Integrating Surf Science into Coastal Management Decision Making

OUR CHALLENGE

The Topanga Lagoon Restoration Project—led by Resource Conservation District of the Santa Monica Mountains, California State Parks, County of Los Angeles, and Caltrans—faced significant surfing community opposition requiring technical assessment of surf quality impacts.

Stakeholder Opposition Quantified:

• 65.33% believed overall surf quality would decrease
• 62.16% expected fewer surfable days
• No established methodology existed for surf quality impact assessment

OUR APPROACH

Surf Science Methodology

We developed surf science—combining wave modeling, stakeholder engagement, and peel angle analysis to quantify surf break quality impacts. This first-of-its-kind approach provides technical insights to regulators and surf communities regarding project impacts on irreplaceable surf breaks.

Technical Implementation

Community-Driven Research:

• Surf focus group surveys identified optimal modeling conditions
• Local knowledge validated against wave buoy data
• Best conditions: long period south swells, medium period west swells

XBeach Wave Modeling:

• 2D nonhydrostatic modeling with 30-minute simulations
• Three wave cases: 2ft/15s/230°, 4ft/11s/255°, 7ft/10s/260°
• Multiple conditions: baseline, drought, wet, sea level rise (6.6 ft by 2100)

Peel Angle Analysis:

• Primary metric: angle between wave front and wave path
• Lower angles = steeper/faster waves; higher angles = slower/turnable waves
• Automated extraction from wave path data

OUR IMPACT

Quantitative Results

Short-Term Project Effects (1 Year):

• Wet conditions: Project slightly increases wave speed on south swells
• Drought conditions: Project causes slightly slower waves in some areas
• All impacts within natural flood/drought variability

 

Long-Term Assessment (5+ Years):

• No project impacts on wave quality for any condition
• Natural processes restore baseline characteristics
• Sea level rise (6.6 ft by 2100) represents primary future threat—far exceeding any project effects

Stakeholder Transformation

Community Response Shift:

• Pre-results: 65% opposition to surf quality impacts
• Post-results: Significant reduction in opposition across all metrics
• Outcome: Supportive surfer comments during environmental review

Technical Validation

• Local surfer knowledge closely matched wave buoy data
• Community input enhanced model accuracy
• Methodology validated through quantitative analysis

Project Benefits

Immediate Outcomes:

• Transformed community opposition into project support
• Provided technical foundation for environmental review
• Enabled project approval through evidence-based assessment

Broader Applications:

• Established standardized surf quality impact methodology
• Created framework for integrating recreational stakeholder concerns
• Demonstrated scalable approach for coastal project evaluation

Methodology Applications

Surf quality impact assessments prove effective for:

• Objective assessment of coastal project impacts on surf resources
• Communication bridge between surf stakeholders and coastal managers
• Conservation support for natural recreational amenities

Future Implementation: This technical approach can be applied to future coastal projects to evaluate stakeholder concerns and inform decision making to conserve recreational amenities and revenues.

Results: No long-term surf quality impacts from restoration project. Community opposition transformed into support. First quantitative surf quality assessment methodology established for coastal management applications.

View surf science poster presented at 2024 ASBPA Conference.