Coastal Property Damage Mitigation Risk Assessment GEOL 4093.

Coastal Property Damage Mitigation

Risk Assessment

GEOL 4093

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

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

New Jerseyization

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

Metropolitan San Juan Dry Beach Widths

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

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

Pandora’s Island—Mitigation on the Beach

Pandora’s Island—Mitigation back from the beach

Pandora’s Island becomes Fantasy Island