RELATIONSHIP OF ANNUAL FLOW WITH HYDROCHEMICAL ANALYSIS OF THE TIGRIS RIVER AND EVUALATION OF WATER FOR DRINKING AND IRRIGATION USESAlyaa Shakir Oleiwi and Moutaz Al-Dabbas
The Tigris River represents one of the main sources of water with the Euphrates River in Iraq. Iraq is plagued by a water shortage as well as water resource management issues and these can be impact on the water quality. For these reason, the study area included the water of the Tigris River to show effect of the shortage of the annual flow on the water quality. The length of the Tigris River in Iraq is 1900 km2 and includes (534) km2 into the study area, Six stations along the Tigris River starting from Mosul station (North part) to the Al-Azizziyah station (Middle part) of Iraq. All samples were analyzed for physiochemical parameters such as water temperature, pH, EC, TDS, TH, major ions (Ca2+, Mg2+, Na+, K+, SO4 2-, Cl-, CO3 and HCO3), and nutrients (NO3). Also, using the available historical climate data includes (Rainfall and Temperature) and Annual flow of the Tigris River for the period (1990-2020). Suitability of water for Irrigation uses was evaluated depending on the criteria or standards of acceptable quality for that use. In addition to the statistical correlation coefficient method was applied also. Water of the Tigris River were classified as CaHCO3- water type at ST.1 and ST.2, While, from ST.3 to ST.6 classified as NaSO4-water type. Suitability of water for drinking purpose is evaluated depending on the criteria or standards of acceptable quality for that use (WHO and Iraqi Standard). All surface water stations of the Tigris River are unsuitable for drinking and not within the standard quality criteria for most of physiochemical parameters. Additionally, ST.1 and ST.2 fell within Excellent class, while, from ST.3 to ST.6 fell within the Permissible class based on the suggested limits of EC value (Ayers and Westcot, 1985) for irrigation. According to the Don (1995) classification of the irrigation water depend on sodium hazard based on SAR values, ST.1 and ST.2 stations of the Tigris River were classified as Good class but from ST.3 to ST.6 which classified as Doubtful class.