Elsevier

Science of The Total Environment

Volume 670, 20 June 2019, Pages 411-424
Science of The Total Environment

Evaluating natural infrastructure for flood management within the watersheds of selected global cities

https://doi.org/10.1016/j.scitotenv.2019.03.212Get rights and content
Under a Creative Commons license
open access

Highlights

  • Natural water storage metrics are applied to upstream basins of five global cities.

  • Strong reliance on forest, soil and wetland storage is found in four basins.

  • Little of this storage is protected making it vulnerable to land-use modification.

  • The basins show different patterns of flood risk magnitude and spatial distribution.

Abstract

Cities are dependent on their upstream watersheds for storage and gradual release of water into river systems. These watersheds act as important flood mitigation infrastructure, providing an essential ecosystem service. In this paper we use metrics from the WaterWorld model to examine the flood management-relevant natural infrastructure of the upstream watersheds of selected global cities. These metrics enable the characterisation of different types, magnitudes and geographical distributions of potential natural flood storage. The storages are categorised as either green (forest canopy, wetland and soil) or blue (water body and floodplain) storages and the proportion of green to blue indicates how different city upstream basin contexts provide different types and levels of storage which may buffer flood risk. We apply the WaterWorld method for examining flood risk as the ratio of accumulated modelled annual runoff volume to accumulated available green and blue water storage capacity. The aim of these metrics is to highlight areas where there is more runoff than storage capacity and thus where the maintenance or restoration of further natural infrastructure (such as canopy cover, wetlands and soil) could aid in storing more water and thus better alleviate flood risks. Such information is needed by urban planners, city authorities and governments to help prepare cities for climate change impacts.

Keywords

Flood storage
Ecosystem services
Green infrastructure
Land-use change
Protected areas, WaterWorld

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