Watersheds & Wetlands

Evaluating Remote Sensing Estimates of Forested Wetland Loss

A report by the National Oceanic and Atmospheric Administration (NOAA) and the US Fish and Wildlife Service (USFWS) determined that wetlands in coastal watersheds in the Great Lakes and Atlantic and Gulf coasts experienced an average net decrease of 59,000 acres/yr during 1998 to 2004. Reports such as these have led to the perception by regulators that silviculture is a cause of wetland loss in some areas of the Southeastern US.

In response to these findings, EPA convened the Interagency Coastal Wetlands Workgroup with EPA, NOAA, US Fish and Wildlife Service, US Department of Agriculture, Natural Resource Conservation Service, Army Corps of Engineers (COE), and Federal Highway Administration to determine factors responsible for eastern coastal wetland loss and evaluate what actions might reduce or reverse wetland loss trends.

Analyses conducted in initial phases of this project by Virginia Tech’s Conservation Management Institute have identified the potential for large differences between photointerpreters in estimation of wetland change. These differences highlight the unmeasured variability in estimates of wetland change based on manual delineation from aerial photographs.

Continued work will allow us to test hypotheses related to bias in approaches, and to further quantify variability in wetland change estimates.