Coastal hazards are natural and manmade events that impact the boundary between the ocean and the shoreline. The Town of Hilton Head Island faces a variety of coastal hazards such as hurricanes, tropical storms - often resulting in floods and coastal erosion - as well as pollution. Often times vulnerability to these hazards is aggravated by pollution, poor coastal construction practices, and destruction of coastal vegetation that are part of dunes, dune systems and buffers. The challenge remains to reduce risk and loss of life, while protecting the natural resources of the Island. Due to the potential storm surge events during a hurricane or tropical storm and the ongoing occurrence of shoreline/beach erosion, these hazards have been highlighted in particular.
People who live and work in coastal areas face unique risks from disasters. Risks from coastal hazards are expected to increase in the future as development and populations continue to grow in coastal areas and a rise in sea level occurs due to climate change. The potential to have lives lost, damage to critical facilities, homes and businesses highlight the need to better understand the impact and possible devastation of coastal hazards on our community. To reduce this risk, it is important to mitigate against the hazards in order to preserve life and protect property.
Storm surge results from the combination of low pressure associated with an oncoming storm and high winds which push on the ocean's surface causing a temporary rise in the level of the sea. The water surges onto the shore, flooding areas inland of the high water mark (a reference mark which indicates the maximum normal stage of tide or flood) and therefore reaching higher along the beach front. Battering waves are capable of reducing buildings to rubble, eroding long stretches of beach, undermining poorly anchored structures and undercutting roads.
The elevation of the coastline significantly influences the kind of damage to buildings. In low-lying coastal areas with beaches, like Hilton Head Island, damage from storm surge is likely to result causing beach erosion that undermines foundations. The level and rate of erosion that is being observed is used to determine the "safe" distance from the shoreline, up to which buildings may be constructed without fear of sea damage. Build your home a safe distance away from the beach to minimize the impact of storm surge. Build your house on columns to prevent sand and water from storm surge and flooding from getting into your house.
Coastal erosion is a natural process that consists of the breakdown of rock and sediments at the shoreline, both above and below the water surface. The removal of sand is caused by wave and tidal action and long-shore currents. This process is usually very significant and is often enhanced by storm events. The extent of erosion from storms is directly related to the number, intensity and duration of the storms. Although susceptible to erosion, beaches form the first line of defense against ocean waves, providing a buffer between the waves and coastal properties. When beaches are cut back during storms they progressively lose this buffering ability, making further coastal erosion more likely. As the beach erodes, vulnerable properties are placed at even greater risk.
A great way to protect coastal property and beaches is to ensure that buildings are positioned a safe distance behind the active beach. The Town of Hilton Head Island has its own guidelines for beachfront development, so it is necessary to contact staff for applicable regulations. Building setbacks and buffers should be regarded as minimum values.