City of Del Mar Local Coastal Plan (LCP) Amendment for Sea Level - - PowerPoint PPT Presentation

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City of Del Mar Local Coastal Plan (LCP) Amendment for Sea Level - - PowerPoint PPT Presentation

Mar 11, 2023 178 likes •493 views

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

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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.

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Del Mar Coastal Hazards

  • 1. Coastal flooding

1983 El Niño storm damage 2016 El Niño wave overtopping

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Del Mar Coastal Hazards

  • 2. Bluff erosion

1941 bluff collapse and train wreck 2016 bluff collapse

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Del Mar Coastal Hazards

  • 3. San Dieguito River flooding

1980 River flooding of Fairgrounds and City FEMA 100-yr floodplain

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LCP Amendment for SLR and Flooding

Funding

  • City funding and in-kind

services

  • CCC/OPC Round 2 grant
  • CCC Round 3 grant award

Work Program

  • Stakeholder outreach
  • Hazards, vulnerability, and

risk assessment

  • Adaptation Plan
  • LCP Amendment
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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

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Climate Change Scenarios

  • Sea level rise: NRC (2012)
  • Precipitation: RCP 4.5 and 8.5

2030 2050 2070 2100 Mid SLR 5 in 12 in 20 in (1.7 ft) 37 in (3.1 ft) High SLR 12 in 24 in 38 in (3.2 ft) 66 in (5.5 ft)

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USGS CoSMoS Initial Results

  • 100-year coastal storm with 5-yr River discharge
  • Beach loss in 2100
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USGS CoSMoS Initial Results

  • 100-year coastal storm with 5-yr River discharge
  • Beach loss in 2100
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Flood Risks

SLR: Flood Risk Annual Chance of Occurrence 0’ 1’ 2’ 3’ 5.5’ Signi- ficant (2016) Mod 10% High 50% High 100% Extreme (1983) Low 1% Mod 5% Mod 15% High 50% High 100% Signi- ficant (1980) Low 4% Mod 15% Mod 25% Mod 50% High 100% Extreme (100-yr) Low 1% Mod 5% Mod 6% Mod 6% Mod 20% Coastal Flooding River Flooding

Accounts for:

  • Beach erosion
  • Change in extreme rainfall and

River discharge

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Beach Erosion Risk

  • The beach above high tide will be lost to erosion

between 2030 and 2070

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Bluff Erosion Risks

Railroad: 2030 (1’) or earlier Property & sewer: 2050 (2’)

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DRAFT Adaptation Plan and Triggers

Adaptation Plan Component/ Vulnerability Adaptation Trigger 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 conversion Mid marsh loss

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DRAFT Bluff Adaptation Plan Framework

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DRAFT Bluff Adaptation Plan Scenario 1. Relocate Railroad

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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

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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

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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

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Del Mar Local Coastal Program Amendment

  • Coastal Commission review
  • Public outreach process
  • Next steps
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Questions?

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High Priority Measures

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Beach Adaptation Plan Framework

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Beach Adaptation Plan – Scenario 1a.

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Beach Adaptation Plan – Scenario 1b. Sea Wall Protection

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Beach Adaptation – Scenario 2. Relocate Structures, Maintain Beach

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River Adaptation Plan Framework

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River Adaptation Plan – Scenario 1. Protection with Partial Retreat

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River Adaptation Plan – Scenario 2. Relocate Structures

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Wetlands Adaptation Plan Framework

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Wetlands Adaptation – Scenario 1. Sediment Placement

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Wetlands Adaptation Plan – Scenario 2. Wetland Expansion/Restoration