Simulation of Flow Over Weirs With Bottom Pipes (Case Study: Bahr Hassan Wasef Weir)

Abstract

The mathematical model is an idealization of a real system and it can be used to study the operation scenarios of an existing or a proposed system. The 1-D Sobek model is a mathematical model which is chosen to simulate the Fayoumi Standard weirs which have been modified by adding pipes to convey much water to downstream direction. Measurements of discharge with these structures are complicated due to existence of the pipes. Field measurements are carried out and simulated using mathematical model to investigate the effect of installing pipes on a clear over fall weir. Bahr Hassan Wasef is simulated with six cross-sections. A kilometer from the beginning of the channel including weir is represented. The used data of cross-sections altitudes, discharges, water levels upstream and downstream the weir, and the head over weir for Bahr Hassan Wasef were measured at the field by a Staff from Ministry of Water Resources and Irrigation in Al-Fayoum and Assiut Irrigation Directorates. The effect of downstream water depth is taken into consideration. The flow results of piped weir are compared with those of weir without pipes. It is found that there is a large difference between them. Equations and curves for computing the discharge of piped weirs are developed using multiple regression analysis on the bases of dimensional analysis. This research might help irrigation engineers to accurately estimate the discharge for such structures.