Determining the effect of changing channel geometry of irrigation canals on dissolved oxygen concentration

Dissolved oxygen (DO) is an important water quality parameter. It is considered the most important parameter. DO concentration in water is affected by different parameters such as volume flow rate, water velocity, and re-aeration rate. Those parameters are directly affected by the geometry of the waterway. Thus, studying the impact of changing channel geometry on DO is very important. Many researchers studied the effect of influential parameters on water quality variables but the influence of channel geometric parameters on DO was not studied thoroughly before. This research aims to study the effect of changing channel geometry on DO concentration. The DO is modeled along the channel using Streeter-Phelps equation. Studied geometric parameters are water depth, bottom width, side-slopes, and channel length. The case study is taken as Sheikh Zayed canal in Egypt. Sheikh Zayed canal is responsible for irrigating Toshka land in the Western Desert of Egypt. It is also responsible for increasing the cultivated area of Egypt by about 550,000 feddans. It was found that the DO concentration is greatly affected by changing the geometry of the canal, as the canal geometry directly influences the flow velocity as well as re-aeration rate. The percentage change of DO concentration with every geometry parameter is for length 6.8%, bed width 1.8%, water depth 4%, and side slopes 1.4%. © 2021 ISEC Press.