Wednesday, July 25, 2007

Spring Creek flood of 1997 Here's a retrospective about the Spring Creek Flood of 1997 from The Fort Collins Weekly. From the article: On the morning of July 28, 1997, almost 21 years exactly after the Big Thompson flood left 145 people dead, the weather box on the Monday newspaper called for partly cloudy skies and a 40 percent chance of thunderstorms. Afternoon and evening newscasts warned of flash flooding. The weather patterns that day kept climatologists guessing; there was potential for a big downpour but when and where became the questions. Even those familiar with easterly flows and up-slope conditions were not prepared for the non-stop sheet of rain that would send 10 to 14 inches of water down on parts of Fort Collins over a 30-hour period -- or the chaos that would soon ensue as the water collected and began to overflow detention ponds and water sewers. No one, in fact, was prepared for the extreme weather conditions, what has since been called the most intense rainfall event in an urban area in the history of Colorado. The skies that day produced more rain than a 500-year flood event, making the flows of sweet, little Spring Creek roughly twice that of the Poudre River during peak runoff. That flow derailed a freight train, killed five women, left hundreds homeless, destroyed two trailer parks and caused more than $100 million worth of damage to Colorado State University. Citywide, there was a total of $250 million in property damage... The weather had been hot and dry for weeks and residents along the Front Range were happy to have a few days of lower temperatures. On July 27, 1997, a cool front came through Northern Colorado; humidity jumped as moist, tropical air traveled north. Late Sunday afternoon, the front triggered typical thunderstorms around the foothills, giving most of Fort Collins light rain. The storms, however, did not clear away like usual summer weather patterns. The moist, southeasterly winds gained power and the storm hung over the foothills, brewing. While cloudy Fort Collins got a short break from the rains, by Monday morning LaPorte had been soaked with up to 10 inches of rain, flooding the small town. "What was interesting was that these were all just precursors," Doeskin says. "It was all a precursor to the main event."[...] On Monday afternoon, the showers began in Fort Collins and as night fell, they increased, making "an interesting evening for weather-casters," Doeskins says. Different parts of Fort Collins received markedly different amounts of rain. While many residents got a "nice shower," those in the western part of the city received the blunt force of the storm's punch. "From a meteorological point of view it didn't look all that impressive," he says. "There wasn't much thunder or lightening or hail. There were bigger, heavier storms in other counties, and comparably ours was humble-looking." But the storm continued to sit over western parts of the city. Between 8 and 10 p.m. rains in southwest Fort Collins were occasionally hitting a density that equated to six inches per hour, sending the water east, downhill through the city. What made the weather different that day was not the heavy precipitation; the Front Range is occasionally hit by storms that drop a couple of inches of rain in an hour. Doeskin says the storm's deadliness came in its stamina, dropping more than five inches in six hours... A total of 10 to 14 inches of rain fell over 30 hours along the foothills, between southwest Fort Collins up to LaPorte. Around town, detention ponds, ditches and runoff channels filled and started to overflow. Streets flooded with chocolate-colored water. Home and business basements served as makeshift stormwater basins. The rain soon created a runoff stronger than 500-year flows, sending the most dramatic waters through the Colorado State University campus and over Spring Creek. At some spots, the surge along Spring Creek was almost two and a half times that of FEMA's 500-year discharge. The waters raged and by 11 p.m. on July 28, Spring Creek had turned deadly. A plugged culvert blew out, sending feet of water into one trailer park. A liquor store exploded and several trailers caught fire. Waters overtopped a railroad track, sweeping rail cars off the tracks, and sending more water onto the trailer parks. More than 200 people were rescued from the area even before the trailer parks flooded. Hundreds of calls poured into police. People found themselves stranded in their houses and trailers, on top of cars and in trees. As flames lit their efforts, rescuers pulled people to safety. Category: Colorado Water 6:23:09 AM     Has the North American Monsoon started? It looks like the North American Monsoon is upon us, at least in the Grand Valley. Here's an article about it from The Grand Junction Daily Sentinel. They write: Rainy, thunderous evenings, followed by hot days. "I think it is safe to say this is the southwest monsoon," said Norv Larson, a meteorologist for the National Weather Service... According to the weather service, this monsoon pattern could last through September. The monsoon will bring cloudbursts of rain and lightning, as has recently been the case, and it will also bring periods of calm days and calm evenings. It all depends on how much moisture is brought up from the southwest, Larson said. "This pattern will hold through typically mid to late September," he said. Category: Colorado Water 6:07:36 AM     Minimum tillage and efficient sprinklers working for some farmers Here's a look at a project using efficient irrigation techniques near Montrose, from The Montrose Daily Press. From the article: Farming innovations through irrigation and tillage have helped third generation farmer Randy Meaker increase efficiency in the field. Members of the Shavano Conservation District visited his farm on the Gunnison Watershed Tour on Tuesday to observe the results of his implementations. Standing in front of his tractor equipped with a Precision Tillage 1tRIPr strip-tiller, Meaker explained how he can now till 100 acres in one pass. "So I've farmed 100 acres to receive the production off of 100 acres," Meaker said. "On a conventional tillage program where you disc and plow and disc and roll and all those things, you've gone over it eight times and farmed 800 acres to get 100 acres of production." The approach he's taken to irrigation, using a center pivot sprinkler rather than furrows, was first thought to be unworkable in the region because of the soils. "There had been no success with previous sprinklers," Meaker said. "They were high pressure systems. Well, high pressure means that you've gotta have a lot of horsepower and a motor to develop pressure. So they were very expensive to run."[...] The sprinkler uses a hydraulically controlled pivot and has proven successful enough for expansion of the demonstration site in 2005 to cover a 92-acre field. Since the Gunnison Tunnel became operational in 1909, local farmers used furrow irrigation systems, Meaker said. These consist of water "going down in rows every 30 inches from a ditch," Steve Hale, Shavano Conservation District Supervisor said. Although this was common, it was not necessarily the best way to irrigate, especially with regard to water conservation. Meaker said the sprinkler systems are "85 to 90 percent efficient" whereas the furrow irrigation is "probably maximum 50 percent efficient." Irrigation water management specialist Randy Kremer said that although Meaker's the only farmer using the 1tRIPr strip-tiller, there are about a half dozen others using minimum tillage techniques. Category: Colorado Water 5:58:43 AM

© Copyright 2007 John Orr. Last update: 8/1/07; 8:16:58 AM.