Groundwater and Solute Budget (A Case Study from Sabkha Matti, Saudi Arabia)

Waleed Saeed,Orfan Shouakar-Stash,Warren Wood,André Unger,Beth Parker

doi:10.3390/hydrology7040094

Waleed Saeed, Orfan Shouakar-Stash + Show 3 more

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https://doi.org/10.3390/hydrology7040094

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Abstract

Sabkha Matti is the largest inland sabkha (2950 km2) in the Arabian Peninsula. The drainage area supporting this sabkha is >250,000 km2 and is the discharge point for part of the ten thousand meter thick regional groundwater systems ranging in age from Precambrian through Miocene in the Rub’ al Khali structural basin. A hydrologic budget was constructed for this sabkha, where water fluxes were calculated on the basis of hydraulic gradient and conductivities measured in both shallow and deep wells. The evaporation rates from the surface of the sabkha were estimated from the published data and indicate that almost all the annual rainfall is lost by surface evaporation. The water flux multiplied by its solute concentration showed that nearly all the solutes in the sabkha were derived by upward leakage from the underlying regional aquifers rather than the weathering of the aquifer framework, from precipitation, or from other sources. Steady-state estimates within a rectilinear control volume of the sabkha indicate that about 1 m3/year of water enters by lateral groundwater flow, 2 m3/year of water exits by lateral groundwater flow, 20 m3/year enters by upward leakage, 780 m3/year enters by recharge from rainfall, and 780 m3/year is lost by evaporation. The proposed conceptual model of the hydrology for sabkha Matti is assumed to apply to the rest of the inland sabkhas of the Arabia Peninsula and to many ancient environments of deposition observed in the geologic record.

Highlights

Sabkha is an Arabic term that is widely used for a salt flat
A water budget for the Sabkha Matti (SM) was developed in order to understand the processes that control the hydrology of the sabkha and to quantify the individual components
The regional-scale system is assumed to operate under a steady-state flow condition, which means that all of the inflows to the assumed to operate under a steady-state flow condition, which means that all of the inflows to the sabkha must equal all of the outflows

Summary

Introduction

Sabkha is an Arabic term that is widely used for a salt flat. Sabkhat (plural of Sabkha) are characterized by flat landscapes, shallow groundwater levels (usually less than one meter), and high water salinities. In the Arabian Peninsula, there are two types of sabkhat: coastal and inland. Coastal sabkhat are marginal marine areas [1,2]. Inland sabkhat are found in basins, away from the coast, and typically surrounded by sand dunes [3]. The formation of both coastal and inland sabkhat are explained by the evaporation of continental groundwaters through the surface, which produces brines and subsequently causes the precipitation of evaporite minerals [1]

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