The Mississippi River Delta region in southern Louisiana is losing land to sea level rise, subsidence, and hurricane damage. The mouth of the Atchafalaya River, a distributary of the Mississippi River, is an exception. It has been building two deltas for the past several decades. The Atchafalaya Delta exemplifies the importance of freshwater and sediment to maintaining and even building land in the delta region.
The Atchafalaya River branches away from the Mississippi River where the Red River joins it. The Atchafalaya takes about 30% of the combined flow of both rivers and carries the water and sediment south.
Just east of the Atchafalaya basin, land is rapidly disappearing from the Louisiana coast. Besides subsidence, sea level rise, and hurricanes, a lack of sediment input from the Mississippi River is also causing land loss, making the region more vulnerable to storms.
Besides the risk to wildlife habitats, coastal Louisiana supports more than 30% of the commercial fisheries in the United States, and five of the country’s top 20 ports are located there. Furthermore, in 2017, the USGS reported that a fifth of the country’s oil and gas is transported through the southern Louisiana wetlands.
The time series of Landsat imagery shows that the deltas do not progressively extend into the Gulf. They are affected by local conditions like tides and the timing of hurricanes and floods. So while the overall trend is extension and delta building, the deltas seem to temporarily contract at times. In the Landsat images, water is dark blue, and vegetation is green.
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