What is going on with Louisianas Gulf coast??
Louisiana is disappearing.
We’ve already lost 2000 square miles of wetlands and were losing what’s left at about 16 square miles a year (a football field every 100 minutes). Louisiana is the most productive coastal estuary in North America south of Alaska. This loss isn’t just an environmental disaster, it’ also an economic disaster. If we lost our coast, the nation would lose 50% of its refining capacity, 20% of its gas supply, 90% of its offshore energy supply, and 31 states wouldn’t be able to ship their grain, coal, etc.. down the river.
How did this happen? Well, all this land was created by deltas of the Mississippi River over 7,000 years. This watershed drains everything from the Appalachians on the East, the Rockies on the West and all the way up into 2 Canadian provinces. Every river and drop of rain from these parts flows into the Mississippi River valley. The river literally carries millions of gallons of water and tons of silt southward every minute. In the spring when all the snow melts, the river floods so much that it pushes all of that sediment and silt to create land, and then pushes so much on the built land that it find a weak spot on the bank, pushes through, and builds a new channel and starts to build a new delta in that course. As long as the river is free, that process cycles over and over again, with the river snaking back and forth every few thousand years but that is no longer the case.
We built out communities in Louisiana on what is a huge sponge of wet mud, which rests beneath the surface and above the first hard rock, which is 400 feet down at the mouth of the river and about 150 below New Orleans. Gravity is always pressing down on this sponge, drying it out and pushing it below sea level. The only three things keeping this from happening is the annual spring floods replenishing the land with more sediment (the most important), the annual cycle of plant growth which drops plant detritus (dirt) to add to the land each year, the third way is when we have high tides (even hurricanes!) that pick up sediment from across the delta and spread it around where needed. The river levees we put up to protect our farms and city from spring floods negatively affected all three processes that keep us from sinking and rapidly sped up the process. It cut off our life source, the Mississippi River. When the levees were finished by the 1930’s, we wrote a death sentence for Louisiana and since then we have continued to starve our wetlands.