Figures

Figure 1. Drainage basin and study area, Chetco River, Oregon.

Figure 2. Flow records for USGS streamflow-gaging station 14400000, Chetco River near Brookings, Oregon.

Figure 3. Example of alternate bar sequence near flood-plain kilometer 11, Chetco River, Oregon.

Figure 4. Channel bed and water-surface elevations along study area, Chetco River, Oregon.

Figure 5. Annual and cumulative navigational dredging volumes, 1962–2008, Chetco River, Oregon.

Figure 6. Annual and cumulative extraction volume for instream commercial gravel mining, Chetco River, Oregon, 1993–2008.

Figure 7. Bar area inundation compared with discharge, Chetco River, Oregon.

Figure 8. Examples of landcover mapping categories, as depicted in an orthophotograph from 2005 near flood-plain kilometer 9 of the Chetco River, Oregon.

Figure 9. Summary of channel change in the study area, Chetco River, Oregon, 1939–2008.

Figure 10. Spatial and temporal variation in gravel bar area for eight time periods, Chetco River, Oregon, 1939–2008.

Figure 11. Reach-segregated distribution of bank material and revetment, Chetco River, Oregon.

Figure 12. Channel changes between flood-plain kilometers 0 and 4.5 encompassing the Estuary Reach, Chetco River, Oregon, 1939–2008.

Figure 13. Channel changes between flood-plain kilometers 4.5 and 8.4 encompassing the North Fork Reach, Chetco River, Oregon, 1939–2008.

Figure 14. Channel changes between flood-plain kilometers 7.5 and 11.5 encompassing the Mill Creek Reach, Chetco River, Oregon, 1939–2008.

Figure 15. Channel changes between flood-plain kilometers 10.6 and 15.2 along the Emily Creek and Upper reaches, Chetco River, Oregon, 1939–2008.

Figure 16. Changes in flood-plain land cover by reach, Chetco River, Oregon, 1939–2005.

Figure 17. Bathymetry for 1939 and 2008 between flood-plain kilometer 0.6 and 3.7, Chetco River, Oregon.

Figure 18. Channel thalweg profiles downstream of river kilometer 18, Chetco River, Oregon.

Figure 19. Cross sections from the flood study survey in 1977, digitized from Soil Conservation Service (1979), and approximately relocated during the U.S. Geological Survey resurveys in September 2008, Chetco River, Oregon.

Figure 20. Specific gage analysis and discharge-measurement cross sections for the USGS streamflow-gaging station, Chetco River near Brookings, Oregon (14400000).

Figure 21. Examples of bar evolution to flood-plain and developed areas between 1939 and 2005, Chetco River, Oregon.

Figure 22. Longitudinal variation in surface-particle size for bar apices along the study area, Chetco River, Oregon.

Figure 23. Particle size distributions for surface and subsurface samples at Fitzhugh Bar, Chetco River, Oregon, Social Security Bar, and Tidewater Estuary Bar.

Figure 24. Variation in clast lithology and size ratio of sandstone and quartzite clasts for sites along the study area, Chetco River, Oregon.

Figure 25. Surveyed channel thalweg in 2008, water-surface, bar surfaces, and water-surface profiles as calculated from HEC-RAS for flows between 50 and 2,000 cubic meters per second for the lower Chetco River, Oregon.

Figure 26. Bedload sampling at USGS streamflow-gaging station, Chetco River near Brookings, Oregon, December 28, 2008.

Figure 27. Discharge and sampling periods for bedload measurements on the Chetco River, Oregon.

Figure 28. Summary flow and bedload transport data for December 28-30, 2008, and February 24-25, 2009, measurements, Chetco River, Oregon.

Figure 29. Particle size distributions for sampled bedload and Fitzhugh Bar surface and subsurface measurement, Chetco River, Oregon.

Figure 30. Streamflow hydraulics, calculated and measured bed-material transport, and location map for vicinity of measurement site near river kilometer 15.3 on the Chetco River, Oregon.

Figure 31. Mean annual calculated bed-material transport capacity for seven cross sections along the lower Chetco River, Oregon, for water years 1970–2008.

Figure 32. Annual transport capacity and mean annual discharge at USGS streamflow-gaging station, Chetco River near Brookings, Oregon.

Figure 33. Discharge and calculated bed-material transport for water year 2002 at reference cross section at flood-plain kilometer 15.3, Chetco River, Oregon.

Figure 34. Example of erosion and deposition classification for morphologic analysis near flood-plain kilometer 7, Chetco River, Oregon.

Figure 35. Areas of bed-material deposition and erosion volumes for selected periods in the Chetco River, Oregon.

Figure 36. Bar thickness values used to calculate erosion and deposition volumes from changes in bar area in the Chetco River, Oregon.

Figure 37. Sediment budget for the lower Chetco River, Oregon.

Revised July 2012

First posted May 26, 2010