Abstract: Land Use and Land Cover Changes on the Mississippi Mainland Coast: 1950-1992

Stephen M. Oivanki, Klaus J. Meyer-Arendt, Barbara Yassin

In order to assess recent development and loss of wetlands in the coastal zone of Mississippi, a study was done of historical changes in land use and land cover on the mainland Mississippi coast. Nineteen U. S. Geological Survey quadrangles having land below the 15-foot contour (the coastal zone study area) were evaluated. The Cowardin classification system of over 200 categories was simplified for use in the study to 7 categories: water, marsh, forest, agriculture, developed, dredge spoil, and beach. Historical data were compiled from U.S. Fish and Wildlife Service classifications of the area done in the 1950s and the 1970s. The 1992 classification was done using 1991-92, 1:24,000 scale, color infrared aerial photography. All data were digitized and comparative analysis as done in ARC/Info.

Interpretation of changes in land use/cover between the three data sets was hampered by inconsistencies in the original interpretations of the 1950s and 1970s data. The 1992 interpretation is by far the most accurate and most consistent with respect to classification of individual land use/cover types. The greatest marsh loss between the 1950s and 1992 occurred on the Waveland quadrangle (698 hectacres) due to residential development, and on the Kreole and Grand Bay SW quadrangles (970 ha together) as a result of erosion and marsh deterioration. Over the whole study area about 3500 ha of marsh were lost between the 1950s and 1992 due to erosion (25%) and development (40%); the remaining losses resulted from conversion to forest or agriculture and overestimation of the marsh acreage in the 1950s. This loss represents about 13% of the total coastal marsh area in mainland Mississippi. Developed land in the study area increased from 5711 to 17,345 ha during the study period.

AAPG Search and Discovery Article #90955©1995 GCAGS 45th Annual Meeting and Gulf Section SEPM, Baton Rouge, Louisiana