Journal of Scientific Engineering Advances

Abstract

Hydraulic structures such as bridges and culverts, when poorly integrated within an open channel, can create backwater effects, increase energy losses, and elevate flood risk. This is particularly critical in urban channel recovery projects, where existing structures may be undersized and new structures are planned without system scale analysis. This study presents a practical methodology for optimizing the hydraulic performance of a 750 m rectangular concrete channel located in Tangier, Morocco, which contains three existing bridges, one ex isting 10 barrel culvert, and two projected culverts. A two dimensional hydraulic model was developed using HEC RAS (version 6.7) to simulate flow under four design flood events (Q10 Q20 Q50 and Q100). Baseline simulations revealed that the existing 10 barrel culvert was the primary bottleneck, contributing the largest energy loss and generating upstream backwater. The three bridges also contributed to water surface rises. The optimized configuration consisted of enlarging the central barrels of the prolonged portion of the existing culvert barrels and optimizing the abutments’ length the two projected culverts. At Q₁₀₀, this configuration reduced the upstream water level by an average of 0.20 m while optimizing the costs. The study demonstrates that a manual iterative optimization approach using 2D HEC RAS—requiring no external programming or optimizers—is effective, transparent, and accessible to practicing engineers. Key practical insights include the importance of system scale optimization over structure by structure improvements, the value of compen satory design when existing structures cannot be fully modified, and the need to size projected culverts based on hydraulic performance and cost minimization. The main limitation is exclusion of sediment transport. The methodology is directly transferable to other urban channel recovery projects involving multiple bridges and culverts.