Prepared in cooperation with Pierce County Public Works and Utilities, Surface Water Management; and King County Department of Natural Resources and Parks, Water and Land Resources Division Geomorphic Analysis of the River Response to Sedimentation Downstream of Mount Rainier, Washington Open-File Report 2012–1242 U.S. Department of the Interior U.S. Geological Survey Cover: Photograph taken from Emmons Vista in Mount Rainier National Park, Washington, showing view of Mount Rainier, Emmons Glacier, and the headwaters of the White River. (Photograph taken by C.S. Magirl, U.S. Geological Survey, August 14, 2011.) Geomorphic Analysis of the River Response to Sedimentation Downstream of Mount Rainier, Washington By Jonathan A. Czuba, Christopher S. Magirl, Christiana R. Czuba, Christopher A. Curran, Kenneth H. Johnson, Theresa D. Olsen, Halley K. Kimball, and Casey C. Gish Prepared in cooperation with Pierce County Public Works and Utilities, Surface Water Management; and King County Department of Natural Resources and Parks, Water and Land Resources Division Open-File Report 2012–1242 U.S. Department of the Interior U.S. Geological Survey U.S. Department of the Interior KEN SALAZAR, Secretary U.S. Geological Survey Marcia K. McNutt, Director U.S. Geological Survey, Reston, Virginia: 2012 For more information on the USGS—the Federal source for science about the Earth, its natural and living resources, natural hazards, and the environment—visit http://www.usgs.gov or call 1–888–ASK–USGS For an overview of USGS information products, including maps, imagery, and publications, visit http://www.usgs.gov/pubprod To order this and other USGS information products, visit http://store.usgs.gov Suggested citation: Czuba, J.A., Magirl, C.S., Czuba, C.R., Curran, C.A., Johnson, K.H., Olsen, T.D., Kimball, H.K., and Gish, C.C., 2012, Geomorphic analysis of the river response to sedimentation downstream of Mount Rainier, Washington: U.S. Geological Survey Open-File Report 2012-1242, 134 p. Any use of trade, product, or firm names is for descriptive purposes only and does not imply endorsement by the U.S. Government. 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Contents Abstract ......................................................................................................................................................................... 1 Introduction .................................................................................................................................................................... 2 Purpose and Scope ................................................................................................................................................... 3 Description of Study Area .......................................................................................................................................... 4 Fluvial Geomorphology .............................................................................................................................................. 5 Sediment Load ....................................................................................................................................................... 5 Sediment Measurement ......................................................................................................................................... 6 Aggradation and Incision ........................................................................................................................................ 6 Debris Flows........................................................................................................................................................... 7 Wood ...................................................................................................................................................................... 8 Conceptual Model of Sediment Delivery from Mount Rainier ........................................................................................ 9 Weathering and Rockfall ............................................................................................................................................ 9 Glaciation ................................................................................................................................................................... 9 Mount Rainier Debris Flows ......................................................................................................................................10 Sediment Transport in River Network .......................................................................................................................11 Serial Sediment Delivery ...........................................................................................................................................12 Geomorphic Characteristics of Mount Rainier Rivers ...................................................................................................12 River Centerlines and Stationing ...............................................................................................................................12 Longitudinal River Profiles ........................................................................................................................................13 Sediment Equilibrium ................................................................................................................................................14 Bed-Material Sediment Size ......................................................................................................................................15 Hydrologic Trends and Geomorphic Response at Gaging Stations ..............................................................................16 Analyzing Hydrologic Gage Data ..............................................................................................................................16 Long-Term Hydrologic Runoff ...................................................................................................................................16 Peak-Flow Events .....................................................................................................................................................17 Implications of 20th-Century Hydrology on Sediment Production and Transport ......................................................18 Geomorphic Response to Hydrologic Events ............................................................................................................18 Sediment Loads of Mount Rainier Rivers .....................................................................................................................19 Previous Sediment-Load Estimates ..........................................................................................................................20 Historical Changes in Plan Form and Profiles in Mountainous River Reaches .........................................................22 Change in Active-Channel Width for Rivers Draining Mount Rainier .....................................................................22 Active-Channel Elevation Relative to Forested-Terrace Elevation ........................................................................24 Change in Elevation of River Profiles ....................................................................................................................25 Sediment Contributions from the Flood Plain due to Expansion of the Active Channel .........................................25 The Link between Superglacial Debris and Downstream Aggradation ..................................................................26 The Link between the 1963 Debris Avalanche and Upper White River Aggradation .............................................27 Sediment Supply from Cascade Uplands outside Mount Rainier National Park .......................................................27 Methodology for Assessing Sediment-Production Potential ..................................................................................28 Roads ................................................................................................................................................................28 Landslides .........................................................................................................................................................29 Soil Creep ..........................................................................................................................................................29 Calibration .........................................................................................................................................................29 Sediment-Production Potential Results .................................................................................................................30 iii Sediment Loads of Mount Rainer Rivers—Continued Estimates of Sediment Loads using Historical and New Data ...................................................................................31 Load Estimates of the Upper Nisqually River ........................................................................................................31 Seasonality in Suspended-Sediment Concentration in Mount Rainier Rivers .......................................................32 Suspended-Sediment Load