Thursday, March 21, 2013

Modernization of flood insurance risk assessments, ending of mandatory policies behind levees recommended ~Mark Schleifstein
~Commenter johnbgood~ "The modern methods would be similar to those the Army Corps of Engineers used in determining the risk of hurricane storm surge and rainfall flooding as part of its design of levee improvements in the new Orleans area after Hurricane Katrina." 

Please do not use that flawed methodology as the standard. There were too many things done wrong by the Corps on that study. The Corps and all of its PR-engineers will state at every public meeting that 152 storms were modeled for the system in New Orleans. But in reality very few have even looked at the modeling and even fewer of the Corps' PR-engineers even understand the modeling they are referencing. The Corps model of 152 storms had many many short-comings. Of the 152 storms, only about half of the storms come within 60 miles of New Orleans. The model does not account for slow moving storms and weak storms. The model under estimates the relative sea level rise. The model under estimates the rate of overtopping. Modeling for a deltaic coast is very complex. The Corps has never stated what was the coastline they assumed in their model. When all of these factors are combined, we have a model that does not relfect the actual flood threat, but is nothing more than a academic exercise in statistics and mathematics. And in some cases even a bad academic exercise. For example, the Corps used the methodolgy to use a small sampl size of storms to model the so-called 100-year flood. Then used the same data to identify the 500-year flood level. The only problem, is the data cannot be manipulated like the Corps did and have any validity. If the 500-year level needs to be determined, then the data used needs to be for the 500-year event not extracted from the data set for the 100-year event and projected to create a so-called 500-year event. That's just bad science.

And to show just how slow things move to correct the flaws. To date the Corps has yet to run and release the version of their model that includes all of the levee improvements made since Katrina. I wonder why.

And don't count on oversight by state agencies. Many of the seats on the boards tasked with oversight, are filled by individuals with no technical background to either understand or review the information they are tasked with over seeing.

The real truth will not come out any time soon because if it did flood insurance rates across the metroploitian area (including the areas behind the levees) would sky rocket. And the business leaders that pull the strings of the elected officials will not let that happen. Because if it did, they would probably lose employees and customers who would relocate to less flood prone areas and their businesses would suffer.

No comments: