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<br />(1974), Hansen and others (1978), and Jarrett and oth.ers (in review) noted that maximum
<br />rainfall amounts in eastern Colorado are located on or near the crest of the Palmer Divide (fig.
<br />1), Jarrett and others (in review) analyzed extreme rainstorm data for eastern Colorado
<br />(McKee and Doesken, 1997) with respect to topographic relief. They found maximum rainfall
<br />amounts exceed 12 inches for convective storm in areas of high topographic relief (crest of the
<br />Palmer Divide, isolated ridges and buttes, Raton Mesa, Cheyenne Ridge, and the foothills);
<br />maximum rainfall was less than about 10 inches for convective storms in areas of low
<br />topographic relief, About 75 percent of the high plains of eastern Colorado has local relief of
<br />less than about 300 ft in less than 3 miles. It is important to note that localized cells of
<br />maximum rainfall in Eastern Colorado are extremely localized (fig, 1; Follansbee and Spiegel,
<br />1937; Follansbee and Sawyer, 1948; Matthai, 1969; Snipes and others, 1974; Hansen and
<br />others, 1978; Hansen and others, 1988), and also that the maximum cells primarily resulted
<br />from different storms,
<br />
<br />Flood data for basins in eastern Colorado that have relatively low TR, which most likely would
<br />not have a substantial orographic enhancement to precipitation, also are shown on figure 4.
<br />Low TR data plot on or below the envelope curve of maximum flooding for Cherry Creek and
<br />substantially below "other" Palmer Divide streams having high topographic relief (fig, 4) and
<br />support the hypothesis that topography enhances rainfall-producing floods,
<br />
<br />2, The two largest rainstorms (1935 and 1965) in Colorado were located on the Palmer Divide
<br />(McKee and Doesken, 19(1), The May 30-31, 1935 Hale-Cherry Creek rainstorm
<br />(Follansbee and Spiegel, 1937; Hansen and others, 1988) was reported to have produced up to
<br />24 inches of rain in about 10 hours with two distinct rainstorm cells (fig, 1), One cell was
<br />located about 150 mi east of Denver near Hale in the Republican River basin (local relief about
<br />300 ft), and a second cell was reported over the headwaters of Cherry Creek basin. Jarrett and
<br />others (in review) reviewed 1935 rainfall-bucket survey data and rainfall data for stations
<br />near the Palmer Divide. They found that maximum rainfall estimates for both cells were
<br />measured in stock tanks, which are used to store water for animals, Approximately 6 to 10
<br />inches of rain fell in the week preceding May 30, 1935, Jarrett and others (in review)
<br />suggest that it is very unlikely preceding rainwater was emptied from the stock tank,
<br />particularly during a severe drought period (Collins and others, 1991), and concluded the May
<br />30-31,1935 total rainfall amount was about 14 to 18 inches for each cell. Flood discharges
<br />from these revised rainfall amounts are more consistent with maximum flood discharges for the
<br />1965 storm, which had similar rainfall amounts but larger flood discharges than in 1935
<br />(Matthai, 1969),
<br />
<br />Historical records indicate significant flooding did not occur in 1935 in Cherry Creek (U.S,
<br />Army Corps of Engineers, 1976) nor in Running Creek (Water Resources Consultants, 1979),
<br />The 1935 Cherry Creek cell apparently was misnamed and should be referred to as the Kiowa-
<br />Bijou cell, which did have large rainfall amounts and extreme flooding in 1935 (Matthai,
<br />1969), The location of maximum rainfall in 1935 and 1965 was on the divide between Kiowa
<br />and Bijou Creeks (fig, 1) where local relief is about 300 to 500 ft in less than a mile, The
<br />June 16-17, 1965 rainstorm did not produce significant rainfall nor any f1oodin9 in the
<br />headwaters of Cherry CreeK and Running Creek (Matthai, 1969; Water Resources Consultants,
<br />1979), The peak discharge was 1,000 ft3/s in Cherry Creek near Franktown (06712000) on
<br />June 16, 1965 at 1945 hrs, but occurred after the flood peak at the Melvin gage; the flood of
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