Figures

Figure 1. The Umpqua River, Oregon, drainage basin and study area. Reaches analyzed are defined by valley geomorphology and tributary junctions. Colored reach extents indicate the geomorphic flood plain. Topography based on U.S. Geological Survey 10-m digital elevation.

Figure 2. Gravel bars and bedrock outcrops in the Umpqua River, Oregon. Descriptions include flood-plain kilometer (FPKM) and North Umpqua River flood-plain kilometer (NUFPKM).

Figure 3. Longitudinal profile and cumulative drainage area of the Umpqua River basin, Oregon.

Figure 4. Mean daily discharge for selected U.S. Geological Survey streamflow-gaging stations in the Umpqua River basin, Oregon.

Figure 5. Annual peak discharge for selected U.S. Geological Survey streamflow-gaging stations in the Umpqua River basin, Oregon.

Figure 6. Channel planform in the Tidal reach of the Umpqua River, Oregon. Insets show historical changes to selected bars, as mapped from aerial photographs. Topography based on U.S. Geological Survey 10-meter digital elevation data.

Figure 7. Channel planform in the Coast Range reach of the Umpqua River, Oregon. Insets show historical changes to selected bars, as mapped from aerial photographs. Topography based on U.S. Geological Survey 10-meter digital elevation data.

Figure 8. Channel planform of the Garden Valley reach of Umpqua River, Oregon. Insets show historical changes to selected bars, as mapped from aerial photographs. Topography based on U.S. Geological Survey 10-meter digital elevation data.

Figure 9. Channel planform of the Roseburg reach of the South Umpqua River, Oregon. Insets show historical changes to selected bars, as mapped from aerial photographs. Topography based on U.S. Geological Survey 10-meter digital elevation data.

Figure 10. Channel planform of the Days Creek reach of Umpqua River, Oregon. Insets show historical changes to selected bars, as mapped from aerial photographs. Topography based on U.S. Geological Survey 10-meter digital elevation data.

Figure 11. Channel planform of the North Umpqua reach of the North Umpqua River, Oregon. Insets show historical changes to selected bars, as mapped from aerial photographs. Topography based on U.S. Geological Survey 10-meter digital elevation data.

Figure 12. Circa 1890s, of the South Umpqua River upstream of Mount Nebo near Roseburg, Oregon. Photograph courtesy of Douglas County Museum (Photograph N5549a).

Figure 13. Hydraulic mining in the Olalla District, Lookingglass Creek drainage, Oregon. Photographs courtesy of Douglas County Museum. (Photographs (A) N5155a and (B) N5155b.)

Figure 14. Annual sediment volume removed between 1949 and 2002 by commercial and navigational dredging in the Umpqua River estuary, Oregon. Commercial dredging focused mainly on the lower Umpqua River below FPKM 40, whereas navigational volumes provided by the U.S. Army Corps of Engineers (USACE) are mainly for the Umpqua River entrance (FPKM 0–3) near Reedsport. Descriptions include Umpqua River Navigation Company (URN).

Figure 15. Examples of mapping units used when creating historical channel maps of the Umpqua River basin, Oregon.

Figure 16. Examples of gravel bars in close proximity to bedrock rapids in the Umpqua River, Oregon.

Figure 17. Relation of bar area to discharge in photographs of the Days Creek, Roseburg, and Garden Valley reaches of the Umpqua River, Oregon, 1995–2009. Linear regressions between mapped bar area and photograph discharge (the discharge when the photograph was made) were used to normalize bar areas to a common, reach-specific discharge.

Figure 18. Summary of historical channel change 1939-2009 for fluvial reaches in the Umpqua River Basin, Oregon. The total area of gravel bars and bedrock in each reach was divided by the centerline length from 2005 to determine the specific area of bars and bedrock in each reach. Arrows in bar area plot show ratio of photograph discharge to minimum photograph discharge for each reach and indicate magnitude of bias introduced by variation in photograph discharge.

Figure 19. (A) The fraction of water, bedrock, and gravel bars in each flood-plain kilometer transect in the Umpqua and South Umpqua Rivers, Oregon, as mapped from 2005 aerial photographs. Downstream of FPKM 25 in the Tidal reach, channel area increases substantially in the lower Umpqua River estuary. (B) Flood-plain width by flood-plain kilometer.

Figure 20. Size and location of mapped gravel bars along the South Umpqua and Umpqua Rivers, Oregon, 1939–2005. Each circle represents the total bar area, aggregated every two flood-plain kilometer transects, and does not necessarily correspond to individual bars. Bar complexes are arbitrary names assigned to particularly gravel-rich areas and may include multiple bars.

Figure 21. Reach-segregated changes in bar area in the Umpqua River basin, Oregon, 1939–2005. Positive balance represents net bar area in each time period separated according to areas that were previously mapped as bars, and newly created bars that were previously mapped as water, flood plain, or bedrock. Negative balances represent total decreases in bar area, separated into areas that became water, bedrock, or flood plain. (A) Coast Range, (B) North Umpqua, (C) Garden Valley, (D) Roseburg, (E) Days Creek.

Figure 22. Examples of channel change at selected sites on the Umpqua and South Umpqua Rivers, Oregon, 1939–2005.

Figure 23. Changes in bar morphology between 1995 and 2000 for select sites on the Umpqua and South Umpqua Rivers, Oregon. Mapping (1995 and 2000) and aerial photographs (2000) span the December 1996 flood.

Figure 24. Historical changes in vegetation density within the active channel for fluvial reaches of the Umpqua River basin, Oregon, 1939–2009. Coast Range and North Umpqua reaches were mapped only in 1939, 1967, and 2005.

Figure 25. Patterns of vegetation colonization on bare gravel bars in the Umpqua River basin, Oregon, 1939–2005, by reach. Positive balance indicates total area of bare bars in each period; decreases in vegetation lead to increases in the area of bare gravel. Negative balance indicates areas where bare gravel was colonized with vegetation.

Figure 26. Historical channel changes in the Umpqua River basin, Oregon, 1920s–2009. Locations of photographs are provided in appendix A.

Figure 27. Historical changes in riparian vegetation in the Umpqua River basin, Oregon, 1920s–2009. Locations of photographs are provided in appendix A.

Figure 28. Comparison of channel position at selected sites along the North Umpqua reach as depicted in General Land Office surveys from 1853 to 1855 and channel maps based on aerial photographs from 1939.

Figure 29. Repeat longitudinal profiles of the main stem Umpqua River between Elkton and the confluence of the North and South Umpqua Rivers, Oregon, 1914–2009. Refer to table 7 for sources of survey data.

Figure 30. Stage–discharge rating-curve elevations for specific discharges for long-term main stem streamflow gages in the Umpqua River basin, Oregon. Source data is from station records housed at the Oregon Water Science Center, U.S. Geological Survey, Portland, Oregon.

Figure 31. Gravel bar volume changes during 2001–09 at instream gravel mining sites along the South Umpqua River, Oregon. Refer to table 8 for data sources and values underlying this figure. For sites with missing surveys, cumulative totals assume no net change for the period of missing data. Mean monthly and annual (water year) peak flows are from the USGS data for streamflow-gaging station on South Umpqua River near Brockway (station 14312000).

Figure 32. Channel planform changes during 1939–2005 between FPKM 7 and 40 for the Tidal reach of the Umpqua River, Oregon.

Figure 33. Comparison of channel planform for the Tidal reach of the Umpqua River, Oregon, as depicted in 1857–74 General Land Office surveys, with aerial photographs from 1939. Refer to figure 6 for a more detailed map of Tidal reach planform and historical changes.

Figure 34. Bathymetric changes to the Tidal reach of the Umpqua River, Oregon, as detected in historical navigation surveys from 1886, 1920, and 1971. Refer to table 7 for information on survey sources.

Figure 35. Cross sections from navigational surveys dating to 1886, 1920, and 1971. Cross sections were extracted from bathymetric surfaces created from historical surveys that were rectified and digitized in this study. Cross section locations are shown in figure 34.

Figure 36. Examples of bed-material sampling sites in the Umpqua River basin, Oregon.

Figure 37. Bed-material grain size, armoring ratios, and lithology for bed-material sampling sites in the Umpqua River basin, Oregon. (A) Median grain size of bar surface and substrate. (B) Armoring ratio at each site computed as ratio of median grain size from the bed-material surface and substrate. (C) Percentage of felsic intrusive clasts. Refer to table 9 and appendix C for particle size and lithology values.

Figure 38. Computed bedload transport rating curves for selected sites in the Umpqua River basin, Oregon. D₅₀ is mean particle diameter; mm, millimeters.

Figure 39. Effect of grain size, slope, water depth, and flow on annual bedload transport capacity. Sensitivity trials conducted for Umpqua Sand and Gravel Bar (FPKM 171.4) for water year 1999 used the Parker (1990a,b) equation.

Figure 40. Longitudinal variation in calculated transport capacity for bed-material sampling sites on the Umpqua and South Umpqua Rivers, Oregon. Data points represent site-specific annual transport, as calculated for 1951–2008, whereas horizontal lines represent median values for each reach. See table 9 for transport capacity values, grain size, and slope data for each sampling site.

Figure 41. Annual computed transport capacity for water years 1951–2008 for selected sites in the Umpqua and South Umpqua Rivers, Oregon.

Figure 42. Relation of reference discharge to mean annual transport capacity in the Umpqua River basin, as computed using the Parker equation.

Figure 43. Regional sediment yield regressions, as calculated for 26 basins in Oregon and northern California.

Figure 44. Predicted bed-material yield for South Umpqua and Umpqua Rivers, Oregon. Total yield was calculated by regressions between bed-material flux and different predictor variables (regressions shown in figure 43). Shown here is the predicted yield and range of yields predicted by the 95-percent confidence limits for each regression.

Figure 45. Examples of disintegrating sandstone clasts derived from the Tyee Formation in the Oregon Coast Range.

Figure 46. Graph showing comparison between longitudinal distribution of clast lithologies in bed-material sampling sites, fraction of contributing area underlain by these lithologies, and expected lithologies based on sediment yield analysis. See table 9 and appendix C for lithology values at sampling sites.

Figure 47. Predicted bed-material yield in the Umpqua River basin, Oregon, under different scenarios of attrition and tributary contribution.

First posted September 29, 2011