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<br />Extensive efforts to mechanically break up hydrophobic soils and slow water and sediment runoff
<br />began very soon after the fire, Most efforts were in basins posing greatest risk to the public:
<br />Sand Draw, Spring Gulch, and Shinglemill Creek, A moderate flood on June 12, 1996 (Casey
<br />Clapsaddle, USFS, written commun" 1996) and the severe flash flood on July 12,1996 washed
<br />out most of the initial rehabilitation efforts, Small amounts of water were applied to burned areas
<br />(simple infiltration tests) in 1996 and 1997, Generally, no water infiltrated and small droplets of
<br />water formed, indicating hydrophobic soils in 1996, During the wet spring of 1997, applied water
<br />infiltrated rapidly, even on very steep hillslopes (>30 'Yo), However, after the soils dried,
<br />infiltration was low due to reformed hydrophobic conditions or other factors, Data monitoring in this
<br />study complements an instrumented, paired-basin analysis being conducted by Casey
<br />Clapsaddle to assess the rehabilitation efforts used in Shinglemill Creek and Morrison Creek
<br />basins (burned area was left untreated),
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<br />Despite extensive rehabilitation efforts in burned area, smaller rainstorms after July 12 in 1996
<br />and in 1997 produced similar rates of runoff (fig. 10), On August 31, 1997, a 63 mm rainfall in
<br />about 30 minutes over the headwaters of Sand Draw, produced a flash flood of about 34 m3/s
<br />from about 1,5 km2, which reflect persistent conditions that exacerbate flash-flood potential and
<br />minimal watershed recovery, Natural debris (trees and sediment) present in many channels
<br />appeared to help slow water and sediment runoff for many events, In addition, small runoff
<br />events (as much as -3 m3/s) from burned hillslopes that reached channels having thick (>3 m)
<br />pea-gravel sediments such as in Sand Draw often infiltrated in a short distance, Long-time
<br />residents indicated that since the fire, streams in the burned area have more flow that usual.
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<br />Base flows as small as 0,2 m3/s after the July 12, 1996, flood were competent to incise and
<br />erode much of the new alluvial fans, Many fans had several agradation-degradation cycles for
<br />small events (peak flows of -1-2 m3/s) since the fire, which reflects channel instability, Lower
<br />tributaries reaches that agraded on July 12, 1996, generally had degraded by about a meter by
<br />the end of 1997, but hills lope erosion continues to contribute sediment to channels, Sediment
<br />from the burned area continued to be transported through the NF and South Platte Rivers to
<br />Strontia Springs Reservoir, About 75 percent of Denver's water comes through the reservoir,
<br />which has a capacity of about 9,74 hm3. From May 1996 to October 1997, about 0,31 hm3 of
<br />sediment washed into the reservoir compared to about 0,14 hm3 in the 13 years since the
<br />reservoir was built (Denver Water Department, written commun" 1997), Snowmelt runoff in the
<br />NF and South Platte Rivers likely will continue to move large amounts of wildfire-produced
<br />sediments towards the reservoir.
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<br />Geomorphic investigations of alluvial sediments in the burned and unburned (in 1996) areas
<br />indicate at least 10 fires/flood sequences have occurred in the study area prior to 1996 (fig, 12),
<br />At least one paleoflood was larger than the July 12, 1996 flood, and runoff after several of the
<br />prehistoric fires produced much thicker alluvial deposits than following the 1996 wildfire,
<br />Radiocarbon dating of organic material in alluvial sediments in a Buffalo Creek tributary indicated
<br />that these sequences span about the last 2,500 years (John Elliott, USGS, written commun"
<br />1997), Additional investigations will help determine the long-term fire and flood history in the
<br />region, which could help forest managers develop policy for prescribed bums and other
<br />management practices,
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<br />Study results can be used to develop and verify hydrologic- and sediment-budget models for
<br />burned watersheds, In conjunction with the NWS, study results and rainfall-runoff modeling was
<br />conducted to help determine threshold-rainfall amounts for flash-flood conditions, These results
<br />were used to refine flash-flood warnings, particularly to minimize the number of false alarms that
<br />can cause complacency of those at risk, The Colorado Water Conservation Board (1997)
<br />prepared an emergency response, hazard-mitigation, and awareness plan for government
<br />officials, residents, and visitors in the Buffalo Creek area,
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<br />Studying only the Buffalo Creek area can not provide answers to all questions about wildfire
<br />hazards in other forest ecosystems, Thus, additional paleoflood studies are needed for burned
<br />(wildfire and prescribed bum) watersheds this century in the Rocky Mountain region, These
<br />could include, but are not limited to, Storm King Mountain, Colorado (1994), Black Tiger in Boulder,
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