Spatial Variations in Chemical Properties of Irrigation Groundwater at Al-Hassa Oasis, Kingdom of Saudi Arabia PDF

Keywords

Groundwater, salinity, cations, anions, sodium absorption, quality degradation, spatial variations, Al-Hassa Oasis, Saudi Arabia

Abstract

The study aimed at investigating the spatial variations in the quality and the chemical composition of the groundwater used in irrigation in Al-Hassa Oasis located in the Eastern Province of the Kingdom of Saudi Arabia. The main findings of the study indicated that there is a spatial variability in the salinity levels, as reflected by the values of electrical conductivity (EC), the major cations (Na+, Ca2+, Mg2+ & K+) and anions (CI, CO,2, HCO, & SO,?), and the values of the sodium adsorption ratio (SAR) and exchangeable sodium percentage (ESP). The results also showed an increasing trend from the southwest and west regions to the north and northeast borders of the Oasis. This direction is well matched with the general direction of groundwater flow in the Oasis. These spatial variations in the groundwater hydrochemical properties may be attributed to the increases for salts dissolved during the passage of the groundwater through the aquifers, increasing salinity due to extensive abstraction of the groundwater and/or due to the direct and indirect recharge occurring to the Neocene aquifer that supplies the irrigation water in the Oasis. In addition, the results indicated that the classification of the irrigation groundwater is high (C3) to very high (C4) salinity and low (S1) to medium (S2) sodicity hazard, with an overall average class of C4-S2. This suggests that the irrigation groundwater in Al-Hassa Oasis is subjected to a process of quality degradation