Assessment of Samarra Barrage Lake Using GIS and Canadian Water Quality Index (CCME)

Abstract

River water is a fundamental necessity for all aspects of life, especially drinking water. Millions of Iraqis depend primarily on the waters of the Tigris river. The aim of the study is to evaluate the water quality of the Samara Barrage Lake for the period between September 2024 and May 2025. Water samples taken from the lake were analyzed to determine fourteen physical and chemical parameters, namely pH, turbidity, DO, TDS, BOD₅, TSS, SO₄, NO₃, Cl^-, PO₄, and ions (Ca, Mg, Na, and K). Ten points were taken within the barrage lake, distributed along its edges and center. Geographic Information Systems (GIS) techniques were used to analyze and map the spatial distribution of the selected indicators. The Canadian Water Quality Index was also used to determine the lake's water quality, and the results revealed that water quality is subject to seasonal fluctuations. In the autumn season (September 2024), the pH, turbidity, and BOD exceeded the limits permitted for drinking water. In contrast, during the winter (January 2025) and spring (May 2025), turbidity and BOD remained above the World Health Organization's permissible limits. This indicates that the Tigris River and Samara lake were subjected to certain conditions, such as erosion, soil degradation, and riverbed disturbance, as well as human activity along the river and even the lake's edges, and water pollution from organic matter due to agricultural and animal waste, in addition to inadequately treated sewage discharged into the river. All other parameters remained within recommended limits throughout the study period. According to the Canadian Water Quality Index (CWQI), the lake's water quality was generally "good," with CWQI values ​​of 81.38 in the autumn, 82.08 in the winter, and 81.8 in the spring. These results highlight the impact of seasonal variations on lake water quality and demonstrate the effectiveness of integrating environmental indicators with GIS-based spatial analysis for surface water monitoring. The results of this study represent a valuable reference for sustainable water resource management and improving water quality in the Samarra barrage lake.