Assessing Coastal Impact of Storms and Sea Level Rise

Pictured above: Post-hurricane LIDAR (Light Detection And Ranging ) image of shoreline showing “lost” houses in white.

Assessing the Impacts of Hurricanes and Extreme Storms

The USGS Coastal and Marine Geology Program supports investigations of the extent and causes of coastal impacts of hurricanes and extreme storms on the coasts of the United States. The objective is to improve the capability to predict coastal change that results from severe tropical and extra-tropical storms. Such a capability will facilitate locating buildings and infrastructure away from coastal change hazards.

Monitoring Shoreline Change: Coastal Erosion and El Niño Events

During the winter of 1997-98, wind-driven waves and abnormally high sea levels contributed to hundreds of millions of dollars in flood and storm damage in the San Francisco Bay region. Recent analyses by U.S. Geological Survey (USGS) scientists of nearly 100 years of sea-level records collected near the Golden Gate Bridge (at Fort Point in the Golden Gate NRA) found that these abnormally high sea levels were the direct result of that year's El Niño atmospheric phenomenon. The USGS continues to investigate the causes of such sea-level changes in order to better protect coastal communities from their effects.

Pictured above: Sea level variations recorded in the Golden Gate NRA record El Niño events and sea level rise since 1900.

The USGS takes aerial photographs to assess coastal erosion from severe storms. Our mission is to acquire precision still and video photography before and after storm events to document storm-related changes to the coastline. USGS acquired baseline coverage of over 1000 km of coastline from the west coast of the US in October, 1997, in anticipation of storms generated by the El Niño warming of the Pacific Ocean.

Pictured above: Point Reyes National Seashore, October, 1997.

Pictured above: Point Reyes National Seashore, April, 1998.

Assessing Coastal Vulnerability to Sea Level Rise:

Pictured above: Map of Atlantic shoreline showing regions with greatest vulnerability to a future rise in sea level.

One of the most important applied problems in coastal geology today is determining the response of the coastline to sea level rise. Prediction of shoreline retreat and land loss rates is critical to the planning of future coastal zone management strategies, and to assessing biological impacts due to habitat changes or destruction. There is presently no national-wide policy or legislature for long-term (50 years or longer) coastal planning and decision-making.

Consequently, facilities are being located and entire communities are being developed without adequate consideration of the potential costs of protecting or relocating them from sea level rise-related erosion, flooding and storm damage. For the first step, in 1999, the project undertook a national inventory phase, to produce a pilot "Susceptibility to Sea-Level Rise" map(s) for the U.S. coast.