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<br />Browning. Tom <br /> <br />From: <br />Sent: <br />To: <br />Cc: <br />Subject: <br /> <br />Robert D Jarrett, Hydrologist, Denver, CO [SMTP:rjarrett@usgs.gov] <br />Wednesday, December 17,19975:05 PM <br />tom. browning @state.co.us <br />Robert D Jarrett, Hydrologist, Denver, CO <br />BC manuscript <br /> <br />Tom <br /> <br />I am faxing the illustrations. Any comments, suggestions, clarifications, <br />etc., would be welcome. Reviewers anre George Leaseley (USGS RF-RF <br />modeler) and Debbie Martin (USGS very active in Boulder wildfire management <br />and now USGS studies at Buffalo Creek. Take care. rj <br /> <br />ps Sorry about the SI units; I have checked them very carefully and will <br />recheck them while manuscript is out for review. Happy to send you <br />conversions (particularly for ac-It). <br /> <br />****************** <br /> <br />Wildfire Flood-Hazard Mitigation and Watershed-Rehabilitation Monitoring <br /> <br />R.D. Jarrett, U.S. Geological Survey, Lakewood, Colorado <br />T.W. Browning, Colorado Water Conservation Board, Denver, Colorado <br /> <br />Abstract A paleohydrologic monitoring approach provides important <br />information to assess the effects of wildfire on water and sediment runoff, <br />assess the effects of watershed-rehabilitation activities, determine <br />watershed recovery time, and help manage forest ecosystems. The approach <br />is flexible, requires minimal resources, and complements comprehensive <br />instrumented monitoring in a short amount of time. The approach was <br />applied to the mountain community of Buffalo Creek, Colorado, which had a <br />catastrophic wildfire in May 18, 1996. Subsequent rainstorms produced 9 <br />floods larger than a 1 DO-year (pre-fire) flood. The largest rainstorm of <br />about 130 mm in an hour (about 2.5 times larger than a 1 DO-year rainstorm) <br />on July 12, 1996 resulted in a flood about 10 times larger than the <br />1 DO-year (pre-fire) flood. Monitoring efforts have been used to determine <br />threshold-rainfall amounts that could produce flash flooding in the Buffalo <br />Creek area. Large quantities of sediment continue to be transported in <br />Buffalo Creek streams since the fire. Investigations of alluvial sediments <br />indicate at least 10 wildfire-flood sequences during about the past 2,500 <br />years in the Buffalo Creek area. <br /> <br />Introduction <br /> <br />"Wildfire is a natural occurrence in this tinder-dry climate. But when <br />humans put themselves in harms's way, a natural phenomenon can be <br />transformed into a natural disaster." Denver Post, Firefight Starts at <br />Home, p. 4G, July 20,1997. Communities are encroaching into <br />forested-mountain areas in many parts of the United States, particularly at <br />the urban interface near metropolitan areas. This growth has significantly <br />increased the risk of natural hazards to people living in or visiting <br />forested areas. Floods and debris flows, particularly in recently burned <br />watersheds, pose a serious threat to human life, property, and the <br />environment; California alone suffers an average annual billion dollars in <br />costs and loses to wildfires (Weise and Martin, 1995). Increased risks <br />remain for several years or decades until burned areas sufficiently recover <br />to pre-burn conditions (Evenstad and Rasely, 1995). Recent wildfires and <br />associated flood and debris-flow hazards such as in southern California <br />Page 1 <br /> <br />, <br />