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Title: Enhanced detection of wetland-stream connectivity using lidar:Implications for improved wetland conservation and management

Author
item LANG, M - Us Forest Service (FS)
item MCDONOUGH, O - University Of Maryland
item McCarty, Gregory
item OESTERLING, R - University Of Maryland
item WILEN, B - Us Fish And Wildlife Service

Submitted to: Wetlands
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/17/2012
Publication Date: 2/14/2012
Citation: Lang, M.W., McDonough, O., McCarty, G.W., Oesterling, R.A., Wilen, B. 2012. Enhanced detection of wetland-stream connectivity using lidar: Implications for improved wetland conservation and management. Wetlands. 32:461-473.

Interpretive Summary: In this report we investigate the influence of stream data source on the apparent spatial relationship between streams and wetlands in an area of low topographic variability and high human modification of the stream network. We specifically address the added information present in new high resolution elevation maps provided by LiDAR (Light Detection And Ranging) remote sensing as compared with information present in aerial photography-derived stream maps that are currently widely used. Finally, we determine the number and total area of wetlands that are connected to a perennial or intermittent stream network and whether or not wetlands with certain hydrology are more or less likely to be connected to the stream network. We found that LiDAR based elevation maps can be used to significantly improve the accuracy of wetland-stream connectivity determinations at various scales. Improved information on wetland-stream connectivity benefits not only the accuracy and efficiency of environmental management decisions through improved decision support tools, but also strengthens the science behind court decisions affecting fate of wetlands based on the Clean Water Act.

Technical Abstract: The importance of wetland–stream connectivity has been heightened due to the current dependence of wetland regulatory status on this connectivity, although the importance of wetland function to adjacent stream health has been and will continue to be substantial regardless of government policies and regulations. Multiple government agencies have sought to gauge the impact of Rapanos and related judgments through the intersection of commonly available stream and wetland datasets at the state and national level. However, the limitations of commonly available stream datasets can lead to significant statistical biases at a broad scale, and these limitations complicate the use of these datasets for site-specific regulatory determinations. However, LiDAR based DEMs can be used to significantly improve the accuracy of wetland-stream connectivity determinations at multiple scales. Improved information on wetland-stream connectivity benefits not only the accuracy and efficiency of environmental management decisions through improved decision support tools, but also strengthens the science behind the “significant nexus” concept by enabling accurate, spatially explicit quantification of wetland-stream connectivity at the landscape scale for comparison with indicators of downstream structure and function. When available, LiDAR based DEMs could be used to improve the accuracy of wetland-stream connectivity estimates. The degree of accuracy gained through the inclusion of LiDAR based information is likely to vary across the landscape based on a number of variables including physiographic region, finer scale geomorphology, human alteration, and meteorological conditions. If not available, users of aerial photography based data sets (e.g., NHD) should be aware of the limitations of these data and communicate these limitations to data users.