Most of the Mississippi River Delta in southern Louisiana is sinking. An area almost the size of Delaware has been lost to subsidence over the past 80 years. However, further west along the coastline is an area of delta buildup.

These two Landsat images show changes to the coastline along the Atchafalaya River outlets between 1984 and 2014. Sediments carried by the Atchafalaya River, a distributary of the Mississippi, are responsible for the growth of two new river deltas seen in the 2014 image. These two deltas are from the main Atchafalaya River (right) and its associated Wax Lake Outlet (left). Both of these channels were used for flood control during the Mississippi River floods of 2012, when water was diverted from the Mississippi through the Atchafalaya River Basin into the Gulf of Mexico.

The slow-moving waters of the Atchafalaya River allow suspended sediments to settle near shore. This creates an optimal land- and marsh-building environment. In contrast, the lower Mississippi River’s waters flow quickly through a narrow channel, carrying most of its suspended sediments far offshore. The coastal marshland that has now been built in the Atchafalaya region gives planners hope that other areas of the Mississippi Delta could be similarly rebuilt or preserved through land and water management.

The continuous acquisition of Landsat imagery now spans more than four decades, providing a valuable historical record that can help researchers and scientists monitor and understand landform changes on the Earth’s surface.