assessment of groundwater quality and its suitability for irrigation using hydrogeochemical properties

Groundwater (gw) are important sources of fresh water for the agricultural sector in tashk-bakhtegan and maharloo basin in fars province, iran. in this study, data were collected from 420 groundwater samples to assess the suitability of groundwater for irrigation using hydrogeochemical properties. the groundwater quality (gwq) was evaluated using 15 hydrogeochemical indices, namely sodium adsorption ratio (sar), magnesium hazard (mh), salinity hazard (sh), chloride (cl- ), permeability index (pi), total dissolved solids (tds), potential salinity (ps), total hardness (th), kelley’s ratio (kr), sodium percentage (sp), chloro-alkaline index i (cai-i), residual sodium bicarbonates (rsbc), synthetic harmful coefficient (k), and base exchange index (r1), along with meteoric genesis index (r2). the results of these indices indicated that the gwq was totally different in the north and south of the study area. water sources were mainly acceptable for irrigation based on sar, mh, sh, cl-, tds, ps, th, kr, sp, cai-i, and k indices in the northern parts, while it showed limitations for use in the agricultural sector in most southern areas. based on pi and rsbc indices, gwq is entirely acceptable for irrigation all over the basin. according to the results of r1 and r2 indices, gwq belongs to na+-hco3 - and shallow water percolating types in the northern parts, while it belongs to na+-so4 2- and deep water percolating types in the southern parts. agriculture and rangelands are mainly located in the center toward north of the basin, where the gwq is more suitable for irrigation. besides, gwq needs to be improved in southern parts and remediation measures are proposed to make it more usable for irrigation purposes.