This work was designed to study the effect of major drains, such as El Rahawy, on the Nile's water quality over time. The data in this study includes six years of physical and chemical variables data, starting from 2015 to 2020, covering three different water streams. The present results showed that the Rosetta branch and Khandaq sharky canal were directly affected by the agricultural drainage of the Rahway drain, with the change over time for the worse. Rayah El Nasery canal enjoyed complete independence from the negative impact of the drain while maintaining the quality at an appropriate level over time. The study predicts a decline in the water quality of the Rosetta branch in the future and recommends exerting more efforts to treat all pollutants that are discharged on the Nile and raise the efficiency of the Rahawy drain.

The Nile River is an important natural and exclusive source of fresh water in Egypt. Water samples were taken monthly from twelve sites from 2015 to 2020 in El Beheira Governorate and eighteen physicochemical parameters were measured. The results show that the Rahawy drain recorded the highest values for most of the physicochemical parameters. The HPI and MI indicators in Rahawy drain were higher (70 % & 100 %) than in other sites, especially in the summer and winter seasons. The Rahawy WQI values were classified as poor quality. The IWQI results indicate that the water quality for the Rahawy was within the "severe restriction" class, with many restrictions to be used in agriculture. The water quality of the Nile River in the south of Egypt is better than that of the north and the water quality recovery takes more time and distance.