Simplification is an important design step of water supply and irrigation
pipes networks. It is recognized by making the original network easier to be understood and analyzed. Water hammer in water-supply networks may give
rise to high and low pressures, due to the superposition of reflected pressure waves. The effect of pipes networks’ simplification on water hammer phenomenon is investigated. This study uses a simple two loops pipes network composed of 12 high density polyethylenes (HDPE) pipes with different diameters, thicknesses, and roughness coefficients representing of a general parallel/series system. The network is fed from a boundary head reservoir and loaded by either distributed or concentrated boundary water demands. According to both hydraulic and hydraulic plus water quality equivalence, three levels of simplifications on the original network are performed. Also, the effect of water demands’ concentration on the transient flow is checked. The transient flow in the network is initialized by either concentrated or distributed boundary water demands which are suddenly shut-off or released. Water hammer and mass oscillation (WHAMO) software which uses the implicit finite difference scheme for solving the momentum and continuity equations at unsteady-state case is used in the simulation. All scenarios produced results showed that both hydraulic equivalence and demands’ concentration simplifications increase the
transient pressure and flow rate in the simplified network compared with the original one. However, hydraulic plus water quality equivalence simplification results in an adverse effect. It was found that, as the degree of simplification increases the transient pressure head and flow rate of the simplified network deviate more from those of the original network. Therefore, simplifications of the distribution networks should be done with very careful caution.