Document text
53 °F Forecast | Road Cams Friday, January 28, 2005 Today's News | Classifieds | Autos | Homes | Jobs | Tempo | Health | Community | Home Delivery SECTIONS Home Page Local News Sports Business Obituaries Life Opinion - Politics Tempo AP News Weather Classified Archives Site Map SPECIAL SECTIONS Since We Asked Outdoor Journal Menu Guide How To Guide Wellness Connection Readers' Choice Real Estate Showcase Real Estate Guide Joy Magazine Homelife Magazine Wedding Guide Passport to the Rogue Valley EXTRA Newspaper in Education Personals Movie Times TV Times E The People Volunteer Opportunities Moving to Southern Oregon? MARKETPLACE Find a Car Find a Home Find a Job Classifieds Place an ad eSouthernOregon Automotive Communities Entertainment Publications Recreation Calendar CUSTOMER SERVICE Frequent Questions Advertising Information Home Delivery Employment Contact Us Media Kit Network Affiliate Oregon Road Conditions & Cams Email Story to a Friend December 20, 2004 The Nauvoo Mobile Estates, above, situated on the banks of Bear Creek one mile north of Ashland, flooded in 1964 (when it was called Alder Park Estates) and again in 1997. Mail Tribune / Jim Craven The ’64 flood It could still happen If the right conditions of snow, rain and warmth occur, the Rogue River Basin could flood again, experts say By BILL KETTLER Mail Tribune What does it take to flood the Rogue River? When will it flood again? The questions inevitably surface after every episode of high water. Looking at previous floods is the easiest way to see how the next one probably will happen. Time after time, Mother Nature uses the same recipe — rain, snow and then more rain — with only minor variations in the ingredients. The recipe looks simple. Start with heavy rain. Add deep snow in the mountains. Mix in warm rain that melts the snow. Stand back and watch the river rise. But it’s more complex than it looks. How long it rains, how much it snows and where the temperature goes will determine whether the Rogue surges out of its banks in an angry brown tide or runs clear and cold down to the sea. Floods don’t happen often. There have been just five major ones (in 1861, 1890, 1927, 1955 and 1964) since Europeans came to Southern Oregon. The most recent high water, in January 1997, was minor in comparison. Advertisement "We don’t see those flood conditions year in and year out, but when they come together it’s like a perfect storm," says Jim Buck, who manages the U.S. Army Corps of Engineers dams at Lost Creek and Applegate lakes. Rain starts the cycle, says Bill Ludwig, a hydrologist for the National Weather Service in Medford. Steady rain over a period of several days saturates the soil until, like a wet sponge, it can’t absorb any more water. "One of the main factors (that determines whether a flood will happen) is soil moisture," Ludwig says. If the soil is soaked, every drop of rain rolls downhill to the nearest stream. If there’s a break in the rain, the soil has time to drain gradually, and streams recede. It takes a lot of rain to soak dry soil. Ludwig notes that several inches of rain fell over most of Jackson County during the first few days of December this year, but there was no flooding because the soil was dry after weeks of meager rain. In December 1964, rain fell almost every day for a couple of weeks before the flood, Ludwig recalls. Soils were saturated, just as they were in December 1996 when big storms rolled across Southern Oregon in the final days of the year. Along with steady rain, snow plays a critical role in the Rogue Valley’s big floods. As a general rule, Ludwig says, there’s an inch of rain in every 10 inches of snow in the Southern Cascades. Steady warm rain can melt fresh, airy snow in hours, pushing huge volumes of water toward the valley floor. "The more (air) space in snow, the more rain will melt it," says Eric Dittmer, director of environmental studies at Southern Oregon University. Temperature becomes a factor in the flood recipe when snow enters the mix. Meteorologists describe winter storms as "warm" or "cold" depending on their origins. Cold storms develop in the icy northern Pacific Ocean; warm storms, in the balmy southern Pacific. Cold air holds less moisture than warm air, so cold storms tend to have relatively less rain and snow than warm storms. Cold storms push freezing levels down and bring snow to the valley floor. Warm storms raise freezing levels and snow melts. If the melting happens quickly, under an assault of warm rain, there’s just that much more water hurrying down creeks toward the Rogue. At higher elevations, the snow depth may fluctuate dramatically if a warm storm blows in right behind a cold one. In 1964, for example, Crater Lake received 18 inches of new snow between Dec. 19 and 20, and the snow depth jumped from 72 inches to 90 inches. Rain continued to fall on Dec. 21 and 22, but the freezing level soared above 9,000 feet, and by Dec. 23 the snow level at Crater Lake had plummeted to 68 inches. The same sequence occurred at the end of December in 1996. Cold storms piled the snow in the mountains, and then warm rain melted it. Soils that had been saturated by earlier rains couldn’t absorb the runoff. "Every drop that fell had to run," was the way Hollie Cannon, the manager of the Talent Irrigation District, described what happened on New Year’s Day 1997, when Ashland residents rediscovered why Water Street had its name. Long before the high water of 1964, Rogue Valley residents had asked Congress for flood control dams in the Rogue Basin. The two that were built, Lost Creek (1977) and Applegate (1980), give water managers ability to reduce the magnitude of a flood, but they offer only limited protection because they intercept the water in only a small portion of the basin’s 5,000 square miles. Just 13 percent of the basin lies upstream from the dam at Lost Creek, and a mere 4 percent upstream from the Applegate dam. Many of the Rogue’s largest tributaries, such as Big Butte Creek and Evans Creek, pour into the river below the dam. "On all those downstream tributaries we have no influence at all," says Buck, of the Army Corps of Engineers. "The further we go downstream (from the dams) the less influence (on flood levels) we have." The dams shave the peak off high water. For a 10-year flood (one that could happen, on average, once in 10 years), the dam at Lost Creek can reduce the maximum flows by 20 percent at Grants Pass. For a 50-year flood, the dam can reduce high water flows by 22 percent. Cities build storm drains to sluice away rain water, but the costs of construction limit their ability to handle large volumes of water that come with major floods. Medford, for example, builds storm drains to handle a one-day, 25-year storm, says Cory Crebbin, the city’s public works director. "Everybody’s comfortable with that (system)," he says, "until it floods." To design a system to handle larger flows would be "prohibitively expensive," he says. Crebbin says high water will return someday when conditions are right. Two major floods occurred just nine years apart (1955 and 1964), but 32 years passed before the next real high water. "We don’t know when it’s going to happen again," he says, "but from the historical record, we know it will." Want to know where the water will go? Find out where it went during the last flood, Dittmer says. "Places that flooded once will flood again." Reach reporter Bill Kettler at 776-4492, or e-mail [email protected] Mail Tribune Home Local News | Sports | Business | Obituaries | Life Opinion - Politics | AP News | Archives | Site Map E Southern Oregon | Classified Copyright © 1997-2005 Mail Tribune. All rights reserved. Privacy Policy | Terms & Conditions Website Feedback ADVERTISERS A D V E R T I S E R S SPECIAL SECTIONS Auto Finder Job Finder Home Finder Joy Magazine Homelife Magazine Tempo Readers' Choice Real Estate Showcase Since We Asked Outdoor Journal Moving to Southern Oregon? Volunteer Opportunities Student Loan Consolidation Conference Calls - $50/Month Home Security Systems Trunks, Footlocker, Trunk, Footlockers