Narragansett Bay Coastal Wetland Trends Analysis 1950s–1990s

In 1999, the Estuary Program continued working with the University of Rhode Island Environmental Data Center, the U.S. Fish and Wildlife Service (USFWS), and the University of Massachusetts to assess the changes in coastal wetlands and their buffers in the Narragansett Bay estuary. Using aerial photointerpretation from two time periods, the extent of wetland losses, gains, and changes in classification were identified baywide between the 1950s and 1990s. The wetland trends information was classified according to Cowardin et al. (1979) and follows the USFWS's National Wetlands Inventory mapping standards. The land use and land cover in the buffer zone were classified using a modified Anderson (1976) method. The minimum mapping unit for areas of change was 0.25 acre.

The photointerpreted information was converted into digital coverages and a geospatial database using GIS technology. The database contains information on the wetland and land use classifications, aerial extent of change, and causes of change. Thematic GIS maps were developed to be distributed to municipalities around the bay and environmental agencies and organizations. Wetland trend reports were prepared summarizing the findings of this study.

The trends analysis project provides a more comprehensive study of coastal wetland impacts and identification of potential restoration sites. Using two or more time periods allows for the recognition of losses that might result from activities such as erosion and sedimentation, filling, and dredging. It is expected that the results of this study will be beneficial to resource managers by providing the data to develop a comprehensive strategy for the protection, restoration, and monitoring of coastal wetlands.