Evaluation of the water quality of the Sirwan River in the Garmian region for irrigation purposes using the Irrigation Water Quality Guidelines (IWQG).

The water quality index (WQI) is one of the simplest ways of converting complex water quality data into an individual value that expresses the state of water quality. The present study aims to assess and classify the quality of water in the Sirwan River within Garmian Region for irrigation uses through using the Irrigation Water Quality Guideline (IWQG). The IWQG determines the risks of soil salinity and sodicity as well as the risks of water toxicity to various types of crops. The water samples were collected from (24) sampling stations in the Sirwan River downstream of Darbandikhan Dam and Jalawlaa Sub-district in December 2021. All the samples were analyzed in terms of physicochemical parameters, including (Ca+2), (Mg+2), (Na+), (HCO3-), (Cl-) and (EC). The results indicated that the (IWQI) values ranged from (42.34) to (56.70) with an average of (53.7), and most of the stations fall within the high restriction category. This indicates that the water quality of Sirwan River is suited for plants with moderate to high salt tolerance, and it can be used in high permeability soils. Salinity control practices should be implemented, except in water that contains low concentrations of (Na+, Cl- and HCO3-). Keywords: Irrigation, Irrigation Water Quality Guideline (IWQG), Sirwan River, Garmian Region, Restrictions