Characterising the pressure-leakage response of pipe networks using the FAVAD equation

This study investigated the feasibility of characterising the pressure-leakage response of water distribution systems using the FAVAD (Fixed and Variable Area Discharges) equation, instead of the conventional N1 power equation. The study was based on 300 network models with randomly distributed leaks and 35 networks generated through a sensitivity analysis. It was found that the leakage rate and average zone pressure head (AZP) before and after pressure reduction may be used in conjunction with the FAVAD equation to estimate the initial leakage area (A_0S) and head-area slope (m_S) of any system. In addition, A_0S and m_s were shown to provide good estimates respectively of the sum of the initial areas and head-area slopes of all the individual leaks in the system. The study found that a dimensionless leakage number may be calculated for any system and used to characterise the pressure-leakage response. Finally, the study showed that it is possible to convert between N1 and the leakage number using a simple equation.