Assessment of Seawater Intrusion in Coastal Aquifers Using Multivariate Statistical Analyses and Hydrochemical Facies Evolution-Based Model

Abstract

Groundwater (GW) studies have been conducted worldwide with regard to several pressures, including climate change, seawater intrusion, and water overexploitation. GW quality is a very important sector for several countries in the world, in particular for Tunisia. The shallow coastal aquifer of Sfax (located in Tunisia) was found to be under the combined conditions of continuous drop in GW and further deterioration of the groundwater quality (GWQ). This study was conducted to identify the processes that control GWQ mainly in relation to mineralization sources in the shallow Sfax coastal aquifer. To perform this task, 37 wells are considered. Data include 10 physico-chemical properties of groundwater analyzed in water samples: pH, EC, calcium (Ca), sodium (Na), magnesium (Mg), potassium (K), chloride (Cl), sulfate (SO4), bicarbonate (HCO3), and nitrate (NO3), i.e., investigation was based on a database of 370 observations. Principal component analysis (PCA) and hydrochemical facies evolution (HFE) were conducted to extract the main factors affecting GW chemistry. The results obtained using the PCA model show that GWQ is mainly controlled by either natural factors (rock–water interactions) or anthropogenic ones (agricultural and domestic activities). Indeed, the GW overexploitation generated not only the GWQ degradation but also the SWI. The inverse distance weighted (IDW) method, integrated in a geographic information system (GIS), is employed to achieve spatial mapping of seawater intrusion locations. Hydrochemical facies evolution (HFE) results corroborate the seawater intrusion and its spatial distribution. Furthermore, the mixing ratio showed that Jebeniana and Chaffar–Mahares localities are characterized by high SWI hazard. This research should be done to better manage GW resources and help to develop a suitable plan for the exploitation and protection of water resources.

Integrated Hydrogeological, Hydrochemical, and Isotopic Assessment of Seawater Intrusion into Coastal Aquifers in Al-Qatif Area, Eastern Saudi Arabia

“…SWI is identified by the anion and cation percentage distribution in the square diagram. Subsequently, the HFE-D model has been utilized in several studies to identify the SWI phase in coastal aquifers worldwide (e.g., [ 47 , 49 ]). We used the Excel macro published by [ 50 ] to establish the HFE-D model for the tested GW samples from both aquifers in the study area, as shown in Figure 10 .…”

Gross Alpha-Particle Activity and High 226Ra Concentrations Do Not Correspond with High 210Po in the Atlantic and Gulf Coastal Plain Aquifers of the United States

“…(Chosen were the clastic-sedimentary regional aquifers: the Piney Point (NACPPAS1A) and Potomac (NACPPAS1B and NACPPAS2B); see Table SI.1.) The first four principal components (PCs) of the PCA model for the NACP PA were chosen as grouping surrogates for the geochemical environment and water type in accordance with similar analyses in other Coastal Plain aquifers. , …”

“…(Chosen were the clastic-sedimentary regional aquifers: the Piney Point (NACPPAS1A) and Potomac (NACPPAS1B and NACPPAS2B); see Table SI environment and water type in accordance with similar analyses in other Coastal Plain aquifers. 43,44 Detailed descriptions of the geochemical model methods and results are given in the Supporting Information. The geochemical models were used to identify reasonable geochemical processes that could account for the evolution of the different geochemical environments regionally allowing for classification of water types associated with the high 226 Ra and 210 Po concentrations.…”

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

“…The most common mapping methods in the groundwater sector are IDW and kriging interpolation. According to several earlier researches (Hajji et al, 2022;Yang et al, 2020;Zolekar et al, 2021), the IDW interpolation method is more accurate than the Kriging tool. Additionally, IDW has a track record of being easy to use, quick, and produces accurate results (K. X.…”