New dataset available on stream and floodplain geometry to inform restoration decisions

Science Center Objects

Issue: The need for stream mapping

The physical shape of streams and floodplains can provide information about how water, sediment, and other matter moves through the landscape. Streams can have deep channels (tall streambanks) disconnected from the floodplain or wide shallow channels that easily spill over the banks into the floodplain during high flows. Mapping where streams fall along this gradient can improve our understanding of the processes that shape rivers, as well as help resource managers target management actions on the landscape.

USGS Study: Mapping stream shapes

The USGS developed a tool called the Floodplain and Channel Evaluation Tool (FACET) (https://code.usgs.gov/water/facet) to remotely map stream and floodplain geomorphic characteristics such as bank height, channel width, and floodplain width. Scientists used FACET to process elevation data derived from lidar in the Chesapeake and Delaware River watersheds. The resulting dataset provides geospatial and tabular output from FACET mapping the shape of streams throughout the Chesapeake and Delaware watersheds. 

Variation in stream shapes in the Delaware River watershed

Variation in stream shapes in the Delaware River watershed.

Key Results and Information

The dataset includes detailed geospatial data organized by sub-watershed (HUC8/10), as well as aggregated data with the mean or median channel measurement for stream segments in the Chesapeake and Delaware watersheds. The dataset includes the following information:

  • Stream network: The stream network shows the location of the stream based on topography. This file can be joined to tables containing a summary of stream geometry measurements for each stream segment.
  • Bank Points: Bank points show the approximate location of the edge of the right and left stream bank. Bank points are used to estimate the width and depth of the stream channel.
  • Floodplain Extent: The floodplain extent is a raster file that displays the “active (field-defined; circa 2-yr recurrence)” floodplain extent. Raster values show the height of each pixel relative the stream channel, allowing the user to display topographic variability within the floodplain.
  • Cross Sections: Channel cross sections show the locations where bank points and stream measurements were extracted based on elevation data. 
  • Tabular Stream and Floodplain Geometry Measurements: Three database tables can be joined to the stream network file to display summarized statistics of stream and floodplain geometry measurements for each stream segment, such as bank height, channel width, and active floodplain width. The full list of metrics can be found in the data dictionary on the ScienceBase page.
Example of FACET output for Wissahickon Creek outside of Philadelphia, PA

Example of FACET output for Wissahickon Creek outside of Philadelphia, PA.

Management Applications

The database can be used to help jurisdictions consider locations for stream restoration and provide baseline information for monitoring stream response. 

For more information

Hopkins, K.G., Ahmed, L., Metes, M.J., Claggett, P.R., Lamont, S., Noe, G.B, 2020. Geomorphometry for Streams and Floodplains in the Chesapeake and Delaware Watersheds: U.S. Geological Survey data release, https://doi.org/10.5066/P9RQJPT1.

The project team included USGS scientists Krissy Hopkins, Greg Noe, Peter Claggett, and Marina Metes, and collaborators Labeeb Ahmed and Sam Lamont. Krissy Hopkins (khopkins@usgs.gov) is the primary contact for the data. 

Date released: April 30, 2020

 

« Return to Chesapeake Bay Activities — Home
« Return to Features, Science Summaries, Videos