Isotopic and geochemical identifications of groundwater salinisation processes in Salalah coastal plain, Sultanate of Oman

Askri, Brahim; Ahmed, Abdelkader T.; Al-Shanfari, Razan Ali; Bouhlila, Rachida; Al-Farisi, Khater Ben Khamis

doi:10.1016/j.chemer.2015.12.002

Cited by 31 publications

(7 citation statements)

References 22 publications

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“…Wells 20, 25, and 33 at the foot of the Dhofar Mountains display fresh groundwater while more saline water is found in the East (well 1), West (well 66), and in the lower central plain (well 19). Regional salinity differences have been described since the 1970s (Askri et al., 2016; Macumber et al., 1998; Shammas & Jacks, 2007) and led to the plain being divided into three zones, the “Eastern Brackish Zone”, the “Central Freshwater Zone” and the “Western Brackish Zone”. The origin of the salinization is not clear.…”

Section: Resultsmentioning

confidence: 99%

Multi‐Tracer Groundwater Dating in Southern Oman Using Bayesian Modeling

Rädle

Kersting

Schmidt

et al. 2022

Water Resources Research

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In the scope of assessing aquifer systems in areas where freshwater is scarce, estimation of transit times is a vital step to quantify the effect of groundwater abstraction. Transit time distributions of different shapes, mean residence times, and contributions are used to represent the hydrogeological conditions in aquifer systems and are typically inferred from measured tracer concentrations by inverse modeling. In this study, a multi‐tracer sampling campaign was conducted in the Salalah Plain in Southern Oman including CFCs, SF6, 39Ar, 14C, and 4He. Based on the data of three tracers, a two‐component Dispersion Model (DMmix) and a nonparametric model with six age bins were assumed and evaluated using Bayesian statistics. In a Markov Chain Monte Carlo approach, the maximum likelihood parameter estimates and their uncertainties were determined. Model performance was assessed using Bayes factor and leave‐one‐out cross‐validation. Both models suggest that the groundwater in the Salalah Plain is composed of a very young component below 30 yr and a very old component beyond 1,000 yr, with the nonparametric model performing slightly better than the DMmix model. All wells except one exhibit reasonable goodness of fit. Our results support the relevance of Bayesian modeling in hydrology and the potential of nonparametric models for an adequate representation of aquifer dynamics.

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Section: Resultsmentioning

confidence: 99%

Multi‐Tracer Groundwater Dating in Southern Oman Using Bayesian Modeling

Rädle

Kersting

Schmidt

et al. 2022

Water Resources Research

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“…The most prevalent ions were sodium and chloride. The concentrations of these two ions suggest that the chemical facies of the soil solutions are strongly influenced by the dissolution of evaporites, mainly halite (Askri et al, 2016; Brinis et al, 2015). Samples with calcic facies were located either in the subsurface or at the depths of the profiles.…”

Section: Discussionmentioning

confidence: 99%

Salinisation of soils in semi‐arid endorheic zone: Case of Chott El Beida (Algeria)

Laoufi,

Ait Mechedal,

Daoud

2023

Land Degrad Dev

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Chott El Beida, North of Algeria (Setif, 585 km2), is an endorheic zone located in a semi‐arid climate. It is among the first chotts listed under the Ramsar Convention on the Wetlands of International Importance. Numerous studies on wetlands in the Setif region have focused on hydrogeology, avifauna, and vegetation. However, only one study has been devoted to soil studies. This study focused on the pedological and geochemical aspects of salinity in this area. This study was conducted on a toposequence of 200 m comprising eight soil profiles. A set of 24 samples were collected from the top to a depth (0–200 cm) and were subjected to a series of physical and chemical analyses. The concentrations of the major elements were used to determine the chemical facies and calculate the saturation indices for each mineral and residual alkalinity using geochemical modelling with PHREEQC. This study shows that the salinity in Chott El Beida is very variable, varying from less saline to extremely saline, moving from the outside to the centre of the chott, with two types of saline profiles: the descending type towards the outside of the chott and the ascending type in the highly saline depression. Geochemical investigations demonstrated that the dominant facies is (Na‐Cl) which is in accordance with the neutral saline pathway. The phenomenon of salinisation in Chott El Beida is controlled mainly by the precipitation of minerals, namely, calcite, aragonite, dolomite, gypsum, and anhydrite, and the dissolution of evaporite minerals. The study of calcite residual alkalinity and generalised residual alkalinity showed that salinisation evolves in the neutral saline path without the risk of alkalinization.

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“…Groundwater is the main water source. This reservoir is under pressure, both qualitatively and quantitatively, from increasing extraction, salinization, and anthropogenic pollution. − The study area is thus a classic example of the “coastal groundwater squeeze”, where limited resources are faced with increasing consumption. In the Salalah plain, these limited resources relate to the shallow coastal aquifer (<100 m deep), which is fed by the mountains in the north and is bounded by the ocean in the south.…”

Section: Methodsmentioning

confidence: 99%

Autonomous Large-Scale Radon Mapping and Buoyant Plume Modeling Quantify Deep Submarine Groundwater Discharge: A Novel Approach Based on a Self-Sufficient Open Ocean Vehicle

Müller

Gros

Leibold

et al. 2023

Environ. Sci. Technol.

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Groundwater discharge into the sea occurs along many coastlines around the world in different geological settings and constitutes an important component of global water and matter budget. Estimates of how much water flows into the sea worldwide vary widely and are largely based on onshore studies and hydrological or hydrogeological modeling. In this study, we propose an approach to quantify a deep submarine groundwater outflow from the seafloor by using autonomously measured ocean surface data, i.e., 222Rn as groundwater tracer, in combination with numerical modeling of plume transport. The model and field data suggest that groundwater outflows from a water depth of ∼100 m can reach the sea surface implying that several cubic meters per second of freshwater are discharged into the sea. We postulate an extreme rainfall event 6 months earlier as the likely trigger for the groundwater discharge. This study shows that measurements at the sea surface, which are much easier to conduct than discharge measurements at the seafloor, can be used not only to localize submarine groundwater discharges but, in combination with plume modeling, also to estimate the magnitude of the release flow rate.

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Isotopic and geochemical identifications of groundwater salinisation processes in Salalah coastal plain, Sultanate of Oman

Cited by 31 publications

References 22 publications

Multi‐Tracer Groundwater Dating in Southern Oman Using Bayesian Modeling

Multi‐Tracer Groundwater Dating in Southern Oman Using Bayesian Modeling

Salinisation of soils in semi‐arid endorheic zone: Case of Chott El Beida (Algeria)

Autonomous Large-Scale Radon Mapping and Buoyant Plume Modeling Quantify Deep Submarine Groundwater Discharge: A Novel Approach Based on a Self-Sufficient Open Ocean Vehicle

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