Stream Network Delineation from High-Resolution Digital Elevation Models.

Abstract

Effective environmental management requires an accurate inventory of the resources to be managed. Decision makers often lack the technical expertise necessary to understand the limitations of environmental data. The State of North Carolina is re-surveying elevations using Light Detection and Ranging to re-delineate floodplains. These data allow analysts to predict flood inundation extents of design storms in order to better manage flood-prone terrain. Conversely, many environmental management functions in North Carolina, such as calculating stream length for hydrologic modeling and riparian buffer protection, rely upon outdated paper maps such as the USGS topographic map series for the determination of the location of stream "blue lines". These cartographic products are inadequate for use in headwater stream mapping when compared to field observations yet no better data source has been found to achieve the accuracy needed for local site planning. This research evaluated the horizontal accuracy and completeness of currently available stream maps compared to stream networks derived from DEMs obtained from the USGS, the North Carolina Floodplain Mapping Program, and interpolated from LiDAR bare-earth elevation points. A unique system combining software and hardware was developed to map headwater catchments with global positioning systems and was used to perform field data collection at nine catchments distributed across four physiographic regions. A method of determining the horizontal accuracy of stream lines shown on maps was developed and used to show that stream networks delineated using high-resolution, interpolated DEMs are more accurately positioned than those on previously published maps or stream networks delineated from currently available DEMs.