City of Del Mar Local Coastal Plan (LCP) Amendment for Sea Level Rise and Coastal Flooding Nick Garrity, PE Reema Shakra, AICP Environmental Science Associates (ESA) Dr. Adam Young, PhD Scripps Institute of Oceanography, UCSD Robert Dickinson Argos Analytics, LLC ESA is where solutions and service meet.
Del Mar Coastal Hazards 1. Coastal flooding 1983 El Niño storm damage 2016 El Niño wave overtopping
Del Mar Coastal Hazards 2. Bluff erosion 1941 bluff collapse and train wreck 2016 bluff collapse
Del Mar Coastal Hazards 3. San Dieguito River flooding FEMA 100-yr floodplain 1980 River flooding of Fairgrounds and City
LCP Amendment for SLR and Flooding Funding Work Program • City funding and in-kind • Stakeholder outreach services • Hazards, vulnerability, and • CCC/OPC Round 2 grant risk assessment • CCC Round 3 grant award • Adaptation Plan • LCP Amendment
Stakeholder & Technical Advisory Committee (STAC) • 9 members including representatives for: – Residents – CA Coastal Commission – Del Mar Fairgrounds – Scripps (SIO) – Non-profits – City Council • 10 STAC meetings and workshops to date to: – Review data gaps and gather historic flood information – Guide Hazards, Vulnerability, Risk Assessment – Provide input and recommendations on Adaptation Plan
Climate Change Scenarios • Sea level rise: NRC (2012) 2030 2050 2070 2100 Mid 20 in 37 in 5 in 12 in SLR (1.7 ft) (3.1 ft) High 38 in 66 in 12 in 24 in SLR (3.2 ft) (5.5 ft) • Precipitation: RCP 4.5 and 8.5
USGS CoSMoS Initial Results • 100-year coastal storm with 5-yr River discharge • Beach loss in 2100
USGS CoSMoS Initial Results • 100-year coastal storm with 5-yr River discharge • Beach loss in 2100
Flood Risks Flood Risk Annual Chance of Occurrence SLR: 0’ 1’ 2’ 3’ 5.5’ Coastal Flooding Signi- Mod High High ficant 10% 50% 100% (2016) Extreme Low Mod Mod High High (1983) 1% 5% 15% 50% 100% Signi- River Flooding ficant Low Mod Mod Mod High (1980) 4% 15% 25% 50% 100% Extreme (100-yr) Low Mod Mod Mod Mod 1% 5% 6% 6% 20% Accounts for: • Beach erosion • Change in extreme rainfall and River discharge
Beach Erosion Risk • The beach above high tide will be lost to erosion between 2030 and 2070
Bluff Erosion Risks Railroad: 2030 (1’) or earlier Property & sewer: 2050 (2’)
DRAFT Adaptation Plan and Triggers Adaptation Plan Component/ Adaptation Trigger Vulnerability High priority measures Near-term Coastal and River flooding Extreme flood risk (5%) Beach erosion Beach width (walkable) Bluff erosion Bluff top offset (35’) San Dieguito Lagoon wetland Mid marsh loss conversion
DRAFT Bluff Adaptation Plan Framework
DRAFT Bluff Adaptation Plan Scenario 1. Relocate Railroad
Del Mar Local Coastal Program Amendment • Existing Local Coastal Program is a policy, regulatory and procedural document that regulates development within the City’s Coastal Zone • The Local Coastal Program includes a Land Use Plan and Implementation Plan
Del Mar Local Coastal Program Amendment • Developing a new chapter in their Land Use Plan to address sea-level rise related hazards – Translates Adaptation Plan principles into goal statements – Develops policies to address each Adaptation Plan measure – Identifies when an update to the Adaptation Plan is appropriate – Adds policies to guide how the City would track triggers – Incorporates other policies from Coastal Commission Sea- level Rise Policy Guidance and City-directed policies
Del Mar Local Coastal Program Amendment • Developing a new chapter in their Implementation Plan – Regulations based on the policies – Overlay map to show who is affected by new regulations – Trigger-based standards
Del Mar Local Coastal Program Amendment • Coastal Commission review • Public outreach process • Next steps
Questions?
High Priority Measures
Beach Adaptation Plan Framework
Beach Adaptation Plan – Scenario 1a.
Beach Adaptation Plan – Scenario 1b. Sea Wall Protection
Beach Adaptation – Scenario 2. Relocate Structures, Maintain Beach
River Adaptation Plan Framework
River Adaptation Plan – Scenario 1. Protection with Partial Retreat
River Adaptation Plan – Scenario 2. Relocate Structures
Wetlands Adaptation Plan Framework
Wetlands Adaptation – Scenario 1. Sediment Placement
Wetlands Adaptation Plan – Scenario 2. Wetland Expansion/Restoration
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