Geophysical characterization of saltwater intrusion in a coastal aquifer: The case of Martil-Alila plain (North Morocco)

Himi, Mahjoub; Tapias, J.C.; Benabdelouahab, Sara; Salhi, Adil; Rivero, L.; Elgettafi, Mohammed; Mandour, Abdennabi El; Stitou, Jamal; Casas, Albert

doi:10.1016/j.jafrearsci.2016.11.011

Cited by 60 publications

(27 citation statements)

References 20 publications

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“…They are highly sensitive to changes triggered by both natural and anthropogenic forcing such as climate, land use, pollution and over-pumping (Comte et al, 2014;Hsieh et al, 2015;Iyalomhe et al, 2015;Klassen and Allen, 2017;Lathashri and Mahesha, 2015). The use of coastal groundwater for drinking, agriculture or industry is however globally compromised by the salinization problem (Ahmed et al, 2017;Argamasilla et al, 2017;Himi et al, 2017). Progressing saltwater intrusion into freshwater aquifers due to over-abstraction have prompted global alert and concern (Ahmed, 2017;Priyanka and Mahesha, 2015;Sonkamble et al, 2014).…”

Section: Introductionmentioning

confidence: 99%

Drivers, patterns and velocity of saltwater intrusion in a stressed aquifer of the East African coast: Joint analysis of groundwater and geophysical data in southern Kenya

Oiro

Comte

2019

Journal of African Earth Sciences

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Fresh groundwater resources in coastal East Africa are crucial for the region's socioeconomic development but are under threat of salinization caused by changes in recharge patterns and increasing abstraction. With the aim of establishing the drivers behind saltwater intrusion and its current spatial extent, we studied the Kenyan South Coast aquifer, a representative, strategic aquifer under increased pressure. Investigations included electrical resistivity tomography (ERT) surveys and in-situ groundwater measurements (water table and basic quality) together with the analysis of available longterm climatic and borehole monitoring data. Over the last 40 years, groundwater electrical conductivity values at the well field increased by about three times and groundwater levels declined by 1 to 3 m over the last decade. When put in perspective with the long-term climate (rainfall, temperature) and abstraction records, these trends in groundwater appear to be primarily driven by increased borehole abstraction (+400 m 3 /day per year in average), whereas observed increasing temperature (+0.02 ℃ per year) and decreasing rainfall (-0.8 mm per year) could potentially act as a secondary control through reduced recharge. However the low statistical significance obtained for both rainfall and temperature trends over the observation period suggests that no clear conclusion can be made with regards to longterm climate impact on groundwater. Groundwater quality mapping showed that proximity to the ocean, ACCEPTED MANUSCRIPT presence of abstraction well-fields and regional geology control groundwater salinity patterns at regional scale. Locally, geophysical data showed that, saltwater intrusion spatial patterns are controlled by local aquifer lithology, groundwater abstraction and freshwater recharge in floodplains. Comparison with previous (1984) resistivity data showed that the saltwater front has advanced toward the well-field by up to 2 km and rose by up to 80 m over the last 30 years, which corresponds to a maximal velocity of about 60 m/y horizontally and 2 m/y vertically. Implementation of groundwater management strategies such as sustainable groundwater exploitation, sourced alternative water supply, and managed aquifer recharge are required to mitigate the effects of seawater intrusion along the East African coastal strip.

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Section: Introductionmentioning

confidence: 99%

Drivers, patterns and velocity of saltwater intrusion in a stressed aquifer of the East African coast: Joint analysis of groundwater and geophysical data in southern Kenya

Oiro

Comte

2019

Journal of African Earth Sciences

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“…In fact, the closer the saline aquitard is to the ground level (Sites C and D), the less accurate the interpolation. Moreover, the presence of sources of salinity other than actual seawater intrusion generates a high disturbance in the AS accuracy; (ii) In some transects, the VES method seems to be greatly influenced by the presence of the saline aquitard, often reproducing the saline aquitard/aquifer contact at a higher elevation than the actual one, rather than reproducing the saltwater/freshwater interface's depth, as already raised by other studies [14,22]; (iii) The TEM method has proved to be the most reliable in capturing the freshwater/saltwater interface in all the configurations encountered in the transects. The values of the statistical indicators used to quantify the efficiency of each method in capturing the freshwater/saltwater interface for all the four field sites (A, B, C and D) are reported in Table 2.…”

Section: Comparison Of the Analytical Solution Ves And Tem Resultsmentioning

confidence: 87%

“…In recent years, the transient electromagnetic method (TEM) has been increasingly used [23], though it is still less frequently employed than electrical resistivity tomography methods. The accuracy of the TEM method has been confirmed in numerous studies [1,14,24].…”

Section: Introductionmentioning

confidence: 75%

“…Delineating the mixing zone with this last method is more challenging than using the original approach since it depends more on hydrogeological data collected. In many areas, because of the rough physiographical characteristics and the limited number of observation wells, the application of the two-dimensional approach is not straightforward [14]. The same applies to density-dependent numerical models, which are more flexible than analytical solutions but need even more data to be set up, calibrated, and validated [15][16][17][18].…”

Section: Introductionmentioning

confidence: 99%

“…The most widespread method used for determining the saltwater/freshwater interface is the electrical resistivity tomography. Because of its good performance, it was used in Belgium [20], in the Lekki Peninsula in Nigeria [21], and in Martil-Alila coastal aquifer in Morocco [14], although it showed to be affected by some limitations. For example, it is impossible to clearly distinguish between geological formations of similar resistivity such as saline sand and saline clay [22].…”

Section: Introductionmentioning

confidence: 99%

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Assessing Aquifer Salinization with Multiple Techniques along the Southern Caspian Sea Shore (Iran)

Golshan

Colombani

Mastrocicco

2018

Water

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This study focuses on the salinization of the coastal aquifer in the Mazandaran Province (Iran) within four different sites. Many factors can lead to declining groundwater quality, but this study focuses on the seawater intrusion area. Therefore, locating the interface between saltwater and freshwater is very important. For this purpose, three characterization methods with different accuracies have been employed: the Verruijt equation, vertical resistivity sounding, and an electromagnetic survey. Vertical resistivity sounding and the electromagnetic survey were performed near existing exploration boreholes and were used to determine the saltwater interface. The results showed that the Verruijt equation provides a reliable localization in two of the sites, but in the other two sites, the determined interface is lower than the observed data. The geoelectrical method showed acceptable results, but often this method cannot distinguish between the saltwater and saline aquitard boundary. The electromagnetic method showed a high accuracy in all the study sites and proved to be the most reliable method compared with the other techniques employed in this study. The results from this study are useful in helping to identify the most suitable technique for locating the freshwater/saltwater interface, especially in those sites where a detailed characterization via multilevel sampling is not feasible for technical or economic reasons.

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Revealing early villages – Pseudo‐3D ERT geophysical survey at the pre‐pottery Neolithic site of Kharaysin, Jordan

Moník

Lenďáková

Ibáñez-Estévez

et al. 2018

Archaeological Prospection

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Electric resistivity tomography (ERT) prospection conducted at the Pre-Pottery Neolithic site at Kharaysin, Jordan, building on previous surface prospection and excavation, found a number of new sub-surface anomalies. Subsequent excavations determined that the anomalies corresponded with the stone walls of habitation structures and possibly terrace walls. These features covered large areas of the site slope, inclusive of clustered settlement structures and frequent building superpositions indicative of multi-phase occupation. Despite the generally arid conditions, the moist soil matrix allowed for the effective use of ERT. This article presents the integrated data of the archaeological excavation and the geophysical survey. As a test case it proves the utility of ERT in the identification of Pre-Pottery Neolithic A (PPNA) and Pre-Pottery Neolithic B (PPNB) sub-surface anthropogenic features.

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Geophysical characterization of saltwater intrusion in a coastal aquifer: The case of Martil-Alila plain (North Morocco)

Cited by 60 publications

References 20 publications

Drivers, patterns and velocity of saltwater intrusion in a stressed aquifer of the East African coast: Joint analysis of groundwater and geophysical data in southern Kenya

Drivers, patterns and velocity of saltwater intrusion in a stressed aquifer of the East African coast: Joint analysis of groundwater and geophysical data in southern Kenya

Assessing Aquifer Salinization with Multiple Techniques along the Southern Caspian Sea Shore (Iran)

Revealing early villages – Pseudo‐3D ERT geophysical survey at the pre‐pottery Neolithic site of Kharaysin, Jordan

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