RISK ASSESSMENT OF URBAN DRINKING WATER SUPPLY SYSTEM: A PILOT SCALE STUDY IN CENTRAL INDIA

Abstract

: Hydraulic integrity problems pose high risk of contamination to treated water within the urban water distribution networks. Routine monitoring and end-of-the-pipe water quality testing do not serve the purpose of preventive risk management in this situation. Many times, contaminated water is consumed prior to its assessment, a major concern for public health in developing countries. The paper presents a strategic approach for identification and quantification of risk in a Large-Size Urban Water Supply Systems (LUWSS). The study uses Geographical Information System (GIS) and Remote Sensing (RS) analysis for mapping, field survey data, and Improved Risk Assessment of Water Distribution System (IRA-WDS) modelling and in-situ measurements of water quality in a pilot study area in Nagpur city. The quantitative risk matrix is generated by quantifying the risk as the product of the probability (likelihood) of occurrence of an event or hazard and the severity of the consequences. Risk characterization from source to consumer indicates High microbial risk due to various activities in the catchment, poor maintenance of the system and intermittent water supply. Model simulations provide exact location of 3% pipes which are in bad condition-that need replacement on priority, and approximately 7% pipes in medium condition - which need regular monitoring and maintenance to ensure drinking water safety. The results are useful to delineate a possible strategy for rehabilitation, and monitoring and maintenance of the network that could be considered to reduce the risks posed by water-quality deteriorating eventsin the distribution systems.