A Peaking Factor Based Statistical Approach to the Incorporation of Variations in Demands in the Reliability Analysis of Water Distribution Systems

摘要

Reliability is becoming a prime issue in the management of water distribution systems. In the literature few studies can be found in which the variation of demand has been considered for reliability analysis purposes. Water demands are not fixed and consideration of the probabilistic nature of demand should lead to more realistic assessments of the performance of water distribution systems. Using water consumption data it was found that possible distributions are the normal and lognormal distributions. Demands for critical periods can be estimated by multiplying the average consumption value by an appropriate peaking factor. This peaking factor approach coupled with the statistical modelling of demands provides a more realistic formulation for incorporating variations in demands in the evaluation of system performance. A major advantage of the proposed approach is that it provides a means of estimating the probability that any critical demand value will be exceeded. A corollary of this statement is that whatever demand values are used to assess the reliability of a water distribution system, the method proposed herein enables confidence levels to be associated with the reliability values obtained. The method is illustrated by means of examples.