Impact of outlets manifold configuration on hydraulic stability and water hammer in pumping stations

• Bentley HAMMER software was used to model the transient behavior under different manifold designs. • The manifold placement affects how the water hammer develops and how much pressure transients surge. According to asymmetric flow paths and intensified momentum shifts, the left manifold configuration produced pressure spikes reaching 1350 kPa, compared to the middle. • Surge tanks reduced water hammer effects and improved main pipeline maximum pressures by 25 %. • Engineers and designers can optimize pumping station design through findings that help minimize water hammer risk occurrences. This study presents a new approach to studying the effects of asymmetric outlet manifold influence on hydraulic stability and water hammer dynamics in the pumping station of the Great Al-Samawah Water Project. The researchers executed transient flow analyses with Bentley HAMMER V8i on four different designs, which included the middle and left-side manifolds, both with and without surge tanks. Results revealed that manifold positioning critically affects pressure surges. The left-side configuration (Case 2C) generated higher peak pressures (1350 kPa) compared to the middle layout (Case 1A, 1329 kPa) due to asymmetric flow paths. Surge tanks reduced maximum pressures by 25 % (Case 1B) and 21 % (Case 2D) relative to unprotected systems. However, the left-side manifold with a surge tank (Case 2D) exhibited higher residual pressures (2750 kPa) than the middle counterpart (2300 kPa), emphasizing the influence of manifold geometry on surge tank effectiveness. An optimal manifold design that maintains symmetry and carefully planned surge tank positions is critical to minimizing risk factors from water hammer occurrences and boosting hydraulic system integrity. The research delivers practical design instructions to engineers that optimize infrastructure resilience by combining configuration enhancements with surge tank integration.