QUALITATIVE ENVIRONMENTAL ASSESSMENT OF DIYALA RIVER WATER UPSTREAM OF ITS CONFLUENCE WITH THE TIGRIS RIVER: AN ANALYTICAL STUDY OF PHYSICOCHEMICAL PARAMETERS AND HEAVY METALS

The lower reach of the Diyala River, southeast of Baghdad, is a vital river system that is nonetheless suffering severe degradation due to persistent human pressures and infrastructure deficiencies. This study assesses the spatial distribution of major untreated sewage outfalls and quantifies the associated environmental risks to nearby residential and urban communities. This study aimed to assess Diyala River water quality by analyzing a range of physical and chemical characteristics at several monitoring sites during the summer and winter seasons, comparing the results against Iraqi standard limits to determine water suitability and identify key pollution sources. The study measured pH, electrical conductivity, turbidity, dissolved and suspended solids, total hardness, cations and anions, nutrients, organic matter, oils, and heavy metals. The results revealed variations across study sites between the summer and winter seasons; while pH values remained within the standard range (7.3–8), concentrations of dissolved salts, electrical conductivity, and total hardness at certain sites exceeded standard limits for river water, reaching levels of 2,173, 4,180, and 1,800 mg/L, respectively, particularly during the summer. Nitrate and phosphate concentrations at several locations exceeded acceptable limits, reflecting the impact of agricultural activities and untreated domestic wastewater discharged into the river. Meanwhile, elevated levels of Chemical Oxygen Demand (COD) and oil were observed, reaching 105 mg/L and 9.8 mg/L, respectively, at certain sites, indicating organic pollution resulting from discharged wastewater. Lead concentrations also exceeded permissible limits for river water; however, concentrations of other elements remained within the acceptable limits established by the Iraqi Ministry of Environment for river water quality assessment.