Critical overflow of the main combined sewer in the city of Lviv: A case study of recent extreme flooding

Abstract

The city of Lviv in Ukraine has a combined sewer system where the main sewer function is performed by the Poltva River, shaped in the underground concrete channel. In this study improved hydraulic model of Lviv sewerage system was developed, taking into account a pressure flow mode, as well as limit discharge capacities, corresponding to the urban flooding. Hydraulic modelling was conducted for the heavy rainfall event on July 5, 2022. A strong correlation was observed between the actual flood volume and the modelled overflow of the main sewer, obtained through hydraulic modelling.