Review of the hydrogeological and hydrochemical aspects of groundwater in the Umm-Er-Radhuma aquifer system, Arabian Peninsula

Abstract

Within the Arabian Peninsula, the Umm-Er-Radhuma aquifer system represents a large groundwater reservoir. Groundwater occurs under semi-confined to rather confined conditions in secondary porosities created by fissures and developed solution openings in carbonate rocks. The general groundwater flow is east-southeast towards the Arabian Gulf under a steep hydraulic gradient. Average transmissivity ranges between 7 × 10 −5 and 0.62 m 2 s −1; permeability ranges between 4 × 10 −5 and 1 × 10 −2 m s −1. The salinity varies from 220 to 15,815 mg l −1 and increases in the direction of groundwater flow. The groundwater is generally saturated with respect to calcite and dolomite and under-saturated with respect to gypsum. The dominant hydrochemical processes in the aquifer are likely to be simple mixing and ion exchanges. Environmental isotopes confirm the groundwater flow direction and the idea of diminished recharge. Towards the coast of the Arabian Gulf evidences of sea water intrusion is indicated.