Since the early 1970s a new subaerial delta has been forming along the central Louisiana coast, an area traditionally characterized by coastal retreat. This delta of the Lower Atchafalaya River has been monitored by using data from the Landsat satellite. With these data, the formation and year-to-year growth of a major new deltaic lobe of this Mississippi River distributary have been measured for the first time. The analyses show that the formation of new land coincides with flood pulses of the river and that, as would be expected, intertidal lands below mean sea level accrete at a faster rate than lands above mean sea level. Measurements indicate that by early 1976 approximately 32.5 km2 of new land had been formed at an average growth rate of 6.5 km2/yr.
Delta growth initiated bay filling and shoreline progradation; the result was creation of extensive new marshlands along the south-central portion of the Louisiana coast.