Global projections of river flood risk in a warmer world

Abstract

Rising global temperature has put increasing pressure on understanding the linkage between atmospheric warming and the occurrence of natural hazards. While the Paris Agreement has set the ambitious target to limiting global warming to 1.5 ∘ C compared to preindustrial levels, scientists are urged to explore scenarios for different warming thresholds and quantify ranges of socioeconomic impact. In this work, we present a framework to estimate the economic damage and population affected by river floods at global scale. It is based on a modeling cascade involving hydrological, hydraulic and socioeconomic impact simulations, and makes use of state-of-the-art global layers of hazard, exposure and vulnerability at 1-km grid resolution. An ensemble of seven high-resolution global climate projections based on Representative Concentration Pathways 8.5 is used to derive streamflow simulations in the present and in the future climate. Those were analyzed to assess the frequency and magnitude of river floods and their impacts under scenarios corresponding to 1.5 ∘ C, 2 ∘ C, and 4 ∘ C global warming. Results indicate a clear positive correlation between atmospheric warming and future flood risk at global scale. At 4 ∘ C global warming, countries representing more than 70% of the global population and global gross domestic product will face increases in flood risk in excess of 500%. Changes in flood risk are unevenly distributed, with the largest increases in Asia, U.S., and Europe. In contrast, changes are statistically not significant in most countries in Africa and Oceania for all considered warming levels.

A global framework for future costs and benefits of river-flood protection in urban areas

“…35 Several studies have assessed flood risk using simple assumptions of current protection standards 3,10,11 . 36 However, they did not assess costs and benefits of further investments in increasing flood protection. 37 This information is useful for planning investments in flood risk management and adaptation 12,13,14 .…”

“…The JRC model has been used to assess future changes in flood risk 36 . However, they only used 362 inundation maps at 30" x 30" (i.e.…”

Global change in streamflow extremes under climate change over the 21st century

“…5864 B. Asadieh and N. Y. Krakauer: Global change in streamflow extremes with relatively stronger impact than for mean precipitation Lambert et al, 2008;Pall et al, 2006). Change in intensity and distribution of precipitation events under climate change is expected to increase the intensity and frequency of flood and drought events in many regions (Alfieri et al, 2015(Alfieri et al, , 2017Krakauer, 2015, 2016;Dankers et al, 2013;Ehsani et al, 2017;Field, 2012;Held and Soden, 2006;Min et al, 2011;O'Gorman and Schneider, 2009;Stocker et al, 2013).…”

A Bayesian framework based on a Gaussian mixture model and radial-basis-function Fisher discriminant analysis (BayGmmKda V1.1) for spatial prediction of floods

“…Recent statistics on flood damages for the period of shows that flooding affected 109 million people around the globe per year (Alfieri et al, 2017) and killed more than 220 000 people (Winsemius et al, 2015). Although the frequency of flooding has decreased in several regions (i.e., in central Asia and America), flood occurrences have increased globally by 42 % (Hirabayashi et al, 2013).…”