Mark Cochrane on nuisance flooding

30 12 2014

One of the ways that climate change is showing up already is by increasing the frequency of ‘so-called’ nuisance flooding. This isn’t the Biblical floods that the news widely reports, which are still relatively rare events, but the minor flooding that closes roads, compromises infrastructure (e.g. storm drains), and ends up in the basements of homes and businesses. I got two doses of this sort of flooding in a storage unit I had this year…

In any case, the main place where this phenomenon has really increased in frequency is along the coasts. The reason being that coastlines are facing the double whammy of heavier rains/storms and rising sea levels. The following graphic sums this up nicely.

NOAA has recently produced a report on the amount of increase in nuisance flooding along the continental United States’ three coastlines. The changes are not subtle. Since the 1960s, nuisance flooding has increased by between 300 and 925%, depending on location. Don’t you wish you could get this kind of returns on your investments? This isn’t all a function of climate change, but it is a function of our activities. In addition to climate related changes to rain and sea, many locations are also slowly sinking due to either the pumping of groundwater or loss of barrier islands as a knock on affect of how we manage rivers and coastlines.

The biggest losers so far are along the east coast, with Annapolis, Maryland going from an average of 3.8 nuisance flood days per year in 1957-1963 to now experiencing 39.3 days per year on average (2007-2013). More than a month under water per year? At what point are we going to have to simply cede these lands back to the oceans? The US is not alone in this. This same trend is happening all around the world.

Annapolis 2012 flooding


Good thing the US Naval Academy is located here…

This trend is only going to get worse year after year as the sea levels continue to rise. All along the coasts, ‘nuisance floods’ that used to happen every 1-10 years now are happening 4 or more times a year. More frequent nuisance floods also means much greater chances of extreme flooding during storms as high winds cause more dangerous storm surges due to the higher sea levels. Along the west coast and in the north east winters are the most likely season for these floods. The rest of the east and gulf coasts are primarily inundated in the autumn. The full report can be found here (link).

Climate change is not about sudden catastrophe so much as it is about the drip, drip of Chinese water torture. How many times would you like to mop out your nicely finished basement or store?




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