A Natural Resource Condition Assessment for Sequoia and Kings Canyon National Parks Appendix 3 – Erosion and Mass Wasting
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National Park Service U.S. Department of the Interior Natural Resource Stewardship and Science A Natural Resource Condition Assessment for Sequoia and Kings Canyon National Parks Appendix 3 – Erosion and Mass Wasting Natural Resource Report NPS/SEKI/ NRR—2013/665.3 ON THE COVER Giant Forest, Sequoia National Park Photography by: Brent Paull A Natural Resource Condition Assessment for Sequoia and Kings Canyon National Parks Appendix 3 – Erosion and Mass Wasting Natural Resource Report NPS/SEKI/ NRR—2013/665.3 John T. Austin Sequoia and Kings Canyon National Parks 47050 Generals Highway Three Rivers, CA 93271 June 2013 U.S. Department of the Interior National Park Service Natural Resource Stewardship and Science Fort Collins, Colorado i The National Park Service, Natural Resource Stewardship and Science office in Fort Collins, Colorado, publishes a range of reports that address natural resource topics. These reports are of interest and applicability to a broad audience in the National Park Service and others in natural resource management, including scientists, conservation and environmental constituencies, and the public. The Natural Resource Report Series is used to disseminate high-priority, current natural resource management information with managerial application. The series targets a general, diverse audience, and may contain NPS policy considerations or address sensitive issues of management applicability. All manuscripts in the series receive the appropriate level of peer review to ensure that the information is scientifically credible, technically accurate, appropriately written for the intended audience, and designed and published in a professional manner. This document contains subject matter expert interpretation of the data. The authors of this document are responsible for the technical accuracy of the information provided. The parks refrained from providing substantive administrative review to encourage the experts to offer their opinions and ideas on management implications based on their assessments of conditions. Some authors accepted the offer to cross the science/management divide while others preferred to stay firmly grounded in the presentation of only science-based results. While the authors’ interpretations of the data and ideas/opinions on management implications were desired, the results and opinions provided do not represent the policies or positions of the parks, the NPS, or the U.S. Government. Views, statements, findings, conclusions, recommendations, and data in this report do not necessarily reflect views and policies of the National Park Service, U.S. Department of the Interior. Mention of trade names or commercial products does not constitute endorsement or recommendation for use by the U.S. Government. This report is available in digital format from the Natural Resource Publications Management website (http://www.nature.nps.gov/publications/nrpm/). Please cite this publication as: Austin, J. T. 2013. A natural resource condition assessment for Sequoia and Kings Canyon National Parks: Appendix 3 – erosion and mass wasting. Natural Resource Report NPS/SEKI/NRR—2013/665.3. National Park Service, Fort Collins, Colorado. NPS 102/120977, June 2013 ii Contents Page Contents ......................................................................................................................................... iii Figures............................................................................................................................................. v Introduction ..................................................................................................................................... 1 Anthropogenic Stressors ................................................................................................................. 1 Erosion ............................................................................................................................................ 3 Processes .................................................................................................................................. 3 Water ................................................................................................................................... 3 Ice ........................................................................................................................................ 3 Gravity ................................................................................................................................ 3 Causes of Erosion .................................................................................................................... 4 General ................................................................................................................................ 4 Fire and Surface Erosion ..................................................................................................... 4 Major Geomorphological Factors Affecting Erosion ......................................................... 5 Steep Rivers in the U.S. ...................................................................................................... 5 Floods and Erosion ............................................................................................................. 7 Anthropogenically Driven Erosion of Meadows ................................................................ 7 Sediment Loads ....................................................................................................................... 8 Stream Gradients and Delta Fans ........................................................................................ 8 Kaweah Sediment Loads..................................................................................................... 8 Merced River Sediment Loads ............................................................................................ 9 Mass Wasting ................................................................................................................................ 11 Rock Falls .............................................................................................................................. 11 iii Contents (continued) Page Landslides .............................................................................................................................. 14 Rock Slides ....................................................................................................................... 14 Causes of Landslides......................................................................................................... 15 Landslide Dams ................................................................................................................ 16 Debris Flows ..................................................................................................................... 18 General ........................................................................................................................................... 18 Causes of Debris Flows ................................................................................................................. 20 Fire as a Trigger of Debris Flows .................................................................................................. 21 Debris Flow Hazard Areas ............................................................................................................. 22 Generals Highway and Colony Mill Road ............................................................................. 23 Map of High Risk Slopes and Mass Wasting Events ............................................................ 25 Suggestions for Management Consideration ................................................................................ 27 Assessment of Erosion ........................................................................................................... 27 Risk Mitigation ...................................................................................................................... 27 Rock Falls .............................................................................................................................. 27 Landslides and Landslide Dams ............................................................................................ 27 Debris Flows .......................................................................................................................... 27 Mass Wasting Spatial Model ................................................................................................. 28 Disclaimer ..................................................................................................................................... 29 Acknowledgements ....................................................................................................................... 29 Literature Cited ............................................................................................................................. 31 iv Figures Page Figure 1. Rock fall about a mile below Tunnel Rock, January 28 2005. ..................................... 13 Figure 2. Cliff-side road in Kings Canyon. .................................................................................. 15 Figure 3. Height of wave crest at Bakersfield after landslide dam failed, New Year’s Day, 1868. ..................................................................................................................................... 17 Figure 4. Map of