subscribe: Posts | Comments

Hurricane Andrew, 20 years later. Any lessons?

2 comments

From USGS paper by Lovelace and McDonnell

by Len Bahr, PhD*

As I write this on Hallowe’en 2012 the national news is dominated by Hurricane Sandy, which may prove to be the most unusual and expensive storm in history.** Sandy is soon to head to Canada, after causing incredible damage, first in the Caribbean and Bermuda and then in Yankeeland.

I recently watched Jim Cantore, on-air cable TV personality for The Weather Channel, interviewed on The Late Show with Dave Letterman. When Dave pressed him on the possible connection between Sandy and climate change, he stated correctly that no single weather event can be proven to be the consequence of global warming. On the other hand he acknowledged doubts that Sandy could have happened 100 years ago, before atmospheric CO2 reached its current level of 391.07 parts per million.

Cantore made similar comments to NBC’s Brian Williams, as posted in DailyKos.com as follows:

You can say that, if we are going to start setting up these high latitude blocks, if we’re going to continue to see the warming signals that are very evident…I mean, you don’t need a (sic) 100k years of data, let’s just take 30 years…the climate is changing clearly, and what you can say is, if we are going to continue to see these signals, we are going to continue to see extreme weather events, one right after the other, whether they be tornadoes, droughts, floods or hurricanes.

Note that Cantore described significant change within the past 30 years…so what about 20 years?

Twenty years ago (1992) I served as Edwin Edwards’ coastal advisor in the 3 year old Governor’s Office of Coastal Activities. On August 26 that year Andrew’s evil eye entered the open mouth of the Atchafalaya Basin west of Morgan City. This trajectory crossed the only healthy and growing part of America’s Delta, where significant deltaic deposition (accretion) had been occurring for twenty plus years.

Hurricane Andrew took two bites at the apple of destruction, one in South Florida and one in Louisiana. The storm caused a whopping $25.5 billion (in adjusted dollar damages) when it first came ashore at Homestead Florida, and Miami dodged a bullet. Andrew then crossed the Florida peninsula, passed into the warm gulf and headed toward Louisiana, regaining most of its strength before coming ashore again.

Following Andrew’s passage, I shared a helicopter tour over the impacted portions of our coast with Roland Guidry, who headed my office’s 3 year old sibling, the Louisiana Oil Spill Coordinator’s Office (LOSCO). I recall that Roland and I saw two principal kinds of damage: redfish offshore and forests onshore.

Louisiana coastal residents came through Andrew relatively unscathed, not just because of relatively low population densities but also because healthy forests intercepted and absorbed the storm energy very effectively.

Andrew’s timing coincided with a raging controversy in Baton Rouge over legislation sponsored by influential recreational fishermen, who invested lots of money and time to ban the harvesting of redfish and speckled trout by commercial fishers practicing their traditional vocation as they had for years. The draconian law was premised on the grounds that redfish were being dramatically overfished and depleted by ignorant, careless and greedy fishers. During that time lots of steaks were consumed by state legislators and senators at Ruth’s Chris Restaurant in Baton Rouge, thanks to members of the Gulf Coast Conservation Association (GCCA)…the instigators of the bill.

During our post-Andrew survey Roland and I passed low along the Timbalier Island shoreline before we headed into the Atchafalaya Basin. We saw (and smelled) a continuous linear pile of bull redfish, the largest I had ever seen, stranded where they had suffocated trying to gulp air. They had presumably become victims of what is called a Jubilee, when strong offshore winds drive surface waters offshore, to be replaced by deoxygenated bottom water and driving finfish and shellfish shoreward to their deaths.

Our observation put the kibosh on the story that the redfish population in the northern gulf was in dire straits. This experience taught me an important lesson about objective environmental science issues and politics

A final note about fish. Among the relatively few damage claims made to FEMA post-Andrew was the loss of wild fish populations, such as what Roland and I observed. The money received was spent to constructing an Atchafalaya Basin fish hatchery facility for the Louisiana Department of Wildlife and Fisheries.

In terms of forest damage, of longer term significance, we saw two contrasting patterns of storm impacts within the forested portion of the lower basin. First there were broad swaths of trees that had given their lives, mowed down as if by a giant scythe and laying in neat parallel windrows like wheat stalks.

Now twenty years have elapsed, we were doing a qualitative survey from a bouncing chopper and I’m not a botanist…but most of the downed trees seem to have been shorter-lived bottomland species, like sweet gum and black willows. In contrast, we saw large intact swaths of coastal forest that had lived to see their next hurricane. These were primarily the two principal coastal forest species, Baldcypress and Tupelo-Gum.

In hindsight I think we still have a unique opportunity to use what remains of the 20 year old evidence of Andrew to document the incredible durability and resistance of coastal forests to withstand and buffer storm surge energy. I think we should consider attempting to reconstruct old evidence from Hurricane Andrew, to improve our comprehension of the value of reforested tracts specifically to absorb hurricane energy.

My question to my coastal science colleagues who were actively researching in 1992, including Gary Shaffer who I believe collected quantitative data on comparative Andrew-caused mortality of Baldcypress vs. other tree species in the lower Atchafalaya Basin. I’d like to ask my hydologic modeling colleagues, including, for example, Harley Winer Alex McCorquodale, Ehab Meselhe and Joe Suhayda to consider what data are still available re the specific trajectory of the storm and how it was likely buffered by the forest.

My hidden agenda for this idea is to sell the coastal protection and restoration community on the justification for taking a serious look at substituting coastal reforestation projects as a substiute for earthen levees, especially in low density parts of the coast.

NOTE: Just before posting I searched the web for a suitable graphic and stumbled on this 1992 USGS paper by John K. Lovelace and Benjamin F. McPherson, on wetland impacts of Hurricane Andrew!  I’m not sure whether the information presented in the paper constitutes a total scoop of my proposed forensic assessment of Andrew, but it may be close.

At any rate, on this the 20th anniversary year of Andrew I’d certainly like to invite these two authors to weigh in with comments as to whether taking a fresh look Andrew would be worthwhile.

*Founding editor leonardbahr@gmx.com

**Currently estimated at $30 billion, half of which is uninsured. This number is highly likely to grow dramatically. The Washington Post carried an October 31 article on the 10 costliest hurricanes. Check it out.

Be Sociable, Share!
Share/Save
  1. Pretty fantastic site thank you so much to your time in writing the posts for all of us to learn about.

  2. Conner Bailey says:

    I have spent many years working in mangrove ecosystems of SE Asia, which provide protection against storm surge associated with cylones and tsunamis. Mangrove ecosystems are under threat due to a variety of factors, not least of which expansion over the past 30 years of coastal shrimp farming. Areas of Aceh on the northern tip of Sumatra in Indonesia where mangrove were removed in favor of shrimp ponds suffered considerably more damage than areas where mangrove remained intact. A study in the Journal of Geophysical Research
    reports results of a model showingn that a 10 year old mangrove forest in a 500 m wide area can reduce a tsunami’s hydrodynamic force by approximately 70%. Mangrove ecosystems are different from baldcyprus and tsunamis are different from hurricanes. That said, I concur with Len and suggest that there may be examples in other parts of the world supporting Len’s view that coastal reforestation is an approach worth exploring.

    Note that I am one of those people sometimes defined by the “ist” of their profession (in this case social scientist), not a hydrologist or geologist or physicist. But I have extensive familiarity with mangrove, which do not grow to the heights of baldcyprus but do resemble a bit of a tangled mess of woody vegetation that works admirably at trapping sediments and, apparently, slowing the rush of water. It will take a bit more global warming before mangrove can be established in Louisiana, I imagine. But there are local alternatives.

Leave a Reply