<br />II. THE EVENTS OF 1996
<br />
<br />A. MAY 1996 BUFFALO CREEK WILDFIRE
<br />On the morning of May 18, 1996 a wildfire was accidentally started in the Pike National Forest via
<br />an abandoned campfire in a campground near Buffalo Creek, The fire quickly spread and burned
<br />approximately 11,900 acres of forested lands, mostly within a two day period, Fire suppression was
<br />initiated by Forest Service fire fighting crews on the 18th, and the fire was officially controlled on
<br />May 24, 1996.
<br />
<br />Of the total burned area, 11,320 acres were National Forest lands, and 580 acres were private lands,
<br />The low, moderate, and high fire intensity areas were estimated to be 1100 acres, 3300 acres, and
<br />7500 acres, respectively, A total of 2400 acres were considered to have hydrophobic (water
<br />repellent) soils, The hydrophobic layers developed in areas where the fuel loadings were highest,
<br />which was mainly within the areas directly under the aerial coverage of conifer canopy,
<br />
<br />The vegetation of the burned area consisted mainly of Ponderosa Pine and Douglas Fir canopies
<br />with a variety of understory growth including Mountain Mahogany, Yucca, Aster, Gooseberry,
<br />Raspberry, Currant, Timothy, Blue Grama, Liatris, Little Blue Stem, and other species, The
<br />dominant soils in the burned area consist of Sphinx and Sphinx/Rock outcrop complex, The
<br />geology is characterized by decomposed granite, The shallow soils are gravely course sandy loams,
<br />and the organic layer was quite shallow and was heavily consumed by the fire, Accelerated erosion
<br />and increased runoff were expected as a result of the fire,
<br />
<br />B. ,JULY 12. 1996 BUFFALO CREEK FLOOD EVENT
<br />
<br />1. Precipitation Event
<br />The summer storm that produced flash flooding in the Buffalo Creek area was a typical convective
<br />type cloudburst event. These events are not uncommon along the foothills and plains in eastern
<br />Colorado, Storms like this form quickly and can produce large amounts of rainfall, hail, and severe
<br />weather conditions within a short amount of time,
<br />
<br />At this time, only preliminary information is available describing the particular storm over Buffalo
<br />Creek, The information is based on field analyses, rain gage information, and interviews with
<br />witnesses and local residents, The information indicates that the storm moved from west to east
<br />and then stalled right over the lower part of the Buffalo Creek watershed, The most intense rainfall
<br />amounts are estimated to be from 2 inches to 3,5 inches within 30 to 90 minutes, The storm may
<br />have covered an area between 10 and 30 square miles. There is some uncertainty about the
<br />antecedent moisture conditions prior to the storm event. Some evidence suggests that there may
<br />have been up to a half inch or inch of rain within a few hours prior to the thunderstorm event. To
<br />provide a point of reference, the lOO-vear, I-hour precipitation depth for southern Jefferson County
<br />is reported to be about 2,1 inches according to the Jefferson County Storm Drainage Design and
<br />Criteria Manual.
<br />
<br />5
<br />
|