Land Area Change in Coastal Louisiana (1932 to 2016)

Authors: Brady Couvillion*, U.S. Geological Survey, Holly Beck, U.S. Geological Survey, Donald Schoolmaster, U.S. Geological Survey
Topics: Geomorphology, Remote Sensing, Coastal and Marine
Keywords: Louisiana, coastal wetlands, wetland change, wetland loss
Session Type: Paper
Day: 4/11/2018
Start / End Time: 3:20 PM / 5:00 PM
Room: Napoleon D3, Sheraton 3rd Floor
Presentation File: No File Uploaded

Coastal Louisiana wetlands are one of the most critically threatened environments in the United States. The analyses of landscape change presented here have utilized historical surveys, aerial, and satellite data to quantify landscape changes from 1932 to 2016. Analyses show that coastal Louisiana has experienced a net change in land area of approximately -4,833 square kilometers (modeled estimate: -5,197 +/- 443 square kilometers) from 1932 to 2016. Previous studies have presented linear rates of change over multidecadal time periods which unintentionally suggest that wetland change occurs at a constant rate, although in many cases, wetland change rates vary with time. A penalized regression spline technique was used to determine the model that best fit the data, rather than fitting the data with linear trends. Trend analyses from model fits indicate that coastwide rates of wetland change have varied from -83.5 square kilometers per year to -28.01 square kilometers per year. Of note is the slowing of the rate of wetland change since its peak in the mid-1970s. Possible reasons for this reduction include recovery from lows affected by the hurricanes of 2005 and 2008, the lack of major tropical storms in the past 8 years, a possible slowing of subsidence rates, the reduction in and relocation of oil and gas extraction and infrastructure since the peak of such activities in the late 1960s, and restoration activities. In addition, many wetlands in more exposed positions in the landscape have already been lost.

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