While water scarcity is a major concern, too much water falling too fast
as rain will cause destructive flooding. Low lying developments around lakes and
rivers are most vulnerable. One feature of global warming is increased rainfall
in areas that previously were flood-free. Floods occur in many countries. In
Canada and the USA recent floods have been called “the worst natural disasters.”
In August 2016, prolonged rainfall in southern parts of the U.S. state of
Louisiana resulted in catastrophic flooding that submerged thousands of houses
and businesses. Many rivers and waterways, particularly the Amite and
Comite rivers, reached record levels, and rainfall exceeded 20 inches (510mm)
in multiple parishes. The flood has been called the worst US natural disaster
since Hurricane Sandy in 2012.
In Canada, floods occur five times as often as wildfires. A major flood
occurred in Alberta. The 2013 Calgary and Southern Alberta Flood started on June
20, 2013 and was focused in communities in and around Calgary. Waters rose
quickly and by June 21, 100,000 people had been evacuated. In Canmore, a town
in Alberta's Rockies, over 220 millimeters (8.7in of rain) fell in just 36
hours, half of the town's annual average rainfall. In the town of High River,
rainfall amounts at one weather station recorded 325 millimeters (12.8in) in
less than 48 hours. The rain falling on already saturated ground, coupled with
the steep watershed and heavy snow loads remaining in the front ranges of the
Rocky Mountains, resulted in a rapid increase in the size and flow of several
river. Total damage estimates exceeded C$5 billion. Receding waters gave way to
a mammoth cleanup of affected areas, aided by a spontaneous volunteer campaign.
[i] Floods paradoxically reduce the supply of fresh
water suitable for human use. Flooding waters collect debris and spread microbes
and toxins into fresh water supplies-ground water, shallow wells and
aquifers may all be contaminated.
Flooded communities have a big job as they attempt to replace homes, roads,
and water supplies. Wet buildings become mold incubators. When Hurricane
Katrina struck New Orleans in August 2005 120,000 homes were damaged by flood
waters. Even when flood damaged buildings dry out, mold growth is often
excessive and prolonged because water remains in walls. Wet fiberglass
insulation and plaster board usually have to be replaced. Some buildings cannot
be restored to healthy conditions. Solomon et al measured high concentrations of
mold indoors and outdoors in New Orleans following the flood. They concluded
that persisting mold growth was a significant respiratory hazard and encouraged
the use of personal protective equipment for workers and returning residents in
order to prevent respiratory morbidity.[ii]
Jarvis described the attempts to deal with flooding and the cost involved:”
Flooding is the most common, and most expensive, natural disaster in the United
States. Private insurers have long declined to cover it, leaving the government
on the hook for disaster assistance after floods, Congress created the National
Flood Insurance Program ( N.F.I.P.)in the late 1960s in response to a
series of expensive floods caused by hurricanes and overflowing rivers. It
offers insurance coverage, some of it subsidized, to communities that meet
floodplain-management requirements; requires people who want loans to buy houses
in dangerous places to buy it; and also provides grants for mitigation projects
meant to reduce flooding damage, like elevating houses or buying out the owners
of flood-prone homes. The N.F.I.P. was meant to encourage safer building
practices. Critics argue that instead it created a perverse incentive — a moral
hazard — to build, and to stay, in flood-prone areas by bailing people out
repeatedly and by spreading, and in that way hiding, the true costs of risk.
And then came Hurricanes Katrina, Wilma and Rita, which in 2005 left the
N.F.I.P. with claims six times higher than it had seen in any previous year. To
cover them, it borrowed $17.3 billion from the Treasury. Hurricane Sandy in 2012
meant another $6.25 billion in debt, along with allegations that insurance
companies distributing FEMA funds were shorting policyholders; 2016, when there
were floods in Louisiana, Texas, Virginia and elsewhere, managed to be the
third-most-expensive year in the N.F.I.P.’s history even with no single standout
catastrophe, deepening the hole further. Servicing the debt is expensive, but
FEMA sees no way to repay it, Roy Wright, the N.F.I.P. administrator, told
Congress last month.”[iii]
[i]Wilkepedia. Alberta Floods. https://en.wikipedia.org/wiki/2013_Alberta_floods
[ii] Gina M. Solomon; Mervi Hjelmroos-Koski; Miriam
Rotkin-Ellman; S. Katharine Hammond. Airborne Mold and Endotoxin Concentrations
in New Orleans, Louisiana, after Flooding, October through November 2005.
Environ Health Perspect. 2006;114(9):1410-1420. ©2006National Institute of
Environmental Health Sciences.
[iii] Brooke Jarvis.
When Rising Seas Transform Risk Into Certainty. Along parts of the East Coast,
the entire system of insuring coastal property is beginning to break down.
NYT Climate Issue. April 18, 2017
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