Sea Level Rise Planning to Outpace Rising Waters: Building Resilient Infrastructure Humboldt County Public Works Hank Seemann, Deputy-Director 2015 CEAC Spring Conference March 26, 2015
Transportation Planning Context Global climate change alters frequency and intensity of natural hazards Sea level rise represents substantially increasing risks for coastal flooding, erosion, and rising groundwater Goal is resilience Just starting to integrate sea level rise considerations into plans and project development 2 Sea Level Rise - Building Resilient Infrastructure March 26, 2015
Transportation Planning Context California milestone documents CA (2008) OPC (2010) NRC (2012) OPC (2013) CCC (2013) Executive Order S-13-08 California Interim Sea Level Rise Guidance Document Sea-Level Rise for the Coasts of California, Oregon, and Washington: Past, Present, and Future Update of California Sea Level Rise Guidance Document Draft Coastal Commission sea-level rise policy guidance Federal Highways Administration - Guidance, pilot studies Humboldt Bay Sea Level Rise Adaptation Planning Group - Regional collaboration of public agency land managers and regulators - Funding by State Coastal Conservancy 3 Sea Level Rise - Building Resilient Infrastructure March 26, 2015
Humboldt Bay Arcata North Spit Tide Gage Eureka 4 Sea Level Rise - Building Resilient Infrastructure March 26, 2015
Humboldt Bay 5 Sea Level Rise - Building Resilient Infrastructure March 26, 2015
Basic Methodology (CCSF, 2014) 1. Science Review 2. Vulnerability Assessment - Screening based on exposure, sensitivity, resilience 3. Risk Assessment - Analyze likelihood and consequence to identify priorities 4. Adaptation Planning 6 Sea Level Rise - Building Resilient Infrastructure March 26, 2015
Part 1: Science Review 7 Sea Level Rise - Building Resilient Infrastructure March 26, 2015
Regional Sea Level Rise Long term tide gage records on relatively geologic stable ground along U.S. West Coast For 20 th century, approx. 2 mm/yr (8 inches/century) Does not include vertical land motion 8 Sea Level Rise - Building Resilient Infrastructure March 26, 2015
Relative Sea Level Rise http://tidesandcurrents.noaa.gov 9 March 26, 2015
Relative Sea Level Rise Estimated historical rate over 100 years: 39 cm (15 inches) Local climate and ocean patterns Humboldt Bay Includes effects of vertical land motion 10 Sea Level Rise - Building Resilient Infrastructure March 26, 2015
Sea Level Rise Projections for Humboldt Bay Region 70 60 50 Rise 40 (Inches) 30 20 10 Relative Sea Level Rise Low Projection Medium Projection High Projection 23 13 11 9 7 5 25 40 64 Relative to Year 2000 Modified from regional sea level rise projections in NRC (2012) Vertical land motion of 2.55 mm/yr downward at North Spit gage Source: NHE (2015) 0 2030 2050 2100 11 Sea Level Rise - Building Resilient Infrastructure March 26, 2015
Part 2: Vulnerability Assessment 12 Sea Level Rise - Building Resilient Infrastructure March 26, 2015
North Humboldt Bay 1870 US Coast and Geodetic Survey 13 Sea Level Rise - Building Resilient Infrastructure March 26, 2015
North Humboldt Bay Railroad built 1900-1901 Railroad 14 Sea Level Rise - Building Resilient Infrastructure March 26, 2015
North Humboldt Bay Built 1900-1901 Railroad 15 Sea Level Rise - Building Resilient Infrastructure March 26, 2015
North Humboldt Bay SR 255 Railroad County Road SR 101 16 Sea Level Rise - Building Resilient Infrastructure March 26, 2015
Shoreline Inventory and Mapping Total length of shoreline: 102 miles (open bays and sloughs) Artificial: 75% Natural: 25% (41 miles) (26 miles) (10.5 miles) Dike Natural Railroad Source: (Laird, 2013) 19 Sea Level Rise - Building Resilient Infrastructure March 26, 2015
Annual Maximum High Tides 10.5 North Spit Tide Gauge, 1977-2014 10 9.5 9.55 feet 9 Water Level (feet NAVD88) 8.5 8 7.5 7 6.5 1977 1983 1988 1993 1998 2003 2008 2013 20 Sea Level Rise - Building Resilient Infrastructure March 26, 2015
Extreme Storm Events Saturday, Dec. 31, 2005 11:18 AM Predicted height: 8.1 feet Verified height: 9.55 feet 21 Sea Level Rise - Building Resilient Infrastructure March 26, 2015
December 31, 2005 22 Sea Level Rise - Building Resilient Infrastructure March 26, 2015
December 31, 2005 23 Sea Level Rise - Building Resilient Infrastructure March 26, 2015
Hydrodynamic Modeling Seamless topographic/bathymetric digital elevation model LiDAR plus various subtidal data sets Source: PWA (2014) 27 Sea Level Rise - Building Resilient Infrastructure March 26, 2015
Hydrodynamic Modeling Environmental Fluid Dynamics Code (USEPA) Configured as two-dimensional model (1,560 horizontal cells) Forced by 100-year stationary hourly sea level height series at ocean boundary Accounts for astronomical tides, storm surge, barometric pressure, ENSO/PDO Source: NHE (2015) 28 Sea Level Rise - Building Resilient Infrastructure March 26, 2015
Sea Level Rise Scenarios for Modeling and Mapping Rise (Inches) 80 70 60 50 40 30 20 2.0 m (79 inches) 1.5 m (59 inches) 1.0 m (39 inches) 0.5 m (20 inches) 10 2012 0 2000 2010 2020 2030 2040 2050 2060 2070 2080 2090 2100 Source: NHE (2015) High Projection Medium Projection Low Projection Scenarios: 2012 and 0.5 meter increments relative to Year 2000 29 Sea Level Rise - Building Resilient Infrastructure March 26, 2015
Sea Level Rise Scenarios for Modeling and Mapping MHHW MMMW 16 MAMW 10-yr 100-yr Water Level (feet NAVD88) 14 12 10 8 6.9 8.2 9.2 9.8 10.5 8.5 9.8 10.8 11.4 12.0 10.1 11.5 12.5 13.0 13.7 6 4 2 0 2012 0.5 m SLR 1.0 m SLR Source: NHE (2015) 30 Sea Level Rise - Building Resilient Infrastructure March 26, 2015
Sea Level Rise Inundation Vulnerability 1870 31 Sea Level Rise - Building Resilient Infrastructure March 26, 2015
Sea Level Rise Inundation Vulnerability 2012 32 Sea Level Rise - Building Resilient Infrastructure March 26, 2015
Sea Level Rise Inundation Vulnerability 2012 33 Sea Level Rise - Building Resilient Infrastructure March 26, 2015
Sea Level Rise Inundation Vulnerability 2012 Mean Monthly Maximum Water Level 34 Sea Level Rise - Building Resilient Infrastructure March 26, 2015
Sea Level Rise Inundation Vulnerability 0.5 meters SLR Mean Monthly Maximum Water Level 35 Sea Level Rise - Building Resilient Infrastructure March 26, 2015
Sea Level Rise Inundation Vulnerability 1.0 meters SLR Mean Monthly Maximum Water Level 36 Sea Level Rise - Building Resilient Infrastructure March 26, 2015
Sea Level Rise Inundation Vulnerability 1.5 meters SLR Mean Monthly Maximum Water Level 37 Sea Level Rise - Building Resilient Infrastructure March 26, 2015
Sea Level Rise Inundation Vulnerability 2.0 meters SLR Mean Monthly Maximum Water Level 38 Sea Level Rise - Building Resilient Infrastructure March 26, 2015
Part 3: Risk Assessment 39 Sea Level Rise - Building Resilient Infrastructure March 26, 2015
Source: GHD, 2014
Sea Level Rise Inundation Vulnerability Mean Monthly Maximum Water Level SR 255 0.5 meters SLR Eureka-Arcata Connections: High exposure Railroad Limited redundancy County Road Dependence on railroad (but no investment or maintenance of railroad for >20 years) SR 101 Caltrans has major role High risk / high importance 41 Sea Level Rise - Building Resilient Infrastructure March 26, 2015
Part 4: Adaptation Planning 42 Sea Level Rise - Building Resilient Infrastructure March 26, 2015
Part 4: Adaptation Planning Basic Approaches: 1. Protect (Defend) - Hard/Soft structures 2. Accommodate - Elevate (fill or causeway), and/or enhance drainage 3. Re-locate (Planned retreat) 4. No action wait and see - Repair damage - Closure / forced retreat 43 Sea Level Rise - Building Resilient Infrastructure March 26, 2015
Boat Launch Facility 44 Sea Level Rise - Building Resilient Infrastructure March 26, 2015
Boat Launch Facility 2010 45 Sea Level Rise - Building Resilient Infrastructure March 26, 2015
Storm Damage Erosion of Road Embankment New Navy Base Road PM 0.22 46 Sea Level Rise - Building Resilient Infrastructure March 26, 2015
Storm Damage Erosion of Road Embankment 1948 2010 47 Sea Level Rise - Building Resilient Infrastructure March 26, 2015
Storm Damage Erosion of Road Embankment December 26, 2008 48 Sea Level Rise - Building Resilient Infrastructure March 26, 2015
Storm Damage Erosion of Road Embankment December 29, 2008 49 Sea Level Rise - Building Resilient Infrastructure March 26, 2015
Storm Damage Erosion of Road Embankment Applied traditional hardened structure as emergency response Permanent Coastal Development Permit still pending 50 Sea Level Rise - Building Resilient Infrastructure March 26, 2015
Living Shoreline / Horizontal Levee 51 Sea Level Rise - Building Resilient Infrastructure March 26, 2015
Living Shoreline / Horizontal Levee 52 Sea Level Rise - Building Resilient Infrastructure March 26, 2015
Living Shoreline / Horizontal Levee Source: Alexander et al (2015) 53 Sea Level Rise - Building Resilient Infrastructure March 26, 2015
Levee around Reclaimed Tidelands (1) Ground elevation: 6 feet Levee crest elevation: 11 to 12 feet County vehicle maintenance facility is one of 31 parcels No single levee owner/manager Challenges: feasibility, funding, permitting, administration County is leading collaboration to do technical studies, exploring use of county-wide flood control district 54 Sea Level Rise - Building Resilient Infrastructure March 26, 2015
Levee around Reclaimed Tidelands (2) Breach in August 2014 at Humboldt Bay National Wildlife Refuge (White Slough, South Humboldt Bay) Flooded 50 acres intended for salt marsh restoration 55 Sea Level Rise - Building Resilient Infrastructure March 26, 2015
Small Bridge Project Design for freeboard Design abutments to facilitate future bridge raising Limiting factor: approach roads Pine Hill Road 56 Sea Level Rise - Building Resilient Infrastructure March 26, 2015
Major Corridor Projects SLR is key to permitting, facility longevity No prospect for planned retreat: must protect/accommodate Need to collaborate and take advantage of multi-benefit opportunities 57 Sea Level Rise - Building Resilient Infrastructure March 26, 2015
Conclusion: Needs and Opportunities for Sea Level Rise Adaptation Solid technical basis with common targets Regional collaboration Communication and integration Multi-benefit projects Permitting flexibility Pilot projects Federal/state investment 58 Sea Level Rise - Building Resilient Infrastructure March 26, 2015