Tidal wetlands natural and human-made changes from 1973 to 1979 in Delaware: mapping techniques and results

Aerial photographs of Delaware's tidal wetlands were obtained in 1973 from which major wetland plant species were distinguished. For map revision, photographs were taken in 1979. Methods used for mapping are described. Comparisons with the original photographs showed wetland changes. The causes were interpreted from the photographs or determined by a visit to the site. Results show an annual wetland loss due to human activity of 8.1 ha per year. This is considerably less than the 179.7 ha per year lost before legislation protecting the wetlands in 1972 and 1973. Natural processes removed 3.9 but added 2.8 ha per year.