More than two years after the devastating hurricanes that struck Louisiana and the Gulf coast of the United States, scientists continue to learn new lessons from the disasters. The storms gave sharper focus to the importance of coastal wetlands and barrier islands. They also drew attention to the critical role that science can play in helping to protect lives and property.
A few weeks ago, Greg Smith returned to the same streets of New Orleans where he had piloted a small boat in the aftermath of Hurricane Katrina in 2005. Smith heads the National Wetlands Research Center for the U.S. Geological Survey, based nearby. His agency helped in the search and rescue efforts.
Smith recalls how researchers took the tools they normally used to survey wetlands and adapted them to locate trapped hurricane victims.
"In the middle of the night our scientists developed a geo-coding program that assigned a latitude and longitude to the street addresses given by 911 [emergency] callers," he said.
The system helped boat operators and helicopter pilots find and rescue 21,000 people.
Smith says scientists also used radar ornithology.
"[We] looked at bird movements on the coast, especially the great migrations using the same radar that the weather service uses [to gauge] precipitation," he said.
In the immediate aftermath of the 2005 storms they observed how the critical habitat for migrating bird populations had been decimated.
During Hurricane Katrina scientists recorded for the first time the storm surge (rise in sea water level) that occurs when a hurricane roars ashore. The data is important because it gives a baseline for predicting potential storm damage to low-lying coastal communities.
Before and after the 2005 storms, satellite imagery coupled with geographic information systems were used to analyze the barrier islands and wetlands. Within hours, scientists observed that 562 square kilometers of wetlands had converted into open water and barrier islands had retreated or disappeared.
USGS Oceanographer Abby Sallenger says the islands were already threatened because of sea level rise and sand erosion.
"You throw in Katrina on top of that and you have a recipe for a real problem," he says.
Sallenger says scientists can now accurately measure wetland or barrier island loss within hours along hundreds of kilometers of coastland with a technology called lidar: essentially, a laser beam deployed from airplanes.
"In cooperation with our partners in NASA and the [Army] Corp of Engineers, we fly this system along the coastline and it measures the topography, the elevations of the coastline. If the system is flown prior to and after the storm," he says, "You can compare the two surveys to come up with the amount and patterns of change which tell us a lot [about] what happened there."
Sallenger says, for example, one island community off the Georgia coast has been hit by four hurricanes since 1979. Each time, the community decided to rebuild. He says officials must be smarter about how and where they develop
"The kinds of data we are taking will help us test the models, the understanding, to put a number on it," he says. "So when somebody asks what is the safest and the most hazardous [locations], we can give a comprehensive answer."
Greg Smith with USGS Wetlands Research Center adds that science offers new ways to build more resilient coastal communities, ones that are ecologically stable and that also meet human needs for energy development, flood control and commercial navigation.
"Our science really needs to be connected to society," he says. "We need to understand what the economic and societal drivers are and how our science can be better planned, executed and reported to meet those needs."
Smith is one of 100 U.S. Geological Survey scientists who've contributed to a new study called Science and the Storms, available online on the USGS website.