A comparative study between the modified and available demand driven based models for head driven analysis of water distribution networks

Most of the currently available models for Water Distribution Network (WDN) hydraulic analysis assume that the nodal demands are independent of nodal heads and fully supplied. However, in practice, discharge of any node is proportional to its head. Considering a head-discharge relationship for each node in the Head Driven Analysis (HDA) method, provides the ability to model WDNs more accurately and realistically. An improved head-discharge relationship is developed and presented in this paper which takes into account two types of demands, volumetric demand and head dependent demand, separately. Most of the HDA-based models use the Newton-Raphson method for simulation. But considering the advantages of the gradient method, e.g. no need for any initial values for nodal heads and robust performance, it is applied in this research through a modified model capable of calculating leakage. The proposed modified model is evaluated using a sample network. Performance of this model is studied in comparison with the results of other available head driven EPANET-based models. Results confirm the ability of the modified model to perform more accurate hydraulic analysis of WDNs and leakage calculation, especially under pressure deficient conditions.