International Conference on Urban Drainage edition:11th location:Edinburgh, Scotland date:31 Aug. - 5 Sept. 2008
Sewer networks and river systems are often studied in a separate way. They may, however, interact in two directions. The first direction is straightforward: sewer effluent and overflow discharges increase the flow and the water levels in the receiving river. In the opposite direction, during storm conditions, high river levels may obstruct urban storm drainage into the river, and consequently the flood risk along the sewer system
may increase. This influence was studied for the Erpe-Mere Municipality combined sewer system in Belgium. Firstly, composite and short duration storm simulati ons were
performed using detailed hydrodynamic SOBEK models. The results of these simulations were used to calibrate simplified conceptual models, which enabled simulation of long historical time series and statistical analysis of simulation results. The study validated the presumption that the sewer-river two-directional interaction enhances both sewer and river flood risks and therefore recommended this effect be taken into consideration during sewer and river infrastructures design. The study recommended and demonstrated the use of simplified models, which after calibration to the full hydrodynamic models using synthetic storms for a range of low to high return periods, reached nearly the same accuracy as the corresponding detailed models but advantageously with shorter computational time.