Methods of Coastal Hazards Assessment David M. Bush Risk Assessment GEOL 4093

Island-scale mapping 1990’s Originally done by hand on clear plastic overlays and tracing paper We didn’t know at the time that it was GIS Andy and R/V Bicycle Elevation Forest Cover

Island-scale mapping1990’s

Analog GIS Andy--R/V Bicycle Elevation Forest Cover

Florida Panhandle, after Opal (1995)

Pawleys Island, SC, after Hugo (1989)

South of Cancun after Gilbert, 1988

B Zone A Zone V Zone Jekyll Island flood zones

Forest No Forest Jekyll Island forest cover

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

Water Low Hazard Moderate Hazard High Hazard Extreme Hazard Jekyll Island preliminary hazard assessment

Mainland Mapping Tracy Rice developed this using fetch instead of SLOSH

Risk Rating ParameterExtremeHighModerateLow Vegetation None, sparse, marsh, 6 Scattered shrub, 4 Dense shrub, 2 Maritime forest, 1 Q-3 Flood zones VE and undes., 8 A and AE. 6 X500, 2 X, 1 SLOSH Category 1-3, 8 Category 4, 5, and upland, 0 Ranges

Geo-indicators Elevation Vegetation Tidal range Bluff configuration Evidence of historical storm impacts Type of structures Density of structures Site relative to stream mouth Soil and drainage Other surrounding features

Geoindicators Assessment General Site Parameters GeoindicatorsHigh RiskModerate RiskLow Risk Elevation < 3 m3-6 m> 6 m Tidal Range microtidalmesotidalmacrotidal Bluff Configuration bare face, recent slump vegetated face, ramp well-vegetated ramp Erosion rate rapidly erodingeroding stable or accreting Evidence of storms obvious possiblenone Total Indicators Of High Risk  Of Moderate Risk  Of Low Risk 

Camden County, GA Study Sites

St. Marys, GA

Elliots Bluff, GA

Puerto Rico Coastal Hazards Maps 1.Shoreline-setting hazards (long-term problems) 2.Marine hazards (short-term impacts of storms) 3.Earthquake and slope hazards (ground shaking, landslides, liquefaction) 4.Riverine hazards (historical floods) 5.Development hazards (high-density or dangerous settings) 6.Engineering hazards (stabilization, nourishment, sand mining)

Methodology, conclusion Each coastal stretch is designated a relative hazard rating based on the following: E = Extreme—more than 4 identifiable hazards H = High—3 to 4 identifiable hazards M = Moderate—at least 2 hazards L = Low—1 or no hazard

Puerto Rico Culebra Vieques

A portion of the Carolina, PR, Coastal Hazard Map.

The portion of Coastal Hazard Map 1, San Juan.

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

Pandora’s Island—Mitigation on the Beach

Pandora’s Island—Mitigation back from the beach

Pandora’s Island becomes Fantasy Island

Topographic Map of Study Area Harrison County, Mississippi

3.2 mile study area

GIS - Map Stacking Example Land cover from air photo Flood zones Land surface slope Katrina damage layer

Debris Line

Total Building Destruction