Cedar Rapids Post-Project Channel Change Evaluation King County Water and Land Resources Division December 2013 Cedar Rapids Post-Project Channel Change Evaluation Prepared for King County Water and Land Resources Division Rivers and Floodplain Section 201 South Jackson Street Seattle, WA 98104 Prepared by Parametrix 411 108th Avenue NE, Suite 1800 Bellevue, WA 98004-5571 T. 425.458.6200 F. 425.458.6363 www.parametrix.com File Name: Master_123113_Clean.docx December 2013 │ 247-1521-109 CITATION King County. 2013. Cedar Rapids Post-Project Channel Change Evaluation. Prepared by Parametrix, Bellevue, Washington. December 2013. Cedar Rapids Post-Project Channel Change Evaluation King County Water and Land Resources Division TABLE OF CONTENTS 1 INTRODUCTION AND OVERVIEW ................................................................... 1-7 1.1 PURPOSE AND SCOPE OF THIS STUDY ......................................................... 1-7 1.2 PROJECT AREA ................................................................................................... 1-7 1.3 HISTORIC RIVER MANAGEMENT EFFORTS ................................................. 1-7 1.4 PROJECT BACKGROUND .................................................................................. 1-8 1.5 STUDIES IN THE PROJECT AREA .................................................................... 1-9 1.6 STUDY APPROACH AND EXPECTATIONS .................................................. 1-10 2 METHODS ......................................................................................................... 2-1 2.1 STUDY ANALYSIS METHODS .......................................................................... 2-1 2.2 STUDY GOALS AND OBJECTIVES .................................................................. 2-1 3 RESULTS ........................................................................................................... 3-1 3.1 CHANNEL PROCESSES ...................................................................................... 3-1 3.1.1 Channel Migration (C1) ................................................................................ 3-1 3.1.2 Scour and Erosion (C2) .............................................................................. 3-15 3.2 AQUATIC EDGE HABITAT (A3) ..................................................................... 3-21 4 DISCUSSION ..................................................................................................... 4-1 5 REFERENCES ................................................................................................... 5-1 LIST OF FIGURES 1 Cedar Rapids Project Reach ................................................................................... 1-1 2 Plan Sheet 5. Cedar River, River Mile 7.2-7.6 Grading Plan-Log Features and Proposed Topography ............................................................................................. 1-3 3 Plan Sheet 3. Cedar Rapids Levee Setback Repair Proposed Site Plan ................. 1-5 4 Plan Sheet 5. Cedar Rapids Levee Setback Repair ELJ Type 1 Plan and Section .................................................................................................................... 1-7 5 Channel Migration Rate (C1) 2007 to 2009 ........................................................... 3-3 6 Channel Migration Rate (C1) 2009 to 2010 ........................................................... 3-7 7 Channel Migration Rate (C1) 2010 to 2011 with March 2010 Orthophoto ........... 3-9 8 Channel Migration Rate (C1) 2010 to 2011 with Summer 2011 Orthophoto ...... 3-11 9 Channel Migration Zones 1936 - 2011 ................................................................. 3-13 10 Scour and Deposition (C2) – 2002 versus 2010 LiDAR Elevation Data ............. 3-17 11 Scour and Deposition (C2) – 2010 versus 2011 LiDAR Elevation Data ............. 3-19 12 Scour and Deposition (C2) Plan View for Cross Section Profiles ....................... 3-23 13 Cross-Section – Section A-A ................................................................................ 3-25 14 Cross-Section – Section B-B ................................................................................ 3-27 December 2013 i Cedar Rapids Post-Project Channel Change Evaluation King County Water and Land Resources Division TABLE OF CONTENTS (CONTINUED) 15 Cross-Section – Section C-C ................................................................................ 3-29 16 Cross-Sections – Section D-D .............................................................................. 3-31 17 Cross-Sections – Section E-E ............................................................................... 3-33 18 Cross-Sections – Section F-F ............................................................................... 3-35 19 Aquatic Habitat/Edge Characteristics (A3) – 2007 .............................................. 3-37 20 Aquatic Habitat/Edge Characteristics (A3) – 2009 .............................................. 3-41 21 Aquatic Habitat/Edge Characteristics (A3) – 2010 .............................................. 3-43 22 Aquatic Habitat/Edge Characteristics (A3) – 2011 .............................................. 3-47 23 Floodplain Vegetation (R1) – 2007 ...................................................................... 3-51 24 Floodplain Vegetation (R1) – 2009 ...................................................................... 3-53 25 Floodplain Vegetation (R1) – 2010 ...................................................................... 3-55 26 Floodplain Vegetation (R1) – 2011 ...................................................................... 3-57 LIST OF TABLES 1 Data Sets Available for Cedar Rapids Post-Project Assessment ............................ 2-1 2 Study Goals and Objectives .................................................................................... 2-2 3 Evaluation Metrics ................................................................................................. 2-2 4 Channel Migration Rates 2007 to 2009 .................................................................. 3-1 5 Channel Migration Rates between 2009 and 2010 ................................................. 3-5 6 Channel Migration Rates 2010 to 2011 .................................................................. 3-5 7 Scour and Deposition Rates 2002 versus 2010 .................................................... 3-15 8 Scour and Deposition Rates 2010 versus 2011 .................................................... 3-15 9 Aquatic Edge Habitat—Summary of Channel Widths 2007 to 2011 ................... 3-21 10 Aquatic Edge Habitat in 2007 .............................................................................. 3-39 11 Aquatic Edge Habitats in 2009 ............................................................................. 3-39 12 Aquatic Edge Habitats in 2010 ............................................................................. 3-39 13 Aquatic Edge Habitats in 2011 ............................................................................. 3-45 14 Floodplain Vegetation 2007 ................................................................................. 3-49 15 Floodplain Vegetation 2009 ................................................................................. 3-49 16 Floodplain Vegetation 2010 ................................................................................. 3-49 17 Floodplain Vegetation 2011 ................................................................................. 3-49 ii December 2013 Cedar Rapids Post-Project Channel Change Evaluation King County Water and Land Resources Division TABLE OF CONTENTS (CONTINUED) APPENDICES A Cedar Rapids Floodplain Stewardship Plan B King County Cedar Rapids Vegetation Assessment Summary C Cedar Rapids Levee Setback and Floodplain Reconnection Project, Project History, Flood Damages, and Responses, 2008–2011 D Cedar Rapids Project Assessment Summary of GIS Analysis Methods E Photographs of January 7, 2009 Flood Event F Floodplain-wide Cross-sectional Figures G Aquatic Edge Habitat Measurements for 2007, 2009, 2010, and 2011 December 2013 iii Cedar Rapids Post-Project Channel Change Evaluation King County Water and Land Resources Division ACRONYMS AND ABBREVIATIONS cfs cubic feet per second County King County ELJ engineered log jam ESA Endangered Species Act FHMP Flood Hazard Management Plan GIS geographic information system LiDAR light detection and ranging RM river mile SR State Route SRFB Salmon Recovery Funding Board USGS U.S. Geological Survey WRIA Water Resource Inventory Area December 2013 iv Cedar Rapids Post-Project Channel Change Evaluation King County Water and Land Resources Division 1 INTRODUCTION AND OVERVIEW 1.1 PURPOSE AND SCOPE OF THIS STUDY This study is a retrospective evaluation to document effects of the 2008 Cedar Rapids levee setback project on the Cedar River channel. This study seeks to quantify changes within the project reach related to channel migration, the establishment of off-channel and in-stream habitat, the extent of scour and deposition within the project reach, and the change in vegetation within the floodplain over time. Natural riverine processes are assumed to create habitat features favored by salmonids and other aquatic species within the Cedar River. Measuring changes in physical characteristics and natural process rates of the river due to project actions is one way of evaluating project effectiveness and will help inform future project design. In addition to this