Pluvial Flooding in European Cities—A Continental Approach to Urban Flood Modelling

Abstract

Pluvial flooding is caused by localized intense rainfall and the flood models used to assess it are normally applied on a city (or part of a city) scale using local rainfall records and a high resolution digital elevation model (DEM). Here, we attempt to model pluvial flooding on a continental scale and calculate the percentage of area flooded for all European cities for a 10-year return period for hourly rainfall (RP10). Difficulties in obtaining hourly rainfall records compromise the estimation of each city RP10 and the Europe-wide DEM spatial resolution is low relative to those typically used for individual case-studies. Nevertheless, the modelling capabilities and necessary computing power make this type of continental study now possible. This is a first attempt at continental city flooding modelling and our methodology was designed so that our results can easily be updated as better/more data becomes available. The results for each city depend on the interplay of rainfall intensity, the elevation map of the city and the flow paths that are created. In general, cities with lower percentage of city flooded are in the north and west coastal areas of Europe, while the higher percentages are seen in continental and Mediterranean areas.

Effects of Impervious Surface on the Spatial Distribution of Urban Waterlogging Risk Spots at Multiple Scales in Guangzhou, South China

“…The term "waterlogging" used in our study was used in previous studies [15,40], which was also called "pluvial flooding" in a few literature works [41,42]. To fully quantify waterlogging, at least three aspects were included, i.e., waterlogging spot location and inundation range and depth.…”

Towards identification of critical rainfall thresholds for urban pluvial flooding prediction based on crowdsourced flood observations

“…A widely used approach is to analyze urban pluvial flooding through hydrodynamic models (Van Bijnen et al, 2012;Candela and Aronica, 2016;Guerreiro et al, 2017;Löwe et al, 2017;Ochoa-Rodriguez et al, 2015;Palla et 5 al., 2016;Thorndahl et al, 2016). Hydrodynamic models include the interaction between overland flows and sewer flows and are usually based on the Saint Venant equations to model flood wave propagation (Ochoa-Rodriguez et al, 2015;Palla et al, 2016;Thorndahl et al, 2016).…”

“…This data is actually also suitable for hydrodynamic modelling. For example, all hydrodynamic models rely on elevation data to characterize overland flow Van Dijk et al, 2014;Guerreiro et al, 2017;Palla et al, 2016;Thorndahl et al, 2016). Digital Elevation Models (DEM) can be used to delineate urban (sub)watersheds with GIS software to analyze preferential overland flow paths of surface runoff.…”

Pluvial Flood Risk Assessment Tool (PFRA) for Rainwater Management and Adaptation to Climate Change in Newly Urbanised Areas

“…In conjunction with urban growth, an increase in the frequency and patterns of high intensity rainfall is expected [13]. The interplay of land cover, urban fabric density, and extreme and high-rate precipitation, which far exceed the capacity of a city's drainage systems and the urban topography, may lead to pluvial flash floods [14][15][16]. A pluvial flood results from intense, often convective, rainstorms, which generate a rapid overland flow and pluvial inundation.…”