Wetlands, Flooding, and Hurricane Katrina
by Sarah Spiegler -- June 2nd, 2011
The historical mismanagement of the Mississippi River
When I tell people that I study environmental management, there is usually a mix of “what an interesting field” and blank looks with questions inquiring politely, what is that?
Well, this summer we are seeing first hand what happens when there is poor environmental management. As this NYtimes article says, the Army Corps of Engineers has “performed nobly in the present emergency.” But the bigger issue is: could the decision to flood the spillway have been avoided this year with better management?
After the huge floods in the 1920s, the levees were built to protect populated areas, but some also were built to attract more development.
The problem with the levees is that while they act as a protection system from river flooding, they also control where the Mississippi River flows (or where it does not flow). Subsidence is a process that occurs when sediment in the marsh settles, decays, compacts, and sinks a little. If new sediment is not added the marsh will therefore begin to decline in elevation and sink into the water. In southern Louisiana, subsidence is a big problem since the levees do not allow sediment to flow freely and redeposit in the wetlands.
Alex Kolker, LUMCON assistant professor, is researching whether the opening of the Morganza Spillway and resulting flooding will result in significant sediment depositions in Terrebonne Parish, where Heidi and I are located this summer.
As you drive down the Bayou, you notice that most houses and communities are built linearly along the fingers of water that reach up from the gulf. At first this seems counter-intuitive that people would build houses along the water. However this is because the highest elevated land is along these Bayou ridges, and thus are actually less likely to flood than surrounding lower elevation areas.
Loss of wetlands
An important statistic: a football field of wetlands is lost here every 30-38 minutes.
Millions of acres of wetlands have been lost over the years in southern Louisiana. This loss is due to the building of the levees, canal dredging from oil and gas, draining from development, and subsidence (both man made and natural). This loss is incredibly significant because wetlands act as natural filters and sponges to soak up water in flooding and hurricane events, and act as a barrier between the Gulf of Mexico and large populated areas in Louisiana.
Many scientists are calling for more spillways to be built that can divert sediment to replenish the wetlands in Louisiana.
This past week we ventured into New Orleans and went to the Katrina and Beyond exhibit in the Louisiana State Museum in the French quarter. The decimated piano of New Orleans native Fats Domino was perched in the main lobby, although he was rescued by a Coast Guard helicopter.
Many stories were displayed in the museum through videos, pictures, and audio recordings about the destruction and personal tragedies, and the heroic efforts of many local people to help rescue their neighbors. Of course especially potent to me were the stories of the people forced to leave their pets behind, never knowing if they would see them again or what would happen to them. Also repeated throughout the exhibit was the resilience of the people and communities in Louisiana.
The exhibit also emphasized the need to restore the wetlands of Louisiana to act as a natural barriers, so that future hurricanes do not continue to result in the huge destruction that occurred during Katrina.
The big question of course is, where will the money to restore the wetlands come from?
Also of note: today (June 1) is day 1 of hurricane season 2011.