Evaluating Nonlinear Methods to Generate Flood Hydrographs for Bridge Scour Applications

Bridge scour evaluations are often performed using streamflow estimates from regional regression relationships. This approach relies on the accuracy of the relationships and does not consider the effects of flow variations. Alternatively, a complete hydrograph can be obtained from a watershed model and used in the scour analysis. However, hydrograph estimation is complicated by nonlinearities in basin response, particularly when large storm events are considered. The objective of this study was to determine whether nonlinearities in hydrologic response and the relationship between flow rates and scour can substantially impact bridge scour evaluations. Nonlinearity in the relationship between excess precipitation and direct runoff was included using variable Clark unit hydrograph parameters in a Hydrologic Engineering Center - Hydrologic Modeling System (HEC-HMS) model. Flow depths and velocities were then generated using a two-dimensional Hydrologic Engineering Center - River Analysis System (HEC-RAS) model. Both models were developed for the Cheyenne Creek watershed west of Colorado Springs. Anticipated scour was quantified using approaches detailed in the Federal Highway Administration’s Hydraulic Engineering Circular manuals. Regression-based peak flow estimates applied as steady state discharges produced larger scour depths than unsteady hydrographs obtained from the hydrologic models. The hydrographs simulated using the variable Clark unit hydrograph parameters produced substantially larger scour depths than those simulated using constant Clark unit hydrograph parameters.

• Record URL:
  https://www.ugpti.org/resources/reports/details.php?id=1112
• Record URL:
  https://rosap.ntl.bts.gov/view/dot/66114
• Summary URL:
  https://rosap.ntl.bts.gov/view/dot/66918
• Supplemental Notes:
  • This document was sponsored by the U.S. Department of Transportation, University Transportation Centers Program.
• Corporate Authors:

  Colorado State University, Fort Collins

  Department of Civil and Environmental Engineering
  Fort Collins, CO  United States  80525

  Mountain-Plains Consortium

  North Dakota State University
  Fargo, ND  United States  58108

  Office of the Assistant Secretary for Research and Technology

  University Transportation Centers Program
  Department of Transportation
  Washington, DC  United States  20590
• Authors:
  • Breverman, Avital L
  • Niemann, Jeffrey D
• Publication Date: 2022-12

Language

• English

Media Info

• Media Type: Digital/other
• Edition: Final Report
• Features: Figures; Photos; References; Tables;
• Pagination: 33p

Subject/Index Terms

• TRT Terms: Bridges; Flood hydrographs; Hydrology; Scour; Streamflow
• Geographic Terms: Wyoming
• Subject Areas: Bridges and other structures; Highways; Hydraulics and Hydrology; Planning and Forecasting;

Filing Info

• Accession Number: 01870540
• Record Type: Publication
• Report/Paper Numbers: MPC 22-491
• Contract Numbers: MPC-619
• Files: UTC, NTL, TRIS, ATRI, USDOT
• Created Date: Jan 24 2023 9:27AM