RES 203 Draft 01 2022-2024 - Laserfiche WebLink

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Integrated Island , Greenhouse Gas Reduction and Climate Adaptation Actions to N Climate Action Plan for the Build Local Resilience to Climate Change � �� • Drought. Drought trends were based on data for the period 1920 to 20128. Incorporating the most current decade into the trend analysis is recommended to build on that dataset moving forward. The Hawaii Mesonet is being expanded to provide advanced weather and climate monitoring with funding from the National Science Foundation, the Hawai'i Commission on Water Resources Management, and others. The County should actively partner with the Hawaii Commission on Water Resources Management and DLNR Department of Forestry and Wildlife on drought projections and management. • Sea Level Rise. The Sea Level Rise Exposure Area with 3.2 feet of sea level rise (SLRXA-3.2) is the best available projection for the end of the century available at this time. Local projections from NOAA point to closer to 4 ft of SLR by 2100 in an Intermediate scenario. In addition, SLRXA-3.2 for Hawaii Island is based solely on passive inundation. New wave modeling with sea level rise conducted by the University of Hawaii is anticipated over the next 5 years. • Extreme Rainfall Events. Riverine flood zones (FEMA Flood Insurance Rate Map (FIRM) A/AE zones), mapped based on modeling historical floods, were used as a proxy for extreme rainfall events. In a changing climate, extreme rainfall events will not be confined to these zones. Further, riverine flood zones do not overlap with coastal flood zones (FEMA FIRM V/VE zones). This results in an underestimation of the hazard risk in areas where a river meets the sea. Finally, the riverine flood zones have not been mapped everywhere in the County, creating gaps in the data, especially in Hamakua, and therefore underestimating the number of overlapping climate hazards. • Coastal Flooding and Erosion with Sea level Rise. For Hawaii Island, coastal flooding with sea level rise was modeled only for passive inundation, with the highest sea level rise scenario at 3.2 feet by 2100. Without considering coastal erosion and wave runup with sea level rise, the Sea Level Rise Exposure Area with 3.2 feet of sea level rise (SLRXA-3.2) for Hawaii Island underestimates the total land area exposed by 35 to 54 percent, depending on location and sea level rise scenario.25 Shoreline change rate studies are being conducted by the University of Hawaii for two pilot sites. • Landslides. Geological studies are needed to better understand the conditions for cliff erosion and failure, especially along the Hamakua coast. • Tropical Cyclones and Storm Surge. Tropical cyclones may make landfall anywhere on Hawaii Island or just come near enough to cause storm surge and high winds. A Category 4 tropical cyclone, modeled to make landfall in Kona and travel northeast, was used in the cascade exposure analysis. Overall, exposure to climate hazards in Cascade 5 should be considered island wide. Focus on Hazards: The cascade exposure and risk analyses completed for this plan focus on climate change related hazards and social vulnerability. A more complete analysis would need to include more detailed data and socioeconomic and environmental indicators. Future cascades should include more detailed analyses of critical infrastructure and hubs beyond County assets, environmental pollution, and historical marginalization. 25 Anderson,T. R., Fletcher, C. H., Barbee, M. M., Romine, B. M., Lemmo, S., &Delevaux,J. M. S. (2018). Modeling multiple sea level rise stresses reveals up to twice the land at risk compared to strictly passive flooding methods. Scientific reports,8(1), 14484. doi:10.1038/s41598-018-32658-x Climate Cascades 15