Coastal Hazards, Risk Assessment, and Property Damage Mitigation David M. Bush University of West Georgia

Components of Risk Hazards Vulnerability

Hazards are the Physical Processes Storms Earthquakes Floods High winds

Vulnerability Fixed habitations and related structures: –Docks –Wharfs –Buildings –Pipelines –Utilities –Roads

Damage Potential—Primary Factors Elevation Forest Cover

Elevation Elevation is a primary factor in determining flood zones Areas above A-zones are at lower risk Areas in V-zones (exposed to wind and waves) are at highest risk

Vegetation Vegetation (especially maritime forest and dense shrub thicket) protects structures from wind damage Vegetation can offer a barrier against storm surge and waves Vegetation anchors sediment, stabilizes landforms, and preserves elevation

Preliminary Risk Assessment FLOOD ZONEVEGETATIONRATING V---Extreme ANone or sparseHigh A Dense shrub or forest Moderate Above ANone or sparseModerate Above A Dense shrub or forest Low

Responses to an Eroding Shoreline Hard Stabilization –Seawalls, groins, breakwaters, etc. Soft Stabilization –Beach replenishment, dune building Relocation or retreat –Move back from eroding shoreline

Hard Stabilization (Seawalls, etc.) Advantages –Most dependable way to save beachfront property Disadvantages –Degrades the recreational beach –Reduces beach access –Costly –unsightly

Modes of Beach Destruction by Seawalls Placement Loss –Seawall is built on the recreational beach Passive Loss –Beach continues to retreat and narrows in front of the seawall Active Loss –Seawall directly causes erosion

Soft Stabilization (Beach Nourishment) Advantages –Widens the beach –Protects buildings while beach is in place Disadvantages –Temporary –Costly –Unknown environmental effects

Relocation or Retreat Advantages –Responds to sea-level rise –Preserves the beach –Saves shoreline stabilization costs –Preserves builidings Disadvantages –Politically difficult –Potentially costly –Loss of land

Mitigation Options Hard Stabilization Soft Stabilization Vegetation Development and infrastructure Zoning and land use planning

Mitigation Engineering –Strengthen or move buildings –Armor the coast Land Use Planning –Limit or reduce development density –Can help implement new techniques such as clustered housing –Easiest with new developments

Our Approach to Mitigation Coastal landform protection, restoration, augmentation Mostly low cost Many things individuals can do Environmentally sensitive Considers geologic/oceanographic processes

PAR For the Shore Preserve, Augment, Restore –Dunes (frontal and interior) –Coastal barriers of all types Mangroves Shoals River mouth bars Maritime forest –Add new sand to island