Evaluation of Climate Change Impacts on Urban Drainage Systems by a Storm Runoff Model with a Vector-Based Catchment Delineation

Problems with efficient dewatering following heavy rainfall events are not uncommon already today because of urbanization beyond the sewer system capacity. Sewer drainage system evaluation are required in many cities and a key issue in this situation is whether to take climate change into account. In this study a simulation model for rainfall-runoff and flood inundation model with a vector-based catchment delineation are used. The set-up of this model is based on so-called “urban landscape GIS delineation” that faithfully describes the complicated urban land use features in detail. Modelling was performed using as inputs design storm with 3 year return periods of 180 minutes duration for climate change scenarios. These future design storms were increased by factors of 10%, 20%, 30%, and 40% and the impacts of incremented rainfall events on the urban drainage system were assessed. It was indicated that the surface runoff would increase at higher percentages than infiltration loss and final surface storage.