Friday, March 24, 2006
Disclaimer: haven't felt up to doing much the last few days, but I had planned on updating my post on this article by Bob Marshall, with links to this article from last week's T/P, this old editorial by Mike Tidwell, and even this post of Tim's. Obviously, today's paper would make any such post pointless. Since I see that oyster has even linked to Tim's post, I'll just limit this to a few comments.
Though I no longer disagree with Tim's post as strongly as I did on first reading, I still think that he overstated his case--imagine the local reaction if a national journal had used the example of a hurricane approaching across Lake Borgne to illustrate ineffectiveness of coastal wetland restoration as a form of hurricane protection. More importantly, I didn't see the point; I didn't see any real likelihood that money that could go to increased levee protection would get diverted to coastal wetlands restoration, until I saw yesterday's paper. As oyster points out, the article does end with a couple of caveats:
"You'll get a lot more benefit from wetlands during a fast-moving storm, because the surge has less time to build," Kemp said. "But in a slow-moving storm -- something that just sits over the area for days -- then you'll eventually just be overwhelmed."
The type of wetlands in a storm's path also are important. For example, that 1960s study by the corps was based on storms that had come ashore in southwestern Louisiana, which has many miles of healthy freshwater marshes crossed by natural ridges forested with oak trees. Southeastern Louisiana's coastal marshes are built on young river deltas and are much thinner and more fragile, with few ridges.
"Even before the amount of erosion that has taken place in southeastern Louisiana, you probably wouldn't see that level of surge reduction as they did in that study," said Joe Suhayda, a retired LSU professor. "So the type or quality of the wetlands is very important.
The article even points out that some levees were made of stronger materials than others, it gives the overall impression that the main difference between levees that held and levees that failed was the degree of buffering (provided by wetlands) between the levees and the storm surge. The accompanying graphic was at least somewhat misleading. The headline of the T/P's homepage went beyond that: Wetlands better defense than levees. But, even if the article overstates the case, the basic premise is valid.
Still, if it came down to it, I can't that imagine too much money would be diverted from levee construction to coastal restoration, at least not until some acceptable level of flood protection is reached. However, it's probably realistic to assume that the federal government won't fund both category five levee protection and any kind of large scale coastal restoration project. At some point, there will almost certainly be a choice to be made between more money for levee construction and less money for coastal restoration or less for levee construction and more for restoration. Though nobody would deny that the area needs at least true category three levee protection, not the "category three protection" that we had before Katrina, at what point beyond that would you be willing to divert money to restoration? Though category five levee protection over questionable restoration projects might seem the obvious choice, I can't imagine that fifty years from now I'd want to be a resident of New Orleans nursing home if the Gulf were as close to south and the west as it is to the east. It wouldn't matter how high or how strong the levees were.
Though I no longer disagree with Tim's post as strongly as I did on first reading, I still think that he overstated his case--imagine the local reaction if a national journal had used the example of a hurricane approaching across Lake Borgne to illustrate ineffectiveness of coastal wetland restoration as a form of hurricane protection. More importantly, I didn't see the point; I didn't see any real likelihood that money that could go to increased levee protection would get diverted to coastal wetlands restoration, until I saw yesterday's paper. As oyster points out, the article does end with a couple of caveats:
"You'll get a lot more benefit from wetlands during a fast-moving storm, because the surge has less time to build," Kemp said. "But in a slow-moving storm -- something that just sits over the area for days -- then you'll eventually just be overwhelmed."
The type of wetlands in a storm's path also are important. For example, that 1960s study by the corps was based on storms that had come ashore in southwestern Louisiana, which has many miles of healthy freshwater marshes crossed by natural ridges forested with oak trees. Southeastern Louisiana's coastal marshes are built on young river deltas and are much thinner and more fragile, with few ridges.
"Even before the amount of erosion that has taken place in southeastern Louisiana, you probably wouldn't see that level of surge reduction as they did in that study," said Joe Suhayda, a retired LSU professor. "So the type or quality of the wetlands is very important.
The article even points out that some levees were made of stronger materials than others, it gives the overall impression that the main difference between levees that held and levees that failed was the degree of buffering (provided by wetlands) between the levees and the storm surge. The accompanying graphic was at least somewhat misleading. The headline of the T/P's homepage went beyond that: Wetlands better defense than levees. But, even if the article overstates the case, the basic premise is valid.
Still, if it came down to it, I can't that imagine too much money would be diverted from levee construction to coastal restoration, at least not until some acceptable level of flood protection is reached. However, it's probably realistic to assume that the federal government won't fund both category five levee protection and any kind of large scale coastal restoration project. At some point, there will almost certainly be a choice to be made between more money for levee construction and less money for coastal restoration or less for levee construction and more for restoration. Though nobody would deny that the area needs at least true category three levee protection, not the "category three protection" that we had before Katrina, at what point beyond that would you be willing to divert money to restoration? Though category five levee protection over questionable restoration projects might seem the obvious choice, I can't imagine that fifty years from now I'd want to be a resident of New Orleans nursing home if the Gulf were as close to south and the west as it is to the east. It wouldn't matter how high or how strong the levees were.
