Deriving global flood hazard maps of fluvial floods through a physical model cascade

Abstract

Global flood hazard maps can be used in the assessment of flood risk in a number of different applications, including (re)insurance and large scale flood preparedness. Such global hazard maps can be generated using large scale physically based models of rainfall-runoff and river routing, when used in conjunction with a number of post-processing methods. In this study, the European Centre for Medium Range Weather Forecasts (ECMWF) land surface model is coupled to ERA-Interim reanalysis meteorological forcing data, and resultant runoff is passed to a river routing algorithm which simulates floodplains and flood flow across the global land area. The global hazard map is based on a 30 yr (1979–2010) simulation period. A Gumbel distribution is fitted to the annual maxima flows to derive a number of flood return periods. The return periods are calculated initially for a 25 × 25 km grid, which is then reprojected onto a 1 × 1 km grid to derive maps of higher resolution and estimate flooded fractional area for the individual 25 × 25 km cells. Several global and regional maps of flood return periods ranging from 2 to 500 yr are presented. The results compare reasonably to a benchmark data set of global flood hazard. The developed methodology can be applied to other datasets on a global or regional scale

Global hydrology 2015: State, trends, and directions

“…New developments in these models are the inclusion of reservoir operations [Haddeland et al, 2006;Hanasaki et al, 2006], hydrodynamic routing , floodplain inundation [Yamazaki et al, 2011], and determining water scarcity at a monthly time scale to account for intraannual variability of availability and demand [Hanasaki et al, 2008b;Wada et al, 2011aWada et al, , 2011b. Apart from global water stress assessments, GHWMs and MHMs have recently been used for modeling global freshwater temperature Van Vliet et al, 2012], global flood hazard and risk [Pappenberger et al, 2012;Hirabayashi et al, 2013;Ward et al, 2013], groundwater depletion [Wada et al, 2010;Gleeson et al, 2011], the contribution of terrestrial water stores to global sea level change Pohkrel et al, 2013], methane emission [Petrescu et al, 2010;Ringeval et al, 2014], and medium range to seasonal streamflow forecasting [Alfieri et al, 2013;Candogan Yossef et al, 2013]. Most of the current MHMs and GHWMs run with a spatial resolution of 30 arc min (50 km at the equator) and with daily time steps.…”

Continuous, large‐scale simulation model for flood risk assessments: proof‐of‐concept

“…Then, simulations were performed for each subdomain on a higher resolution of 100 × 100 m. Finally, flood extent maps were merged into a single one. Even on a global scale, inundation models are applied now for flood hazard mapping (Yamazaki et al, 2011;Pappenberger et al, 2012) or flood risk assessments (Winsemius et al, 2013). The methods are dominated by simple inundation models and coarse resolutions of 1 × 1 km or more that are appropriate for global scale, however, less suitable for flood risk assessments on large basin scale covering some 10 000 km 2 .…”

Large‐scale high‐resolution pluvial flood hazard mapping using the raster‐based hydrodynamic two‐dimensional model FloodAreaHPC

“…There are two main methodologies in flood hazard mapping: event-based and continuous modelling. In fluvial flood hazard assessment, there are new approaches of applying continuous modelling using a coupled hydrologichydraulic model on a large scale (Pappenberger et al, 2012;Grimaldi et al, 2013aGrimaldi et al, ,2013bGiustarini et al, 2015). The advantage compared to an event-based approach is that with a fully-continuous approach there is no need to use the concept of design hyetographs and design hydrographs.…”