Hydraulic and Environmental Reliability Model of Urban Drainage

The aim of the paper is to describe HELLMUD Tool developed for supporting decision-making process concerning sewer rehabilitation. Brief overview of methodology for calculation of probability of hydraulic and environmental failure, development of HELLMUD software tool and its application on real sewer network are main parts of the paper. Hydraulic and environmental performance of a sewer system on pipe and CSO (Combined Sewer Overflow) level were determined by means of 17 criteria, consequently transformed into five complex criteria describing and evaluating each pipe and CSO — hydraulic, velocity and infiltration risk (hydraulic viewpoint), exfiltration risk and CSO evaluation (environmental viewpoint). HELLMUD Tool was applied on Ivancice catchment. Reliability analysis provided by HELLMUD Tool can be used in the decision making process for evaluation or ranking rehabilitation projects, or to design of long term rehabilitation strategies.