Reliability Analysis for Water Supply Distribution and Storm Water Drainage Systems: State of the Art Review

Abstract

For urban community, the water supply system is one of the vital services. Hydraulic design of reservoirs, tanks and the water distribution or wastewater networks is carried out for the design capacity. Codes and standards generally lack the provisions for incorporating concept of reliability in design. A very important hydro system for urban life, especially for coastal cities experiencing torrential rains like Mumbai, is the storm water drainage system. Reliability estimates for the storm water drainage network under the extreme event conditions form another challenge. The various uncertainties involved in water supply systems would include temporal variations of the demand, structural failure of the pipeline or storage tanks, malfunctioning of the valves or pumps, data handling and modelling uncertainties. In case of the storm water drainage systems, the uncertainties could be the storm characteristics, the infiltration and local detentions, or the local choking of the drainage network. The reliability approaches adopted for hydro systems over last few decades include: probability distribution functions and joint probability distributions functions, variance-based methods, perturbed physics models, capacity weighted reliability index, copulas, rank histogram and rank bipolar diagram, method of least square technique, Monte Carlo simulations, fuzzy logic, artificial neural network, functional resonance analysis method, ensemble techniques, Advanced First Order Second Moment method and Bayesian approaches. In this article, the state of the art is presented for reliability estimation for the different essential systems related to water supply, wastewater network, and storm water drainage and flood risk assessment for urban areas.