Multi-Hazard Mitigation Plan: 19. Mitigation Strategy

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Chapter 19:Mitigation Strategy • Emergency Services. Actions that protect people and property during and immediately after a disaster or hazard event (e.g., warning systems, emergency response services, protection of critical facilities). • Structural Projects. Actions that involve the construction of structures to reduce the impact of a hazard(e.g., dams,levees, flood walls, seawalls, diversion ditches). 19.2.1 Hurricanes and Wind Storms Mitigation actions include improving emergency services and protecting property through enhanced structural integrity: • Warning Systems. Warning has improved with the use of weather satellites, weather buoys, and tracking aircraft, but it is not possible to predict, more than a very few hours ahead,just where in the islands the main force of a hurricane will impact. Hurricane Iniki exemplified the sudden unpredictable track of a hurricane. However, the intensity of a storm approaching the islands is known before it makes landfall and thus the effects may be anticipated. Although the position of a storm refers to its center (the "eye"), hazardous wind, rain, and surf can extend 200 miles from the center. Therefore advance warning and preparation for a hurricane must consider the potential periphery effects. All cyclonic storms in this part of the ocean are carefully monitored by the Central Pacific Hurricane Center, which is established at the National Weather Service forecast office in Honolulu at the start of the "hurricane season" on June 1. "Warning" is actually provided in several stages: advisories of tropical depressions (incipient storms); warning of tropical storms (winds less that 74 mph); hurricane watch (hurricane within 36 hours) and hurricane warning (hurricane conditions - winds over 73 mph expected within 24 hours). [Note:74 mph—64 knots, sometimes used in reports]. • Hurricane Shelters. Sheltering and preparation in Hawaii is primarily the responsibility of residents themselves, since major evacuation as is done in the Gulf and Atlantic coasts is obviously impractical. Adequate public shelters capable of withstanding hurricane-force winds are limited; they can hold 80% of the population who will seek shelter,by State Civil Defense standards. These standards expect only 35% of the population to seek public shelters. Most of the shelters shown are schools and some are marginal for this purpose but are the best refuge available. Homeowner's preparations are vital and have been publicized in print by the UH Social Science Research Institute (SSRI)10x and are repeated by Civil Defense via the media during a hurricane watch. However, evacuation of coastal areas threatened by storm surge is done in an ad hoc fashion by using the tsunami evacuation maps. These maps have some validity for this purpose in areas such as Kailua-Kona, (although they may be too small) but may encompass too large an area such as in Hilo, where some buildings in the zone are more important as shelters. There is a paradox in hurricane evacuation- it is important not to expose people to wind hazards while avoiding the flooding hazard. • Structural Integrity. Structural integrity has only been tested on this island by winter storms (winds over 40 mph; Chapter 4). In areas with frequent hurricanes, such as Guam, the most vulnerable structures are damaged or removed by prior events. Since we have been lucky enough to not have such experience, a high percentage of homes and also commercial 108 Social Science Research Institute,UH,"Hurricanes in Hawaii:What Are The Risks of Damage?", undated. 19-3 Hawaii County Multi-Hazard Mitigation Plan