes. As water-rock interaction processes, dissolution of carbonate and evaporite, weathering of silicate, ions exchange regulates major ion chemistry.

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“…Groundwater quality index for SWI (GQI swi ) Many researchers have used solely the saltwater fraction (f sea ) (Eq. 1) to assess SWI(Daniele et al, 2022;El Yous et al, 2022;Slama et al, 2022;Sonkamble et al, 2014), however, this index may not be su cient on its own due to its numerous aws(Tomaszkiewicz et al, 2014). Alternatively,Tomaszkiewicz et al (2014) developed the Groundwater Quality Index speci c to SWI (GQI swi ) (Eq.…”

mentioning

confidence: 99%

A geochemical approach in assessing seawater intrusion by integrating geospatial techniques: a case study of Ghiss-Nekor coastal aquifer, Central Rif of Morocco

BOURJILA

¹

,

Dimane

²

,

GHALIT³

et al. 2023

Preprint

View full text Add to dashboard Cite

For effective coastal aquifers management, it is strongly required to effectively analyze seawater intrusion (SWI). This study used an integrated approach of hydrogeochemical, statistical, geological, and geospatial techniques to assess the extent of SWI in the Ghiss-Nekor aquifer by evaluating the physicochemical parameters of 52 groundwater samples. Two main groundwater facies were identified, Na-Cl (38%) and Ca-Mg-Cl-SO4 (62%). The correlation matrix and a principal component analysis (PCA) depicted that the high salinization in the study area is influenced by both geogenic and anthropogenic factors, including a potential mixing with seawater. A single indicator or a small number of techniques were insufficient to evaluate SWI owing to the multiple causes of salinization in the study area. As a result, we coupled various geochemical indicators with geospatial methods to assess this complicated phenomenon. Accordingly, several ionic ratios (Cl/HCO3, SO4/Cl, Na/Cl, and Mg/Mg+Ca) and SWI indices (GQIswi and SMI) were overlaid to generate the final map that highlights the regions prone to SWI. Most of the SWI spots were discovered within two kilometers or less from the coast. The saline water detected far from the coast was interpreted as the encroachment of seawater from the Souani area being trapped where the clay-marly substratum is deep. These results support the application of geospatial tools to manage groundwater resources in water-stressed areas with complex aquifer systems, by combining various ionic ratios and indices. These findings will assist decision-makers in the Al Hoceima region in developing suitable groundwater management plans and strategies.

show abstract

Hydrogeochemical and statistical approach to characterize groundwater salinity in the Ghiss-Nekkor coastal aquifers in the Al Hoceima province, Morocco

Cited by 39 publications

References 34 publications

A geochemical approach in assessing seawater intrusion by integrating geospatial techniques: a case study of Ghiss-Nekor coastal aquifer, Central Rif of Morocco

A geochemical approach in assessing seawater intrusion by integrating geospatial techniques: a case study of Ghiss-Nekor coastal aquifer, Central Rif of Morocco

Hydrogeochemical characterization of groundwater in a coastal area, central western Senegal

A geochemical approach in assessing seawater intrusion by integrating geospatial techniques: a case study of Ghiss-Nekor coastal aquifer, Central Rif of Morocco

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