In this study, the physical and chemical characteristics of wet and dry season groundwater quality parameters of 35 wells within the provincial boundaries of Sivas were used for calculations such as sodium adsorption ratio (SAR), Kelly's ratio (KR), sodium percentage (Na%), permeability index (PI), residual sodium carbonate (RSC) and magnesium hazard (MH), which are used in irrigation water quality ratings. Also, the irrigation water quality index (IWQI) was calculated for all groundwater sources within the study area. Groundwater quality parameters and the spatial distribution of the parameters calculated throughout the study were mapped using GIS, and irrigation water quality evaluation was performed in accordance with USA Salinity Laboratory diagram and irrigation water quality standards. The correlations between the irrigation water quality parameters were determined using Pearson correlation analysis. IWQI values showed that the majority of groundwater samples (45.7%) are in the 'weak' (MR: medium rating) category for the dry season, whereas 42.9% of groundwater samples fall within the 'very weak' (HR: high restriction) category for the wet season. (c) 2019 John Wiley & Sons, Ltd.