Simple 911 calls and advanced satellites joined to build the emergency response for Hurricane Katrina, writes Dick Ahlstrom.
Navigating around a city with a map is no bother but what do you do if everything is under seven metres of water? A boat will get you under way but how do you find a specific address if all you can see are rooftops?
This was the challenge faced by rescue workers struggling to respond to the inundation of New Orleans in the aftermath of Hurricane Katrina.
Being able to get to a specific location quickly despite the disappearance of roads was often a matter of life or death in the days after the storm, states Prof Andrew Curtis. Rescue helicopters needed a way to navigate across the city and had to know where dry areas were to be able to land.
A lecturer in the department of geography and anthropology at Louisiana State University, Baton Rouge, Curtis and his graduate students became part of the emergency response to Katrina, providing essential geospatial information to a wide range of services.
Basically it comes down to being able to tell people where to go, and being able to do this relies on using a Geospatial Information System (GIS).
"GIS is a tool for dealing with spatial information," says Curtis, who is originally from Peterborough, England. This information can come from dozens of sources and GIS tries to find ways to integrate the various inputs into a single spatial reality.
"It can be trend information from sensors, the street network, population locations, but also data can be generated and added on a daily basis," he says.
Most people would think immediately about the GPS (Global Positioning System) satellite network that can tell you within a metre or two where on the planet you stand. But this alone was no help when all other reference points across a submerged New Orleans were lost underwater.
Instead GPS became but one of a range of inputs as the authorities began to respond to the devastation left in the wake of Katrina.
Curtis was well placed to become involved. He is director of the World Health Organisation's Collaborating Centre for Remote Sensing and GIS for Public Health at LSU. He also became director of the GIS operations for the Hurricane Katrina relief project.
He told his story of the chaos that followed Katrina at a conference hosted last week at the National Centre for Geocomputation in NUI Maynooth. The meeting heard about new developments in GIS from a number of international authorities including the centre's own staff.
Curtis told Science Today how an emergency command centre was established at Baton Rouge, about 50km north of New Orleans. Each key agency such as the Red Cross, Army Corps of Engineers, police and others had a desk and requests for aid, assistance or information was made across these desks.
The GIS desk was in particular demand, says Curtis. "Each desk had a task to do and if they needed spatial information they would go to the GIS desk."
They quickly set up the GIS basics by integrating existing map data with satellite imagery that showed where flooding had occurred. The team was able to use before-and-after images to learn where there had been open ground rather than an area flattened by the storm, useful information if trying to get a helicopter out for a rescue.
"Our graduate students were in the command centre 24 hours a day to co-ordinate rescue missions. They would ask us what were the co-ordinates for a particular address," he says.
Plugging in a variety of information sources is fundamental to GIS, says Curtis. Soon after the levies were breeched, rescuers needed to know where the flooding was and the depth of water. Useful information came in from people dialling the emergency number "911" who gave their addresses and told how high up the water had reached.
Another consideration was locating dry areas where helicopters could land. They needed places that were safe but close to where a rescue was required.
The same held true for pick-ups using inflatables. The GIS desk provided the co-ordinates and rescuers could navigate via the GPS system.
Curtis's "mission" lasted about three weeks, after which civil authorities took over. GIS services are likely to come into play the next time a natural disaster occurs, he adds. "This has got to be the way we go into disaster recovery in the future."