Flooding of Urban Drainage Systems: Risk Analysis Study

Abstract

Floods are considered as to be among the most severe natural disasters because of their unpredictability, their overwhelming power and the difficulty to assess the related risks. Consequently, flooding damage is inevitable. This paper focuses on the identification of potential flood hazards in urban drainage systems. The flooding causes and modes are analyzed by two main methods: fault tree and event tree. The frequencies of natural events and operational obstacles are estimated based on measured climate data and operational records. Consequences of flooding are classified based on the people at risk, the property damages and environmental impacts. As a result, the flooding risks are described in combination with frequency analysis and consequence analysis, which can be used as a basis for rational flooding mitigation strategies. Nasik municipality in Maharashtra is used as a case study. The study indicates that it is valuable to analyze the risks of flooding in such an integrated way in order to control and reduce the risks as low as reasonably practical. The study also reveals that the joint risk of different hazards is significant and definitely deteriorates the flooding situation. Needless to say, that the value of such analysis is a function of the availability, comprehensiveness and quality of the applied data.