Scientist and researchers were recognized the important of water quality, Water resources are especially susceptible aquatic systems to many pollutants sources. Determination of water quality characteristics are very significance in term of the environmental considerations. This study aims to assess the water quality of the Euphrates river in the Fallujah Euphrates Reach (FER) by measuring the concentration of chemical and physical properties of water using multiple devices. CWQI and WAWQI were also used to assess the quality of water and indicate its suitability for drinking purposes, based on standard specifications from IQS, WHO, and USEPA as a criterion for comparison purposes. The findings show that with the use of CWQI, the quality of water was fair based on IQS, good based on WHO, and marginal based on USEPA, while the quality ranged between good, poor, very poor, and unsuitable for drinking purposes as a result of using WAWQI, with the exception of station 7, where the value of the WAWQI was greater than 100 mg/L, which indicates that the water is not suitable for drinking purposes as a result of the pollution of this station from a point source, which caused the high concentration of turbidity, sulfate, BOD5, and total dissolved solids, and decreased the DO concentration in this station compared to the rest of the stations, which were within the permissible.

The main objective of this research is an examination of the applicability of the QUAL2K mathematical model on large rivers like the Euphrates, and it is the first study of its kind conducted on this important section within Fallujah Euphrates Reach (FER), using this model for the purpose of evaluating the quality of water and creating a database to predict the quality of river. The tests were conducted during January and April of 2022, where they were calibrated and verified for DO and CBOD5 at a distance of 12.86 km. Google Earth pro and Arc-GIS were utilized to provide certain data as input into the QUAL2K model. The model was calibrated in January using the trial-and-error technique, and the verification was completed in April using the model calibration parameters. For the purposes of evaluating the model's performance, statistical measures such as mean absolute error (MAE), root mean square error (RMSE), and relative error (RE) were used. In addition, three different scenarios were applied (pollution load modification, flow augmentation for point sources, and flow augmentation for headwater) to improve the water quality of Euphrates river. The results show that the difference between observed and anticipated values had a relatively small error percentage, which means that this mathematical model can be applied to this important section of the river. While the concentration of DO was within the permissible limits to perpetuate aquatic life and maintain the ecological health of the river, the concentration of CBOD5 was also within the limits in some locations. In addition, the scenario represented by modifying the pollution loads represented by BOD5 for sewage water were effective in raising the concentration of DO in the river, while increasing point sources discharge and headwater flow does not yield meaningful results.

This study aims to assess the water quality of the Euphrates river in the section Fallujah Euphrates Reach (FER), in the city of Fallujah, western Iraq. Six heavy metals: 〖Cr〗^(3+), 〖Fe〗^(2+), 〖Zn〗^(+2), 〖Mn〗^(+2), 〖Ni〗^(+2) and 〖Pb〗^(+2) and ten water stations were chosen for the purpose of knowing whether or not these minerals are available in this important section of the Euphrates river and their concentrations in the river water because these minerals are harmful to health due to its lack of decomposition and accumulation within the organs of the body of living organisms. The samples were analyzed using Inductively Coupled Plasma Atomic Emission Spectrometry ICP-OES. Heavy Metal Pollution Index (HMPI), Heavy Metal Evaluation Index (HMEI), and Contamination Degree (CD) were employed to evaluate water quality. The findings were revealed that concentration of 〖Fe〗^(2+), 〖Ni〗^(+2) , and 〖Zn〗^(+2) exceeded the permissible limits based on Iraqi standard IQS, World Health Organization WHO, and United States Environmental Protection Agency USEPA standards, whereas 〖Cr〗^(3+) , 〖Pb〗^(+2), and 〖Mn〗^(+2) concentrations were non-existent. Based on HMPI, HMEI and CD values, pollution of the Euphrates river is low. which indicates a small amount of pollution, and because the Euphrates water discharge is high, the concentration of heavy metals does not affect the river water. According to national and international guidelines, FER suffers from a low level of heavy metal pollution. However, the (CD), (HMPI), and (HMEI) indices indicated that FER water quality was satisfactory. In other words, the water quality of the Euphrates river in the current study reach is good, but that does not mean that the water is used without treatment to be pumped into the city. It has a low pollution rate, but that may have a negative impact on the health of consumers.