Area studies reveal the immense change brought about by these storms.
In Louisiana, Dr. Shea Penland and his colleagues at the LGS reported that Andrew stripped sand from 70 percent of the barrier islands leaving exposed old coastal marsh. More than 80 percent of oyster reefs behind the barrier islands were smothered by a 0.3-0.9-meter thick blanket of sediment. More than 70 kilometers of valuable dune habitat providing storm protection to estuaries, wetlands, and the coastal population were destroyed. In Hawaii, Dr. Charles Fletcher and his colleagues at the University of Hawaii cooperated with USGS scientists in a study of the effects of Hurricane Iniki, the most powerful hurricane to strike the Hawaiian Islands this century. They report that Iniki caused massive beach-face erosion and overwash of the coastline which penetrated up to 300 meters reaching elevations of nearly 9 meters.
Seafloor change from the 1930's to the 1980's for the region of coastal Louisiana hardest hit by Hurricane Andrew shows historical patterns of seafloor erosion and accretion. This information was collected as part of the USGS's Louisiana Barrier Island Erosion Study, and will be used as a baseline to determine the effect of Hurricane Andrew on coastal areas already undergoing rapid change. [larger version]
USGS scientists have used historical data to show that
Louisiana is eroding rapidly.
The Louisiana barrier island shoreline is eroding at a rate, in some places, exceeding 20 meters per year as a result of both hurricanes and normal processes. The land is subsiding because of compaction of the Mississippi delta sediments. The net effect of subsidence is that sea level is rising at a rate of about 1 centimeter per year, ten times the world rate. USGS scientists take advantage of this natural laboratory to study erosion and deposition patterns resulting from sea-level change. The Louisiana barrier islands protect productive estuarine and wetland environments that support a $10 billion per year fishing industry. Erosion of the barrier islands is so severe that their ability to function as effective buffers for the prevention of wetlands loss has been dramatically reduced. Louisiana's wetlands are
disappearing at rates of 40 square kilometers per year. In a few decades the barrier islands may be gone and the wetlands will be lost even faster.
