Quantification of anticipated future changes in high resolution design rainfall for urban areas

Good performance of sewer systems is of paramount importance in modern cities. The last decades have shown an increase in the frequency of large storms, leading to flooding of urban areas, implying large direct and indirect costs to society. It is becoming necessary to assess to what extent changes in extreme rainfall will continue due to anthropogenic greenhouse gas emissions and socio-economic development paths. Changes in rainfall are usually predicted using General Circulation Models. However, these models cannot be used directly to predict changes in extreme point rainfall because the temporal and spatial resolution is too coarse. This paper presents an approach to overcoming the scale problem by constructing a model of rainfall based on the Random Parameter Bartlett–Lewis rectangular pulse model in combination with a multi-scaling disaggregator. The model performs well and indicates that an increase of 2–15% in extreme rainfall can be expected in Denmark the next 80 years.