Prepared in cooperation with the U.S. Environmental Protection Agency and the Montgomery County Department of Environmental Protection Geomorphic Characteristics of Tenmile Creek, Montgomery County, Maryland, 2014–16 Scientific Investigations Report 2018–5098 U.S. Department of the Interior U.S. Geological Survey Cover. Photograph showing Tenmile Creek, looking upstream near U.S. Geological Survey streamflow-gaging station 01644388. Photograph by Michael A. Clark, U.S. Geological Survey, May 1, 2014. Geomorphic Characteristics of Tenmile Creek, Montgomery County, Maryland, 2014–16 By Edward J. Doheny and S. Matthew Baker Prepared in cooperation with the U.S. Environmental Protection Agency and the Montgomery County Department of Environmental Protection Scientific Investigations Report 2018–5098 U.S. Department of the Interior U.S. Geological Survey U.S. Department of the Interior RYAN K. ZINKE, Secretary U.S. Geological Survey James F. Reilly II, Director U.S. Geological Survey, Reston, Virginia: 2018 For more information on the USGS—the Federal source for science about the Earth, its natural and living resources, natural hazards, and the environment—visit https://www.usgs.gov or call 1–888–ASK–USGS. For an overview of USGS information products, including maps, imagery, and publications, visit https://store.usgs.gov. Any use of trade, firm, or product names is for descriptive purposes only and does not imply endorsement by the U.S. Government. Although this information product, for the most part, is in the public domain, it also may contain copyrighted materials as noted in the text. Permission to reproduce copyrighted items must be secured from the copyright owner. Suggested citation: Doheny, E.J., and Baker, S.M., 2018, Geomorphic characteristics of Tenmile Creek, Montgomery County, Maryland, 2014–16: U.S. Geological Survey Scientific Investigations Report 2018–5098, 34 p., https://doi.org/10.3133/sir20185098. ISSN 2328–0328 (online) iii Acknowledgments The authors would like to thank Taylor Jarnagin of the U.S. Environmental Protection Agency, Office of Research and Development, National Exposure Research Laboratory, in Research Triangle Park, North Carolina for long-term project support and extensive assistance with project planning and technical input. Thanks also are extended to Jennifer St. John and Eric Naibert of the Montgomery County Department of Environmental Protection, and to Keith Van Ness, formerly of the Montgomery County Department of Environmental Protection, for long-term project support, as well as assis- tance with project planning and technical input. The authors would like to thank Mr. Norman Meese, a private citizen of Montgomery County, Maryland, for allowing project staff onto his property to access and instrument the study reach. Thanks are extended to Michael A. Clark, Andrew J. Greise, Cory D. Wright, Carl W. Koch, and Logan J. Jeffries of the USGS Frostburg, Maryland office for assistance with site selection and preparation, as well as data collection in the field. Thanks also are extended to Anthony J. Tallman, Christopher R. Lewis, and Kenneth T. Reinhardt of the USGS Dover, Delaware office for assistance with instrumenting the study reach, as well as data collection in the field. Jonathan J.A. Dillow of the USGS MD-DE-DC Water Science Center also is thanked for assis- tance with project management, and for providing input on technical issues. iv Contents Acknowledgments ........................................................................................................................................iii Abstract ...........................................................................................................................................................1 Introduction.....................................................................................................................................................2 Purpose and Scope ..............................................................................................................................2 Description of Tenmile Creek Watershed .........................................................................................2 Description of Study Area ...................................................................................................................4 Methods of Data Collection .........................................................................................................................4 Streamflow .............................................................................................................................................4 Precipitation...........................................................................................................................................6 Longitudinal Profiles .............................................................................................................................7 Cross Sections.......................................................................................................................................7 Pebble Counts........................................................................................................................................8 High-Water Marks ..............................................................................................................................10 Geomorphic Characteristics ......................................................................................................................11 Longitudinal Profiles ...........................................................................................................................11 Cross-Section Geometry ...................................................................................................................13 Grain-Size Analysis.............................................................................................................................18 Stream-Channel Classification .........................................................................................................24 Shear-Stress Analysis ........................................................................................................................26 Data Limitations............................................................................................................................................28 Summary........................................................................................................................................................28 References Cited..........................................................................................................................................29 Glossary .........................................................................................................................................................31 Appendix 1. Changes in Cross-Section Geometry at Permanent Cross Sections for Bankfull Conditions, Tenmile Creek Study Reach, April 2014 through September 2016.....................33 Figures 1. Map showing location of Tenmile Creek watershed, Montgomery County, Maryland ....3 2. Map showing detailed view of Tenmile Creek watershed and study reach, Montgomery County, Maryland ..................................................................................................5 3. Photograph showing view looking downstream at lower section of Tenmile Creek study reach ....................................................................................................................................6 4. Map and photographs showing locations of permanent cross sections that were established in the Tenmile Creek study reach, 2014 ...............................................................8 5. Diagram showing examples of longest, intermediate, and shortest axes for measuring median particle diameter of pebbles during pebble counts ..............................8 6. Graph showing grain-size distribution developed from the pebble count at cross section Dd, Tenmile Creek study reach, April 23, 2014 ........................................................10 7. Photograph showing crest-stage gage for obtaining high-water marks in the Tenmile Creek study reach ........................................................................................................10 8. Graph showing longitudinal profile of channel features in the Tenmile Creek study reach from field survey conducted on April 24, 2014 ............................................................11 9. Graph showing comparison of riffle, pool, and run distribution in the Tenmile Creek study reach, April 2014 through September 2016 ..................................................................12 v 10. Graph showing cross-section geometry at permanent cross section Aa, April 2014 through September 2016 ............................................................................................................13 11. Graph showing cross-section geometry at permanent cross section Bb, April 2014 through September 2016 ............................................................................................................13 12. Graph showing cross-section geometry at permanent cross section Cc, April 2014 through September 2016 ............................................................................................................14 13. Graph showing cross-section geometry at permanent cross section Dd, April 2014 through September 2016 ............................................................................................................14