Future challenges in urban drainage systems under global warming

Abstract

The increase of extreme rainfall intensity and frequency as a result of climate change are predicted to put heavier pressures on existing sewer systems, which could result in urban flooding. By considering different possible levels of greenhouse gas emissions and through the development of sophisticated climate models, it is possible to predict what climate change might look like during the coming century. The broad objective of this chapter is to improve engineers, planners and designers’ appreciation of the potential risks associated with urban drainage systems. This work is applied to a selected site in the North West of England to predict future rainfall using a downscaling model of HadCM3 outputs. The methodology employs the estimated uplift for the future design storm to the existing combined drainage system which is designed according to the current UK standards. Thus the system should sustain rainfalls with a specific return period without detriment to the level of services. Results obtained from InfoWorks CS used in the simulation of the drainage system demonstrated that there is considerable change in the number of flooded manholes together with surcharge in some sewers for winter and summer seasons during the 2080s.