🌊Coastal Resilience Engineering Unit 4 – Coastal Hazards: Risk Assessment

Key Concepts and Definitions

• Coastal hazards refer to natural phenomena that pose threats to coastal communities, infrastructure, and ecosystems
• Risk assessment involves identifying, analyzing, and evaluating potential hazards and their associated risks
• Vulnerability describes the susceptibility of a system or community to the adverse effects of a coastal hazard
  • Depends on factors such as exposure, sensitivity, and adaptive capacity
• Resilience is the ability of a system to absorb, recover from, and adapt to disturbances while maintaining essential functions and structures
• Mitigation strategies aim to reduce the likelihood or severity of coastal hazard impacts through various measures (beach nourishment, seawalls)
• Adaptation involves adjusting to actual or expected climate change effects to moderate harm or exploit beneficial opportunities
• Exposure refers to the presence of people, assets, or ecosystems in places that could be adversely affected by coastal hazards
• Sensitivity is the degree to which a system is affected by or responsive to a coastal hazard

Types of Coastal Hazards

• Sea level rise gradually increases the risk of coastal flooding, erosion, and saltwater intrusion into freshwater resources
• Storm surges are abnormal rises in sea level caused by strong winds and low atmospheric pressure during storms (hurricanes, typhoons)
  • Can lead to severe coastal flooding and damage to infrastructure
• Coastal erosion is the loss of land along the shoreline due to various factors (waves, currents, human activities)
  • Threatens beaches, dunes, and coastal properties
• Tsunamis are large, powerful waves generated by undersea earthquakes, landslides, or volcanic eruptions
  • Can cause rapid flooding and devastation in coastal areas
• Rip currents are strong, narrow channels of fast-moving water that flow away from the shore
  • Pose a significant risk to swimmers and beachgoers
• Coastal subsidence is the gradual settling or sinking of land due to natural or human-induced causes (groundwater extraction, sediment compaction)
  • Exacerbates the effects of sea level rise and flooding
• Saltwater intrusion occurs when seawater moves into freshwater aquifers, contaminating water supplies and affecting ecosystems

Risk Assessment Methodologies

• Hazard identification is the process of recognizing and defining the potential coastal hazards in a given area
• Probability analysis estimates the likelihood of a coastal hazard occurring within a specific timeframe
  • Uses historical data, statistical models, and expert judgment
• Consequence analysis evaluates the potential impacts of a coastal hazard on people, property, infrastructure, and the environment
• Risk matrix is a tool that combines the probability and consequence of a hazard to determine its overall risk level (low, medium, high)
• Quantitative risk assessment uses numerical data and models to estimate risk, providing more precise results but requiring extensive data
• Qualitative risk assessment relies on descriptive scales and expert judgment to categorize risk, useful when data is limited
• Multi-hazard risk assessment considers the combined effects of multiple coastal hazards and their interactions
• Stakeholder engagement involves incorporating the knowledge, concerns, and priorities of affected communities and organizations into the risk assessment process

Data Collection and Analysis

• Historical data (tide gauge records, satellite observations) provides information on past coastal hazard events and long-term trends
• Geospatial data (digital elevation models, land use maps) is used to analyze the physical characteristics and exposure of coastal areas
• Oceanographic data (wave heights, currents, sea surface temperatures) helps understand the dynamics and variability of coastal processes
• Socioeconomic data (population, infrastructure, economic activities) is essential for assessing the vulnerability and potential impacts of coastal hazards
• Remote sensing techniques (aerial photography, LiDAR) enable the acquisition of high-resolution data over large areas
• Field surveys and measurements provide ground-truth data to validate and calibrate models and remote sensing data
• Statistical analysis techniques (trend analysis, extreme value analysis) are used to identify patterns, trends, and probabilities in coastal hazard data
• Data integration and management involve combining and organizing data from various sources to support risk assessment and decision-making

Vulnerability Assessment

• Exposure assessment identifies the people, assets, and ecosystems that are located in areas prone to coastal hazards
  • Uses geospatial data and mapping techniques
• Sensitivity analysis evaluates how different elements of a system respond to and are affected by coastal hazards
  • Considers factors such as building materials, infrastructure design, and ecosystem resilience
• Adaptive capacity assessment examines the ability of a system to adjust, cope with, and recover from coastal hazard impacts
  • Depends on factors like financial resources, technology, and institutional support
• Social vulnerability assessment focuses on the characteristics of populations that influence their susceptibility to coastal hazards (age, income, education)
• Physical vulnerability assessment evaluates the potential damage to buildings, infrastructure, and other assets based on their exposure and sensitivity
• Ecosystem vulnerability assessment considers the impacts of coastal hazards on natural habitats, biodiversity, and ecosystem services
• Indicators and indices are used to quantify and compare vulnerability across different areas or sectors (Coastal Vulnerability Index)

Impact Prediction and Modeling

• Inundation modeling simulates the extent and depth of coastal flooding based on sea level rise, storm surge, and wave conditions
  • Uses digital elevation models and hydrodynamic models
• Erosion modeling predicts the potential loss of land and changes in shoreline position due to coastal erosion
  • Considers factors like wave energy, sediment transport, and coastal morphology
• Damage assessment estimates the potential economic losses and impacts on buildings, infrastructure, and assets based on hazard intensity and vulnerability
• Ecosystem impact modeling evaluates the effects of coastal hazards on habitats, species, and ecological processes
  • Uses ecological models and habitat suitability analysis
• Socioeconomic impact assessment predicts the potential consequences of coastal hazards on communities, livelihoods, and economic activities
  • Considers factors like population displacement, business interruption, and recovery costs
• Uncertainty analysis assesses the limitations and variability of impact predictions due to data gaps, model assumptions, and future scenarios
• Scenario planning explores different possible future outcomes based on alternative assumptions about hazard intensity, vulnerability, and adaptation measures

Risk Mitigation Strategies

• Hard engineering solutions involve the construction of physical structures to protect against coastal hazards (seawalls, breakwaters, levees)
  • Can provide immediate protection but may have negative environmental impacts and high maintenance costs
• Soft engineering approaches use natural materials and processes to enhance coastal resilience (beach nourishment, dune restoration, living shorelines)
  • Provide multiple benefits but may require frequent maintenance and have limited effectiveness against severe hazards
• Land use planning and zoning regulations guide development away from high-risk areas and promote sustainable coastal management practices
• Building codes and standards ensure that structures are designed and constructed to withstand the impacts of coastal hazards
  • Includes requirements for elevation, flood-proofing, and wind resistance
• Early warning systems detect and communicate the approach of coastal hazards (tsunamis, storm surges) to enable timely evacuation and emergency response
• Public awareness and education programs inform communities about coastal hazards, risk reduction measures, and emergency preparedness
• Nature-based solutions harness the natural capacity of ecosystems to mitigate coastal hazards (mangrove restoration, coral reef conservation)
  • Provide co-benefits for biodiversity and ecosystem services

Case Studies and Real-World Applications

• The Dutch Delta Works is a series of dams, sluices, and storm surge barriers designed to protect the Netherlands from coastal flooding
  • Showcases the effectiveness of hard engineering solutions in a low-lying, densely populated coastal area
• The Maldives is implementing a comprehensive coastal protection strategy that combines hard and soft engineering measures to address sea level rise and erosion
  • Highlights the challenges faced by small island developing states in adapting to coastal hazards
• The Chesapeake Bay Living Shorelines Initiative promotes the use of natural materials and vegetation to stabilize shorelines and enhance coastal resilience
  • Demonstrates the potential of nature-based solutions in mitigating coastal hazards while providing ecological benefits
• The Bangladesh Delta Plan 2100 is a long-term strategy for sustainable coastal management that integrates risk assessment, adaptation planning, and socioeconomic development
  • Emphasizes the importance of a holistic and participatory approach to coastal resilience in a highly vulnerable region
• The U.S. National Flood Insurance Program provides flood insurance to property owners and encourages communities to adopt floodplain management regulations
  • Illustrates the role of financial mechanisms in promoting risk reduction and resilience
• The Sendai Framework for Disaster Risk Reduction 2015-2030 is a global agreement that sets targets and priorities for reducing disaster risks, including coastal hazards
  • Underscores the need for international cooperation and knowledge sharing in advancing coastal resilience