Introducing a Pressure Index for Water Distribution Networks' Augmentation Planning Strategy

Potable Water Distribution Systems (WDS) need augmentation strategies based on a determined and pre-defined time intervals. The main aim of potable water systems augmentation is maintaining the standard and acceptable level of service after occurrences of increase in design serviced population, asset ageing and/or serviced area. It is obvious that systems augmentations require significant amount of budget allocation, which is the main constraint for the water authorities for the implementation of any augmentation plan. In general, two main factors are playing roles in planning of WDS augmentation strategies; namely, the parameter of 'Level of Service' on one hand and the factor of 'Augmentation Cost' on the other. The main goal of a proper planning in a WDS is the prediction of a system's water demand in future and suggestion of an appropriate and efficient solution for the predicted demand. Till now, no research has been conducted to establish a relationship between 'Level of Service' and 'Augmentation Cost'. In this paper, a new index is introduced to measure the level of service of a water distribution system from its pressures point of view. Since there is no existing factor for the rating of a water network from its pressures point of view, a new factor named 'Pressure Index (PI)' incorporating number of pipe nodes for five different pressure regimes is defined. The PI factor is expected to show improvement after a WDS augmentation which is the indicator of that WDS pressures improvement and therefore the effectiveness of proposed planning scheme. As a case study, three existing water network systems in Castlemaine area near central Victoria is investigated and relationship with the augmentation costs and PI factors is presented.