Floodplains in the Anthropocene: A Global Analysis of the Interplay Between Human Population, Built Environment, and Flood Severity

Abstract

This study presents a global explanatory analysis of the interplay between the severity of flood losses and human presence in floodplain areas. In particular, we relate economic losses and fatalities caused by floods during 1990–2000, with changes in human population and built‐up areas in floodplains during 2000–2015 by exploiting global archives. We found that population and built‐up areas in floodplains increased in the period 2000–2015 for the majority of the analyzed countries, albeit frequent flood losses in the previous period 1990–2000. In some countries, however, population in floodplains decreased in the period 2000–2015, following more severe floods losses that occurred in the period 1975–2000. Our analysis shows that (i) in low‐income countries, population in floodplains increased after a period of high flood fatalities; while (ii) in upper‐middle and high‐income countries, built‐up areas increased after a period of frequent economic losses. In this study, we also provide a general framework to advance knowledge of human‐flood interactions and support the development of sustainable policies and measures for flood risk management and disaster risk reduction.

Urbanizing the floodplain: Global changes of imperviousness in flood-prone areas

“…Despite the variability in the datasets, we consistently found that the population size has increased in urban areas on the floodplain. It is difficult to attribute the accelerated urbanization rates on the floodplain as driven by population or related to commercial and industrial purposes 16 , but these results do agree with recent work that wound that built-up areas and population on the floodplain have increased in most of the world's countries 13 .…”

“…Recent work shows that built-up areas on floodplains have increased 9 , although most studies have been regional 10,11 without a global assessment 1 of floodplain encroachment in both space and time. Moreover, other recent studies have examined the relationship between population dynamics and flooding but have focused on the population response to flood events [12][13][14] . In this paper, we combined maps of fluvial and pluvial flood inundation with maps of urban area changes to quantify floodplain encroachment globally as a function of flood probability rather than the actual occurrence of flooding.…”

Analysis of 220 Years of Floodplain Population Dynamics in the US at Different Spatial Scales

“…However, major urban settlements around the world are still located in floodplain areas or deltas [2]; on average, every year, more than 100 million people are affected by flooding [3,4]. Furthermore, economic flood losses and flood fatalities are on the rise, due, among other factors, to the value of assets in floodplains and the enhanced frequency and magnitude of floods [1,[5][6][7][8].…”

Global riverine flood risk – how do hydrogeomorphic floodplain maps compare to flood hazard maps?

“…Di argue that flood hazard maps and hydrogeomorphic floodplain maps are complementary and should both be used for identifying flood-prone zones in data-scarce regions, following the precautionary principle (Foster et al, 2000). The recently developed global floodplain map GFPLAIN250m (Nardi et al, 2019), hereafter GFPLAIN, built by hydrogeomorphic terrain analysis, has raised interest due to its potential for large-scale riverine flood risk applications (Akhter et al, 2021;Mazzoleni et al, 2020;Nardi et al, 2019).…”