How Pluvial Floods in Urban Areas Vary with Rain Return Period
Examensarbete för masterexamen
Infrastructure and environmental engineering (MPIEE), MSc
Urban floods are the most frequently occurring natural disasters, posing significant threats to cities worldwide. The risk for pluvial floods (i.e. floods due to intense rain fall) is increasing, and thereby, several initiatives have been established worldwide. The aim of this study is to develop a tool to simplify the process of implementing a cloudburst area in different types of residential areas by estimating a manageable rain return period. The study evaluated floods generated by rain from return periods in the range of 10-100 years, in four different residential areas with nearby cloudburst areas, all located in the City of Gothenburg. Further, the study included an evaluation of the site characteristics of each residential area. Ten rain events (each representing a different return period) were simulated using the hydrodynamic modeling software MIKE+. Simulations were conducted both without and with cloudburst areas. From the results of the simulations without cloudburst areas, a relation between flood and rain return period was established for each residential area separately. No general relation was identified for all investigated areas. However, a correlation was found for two of the areas consisting of townhouses. Based on the correlation between the two areas, a framework for a tool was developed. The developed tool provides an estimation of the manageable rain return period due to the implementation of a cloudburst area in residential areas with townhouses. From the study, it is concluded that to accomplish full utilization of the cloudburst area it is necessary to evaluate both if other measures are required and the most suitable location of the cloudburst area. From the evaluation of site characteristics, different physical parameters were identified to influence the resilience against floods in different areas, e.g. sewer network capacity, building structure, and depression storage capacity. Further, this study concluded that topography had a distinct impact on flooding in all areas.
flood management, hydrodynamic modeling, MIKE+, pluvial flood, rain return period, urban flood.