Assessment of water quality for irrigation purposes: A case study of King Talal Reservoir

This study aims to assess water quality of King Talal Reservoir (KTR) for irrigation purposes (diluted wastewater with runoff water). Physicochemical properties of irrigation water were measured at monthly bases from 2015-2021 and the quality was assessed by the electrical conductivity (EC), sodium adsorption ratio (SAR), permeability index (PI), residual sodium carbonates (RSC), and metal contents. In addition, the USSL and Doneen diagrams were used to assess the suitability of water for irrigation. Average values of EC was 1.89 dS m(-1), SAR ( 5.15), Na (230.4), Ca (90.6), Mg (33.5), Cl (309.6), SO4 (216.2), and HCO3 (271.7) mg L-1. Water of KTR is classified as C3 (high salinity), S1-S2 low to medium (sodicity) according to the USSL diagram, low alkalinity (RSC < 1.25) hazard., and have no restriction on permeability (Doneen). Metal levels (Cu, Fe, Zn, Mn, Ni, Cd, Cr, Pb, and Co) were safe and below the maximum permissible limit suggested FAO and the Jordanian (FAO) guidelines indicating safe use of irrigation water. The study suggests that adequate practices and protection measures are needed to minimize the detrimental effects of long term irrigation with such water on agricultural lands. In addition, based on anticipated yield reductions and best agro-economic returns, medium tolerant crops for salinity are recommended to be used.