Coastal flooding will disproportionately impact 31 million people
globally
Study is first to assess the impact of climate change on the global
population of river deltas

Date:
October 2, 2020
Source:
Indiana University
Summary:
Researchers analyzed these geographic regions, which include cities
like New Orleans, Bangkok, and Shanghai, using a new global dataset
to determine how many people live on river deltas, how many are
vulnerable to a 100-year storm surge event, and the ability of
the deltas to naturally mitigate impacts of climate change.



FULL STORY ========================================================================== Thirty-one million people living in river deltas are at high risk of experiencing flooding and other impacts from tropical cyclones and
climate change, according to a study by Indiana University researchers.


==========================================================================
"To date, no one has successfully quantified the global population on
river deltas and assessed the cumulative impacts from climate change,"
said Douglas Edmonds, the Malcolm and Sylvia Boyce Chair in the Department
of Earth and Atmospheric Sciences and lead author on the study. "Since
river deltas have long been recognized as hotspots of population growth,
and with increasing impacts from climate change, we realized we needed
to properly quantify what the cumulative risks are in river deltas."
The findings are the result of a collaboration facilitated by IU's
Institute for Advanced Study with support from the Environmental
Resilience Institute.

The team's analysis shows that river deltas occupy 0.5 percent of
the earth's land surface, yet they contain 4.5 percent of the global
population -- a total of 339 million people. Because river deltas form at
the ocean at or below sea level, they are highly prone to storm surges,
which are expected to occur more frequently due to climate change-fueled sea-level rise and coastal flooding.

In the study, IU researchers analyzed these geographic regions, which
include cities like New Orleans, Bangkok, and Shanghai, using a new
global dataset to determine how many people live on river deltas, how
many are vulnerable to a 100-year storm surge event, and the ability of
the deltas to naturally mitigate impacts of climate change.

"River deltas present special challenges for predicting coastal floods
that deserve more attention in discussions about the future impacts of
climate change," said IU Distinguished Professor of Anthropology Eduardo Brondizio, a co-author of the study who has been working with rural
and urban communities in the Amazon delta for 3 decades. "Our estimates
are likely a minimum because the storm surge and flooding models do not
account for the compound interactions of the climate impacts, deficient infrastructure, and high population density." With Edmonds and Brondizio, co-authors on the study include Rebecca Caldwell and graduate student
Sacha Siani.

In addition to the threat of flooding, many of the residents in river
deltas are low-income and experience water, soil, and air pollution,
poor and subnormal housing infrastructure, and limited access to public services.

According to the study, of the 339 million people living on deltas
throughout the world, 31 million of these people are living in the
100-year storm surge floodplains. To make matters worse, 92 percent of
the 31 million live in developing or least-developed economies. As a
result, some of the most disadvantaged populations are among the most
at-risk to the impacts of climate change.

"These communities are already dealing with health risks, lack of
sanitation and services, poverty, and exposure to flooding and other environmental risks.

Climate change is exacerbating all of these issues and creating more
impacts," Brondizio said.

To conduct their study, the researchers created a global dataset of delta populations and areas, aggregating 2,174 delta locations. They then cross- referenced the dataset with a land population count to determine how many people were living in the deltas. To determine the natural mitigation
capacity of the deltas, researchers looked at the volume of incoming
sediment deposited by rivers and other waterways flowing out to sea. The
volume of incoming sediment was compared to the relative area of the
delta to determine if the delta would be considered sediment starved
and thus unable to naturally mitigate flooding.

Decades of engineering have expanded the habitable land area of river
deltas, but they've also starved the regions of flood-preventing
sediment. Without the sediment being renewed naturally, the shorelines
will continue to recede, worsening the impacts of storm surges "To
effectively prepare for more intense future coastal flooding, we need to reframe it as a problem that disproportionately impacts people on river
deltas in developing and least-developed economies," said Edmonds. "We
need better models for the climate impacts that are capable of stimulating compound flooding in densely populated areas so that exposure and risk
can be mapped to more accurately assess risk and vulnerability."

========================================================================== Story Source: Materials provided by Indiana_University. Original written
by Joe Lange. Note: Content may be edited for style and length.


========================================================================== Journal Reference:
1. Douglas A. Edmonds, Rebecca L. Caldwell, Eduardo S. Brondizio,
Sacha M.

O. Siani. Coastal flooding will disproportionately impact
people on river deltas. Nature Communications, 2020; 11 (1) DOI:
10.1038/s41467-020- 18531-4 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2020/10/201002091055.htm

--- up 5 weeks, 4 days, 6 hours, 50 minutes
* Origin: -=> Castle Rock BBS <=- Now Husky HPT Powered! (1337:3/111)