The devastation of Hurricane Katrina along the Gulf Coast was due to winds and tidal surge; ironically, New Orleans survived the hurricane fairly well: it main problems came a day later, when the Levees broke, stranding many for days because they decided to take temporary refuge in the city instead of leaving.

A lot of fingerpointing and blame followed (much of it more political than realistic). As this Popular Mechanics article points out, the actual response was enormous and saved thousands of lives, yet the press ignored the heroism of hundreds of thousands of those who helped.

In the aftermath, some placed blamed on the US Army Corps of Engineers for badly built levees that failed during the heavy rain from the hurricane.

Post disaster investigation blamed the extensive failure of the flood walls to overtopping from heavy rain or being built on the wrong type of soil, but there has been a lot of controversy about why the 17th Street Canal failed. There was some question on why the floodwall here failed, where the water level never overtopped the wall.

But this week, a report suggests that the real culprit that weakened the levees was a simple bug: The Formosan Subterranean termite.

This termite has long been blamed for flood wall damage in China. Now it seems that the US will have to take termite infestation into account when constructing levees and flood-walls in the Southeastern US.

From MedicalNewsToday:

After the dikes were breached in 2005, Henderson and his colleague Alan Morgan inspected 100 seams for evidence of termites….70% of the seams in the London Avenue Canal, which experienced two major breaks during Katrina, showed evidence of insect attack, as did 27% of seams inspected in the walls of the 17th Street Canal.

It seems that the floodwall seams were sealed with a substance named Bagasse,  which is made from sugarcane residue, and the termites just love to eat the stuff. The damage could result in the flood-walls failing at the seems.

There is also the possibility that termite tunnelling in the area of various levees would result in “piping”, where water starts going down the tiny tunnels causing them to get larger until they undermine the structure. Such a scenario might have been one of the causes of locals living near the 17th street canal noticing water leakage in their yards.

So one of the mysteries on why the flood-walls in New Orleans were breeched may have been solved.

The bad news?

The New Orleans area has hundreds of miles of canals and levees that will now have to be examined for termite infestation to prevent similar flooding in the future.

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Nancy Reyes is a retired physician living in the rural Philippines. Her website is Finest Kind Clinic and Fishmarket.

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