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10 Facts About Floods

Floods are defined as the sudden covering of normally dry land with water, usually from melting snow, burst dams, storm surge, or heavy rains. Floods can occur in any of the 50 states of the United States, and are the most common reason for a Declaration of Emergency announced by the President. Hurricanes almost always result in flooding disasters, and climate scientists believe that these massive storms will become more frequent and more destructive over the coming decades. As flooding becomes more frequent and more widespread, there will be floods in places that have rarely suffered this fate in the past. Today we take a look at some facts about floods, including a few that may be quite surprising.

Flood damage is rarely included in home or property insurance policies. Unfortunately, this very often comes as a surprise to the homeowner. To be covered for flooding, a special flood insurance policy must be purchased. In some areas, this policy can be prohibitively expensive or even not available at all!

Red car floating in flood waters in Oklahoma

Kingfisher, OK, August 19, 2007 — This red car was washed off the highway and it occupants had to be rescued when Tropical Storm Erin flooded the area. Marvin Nauman/FEMA photo

It does not take much water to carry off a vehicle. Even a bus can be swept away by as little as two feet of water! Every year drivers who are attempting to flee floods make the deadly decision to drive through shallow but fast-moving floodwater, only to be caught up in the flood with no control over the vehicle.

Floods can happen in places where not a drop of rain is falling. The most common scenario is a placid river that suddenly becomes a death trap when a flash flood appears from unseen heavy rain upstream. These flash floods can present a wall of water up to 20′ high, with absolutely no warning!

Natural flooding is essential for farming. We all learned in grade school about the Fertile Triangle and the cradle of civilization, and that this annual flooding from the Tigris and Euphrates was necessary for the deposit of rich new soil for agriculture. Today farmers around the world still depend on floods for the same reason, and have adopted seasonal migrations to avoid the damage while reaping the benefits of this regular flooding.

The world’s most deadly flooding took place in the year 1931, along the Yellow River in China. Between 1-4 million people lost their lives during a series of floods that year.

The most common source of flooding is a river that overflows its banks during heavy snowmelt or rainfall. People who live or own businesses near rivers or estuaries must be prepared for flood damage year after year.

Wetlands are extremely important as flood mitigation agents. Wetlands act as a natural sponge to absorb extra water safely. Communities that preserve natural wetlands or even create new ones are likely to fare better during heavy rainfall or storm surges. Conversely, communities that destroy or develop wetlands are likely to experience destructive ‘areal flooding’ which occurs when there is no place for the water to go. Areal flooding occurs when wetlands are not available, and the land surface is saturated or non-permeable, such as concrete.

A full 17% of urban land resides within the 100-year flood plain. This is very bad news for these areas, as we have seen these so-called 100-year floods happening with increasing frequency- much more often than every 100 years!

Floods can happen even in a desert. As our climate changes and weather patterns shift, heavy rainfall can occur in places that were formerly reliably dry. Deserts, with arid soil and little vegetation, cannot absorb water quickly, leading to flooding.

Flood prevention measures return almost $5 for every $1 invested. With floods becoming more common every year, those who own homes or other properties must now race to invest in flood panels and other mitigation methods before heavy losses are incurred.

Source:: FloodBarrierUSA

Bomb Cyclone Unleashes Historic Flooding

During the middle of March, a dire warning was widely broadcast regarding a severe winter storm system that was poised to strike the U.S. Midwest. In recent years, we have been presented with several sensational new weather catchphrases, such as ‘polar vortex’ and ‘bombogenesis’. The extreme weather warning of this week was also given a horrifyingly descriptive name: we were told that the thing bearing down on a huge portion of the U.S. was called a ‘bomb cyclone’.

It turns out that these terms are not new at all, and have been in use for some time in meteorological circles. Polar vortex, bombogenesis, and bomb cyclone are all actual meteorological terms that describe specific weather conditions. For example, the term bomb cyclone is also called explosive cyclogenesis, and describes an explosively strengthening storm that is capable of unleashing immense power and destruction. That power and destruction was inflicted on a large swath of the Rockies and Great Plains regions, from Nebraska all the way down to Texas.

NOAA satellite image of bombogenesis - March 13, 2019

A satellite image taken on March 13, 2019 shows a large storm system moving towards the eastern United States. GOES-East/NOAA

The storm itself was brutal. Interstates were shut down or blocked by debris, and transportation was all but impossible. The ferocity of the storm was unimaginable — an intense white-out blizzard made even more horrifying by hurricane-force winds — even a few tornadoes — all combined with frigid temperatures so low they were deadly in their own right. It was truly a worst case scenario!

Fortunately, the storm itself did not last long, and by some miracle there was only one fatality attributed to the blizzard. Immediately afterwards, however, a new threat gathered steam. All that snow and hail began to melt in the warmer spring weather that followed the bomb cyclone, and rivers and streams began to swell. Interstates once again became impassable, this time due to flooding rather than snow and ice.

Probably the worst-hit state was Nebraska, which suffered widespread transportation hazards; including sections of vital interstate highways closed, bridges washed out or damaged, and even a nuclear power plant reportedly under threat from encroaching floodwaters. The nuclear plant was later declared safe and operating at full steam, thanks to its advanced system of protective flood barriers. Still, more than half the counties in the state had been declared under a state of emergency, and citizens were urged to stay home if possible.

Throughout the affected region, historic floods devastated farms, homes, and businesses — with rivers cresting at 18′ or more. The states of Iowa and Michigan are also suffering from the aftermath of the bomb cyclone, and authorities continue to struggle with widespread flooding that may take weeks to recede. Although power has been largely restored, supply chains have been disrupted and goods and supplies are under-stocked in many areas.

Sadly, the farmers and ranchers that have already been struggling with other financial disasters will be the hardest hit by these unseasonal and unexpected floods. The massive flooding that has struck huge portions of this farm-dotted landscape has swept away livestock, barns, homes, fields, topsoil, and even expensive heavy equipment. For many farm families, these floods will inflict the final blow.

Source: FloodBarrierUSA

Cities Devise Plans to Combat Climate Change

As government leaders debate climate change, officials and community leaders in cities across the U.S. are taking action to prepare for climate change impacts they believe are inevitable.

In March, New York City Mayor Bill de Blasio proposed a $10 billion plan to build out the Lower Manhattan coastline by as much as 500 feet to protect it from frequent flooding. The area, which includes Wall Street and the South Street Seaport, suffered $19 billion in damage in 2012 when storm surge from Hurricane Sandy flooded real estate, subways and other critical infrastructure.

de Blasio described the proposal as “part of an overall resiliency plan for Lower Manhattan that includes a $500 million project to fortify the area with U-shaped expanse of grassy berms and removable storm-barriers that can be anchored in place as storms approach.”

Detractors of the plan cite concerns about its impact on the marine habitat and coastal environment. Some feel it doesn’t go far enough to protect other parts of the city vulnerable to flooding. The plan also faces additional hurdles that include coordination with Congress, the U.S. Army Corps of Engineers and other entities that may hold it back. (For more about the plan, read the Bloomberg News story www.bloomberg.com/news/articles/2019-03-14/de-blasio-seeks-to-flood-proof-lower-manhattan-by-adding-land.)

Similar proposals by former NYC Mayor Mike Bloomberg and the NYC Economic Development Corporation’s federally-funded $30 million “RISE : NYC” competition have done little to improve the city’s resiliency so far.

Neighborhood Fix

David Levy, professor of Management, Director of the Center for Sustainable Enterprise and Regional Competitiveness, University of Massachusetts, warns “beware the big fix.” His team studied the feasibility of constructing a large barrier across Boston Harbor that would deploy large gates to protect the city from storms. The plan would cost the city an estimated $12 billion over 30 years. The study determined the high cost could not be justified in the face of uncertainty about sea-level rise and global warming.

According to Levy, most resiliency projects provide no immediate benefits and are hard to sell to the public. He recommends a “neighborhood-level approach” that includes “upgrades in housing, transportation and infrastructure.” Additionally, investment by private property owners in flood protection measures like flood gates and flood doors would lessen the public burden.

Some cities have taken steps in this direction. Last year, Miami voters approved a $400 million bond to pay for resiliency projects. In Harris County, Texas, voters still rebuilding after Hurricane Harvey approved $2.5 billion for flood protection. In San Francisco, a $425 million bond to shore up a sea wall was approved. (Read Levy’s article here, theconversation.com/climate-change-resilience-could-save-trillions-in-the-long-run-but-finding-billions-now-to-pay-for-it-is-the-hard-part-108143).

Nuisance Flood Threat

It’s not just major storms that threaten cities. Frequent nuisance flooding in Atlantic City, New Jersey and Annapolis, Maryland is taking an economic toll. According to a Stanford University study, Annapolis lost as much as $172,000 due to 3,000 missed customer visits in 2017 due to flooded businesses. (Read more here, www.bdcnetwork.com/persistent-flooding-having-economic-impact-coastal-cities.)

The most vulnerable cities seem to understand that the climate is changing and they are making efforts to prepare for what’s coming. Given the intensity of recent storms, the sooner the better.

 

Photo credit: By Edgar El, CC BY 3.0, https://commons.wikimedia.org/w/index.php?curid=60246822

The Trouble with Greenland’s Glaciers

Jakobshavn-Isbrae glacier

Scientists have learned that the glaciers of Greenland and Antarctica are melting far faster than previously suspected, creating a flooding hazard to coastal communities all over the world. It is now known that many glaciers that appear to be healthy and solid from above are in fact melting from within, below the surface. This subsurface rot is suddenly revealed when huge glacier formations suddenly fracture, revealing a large empty space beneath, where the ice has already melted. A good analogy is to think of a decayed tooth. The tooth may look and feel strong, but if a cavity lurks beneath the healthy enamel, it can eat away at the tooth from inside, until it one day breaks apart. This is currently happening to huge glaciers in various parts of the world.

There is one place on earth that is causing the most concern regarding global warming in general and melting glaciers in particular. This is the great frozen island of Greenland, which is entirely covered by a huge ice sheet. For reasons not yet fully understood, the glacial ice sheet that covers Greenland is melting much faster than other glaciers. The melting and fracturing of massive glaciers in Antarctica has been reported in the news frequently, with alarming video of enormous icebergs calving and breaking apart. One glacier on the Larsen Sea Shelf calved a stupefyingly huge chunk in late 2018, and the iceberg that broke off was more than four times the size of Manhattan! As scary as this Antarctic melt truly is, the melt that is taking place in Greenland is even worse.

This Landsat data image shows how the Jakobshavn-Isbræ glacier retreated, from left to right, up the Ilulissat fjord between 1851 and 2006. Courtesy NASA Earth Observatory

But all this melting of glaciers and calving of icebergs is not causing hazards exclusively on a local basis. It is not only polar bears and walruses that will be negatively affected by this rapid melt. The freshwater that is pouring into our seas from the melted glaciers in Greenland is creating many, many other threats — up to our own front door, thousands of miles away. For example, the introduction of all this suddenly unlocked freshwater affects salinity, ocean currents, atmospheric conditions, and of course, sea level rise. All these factors affect much more than our oceans!

By the end of this century, it is expected that the planet will see a sea level rise of between half a meter and two meters, or perhaps even more. We have all seen the scary projected maps showing half of Florida swallowed by the sea, but unless we live on the Florida coastline, many of us still continue to underestimate the devastation that sea level rise will bring to all of us. In addition to losing millions of homes, farms, businesses, harbors, infrastructure, and even fisheries, sea level rise will also impact all of us by putting into motion the forces that create stronger and more frequent hurricanes, tornadoes, droughts, monsoons, and even wildfires. In short, we will all be affected, to some extent, by the glaciers melting in Greenland, no matter where we live.

While the worst of this dire future remains outside the life span of people alive today (and it is hoped that corrective measures may be able to reverse or slow the threats) some of these effects are already being felt today. Sea level rise is indisputably eating away at our coastal communities, and flooding is an ever greater threat with each year that goes by. Fortunately, great innovations in the area of flood defense are giving businesses and homeowners important flood-fighting weapons in the struggle against floods. Even as floods become more powerful and frequent, so the flood barriers are constantly being improved and adapted to stay one step ahead of the threat.

Source:: FloodBarrierUSA

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