Authors:
Hayder Mohammed Kadhim, Mohammed S. Shamkhi, Ahmed Samir Naje

Addresses:
Department of Water Resources Engineering Management, College of Engineering, Al-Qasim Green University, Al-Qasim, Babylon, Iraq. Department of Structures and Water Resources, Faculty of Engineering, University of Kufa, Kufa, Najaf Governorate, Iraq. College of Engineering, University of Warith Al-Anbiyaa, Karbala Governorate, Iraq.

Abstract:

The steady-state and transient flow behaviours of the Al-Hashimiyah Water Treatment pipeline system are examined in this hydraulic evaluation. The steady-state analysis showed a flow velocity of 5.66 m/s, a Reynolds number of 1.18 × 10⁶, and a Darcy-Weisbach friction factor of 0.008. Total head losses, including friction and minor losses, were within the 70 m pressure head limit. A robust hybrid numerical model that merges the Method of Characteristics (MOC) and Method of Integration (MOI) accurately simulates pressure surges induced by unexpected valve closures and pump failures. In simulations, surge pressures reached 205.13 m at 0.347 m³/s, exceeding operational safety requirements, whereas at 0.111 m³/s they remained below 65.56 m. Pump power interruptions caused large pressure dips and negative pressures, leading to vapour pressure violations and increased cavitation risk. Researchers designed and simulated a surge tank with a diameter of 12 m and a height of 15 m, with an effective volume of 1,700 m³, to mitigate transient impacts. The surge tank 70 m downstream of the initial pumping station lowered peak surge pressures by 24.6%. Sensitivity analyses showed that key hydraulic parameters affected the transient response: increasing the pipe diameter from 0.20 m to 0.35 m reduced surge pressure from 191.21 m to 122.32 m, and increasing the friction factor from 0.003 to 0.012 reduced surge pressure from 187.40 m to 149.80 m.

Keywords: Transient Flow; Water Hammer; Surge Tank; Pipeline System; Sensitivity Analysis; Water Transmission Systems; Hydraulic Evaluation; Hydraulic Engineering; Water Treatment.

Received on: 22/12/2024, Revised on: 25/02/2025, Accepted on: 19/05/2025, Published on: 16/12/2025

DOI: 10.69888/FTSESS.2025.000556

FMDB Transactions on Sustainable Environmental Sciences, 2025 Vol. 2 No. 4, Pages: 210-226

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