Role of dams in reducing global flood exposure under climate change

Abstract

Globally, flood risk is projected to increase in the future due to climate change and population growth. Here, we quantify the role of dams in flood mitigation, previously unaccounted for in global flood studies, by simulating the floodplain dynamics and flow regulation by dams. We show that, ignoring flow regulation by dams, the average number of people exposed to flooding below dams amount to 9.1 and 15.3 million per year, by the end of the 21st century (holding population constant), for the representative concentration pathway (RCP) 2.6 and 6.0, respectively. Accounting for dams reduces the number of people exposed to floods by 20.6 and 12.9% (for RCP2.6 and RCP6.0, respectively). While environmental problems caused by dams warrant further investigations, our results indicate that consideration of dams significantly affect the estimation of future population exposure to flood, emphasizing the need to integrate them in model-based impact analysis of climate change.

Assessment of damage during the formation and passage of mudflows in the Tashkent region

“…Precipitation is considered dangerous, the amount of which in 12 hours or less exceeds 15 mm in case of rain and 7 mm in case of snow. The corresponding criterion for especially hazardous precipitation, which is considered a natural phenomenon, is considered to be fallout for the same period of 30mm with rain and 20mm with snow [21][22][23][24][25][26][27][28].…”

Comment on essd-2021-58

“…Since around the 1950s, the world has seen an unprecedented boom in large dam construction as a response to the evergrowing human demands for water and energy (Chao et al, 2008;Wada et al, 2017). Today, dams and their impounded reservoirs are ubiquitous across many global basins, providing multiple services that range from hydropower and flood control to water supply and navigation (Belletti et al, 2020;Biemans et al, 2011;Boulange et al, 2021;Doll et al, 2009;Grill et al, 2019). These benefits were, however, often gained at the costs of fragmenting river systems, submerging arable lands, displacing population, and disturbing climate regimes (Carpenter et al, 2011;Cretaux et al, 2015;Degu et al, 2011;Grill et al, 2019;Latrubesse et al, 2017;Nilsson and Berggren, 2000;Tilt et al, 2009;Vorosmarty et al, 2003;Wang et al, 2017).…”

“…Since its publication, GRanD has been applied extensively by a variety of studies, although its focus is on the world's largest dams (e.g., >0.1 km 3 ) and its quantity (7320 dams) is only a fraction of the 59,000 dams documented in WRD. A spatially resolved inclusion of additional large dams, such as those in compliance with the ICOLD definition, has been increasingly desired by the hydrology community and encouraged by growing collaborations from multiple disciplines such as biogeochemistry, ecology, energy planning, and infrastructure managements (Belletti et al, 2020;Boulange et al, 2021;Grill et al, 2019;Lin et al, 2019;Wada et al, 2017). resulted in the georeferencing of 11,859 WRD dams.…”

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

“…Although the simulation that we used to delineate the floodplain globally relied on a state-of-the-art hydrodynamic model, it only approximately accounted for flood protection measures (see Methods for details). The presence of flood defenses such as dams and levees would reduce the flood risk to the exposed population 32 , and there have been recent efforts to improve their representation in high-resolution, large-area models 33 . On the other hand, there have been a number of studies positing that the installation of structural protection measures changes the perception of risk at an institutional level leading to the further urbanization and population increase (or resettling after a flood event) in flood-prone areas 12 .…”