A Precarious Landscape

2/1/16
A Precarious Landscape

It took the Mississippi river approximately 7,000 years to build up the land in and around New  Orleans. It is alluvial land which is unconsolidated sediment deposited by the river and thus  highly prone to subsidence or sinking. Bedrock is not even reached until around 75 feet down.  We call the land gumbo and it makes for a precarious landscape to settle a city on but perhaps  we can forgive our founding father Bienville this transgression when we analyze the negative  changes wrought upon the landscape in the modern era.   Subsidence has historically been managed naturally by the river overflowing its banks and  depositing new sediment at a sufficient rate to counteract the erosion process. Once Europeans  arrived, they found this constant flooding counter intuitive to a permanent residence and began  to reinforce the natural levees in order to prevent this timeless cycle. No flooding means no  sediment which equals accelerated erosion. In the 1930’s this was exacerbated by the oil and  fishing industries that began cutting salt water channels into freshwater marshland which killed  the grasses and trees holding that land in place. What resulted from a combination of a  dammed river and saltwater channels was extreme land loss on a scale that is hard to imagine.  The Louisiana coastline is the fastest disappearing land mass in the world. It is disappearing  faster than the Amazon rain forest. A football size piece of land washes away every hour. Every  single hour! In just 80 years, some 2,000 square miles have been lost. Over the next 50 years,  we are looking at the greatest natural disaster in our nation’s history. The extreme land loss  coupled with rising ocean levels spells disaster. The National Oceanic and Atmospheric  Administration scientists are predicting that by 2100, the Gulf of Mexico could rise by 4.3 feet  across a landscape whose average elevation is only 3 feet. Everything outside of the levee  protection zone would be underwater and New Orleans would be practically sitting in open  water. This tragedy is unfolding every single day. If cartographers were to update the map of  Louisiana, most Americans would be appalled to learn that the so­ called boot is no longer there.  It has long ago turned into ocean.  Migratory birds making their trek from Canada to South America stop in the food rich Louisiana  delta to refuel for their long journey. As the land goes, so does their food. Already less and less  birds are seen. Unique cultures, like the insular Cajun communities that depend on the land are  seeing their way of life become extinct and with it goes a 17th century French dialect. Lower  Louisiana is home to half of the country’s oil refineries. This area serves 90% of the nation’s  offshore energy production and 30%  of its total oil and gas supply. Two million people would  need another place to live. The economic costs would be staggering.  There is controversy over the best course of action but while men argue the finer points, another  football size piece of land goes under. One proposal is to allow the river  in places to overflow its  banks in order to rebuild land. This would mean the displacement of some communities and  quite a bit of government funding. New Orleans is starting to embrace the Dutch model which  does not fight against the sea but embraces it via numerous canals. There are options on the  table but we had better settle on one soon. Louisiana is running out of time.

-Sandy
Crescent City Historic Tours