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Table 2-Effects of prescribed fires and wildfires on water yield based in different vegetation types, <br /> Flow Recovery <br />Location Preclpltation Flow Added Period Reference <br /> (in) (mm) (in) (mm) (%) (years) <br />Douglas-fir, OR 98 2480 Bosch and Hewlett 1982 <br />Control 74 1890 - - <br />Cut 82%, Bumed SB 2230 20 >5 <br />Douglas-fir, OR 94 2390 Bosch and Hewlett 1982 <br />Control 54 1380 - - <br />Cut 100°k, Bumed 72 1840 34 >5 <br />Ponderosa Pine/Douglas-fir, WA 23 580 Helvey 1980 <br />Control (Prebum) 9 220 - - <br />Wildfire (Posthum) 12 315 42 ? <br />Chaparral, AZ 29 740 Davis 1984 <br />Control 3 75 - - <br />Prescribed Fire 6 155 144 >11 <br />Chaparral, AZ 23 580 Hibbert and others 1982 <br />Control 3 75 - - <br />Wildfire 5 130 59 ? <br />Chaparral, AZ 26 655 Hibbert 1971 <br />Control 0 0 - - <br />Wildfire 5 125 >99 >9 <br />Control 0.7 20 - - <br />Wildfire 11 290 1421 >9 <br />Pinyon-Juniper, AZ 19 480 Hibbert and others 1982 <br />Control 1 25 - - <br />Prescdbed Fire 1.5 40 12 5 <br />Juniper-Grass, TX 26 660 Wright and others 1982 <br />Control 0.1 2 - - <br />Prescribed Fire 1 25 1150 5 <br />Rx Fire, Seeded 0.4 10 400 2 <br />Aspen-Mixed Conifer Bosch and Hewlett 1982 <br />Control 6 155 - - <br />Wildfire 8 190 22 5 <br />peakflows from recently burned areas that were in- <br />creased 556 percent above that for adjacent areas <br />(Croft and Marston 1950). Anderson and others (1976) <br />produced a good review of peakflow response W dis- <br />turbance (table 3). Wildfires generally increase <br />peakflows. Peakflow increases of 500 to 9,600 percent <br />are common in the Southwest, while those measured <br />in the Cascade region are much lower (Anderson and <br />others 1976). For example, the Tillamookburn in 1933 <br />in Oregon increased the total annual flow of two <br />watersheds by 9 percent and increased the annual <br />peakflow by 45 percent (Anderson and others 1976). A <br />310 ac (127 ha) wildfire in Arizona increased summer <br />peakflows by 500 to 1,500 percent, but had no effect on <br />winter peakflows. Another wildfire in Arizona pro- <br />duced a peakflow 58 times greater than an unburned <br />watershed during record autumn rainfalls. Peakflow <br />increases following wildfires in Arizona chaparral of <br />up to 45,000 percent have been reported (Glendening <br />and others 1961). Watersheds in the Southwest are <br />prone to these enormous peakflow responses because <br />of climatic, topographic, and soil conditions. These <br />include intense monsoon rainfalls common in that <br />region at the end of the spring fire season; steep <br />terrain; shallow, skeletal soils; and water repellency, <br />which often develops in soils under chaparral vege- <br />tation. Recovery times can range from years to many <br />decades. Studies have shown both increases (+35 per- <br />cent) and decreases (-50 percent) in snowmelt <br />peakflowa following fires (Anderson and others 1976). <br />Burnedwaterehedagenerallyreapondtorainfallfaster <br />than unburned watersheds, producing more "flash <br />flooda° (Anderson and others 1976). Water repellent <br />soils and cover lose will cause flood peaks to amve <br />faster, rise to higher levels, and entrain significantly <br />greater amounts of bedload and suspended sediments. <br />Flood warning times are reduced by "flashy' flow, and <br />the high flood levels can be devastating to property and <br />human life. Although these concepts of atormflow tim- <br />ingare well-understood within the context of wildland <br />USDA Forest SerYCe Gen. Tech. Rep. RMRS-GTR-63.2000 7 <br />