![]() Historically, sediment deposition and increases in plant growth and land building outpaced the natural subsidence, resulting in coastal land gain. Land formed by river sediments naturally subsides and sinks over time as part of the delta cycle. Since 1850, the amount of sediment in the Lower Mississippi River has decreased by more than 70 percent. Valuable land-building sediment is trapped behind locks and dams on the Missouri, Mississippi and Ohio Rivers. Additionally, thousands of miles of oil and gas canals have been dug to accommodate energy infrastructure and extraction, altering the natural hydrology, disrupting the salinity balance and killing the vegetation of freshwater wetlands, causing them to subside underwater. Over the decades, these activities have directly impacted thousands of acres of coastal wetlands and modified the coastal hydrology, speeding up land loss. Thousands of offshore oil rigs and onshore wells dot the state’s coastline, including significant refinery capacity and thousands of miles of pipelines connecting it all. When waterways such as the Mississippi River Gulf Outlet (MRGO), Houma Navigational Canal and Freshwater Bayou Canal get built, they allow far more saltwater damage to occur. The vast network of shipping channels along the coast allow salt water to penetrate deep into the wetlands, destroying the ecosystem that was built by fresh water. Without land-building sediment from the river, the delta is doomed to continue shrinking, endangering people, wildlife and jobs in coastal Louisiana. ![]() ![]() Instead of being deposited in nearby wetlands and replenishing marshes, this sediment is completely wasted-lost out of the mouth of the river and deposited far into the Gulf of Mexico. Leveeing of the river cut the tie between the sediment-filled river and its delta, stopping the cycle of new wetland growth. The problem is the delta’s wetlands were and still are built and sustained by sediment delivered by the river. One of the most significant causes of land loss is the straitjacketing of the lower Mississippi River with huge levees to control the river and protect communities, economic infrastructure and other resources from river flooding. Causes of Land Loss Leveeing of the Mississippi River The Mississippi River Delta and coastal Louisiana are disappearing at an astonishing rate: a football field of wetlands vanishes into open water every 100 minutes. Since the 1930s, Louisiana has lost over 2,000 square miles of land, an area roughly the size of Delaware. Many factors have contributed to this collapse.
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |