As Hurricane Floyd continues to bring heavy rain and dangerous storm surges to the Atlantic Coast, USGS scientists are tackling the challenges that a storm of this intensity brings to coastal resources -- from flood-swollen rivers, to saturated hillsides, to vulnerable barrier islands, to altered wildlife habitats.
Flooding
The USGS network of streamflow gaging stations located in every state continuously provide information on the rising floodwaters from the rain associated with Hurricane Floyd. Information transmitted via satellite is available to federal, state and local emergency-management officials and to the public at http://water.usgs.gov/realtime.html. This real-time information is indispensable for emergency preparedness and the rapid communication of flood information to National Weather Service river forecast centers, the U.S. Army Corps of Engineers, and the Federal Emergency Management Agency.
Although many USGS offices along Floyd's path were closed on Thursday as a safeguard for their employees, essential staff were in the field monitoring the flood conditions, making flood measurements and flagging high-water marks.
As of Thursday evening, September 16, at 5:00 PM:
- In North Carolina the Tar and Neuse Rivers were above flood stage and
continue to rise. USGS crews have been hampered in reaching stream measurement
sites due to flooded roads, toppled trees and power lines, and road blocks as
utility crews work to restore power.
- The most severe flooding in South Carolina occurred in the Waccamaw
River basin. In the area near Longs, South Carolina, the Waccamaw River may
crest near or exceed the historical high streamflow based on 49 years of
continuous streamflow data. Western portions of both North and South Carolina
continue to experience severe drought conditions.
- Flooding in Maryland and Delaware was occurring in the Patuxent River
watershed and on most of the Delmarva Peninsula.
- Meherrin, Nottoway, and Blackwater Rivers in southeastern Virginia were
above flood stage.
- In New Jersey, flooding was occurring along the Rahway River near Springfield and the Raritan River at Bound Brook.
Water-quality Monitoring
As Hurricane Floyd continues along the coast, the immediate water-quality concern is the material washed into streams by surface runoff from heavy rains. USGS teams will be in the field for several days collecting stream water-quality samples. The samples will be analyzed for concentrations of bacteria, nutrients (nitrogen and phosphorus), pesticides, and sediment. The possible presence of fecal coliform and E.coli bacteria in drinking-water supplies is a primary human health concern during and after floods. An excess of nutrients can result in algal blooms, including Pfiesteria. Sediment in the water column can significantly reduce the amount of light that reaches submerged aquatic vegetation relied on by many organisms.
Large rainfall events associated with tropical storms have caused extended periods of poor water quality along the coast. The USGS has documented extremely low dissolved-oxygen concentrations for several weeks after heavy amounts of decaying organic matter (limbs, leaves, grasses, animal waste) flowed from swamps and tidal marshes into rivers after hurricanes Hugo, Bonnie, and Fran.
This past spring, the USGS began a two-year study at the Cumberland Island National Seashore, near the Georgia/Florida line, to study water-quality conditions and aquatic communities. Hurricanes and tropical storms in the area may provide a glimpse of how coastal and climatic processes affect water-quality conditions and aquatic communities on barrier islands.
Coastal Erosion and Storm Surge
USGS geologists, in cooperation with National Aeronautics and Space Administration and the National Oceanic and Atmospheric Administration, will monitor changes along the coastline as they relate to storm surge and wave action. This will be measured from the air using a Scanning Radar Altimeter. By relating storm surge and wave heights to coastal changes, future hurricane impacts can be predicted more accurately.
Mapping hurricane storm surge data is critical for understanding the volume of water and amount of sediment that inundates the coast during a hurricane. Coastal surveys are scheduled to be flown on Saturday, September 18 to assess coastal changes resulting from Hurricane Floyd.
Biological work
Hurricanes play a dynamic role in shaping coastal systems because of their ability to massively change wildlife habitats of barrier islands, coastal marshes, and forests. USGS scientists are gearing up in the wake of Hurricane Floyd to assess damage to wildlife and habitat from Florida to Maine.
USGS biologists will use computer models to predict effects on wildlife habitat; remote sensing and geographic information systems will be used to study and monitor wetland responses to hurricanes; and research will be conducted to determine hurricane effects on coastal erosion and wetland forests.
While several years of research are needed before fully determining the effects of hurricanes on birds, USGS biologists expect that shorebird migration has been seriously disrupted and that many coastal species may have been pushed to far-inland sites. Sandpipers, plovers, knots, and others may end up feeding and roosting in agricultural fields in eastern Tennessee or Kentucky.
The endangered Northeast breeding population of roseate terns may have dodged the hurricane because it is late in the season. Most terns should be well on their way from their summer staging area in Cape Cod, Mass., to northern South America where they spend the winter. USGS biologists will not know the impact on this particular species until next summer, when a census is conducted of the major colonies in New York, Connecticut, Massachusetts, and Maine.
Ongoing USGS studies on the effects of deer browsing on vegetation in the flood plain of the Patuxent River in Maryland may have been obscured by the damaging effects of Hurricane Floyd.
USGS biologists will evaluate the impacts of Hurricanes Floyd and Dennis on sediment deposition in the Virginia coastal marsh study areas established this spring.
Landslides
Although Floyd has remained near the coast, past hurricanes that traveled inland to the Appalachian Mountains brought large amounts of rain to steep hillsides and caused landslides. During Hurricane Camille in 1969, for example, intense rainfall triggered debris flows in Nelson County, Virginia causing 150 deaths.
In the Blue Ridge Mountains of central Virginia rainfall having an intensity of about two inches per hour and lasting for four hours, or one inch per hour for 10 hours, is likely to trigger debris flows and other types of landslides on steep slopes. As of mid-day on September 16, rainfall amounts received in the mountainous parts of central Virginia have been significantly below these amounts, making the likelihood of landsliding very low.
As the nation's largest water, earth and biological science, and civilian mapping agency, the USGS works in cooperation with more than 2,000 organizations across the country to provide reliable, impartial scientific information to resource managers, planners, and other customers. This information is gathered in every state by USGS scientists to minimize the loss of life and property from natural disasters, contribute to the sound conservation and the economic and physical development of the nation's natural resources, and enhance the quality of life by monitoring water, biological, energy, and mineral resources.
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