Naturally Unnatural

As an Environmental Engineering student one of the things that really struck me about the Hurricane Katrina was the failure of levees and the enormity of the flood......

I took a Hydraulics course last term with Dr. Annable, one of the top stream restoration Engineers in North America. His solution to a lot of stream/waterway problems is to restore the streams along with the flood plains in the most natural way possible-which means you dont have concrete lined streams; you allow the streams to flood once in a while rather than have a HUGE flood after many years;you have natural vegetation along the stream shoreline, etc etc......

I found this article by NYT on the Hurricane which agrees with Professor Annable's line of thinking :

'....When most transport was by water, people would of course settle along the Mississippi River, and of course they would build a port city near its mouth. In the 20th century, when oil and gas fields were developed in the gulf, of course people added petrochemical refineries and factories to the river mix, convenient to both drillers and shippers. To protect it all, they built an elaborate system of levees, dams, spillways and other installations.

As one 19th-century traveler put it, according to Ari Kelman, an environmental historian at the University of California, Davis, "New Orleans is surprising evidence of what men will endure, when cheered by the hopes of an ever-flowing tide of dollars and cents."

In the last few decades, more and more people have realized what a terrible bargain the region made when it embraced - unwittingly, perhaps - environmental degradation in exchange for economic gains.

Abby Sallenger, a scientist with the United States Geological Survey who has studied the Louisiana landscape for years, sees the results of this bargain when he makes his regular flights over the Gulf Coast or goes by boat to one of the string of sandy barrier islands that line the state's coast.

The islands are the region's first line of defense against hurricane waves and storm surges. Marshes, which can normally absorb storm water, are its second.

But, starved of sediment, the islands have shrunk significantly in recent decades. And though the rate of the marshes' loss has slowed somewhat, they are still disappearing, "almost changing before your eyes," as Dr. Sallenger put it in a telephone interview from his office in St. Petersburg, Fla. "Grassland turns into open water, ponds turn into lakes."

Without the fine sediment that nourishes marshes and the coarser sediment that feeds eroding barrier islands, "the entire delta region is sinking," he said. In effect, he said, it is suffering a rise in sea level of about a centimeter - about a third of an inch - a year, 10 times the average rate globally................................."

Another relevant article from the BBC website :

".......The levee system meant that the Mississippi, a vast river that drains the whole of the eastern US, was tamed by man.

Without regular river floods to feed the swampy delta with precious silt and nutrients, vast swathes of Louisiana's coastal wetlands have disappeared in the past 75 years.

Sprawling coastal wetlands can bear the brunt of a hurricane better than the concrete passageways of a modern city.

The US Geological Survey calls the wetlands a "natural buffer" in a high-risk area. Plans to stop further erosion have run aground in Congress.

Erosion meant that instead of falling on the delta, Katrina's rains swelled the Mississippi and filled Lake Pontchartrain.............."