Analysis of water distribution networks operating under intermittent supply conditions using SWMM 5.1

Abstract

Intermittent water supply is prevalent among most of Syrian municipalities, residents are forced to install household tanks in order to collect water during the supply period, ground tanks can be installed, or water is pumped directly from the network, this leads to the network being completely or partially emptied of water during the cut-off period, and the atmospheric pressure dominate within the pipes, the network operates under open channel conditions. At the beginning of the next supply period, the network is charged with water, which expels the air from the pipes, so the pressure within the pipes increases rapidly and the water passes at high speeds, and a high-pressure wave similar to a water hammer can be formed. Hydraulic models create an effective tool for understanding the behavior of the network, identifying its problems and weaknesses, finding and experimenting appropriate solutions to avoid the negatives of intermittent supply without the need to work on the actual networks. The used water networks models such as EPANET2.2 consider that the network is completely filled with water during the entire simulation period, which makes it unsuitable for understanding the behavior of the network during the charge period. The research aims to use the SWMM5.1 to study the charging period. The research result shows, that the air expelled during the sudden charge of the network, leads to high velocity values that last for a short period of time and reaches 14m/s, with a large fluctuation in its values, a high-pressure wave is also formed with a large fluctuation in its values before getting stable. For the gradual supply or when the network is full of water at the beginning of the supply period, the resulting velocity does not exceed 4m/s, and there are no large fluctuations in its values, the pressure increases gradually until reaching the stability value. It was found that the SWMM is suitable for the simulation of network charge at the beginning of the supply period.