Better mapping might avert landslides October 27, 2008Posted by Bahadir Sahin in English, Haber (News).
Tags: emergency maangement and GIS, Geographic Information System, GIS utilization in disaster preparedness
Landslides happen fast and without warning.
Or do they?
“Every landslide has a collection of causes. If there were documentation of their locations and causes, landslides — which are usually triggered by human activity — would be much easier to predict,” said Helen Delano, senior geologic scientist for the Pennsylvania Geologic Survey, who recently talked about the problem at a U.S. Geologic Survey convention in Houston.
Yet information about landslide-prone areas such as Western Pennsylvania — if it exists — is often old, scattered and poorly organized. That makes planning difficult, if not impossible, for everyone from road builders, developers and homebuyers to emergency responders.
Incomplete information coupled with a build-anywhere temptation is prompting federal and state officials to call for better mapping of vulnerable areas.
Mapping wold take plenty of work and money and can never really be completed, Delano said.
“We can’t cover every inch of Pennsylvania. Ever. But there’s plenty of room for improvement.”
In an age of high-tech digital mapping such as Google Earth, Pennsylvania still uses geologic maps drawn in the early 1970s that are now scanned onto state Web sites. And they cover only about half the state.
“They are better than nothing. They are a good tool, but not complete,” Delano said.
At the federal level, information is even more scant. For example, the government has no single national database with landslide information from the 50 states, despite the obvious use it would be to the Federal Emergency Management Agency and other groups.
The U.S. Geological Survey based in Golden, Col., is launching a publicly accessible Web site with state information about landslide histories. In Pennsylvania, legislation that would require official designation of geologically hazardous areas was introduced in committee last month by Rep. Tom Petrone, D-Crafton.
House Bill 2759 would require collection of information about landslides, sinkholes and areas prone to sinking or shifting from the collapse of underground mines.
Petrone’s district borders Kilbuck, site of the notorious 2006 landslide that closed a rail line and a state highway used by thousands of commuters.
“The Kilbuck slide is quite well-known around the country,” Delano said. “People in Denver, Houston and California have heard of Kilbuck. … Kilbuck is well-known because it occurred in a crowded area and disrupted traffic for weeks.”
The slide, at a site being prepared for construction of a shopping center anchored by Wal-Mart, dumped about 350,000 cubic yards of dirt and debris onto Route 65 and nearby Norfolk Southern Railroad tracks. The highway was closed for about two weeks, and train travel disrupted for days. One outbound lane of Route 65 remains closed.
“Some of these sites — like Kilbuck and like The Foundry in Washington County — probably are just not suited for development,” said Jon Castelli, Petrone’s executive director. “There has to be a process in place to make sure it’s done right,”
The Foundry, a South Strabane shopping mall, has experienced persistent problems with unstable soil since opening last year. Three retailers, including a J.C. Penney store, closed in May and June because of it.
More accurate and detailed maps would be invaluable in Allegheny County, one of the most landslide prone regions in the country, said Bill Gray, a geotechnical engineer and geologist with DiGioia Gray Associates in Monroeville.
“That information really is not always available,” Gray said. ” When you are dealing with these geotechnical problems, this sort of mapping would be a great help.”
Three state roads in Allegheny County remain closed by landslides, which Bill Adams, a geotechnical engineer at PennDOT’s District 11 office in Bridgeville, said is routine.
Southwestern Pennsylvania sits in the Appalachian plateau, the largest landslide-prone region in the United States.
Even so, there’s little public awareness of risk from landslides, Delano said.
“It’s really not something that’s on the radar of most home buyers, or even developers, in the way it should be.”