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February 12th, 2018

The future of flood mapping: Making a difference in flood response and modeling

Flooding after a hurricane or other natural disaster can be more devastating than the disaster itself. The Dartmouth Flood Observatory has over 20 years of experience in providing interactive flood maps for natural disaster responders. Their maps help responders navigate around flooded areas to provide aid. They can also help planners identify areas prone to flooding in a changing climate.

Robert Brakenridge started the project while he was a professor at Dartmouth College in 1993. After the so-called “Great Flood of 1993” in the Mississippi River Valley, Brakenridge says he became interested in using satellite imagery to map major flooding in highly populated areas. At the time, he says, this was not something that anyone did. 

The Dartmouth Flood Observatory takes GIS, or geographic information systems, and combines it with remote sensing from satellite imagery to create interactive online maps that show how much flooding is occurring in certain areas around the world.

Interview with Robert Brakenridge and Albert Kettner on their hopes for faster, more helpful mapping of flooding and flood-prone areas. Video by Anna Scott.

“It was sort of eye opening for some of the satellite people to see actual maps made from their images,” Brakenridge said. Before his project, remote sensing and GIS rarely mixed.

“What we were doing—starting with remote sensing and then moving into GIS output—that was something that a lot of my remote sensing colleagues didn’t know how to do. They didn’t know what GIS was,” Brakenridge said.

Brakenridge’s colleague, Albert Kettner, became involved with the project once Brakenridge moved to the University of Colorado Boulder in 2011, where they joined INSTAAR and the Community Surface Dynamics Modeling System (CSDMS).

“I have a GIS background, I have remote sensing background and I’m a modeler, so the subject interested me,” says Kettner.

He has since worked with Brakenridge to increase the efficiency of their data processing by automating everything that he can. With Kettner’s help, the maps on the website have been able to reach audiences across the globe.

“You can see if the current flooding is actually exceeding what we have mapped in history so you can say something about the severeness of flooding,” Kettner said.

He says that people can overlay data involving population or agriculture statistics in certain areas to better understand the impact of flooding.

Brakenridge recalls Cyclone Nargis, which had a death toll of over 130,000 in Myanmar in 2008.

“I just remember saying, ‘Well, what you really have here is a map of the future.’ It’s sort of an odd thing to say at the time when all these people have just been affected by this terrible event, but that was now going on ten years ago,” he said.

He says that simply recording data from presently flooded areas can be useful when identifying areas at risk of future flooding. With climate change well underway, Brakenridge said, people are increasingly interested in predicting the ways that flooding will worsen.

“People are always interested in prediction. Obviously, you want to know what the future holds, but it’s hard to make that bridge,” he said. “What we’re doing is very relevant, but we don’t have the easy answers.”

Unfortunately, it seems that satellite technology is not as instantaneous as people want it to be.

“When the flooding was actually happening in Houston [after Hurricane Harvey], we didn’t do anything. We were just waiting, sitting for days because it was clouded,” Kettner said. They couldn’t see anything from their daily sensor with clouds in the way. The flood observatory had to wait for images from the European Space Agency in order to get a full picture of the flooding in Houston.

“You’re sitting there waiting for days for an image to come in, and that’s going to change I think. That has to change,” Kettner said.

Even though waiting for imaging technologies can be frustrating, he pointed out that technology in the United States is better than most.

“The U.S. has the resources to do that. I think many of the European countries can as well, but there are whole continents that don’t have capability, nor the knowledge to create those maps,” Kettner said. “Our flood mapping can give you a history of what happens, from a flooding point of view, on a continent or in a country. For planners, that could be very useful.”

Both scientists are hopeful for the future of satellite technology. Thanks to mobile phones, they say information should become even more accessible in the years to come. One of their visions is an app similar to Google Maps that could provide interactive, downloadable data for disaster responders in remote areas as well as people in the U.S. affected by flooding in their own homes.