Reliability and Risk in a Water Supply System Emphasising Drought Periods

Abstract

While the issue of defining risk and the associated problem of providing acceptable levels of reliability in urban water distribution networks has received a considerable degree of attention over the last few decades, there is still no universally accepted and computationally feasible measure for assessment of reliability of water distribution network nor an agreement or understanding of what constitutes an acceptable level of reliability (Goulter, 1995). In order to provide comprehensive interpretations of the reliability performance of the network, most approaches to consideration of risk and reliability of water supply systems attempt to examine, implicitly or explicitly, the complete range of events which contribute to, or detract from, the reliability of the system. Extreme events such as droughts which are major determinants in the assessment of risk and reliability in water distribution networks are clearly contained in the spectrum of events which must be considered in these approaches. This paper examines

• (i) the risk to water distribution networks that droughts constitute,

• (ii) the associated impacts of those risks on the reliability of the system, and

• (iii) new concepts and strategies for the management, design and operation of water supply systems which can be employed to improve their performance, in terms of reliability and risk, in the face of drought situations.