Fluvial geomorphology and suspended-sediment transport during construction of the Roanoke River Flood Reduction Project in Roanoke, Virginia, 2005–2012

Scientific Investigations Report 2015-5111
Prepared in cooperation with the U.S. Army Corps of Engineers
By: , and 

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Abstract

Beginning in 2005, after decades of planning, the U.S. Army Corps of Engineers (USACE) undertook a major construction effort to reduce the effects of flooding on the city of Roanoke, Virginia—the Roanoke River Flood Reduction Project (RRFRP). Prompted by concerns about the potential for RRFRP construction-induced geomorphological instability and sediment liberation and the detrimental effects these responses could have on the endangered Roanoke logperch (Percina rex), the U.S. Geological Survey (USGS) partnered with the USACE to provide a real-time warning network and a long-term monitoring program to evaluate geomorphological change and sediment transport in the affected river reach. Geomorphological change and suspended-sediment transport are highly interdependent and cumulatively provide a detailed understanding of the sedimentary response, or lack thereof, of the Roanoke River to construction of the RRFRP.

Bed-sediment composition was usually finer in post-construction than pre-construction measurements, yet the annual changes in composition were not significantly different; thus, there was minimal evidence that RRFRP construction practices alone induced fining of bed materials. Cross-sectional surveys revealed variability in bankfull and base-flow channel geometry metrics, but no significant differences in this variability were detected between pre- and post-construction measurements, excluding designed alterations in channel geometry. A lack of channel-forming streamflow events, however, limited the ability to fully characterize the stability of the constructed channel and floodplain features, as bankfull flow events occurred only 2 of the 8 years of study. Therefore, additional channel surveys may be needed in the future, once sufficient channel-forming events have occurred, to fully assess stability. Relations between turbidity and suspended sediment were statistically indistinguishable between the upstream and downstream limits of the RRFRP construction reach. These relations did not change over time, indicating no significant changes in suspended-sediment composition or source in the construction reach during the period of study.

Results of the geomorphological and suspended-sediment monitoring components were largely in agreement and consistent with those of a related effort that monitored the logperch population before and during construction. These findings suggest that construction and sediment-control practices sufficiently protected in-stream habitat and the organisms that inhabit those locations, namely the Roanoke logperch, during the period monitored.

Suggested Citation

Jastram, J.D., Krstolic, J.L., Moyer, D.L., and Hyer, K.E., 2015, Fluvial geomorphology and suspended-sediment transport during construction of the Roanoke River Flood Reduction Project in Roanoke, Virginia, 2005–2012: U.S. Geological Survey Scientific Investigations Report 2015–5111, 53 p., http://dx.doi.org/10.3133/sir20155111.

ISSN: 2328-0328 (online)

ISSN: 2328-031X (print)

Study Area

Table of Contents

  • Acknowledgments
  • Abstract
  • Introduction
  • Hydrologic Conditions
  • Geomorphological Responses
  • Suspended-Sediment Transport
  • Synthesis of Study Results
  • Summary
  • References
  • Appendix 1. Geomorphic survey benchmark and transect control location coordinates
  • Appendix 2. Roanoke geomorphology surveys database (available online at http://dx.doi.org/10.3133/sir20155111).
  • Appendix 3. Photographs for each geomorphology monitoring site, Roanoke, Virginia (available online at http://dx.doi.org/10.3133/sir20155111).

Additional publication details

Publication type Report
Publication Subtype USGS Numbered Series
Title Fluvial geomorphology and suspended-sediment transport during construction of the Roanoke River Flood Reduction Project in Roanoke, Virginia, 2005–2012
Series title Scientific Investigations Report
Series number 2015-5111
ISBN 978-1-4113-3967-5
DOI 10.3133/sir20155111
Year Published 2015
Language English
Publisher U.S. Geological Survey
Publisher location Reston, VA
Contributing office(s) Virginia Water Science Center
Description Report: vii, 53 p.; Appendixes 2-3
Time Range Start 2005-01-01
Time Range End 2012-12-31
Country United States
State Virginia
City Roanoke
Online Only (Y/N) N
Additional Online Files (Y/N) Y