|
Ср, Июн 11, 2008 11:19am  - 5798 d back | ↑↓ |
|---|
www.chicagotribune.com/news/nationworld/chi-lake-delton-wedjun11,0,1811293.story
chicagotribune.com
‘THE FORCE OF WATER’
How a lake went down the drain
By James Janega
Tribune reporter
11:05 PM CDT, June 10, 2008
Wisconsin officials said they had no idea Tuesday how they might stanch the flow of water still pouring from what had been Lake Delton, and they weren't even sure precisely how the giant leak started.
But they agreed that something must be done quickly to help the tourism industry that is built around the Wisconsin Dells' popular lake. Some have written off the idea of restoring the lake by summer's end.
"It's hard to describe the force of water when it wants to move in one direction," Wisconsin Gov. Jim Doyle said. "It isn't that it broke through a dam. It pushed aside about 250 yards of earth, maybe 15 feet deep and 50 yards across. It pushed the edge of the lake until it fell into the Wisconsin River."
Civil engineering experts and geologists blame prodigious downpours that in recent weeks soaked and softened the low point between Lake Delton and the river.
A spillway and dam couldn't keep pace with the lake's rising waters, which cut a yellow gash in the ancient, erosion-prone sandstone that ran straight to the river. And then the lake went down the drain.
Dams and spillways are designed to be overtopped, said Northwestern University civil engineering professor Charles Dowding. But when the spillway into the Wisconsin River couldn't accommodate the lake's overflow, the water found another way out 400 yards north.
A few things could have happened next.
The water could have flowed over County Highway A and eroded the embankment on the other side, Dowding said. It may have widened an opening at a drainage culvert. It may have pressed down on groundwater and forced it through the softened earth. "Possibly, all three," he said.
The result reminded University of Wisconsin-Madison sedimentary geologist Shanan Peters of a glacial lake draining, which is exactly what exposed the Dells millenniums ago. A finger of water found its way through loose soil and the soft sandstone, and then a torrent followed it.
Civil and military engineers on Tuesday began trying to figure out how to repair the breach, with discussion centering on a temporary fix followed by a long-term solution.
"It's too early to tell, but we are committed to getting the lake back," Doyle said.
But even after the damage is repaired, it will take several weeks for Lake Delton to refill naturally. When the man-made lake was drained and dredged in the late 1980s, it took weeks before the lake was restored enough to allow fish to be restocked. That's why some believe there will be no lake to enjoy this summer.
Tuesday's efforts to deal with the drained lake involved engineers from the Wisconsin Army National Guard and the U.S. Army Corps of Engineers, plus a smattering of experts and officials from state agencies as varied as the Department of National Resources and Department of Transportation.
Nor was their work confined to the bizarre crater that once had been Lake Delton.
In the state Emergency Operation Center, a computerized event log compiled eyewitness accounts from county officials, state troopers and DNR workers reporting an ever-growing list of dams straining, seeping and overspilling in the southern half of Wisconsin. Engineers assessed damage across 30 counties, prompting officials to demand precision when asked about their efforts Tuesday.
"Which damage area?" Lt. Col. Tim Donovan of the Wisconsin National Guard asked. "We have a lot of them today."
jjanega@tribune.com
|
|
| Ср, Июн 11, 2008 11:31am Edna - 5798 d back | ↑↓ |
|---|
Ужос! 
|
|
Chicago.Ru не несёт ответственности за достоверность размещенной информации © 2000-2024 Chicago.Ru
|
