Levees

September 01, 2021

One of Melissa’s bucket list ventures was to attend Mardi Gras in New Orleans.  We were finally able to do so in 2016.  Even though this was eleven years after Hurricane Katrina devastated the city, the aftermath was still evident in the quarters along the river where the levees had failed.  When Hurricane Katrina came ashore in August 29, 2005, there were over 50 failures of the levees and flood walls protecting New Orleans and its suburbs.  The levee and flood wall failures caused flooding in 80% of New Orleans and all of St. Bernard Parish.  I recalled our visit and the devastation still evident as Ida tested the levees over the weekend. 

When I looked online, I found the Army Corps of Engineers had assured the city the new $14 Billion fortified system would hold.  The new levees and retaining walls had come into question as early as 2017.  “These systems that maybe were protecting us before are no longer going to be able to protect us without adjustments,” said Emily Vuxton, policy director of the environmental group Coalition to Restore Coastal Louisiana.  The cost for needed repairs could be hundreds of millions of dollars, mostly paid for by federal taxpayers.  Vuxton believes the work and cost are necessary to protect the people of New Orleans.  The protection system was rebuilt over a decade and was finally finished in 2016 with installation of the last pumps.

After the work was completed, the Army Corps projected the system will “no longer provide [required] risk reduction as early as 2023.”  This projection illustrates the rapidly changing conditions brought on by sea levels rising faster than expected and erosion wipes out protective barrier islands and marshlands in southeastern Louisiana.  The primary concern are the earthen levees that form the backbone of the 350-mile maze of protection that includes concrete floodwalls, pump stations and gated structures.  The levees are losing height as they start to settle.  This is a natural phenomenon but is exacerbated by the soft soils in southern Louisiana.  Some floodwalls are built into the levees, so they are sinking as well. 

Thoughts:  Much of the flooding during a hurricane comes from the storm surge as winds push sea water inland.  Fortunately, estuaries can help protect the coast from some of the harmful effects.  The wetlands surrounding an estuary act like sponges, soaking up the storm surge and reducing the impact on coastal communities.  Sand dunes help absorb much of the energy of lashing waves, and salt marshes help reduce erosion caused by heavy rains accompanying a hurricane.  Unfortunately, the marshes along streams and estuaries are disappearing fast.  Nitrogen from fertilizers and sewage makes marshes grow faster, but the roots grow smaller so the soil can’t hold the bigger plants, causing soil banks to collapse and marshes to turn to mud.  Nature works as a system that we have placed in precarious balance.  We need to move beyond the band-aids and address the real issues of climate change.  Follow the science.  Change is coming and it starts with you.