Chapter: A property owner in Hawaii wants to build a struct…

Chapter: A property owner in Hawaii wants to build a structure closer to the shoreline than permitted by current zoning regulations. What is the owner MOST likely to need? (EN)

Shoreline Setbacks and Their Scientific Basis in Hawaii

Shoreline setbacks are a critical component of coastal management in Hawaii. They are legally mandated distances between a structure and the certified shoreline, designed to mitigate coastal hazards, protect natural resources, and ensure public access. Understanding the scientific rationale behind these setbacks is essential for comprehending the challenges faced by a property owner seeking to build closer to the shoreline than current regulations allow.

Erosion: Hawaii’s coastlines are dynamic environments subject to continuous erosion. Wave action, sea-level rise, and storm surge contribute to land loss.
- Wave Energy: The energy of a wave is proportional to the square of its height:
  - E = (1/8) * ρ * g * H²
    - Where:
      - E is wave energy per unit area
      - ρ is the density of seawater
      - g is the acceleration due to gravity
      - H is wave height
  Higher wave heights, often associated with storms and rising sea levels, dramatically increase wave energy, accelerating erosion. Shoreline setbacks act as a buffer, protecting structures from direct wave impact and reducing structural damage.
  * Sea-Level Rise (SLR): Climate change is causing global sea-level rise, which exacerbates coastal erosion. Even small increases in sea level can significantly impact shoreline positions. The Bruun Rule estimates shoreline recession due to SLR:
  - R = (L / h) * S
    - Where:
      - R is the shoreline recession
      - L is the length of the active profile (distance from the dune crest to the closure depth)
      - h is the height of the active profile
      - S is the sea-level rise
  This demonstrates that even a modest SLR (S) can result in significant shoreline recession (R), especially on gently sloping beaches. Setbacks provide a safety margin against future land loss due to SLR.
  * Experiment: Conducting physical modeling experiments in wave tanks can simulate the effects of different wave conditions and sea levels on beach erosion. These experiments typically involve constructing scaled-down beach profiles in the tank and measuring shoreline changes under controlled conditions. Varying wave height, wave period, and water level allows researchers to quantify the relationship between these parameters and erosion rates.
Coastal Hazards: Besides erosion, coastlines are vulnerable to other hazards, including tsunamis, hurricanes, and king tides.
- Tsunamis: Large, destructive waves generated by underwater earthquakes or landslides. Shoreline setbacks provide a crucial buffer zone, reducing the impact of tsunami inundation on inland structures. Tsunami hazard zones are often determined by numerical modeling, which simulates tsunami propagation and inundation patterns. The run-up height (vertical distance above sea level reached by the tsunami) is a key parameter considered in these models.
- Storm Surge: Abnormal rise in sea level during a storm, primarily caused by strong winds pushing water towards the shore. Storm surge can inundate low-lying coastal areas, causing significant damage. Setbacks help minimize the risk of storm surge damage to buildings.
- King Tides: Highest tides of the year, occurring when the sun and moon are aligned, and the moon is closest to Earth. King tides can cause flooding in low-lying coastal areas, highlighting the vulnerability of development near the shoreline.
- Ecological Considerations: Coastal ecosystems, such as beaches, dunes, and estuaries, provide vital habitat for various species and perform essential ecological functions.
- Beach Nourishment and Sediment Transport: Natural beach nourishment occurs through the transport of sediment by waves and currents. Structures built too close to the shoreline can disrupt these natural processes, leading to beach degradation. Setbacks help preserve natural sediment transport pathways and maintain beach stability.
- Dune Stabilization: Dunes provide a natural barrier against erosion and storm surge. Development too close to the shoreline can damage dune systems, reducing their protective capacity. Vegetation also plays a key role in dune stabilization.
- Public Access: The Hawaii State Constitution guarantees public access to the shoreline. Shoreline setbacks help ensure that access is maintained, preventing private development from encroaching on public trust lands.

Variances and Special Management Area (SMA) Permits

Given the scientific basis for shoreline setbacks, a property owner seeking to build closer to the shoreline than permitted is MOST likely to need a variance or a Special Management Area (SMA) permit, or potentially both, depending on the specific regulations in the jurisdiction.

Variance: A variance is an exception to zoning regulations granted when strict adherence to the rules would create undue hardship for the property owner. To obtain a variance, the owner typically needs to demonstrate that:
1. The strict application of the zoning regulation would cause unnecessary or unreasonable hardship.
2. The hardship is due to unique circumstances peculiar to the property, such as its shape, size, or topography.
3. The variance would not be contrary to the public interest, safety, health, or welfare.
4. The variance is the minimum necessary to alleviate the hardship.
The burden of proof rests on the applicant to demonstrate that these conditions are met. The local zoning board or planning commission will consider the application and may require supporting documentation, such as engineering studies, environmental assessments, and public testimony.
Special Management Area (SMA) Permit: In Hawaii, coastal areas are often designated as Special Management Areas (SMAs). These areas are subject to stricter regulations than other parts of the island to protect coastal resources. If the proposed construction is within an SMA, the owner will need to obtain an SMA permit. This process typically involves:
1. Submitting a detailed application describing the proposed project and its potential impacts on coastal resources.
2. Preparing an Environmental Assessment (EA) or Environmental Impact Statement (EIS), depending on the scope and potential impacts of the project.
3. Consulting with relevant government agencies and community groups.
4. Obtaining approval from the local planning commission or other regulatory body.
The SMA permit process is designed to ensure that development in coastal areas is carefully managed to minimize environmental impacts and protect public interests.

Demonstrating Absence of Harm

Regardless of whether a variance or SMA permit is sought, the property owner will likely need to provide scientific evidence demonstrating that the proposed construction will not cause harm to coastal resources or increase risks to public safety. This may involve:

Wave Runup Studies: Modeling wave runup under various storm scenarios to assess the potential for wave damage to the structure and surrounding areas.
Erosion Rate Analysis: Conducting a detailed analysis of historical erosion rates and projecting future shoreline changes, considering sea-level rise.
Geotechnical Investigations: Assessing the stability of the soil and foundations to ensure that the structure can withstand coastal hazards.
Environmental Impact Assessments: Evaluating the potential impacts of the construction on coastal ecosystems, such as beaches, dunes, and marine life.
Mitigation Plans: Developing plans to mitigate any adverse impacts identified in the assessments, such as beach nourishment, dune restoration, or drainage improvements.

By presenting strong scientific evidence and demonstrating a commitment to mitigating potential impacts, the property owner may increase their chances of obtaining the necessary permits to build closer to the shoreline. However, it’s important to recognize that coastal regulations are often stringent, and approval is not guaranteed.

Chapter Summary

Scientific Summary: Shoreline Setback Variances in Hawaii
Main Points & Conclusions:
- Shoreline Setbacks & Erosion: Hawaii’s shoreline setbacks are designed to mitigate coastal hazards (erosion, sea-level rise, storm surge), protect natural resources (beaches, dunes, coral reefs), and preserve public access. Building closer than permitted exacerbates erosion by interfering with natural sediment transport processes, reducing beach width and potentially damaging adjacent properties. Construction near the shoreline can also negatively impact coastal ecosystems by increasing sedimentation and altering hydrological patterns.
- Sea-Level Rise (SLR) Acceleration: SLR projections indicate accelerated erosion rates in Hawaii. Structures built closer to the shoreline become increasingly vulnerable to inundation and damage, posing risks to human safety and property. Coastal land loss will likely increase significantly in the coming decades due to SLR.
- Dynamic Shoreline Considerations: Hawaiian shorelines are dynamic systems influenced by seasonal wave energy, long-term sediment supply variations, and episodic events like storms and tsunamis. Static setback lines may not adequately account for these fluctuations, potentially placing structures at risk. Accurate and up-to-date shoreline surveys are essential to properly determine setback compliance.
- Erosion Rates and Coastal Engineering: Historical erosion rates, derived from aerial photos, LiDAR data, and ground surveys, are key scientific inputs for determining appropriate shoreline setbacks. Coastal engineering solutions, such as seawalls or revetments, although sometimes considered, can have significant negative impacts on beach systems, potentially leading to increased erosion on adjacent properties and loss of recreational beach area. Soft engineering solutions, such as beach nourishment, are sometimes considered but require careful planning and monitoring.
- Environmental Impacts: Construction near the shoreline can disrupt sensitive coastal ecosystems. Dredging, filling, and increased runoff can harm coral reefs, seagrass beds, and other marine habitats. Native Hawaiian plants and animals are also vulnerable to habitat loss and disturbance.
Implications & The Need for Scientific Justification:
- Variance Application Requirements: To build closer to the shoreline than permitted, the property owner is most likely to need a shoreline setback variance from the relevant county planning department or state agency (e.g., the Department of Land and Natural Resources (DLNR)).
- Scientific Justification for Variance: A variance application typically requires rigorous scientific justification. This includes:
- Detailed Site-Specific Erosion Assessment: A professional assessment of the site’s erosion history, current erosion rates, and future vulnerability to SLR.
- Coastal Hazard Analysis: A comprehensive analysis of potential coastal hazards, including wave run-up, storm surge inundation, and tsunami risk.
- Environmental Impact Assessment: An evaluation of the potential environmental impacts of the proposed construction on coastal ecosystems.
- Mitigation Plan: A detailed plan outlining measures to mitigate potential negative impacts of the construction on erosion, coastal resources, and public access.
- Alternatives Analysis: Evaluation of alternative designs or building locations that would minimize impacts on the shoreline.
- Burden of Proof: The property owner bears the burden of demonstrating that the proposed construction will not significantly increase erosion, harm coastal resources, or endanger public safety. This requires convincing scientific evidence.
- Independent Review: The county or state agency will typically subject the variance application and supporting documentation to independent review by qualified coastal scientists and engineers.
- Public Trust Doctrine: Hawaii operates under the Public Trust Doctrine, which mandates the state to protect natural resources for the benefit of present and future generations. Granting a variance that jeopardizes shoreline resources is inconsistent with this doctrine and is likely to be scrutinized.
- Denial of Variance: Lack of sufficient scientific evidence or the presence of significant potential negative impacts are likely to result in the denial of the variance application.

Chapter: A property owner in Hawaii wants to build a structure closer to the shoreline than permitted by current zoning regulations. What is the owner MOST likely to need? (EN)