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<br />AUG-29-2000 rUE 10:03 AM <br /> <br />FAX NO, <br /> <br />p, 04 <br /> <br />indicated the rainstorm started between 12:30 and 1 pm with 3,25 inches In about 2 hours and <br /> <br />about 2 inches in 75 minutes. He said it rained very hard for 75 minutes, then tappered off for <br /> <br />a short time, then had another Inch of rain, and overnight had another 0.75 inches. Mr. Hess <br /> <br />appears to live very near the CoCoRaHS report of 2.01 inches ending on 8/17, which makes it 2 <br />times as much rain (possible given large rainfall gradients or I could have the locations off). <br /> <br />During my visit to the Bobcat burned area, I noted locations of fresh hillslope (rill and gully <br /> <br />dimensions) and runoff from roads (e.g., steep, unvegetated surfaces) to help estimate rainfall <br /> <br />amounts. This relative erosional data is "calibrated" to erosion characteristics where rainfall <br /> <br />data are available. The rainfall data and hillslope erosion information indicate the localized <br /> <br />nature of the rainstorm (and also is reflected in streamflow runoff). <br /> <br />./ ) <br /> <br />y' ~ I I drew a preliminary isohyetal map (lines of equal precipitation) that demonstrate the <br />---- () V . <br />J.... . '::>extremely localized nature of the August 16th storm (figure 1; base map is the CoCoRaHS data <br /> <br />for August 17, 2000). The center of the storm and primary "footprint" was over the upper <br /> <br />~r\'Uk:t1J- <br /> <br />:9'IAA <br /> <br />half 01 Bobcat Gulch westerly over the northwest headwaters of Cedar Creek basin (SM and Jug <br /> <br />Court gages). Because there was little rainfall runoff in Cedar Creek at Cedar Cove (next <br /> <br />section) with nearly 50 percent of the basin that burned, the storm must have been limited on <br /> <br />the eastern side near Cedar Springs Pond. The footprint encompassing runoff was probably less <br /> <br />than 10 square miles; the footprint lrom the storm was somewhat larger. <br /> <br />{, '} 2- <br />, -,;:P <br /> <br />Rainfall-frequency-duration relations prOVided in NOAA Atlas 2 (Miller at aI., 1973) were <br /> <br />plotted to help ascertain the recurrence interval of the August 16, 2000 rainstorm (figure 2). <br /> <br />Maximum recorded rainfall values within the center of the storm (above) were plotted on <br /> <br />figure 2. The recurrence interval is about 4 years for the Storm Mountain gage, but unofficial <br /> <br />3 <br />