Scientific Investigations Report 2006-5023
U.S. GEOLOGICAL SURVEY
Scientific Investigations Report 2006-5023
Calculation of Scour Depth at the Parks Highway Bridge on the Tanana River
at Nenana, Alaska, Using One-and Two-Dimensional Hydraulic Models
Prepared in cooperation with the Alaska Department of Transportation and
Public Facilities and Federal Highway Administration
By Dustin E. Langley
Table of Contents
Conversion Factors and Datums
Abstract
Introduction
Hydraulic Modeling
Scour Calculations
Comparison of Models
Summary and Conclusions
References Cited
Figures
Figure 1. Location of the Parks Highway
Bridge (Alaska Department of Transportation and Public Facilities Bridge #201)
scour-analysis site on the Tanana River at Nenana, Alaska, and the reach included
in hydraulic models.
Figure 2. Maximum, mean, and minimum
daily discharge for 38 years of record (1962-2000) for U.S. Geological Survey
streamflow-gaging station 15515500, Tanana River at Nenana, Alaska.
Figure 3. Grain-size distribution of
bed-sediment samples collected by the U.S. Geological Survey from Tanana River
at Nenana, Alaska, June 7, 1964.
Figure 4. Cross sections and river
stations, hydraulic model center lines, and river junctions used in the one-dimensional
model for scour analysis of Tanana River at Nenana, Alaska.
Figure 5. Model mesh and streambed
elevations used for the two-dimensional model of Tanana River at Nenana, Alaska.
Figure 6. Water-surface profiles for
six discharge scenarios on Tanana River at Nenana, Alaska, simulated using one-
and two-dimensional hydraulic models.
Figure 7. Velocity vectors and magnitudes
on the Tanana River near the mouth of the Nenana River, Alaska, simulated using
a two-dimensional hydraulic model.
Figure 8. Comparison of discharge in
Tanana Slough for six discharge scenarios simulated using one- and two-dimensional
hydraulic models.
Figure 9. Depth of pier scour, calculated
using output from one- and two-dimensional hydraulic models, and angle of attack
at bridge pier 3 for five discharge scenarios representing floods on the Tanana
River near Nenana, Alaska.
Figure 10. Streamflow velocity along
cross-section 1.377 on the Tanana River near Nenana, Alaska, measured on August
19, 1998, and simulated using one- and two-dimensional hydraulic models.
Tables
Table 1. Estimated annual sediment load
of the Tanana River, Alaska, 1977–79.
Table 2. Boundary conditions for discharge
scenarios for the Tanana River at Nenana, Alaska, simulated using one- and two-dimensional
hydraulic models.
Table 3. Material types and associated
roughness values for the Tanana River at Nenana, Alaska.
Table 4. Values used to calibrate the
two-dimensional hydraulic model for the Tanana River at Nenana, Alaska.
Table 5. Calculated depths of pier scour,
contraction scour, and angles of attack at pier 3, and associated variables,
Tanana River at Nenana, Alaska.
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Send questions or comments about this report to the author, D.E.
Langley, (907) 479-5645 ext. 224.
For more information about USGS activities in Alaska, visit the USGS
Alaska Water Science Center home page.
U.S.
Department of the Interior | U.S. Geological
Survey
