Advancements in water distribution network simulation by Enhanced GGA

The advent of information technology and geographical information systems in water industry allows a detailed description of Water Distribution Network (WDN) topology and its boundary conditions. However, the complexity of network analysis and the mathematical problem size related to the hydraulic simulation considerably increase, especially for large WDN. The present paper introduces a network simplification strategy based on a correction paradigm adopted by Giustolisi and Todini in the Enhanced Global Gradient Algorithm (EGGA). Starting from the original topology of the analyzed WDN, the proposed strategy identifies the serial nodes/sections (i.e. those adjacent to two nodes/pipes only) which are iteratively removed from network topological representation. Therefore, the new network topology contains only those nodes joining three or more pipes or the terminal nodes of branched sections. Such a topological simplification results into a lower dimension of the topological matrices underlying the hydraulic simulation model. This way the WDN analysis can be performed using the EGGA formulation increasing computational efficiency, especially for large-size networks, without forfeiting energy and mass balances of the original hydraulic system. The paper reports the general formulation of EGGA and the strategy is tested on two large-size networks (of 1,461 and 12,513 internal nodes). The results are compared with those obtained using the original WDN topology and the classic Global Gradient Algorithm (GGA). Thus, it has been demonstrated that the EGGA strategy of simplification allows achieving a computational efficiency while correctly representing the hydraulic behaviour of the network.