Flooding is a way of life in the city of Roanoke. The city has had major floods in 1940, 1972, 1977 and 1985. The last flood was a hundred-year flood causing millions of dollars in damage and costing several lives. In the late 1990's the city decided to enlist the U.S. Army Corps of Engineers to relieve the flooding problems.
The Corps proposed channeling the Roanoke River, which runs through the city and several surrounding localities. The Corps and the city said the project would reduce the amount of flooding by 50 percent. But other localities pulled out of the project saying it would provide little benefit in reducing flooding.
They were right.
Using mapping, flooding data and interviews with flooding experts we were able to show that the city was actually helping to create the very problems that the flood control was trying to fix. Our analysis showed that there were over a thousand properties in the flood plains in the city.
And despite the numerous floods that have occurred in the last 20 years, more structures continued to be built. Even a new multi-million dollar bio-medical center is slated to be built in the flood plains.
It's a recipe for disaster that we were only able to show using GIS. Even the city had no idea of just how many structures were in the flood plain.
The stories prompted dozens of letters to the paper, and local, state and federal officials are beginning to take a closer look at building in the flood plains in Roanoke. Many residents are pushing the city to remove more structures from the flood plains. Officials from FEMA are also looking at the flood plain development in the city.
This project showed me the power of GIS, but it also showed me that you have to be careful when using the powerful tool.
I began looking into the flood dangers when three nearby localities pulled out of the flood control project and started moving homes and business out of the flood plains. I asked the city why it wasn't doing the same and how many structures were in the flood plains. They said they did keep a database of buildings in the flood plains, so we began to try and find out for ourselves.
For a couple hundred dollars, I purchased the building permit database of structures built since the last great flood, and bought digital maps from Federal Emergency Management Agency.
With help form Andy Lehren at Dateline NBC, I culled the flood plains from the digital maps. I then overlaid the locations of buildings with maps of the city and the local river.
I did several interviews and thought I had my story done until I noticed something in the building permit database. It was a structure owned by The Roanoke Times, my employer, but no one had ever heard of it. My analysis showed that it was in the flood plain and had been built fairly recently. I called former employees to see if they knew about it. No one did. Finally, with maps in hand, I drove to the address. I found an empty lot.
Panicked, I called the city back to find out what was wrong with the data. It took several days, but they finally got back to me and said the address showing a Roanoke Times' owned building in the flood plain was actually a temporary structure that had been put up for a local festival. There were dozens of other addresses in the building permit database like that. The city had no way of showing permanent structures in it database; using it, you couldn't tell a sign from a house.
There goes the story I thought. Then I remembered that a few weeks earlier, I had gotten the city's real estate database. The database had all permanent structures in it, the year built, type of building, everything I needed to complete the project. The impact of this project is still on-going.
Ron Nixon can be reached by e-mail at ronn@roanoke.com