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27 V. VERIFICATION OF RESULTS 5.1 Comparison of Regression Equations for Peak Runoff To verify the results of the MULTSED physical process model, the peak dis- charges for the 10-year, 24-hour and 100-year, 24-hour storm events were com- pared to two different methods used to estimate peak discharges. The two methods were raked from "Rainfall-Runoff Modeling and Preliminary Regional Flood Char- acteristics of Small Rural Iiatersheds in the Arkansas River Basin in Colorado" (SRI~ARB) and "Manual for Estimating Flood Characteristics for Natural-Flow Stream9 in Colorado, Technical Manual Number 1' (TM-1). A discussion of the development of regression equations for the two methods is presented in the General Description of Hydrology Report. Neither method vas developed with L areas less than 0.5 square miles and, therefore, comparison of tha Tipple Area drainage vas not made. f Comparison of peak discharge versus effective drainage area for the 10- • year, 24-hour and 100-year, 24-hour storm events as calculated by SRWARB, TM-1 • and MULTSED is shown in Figure 5. The 100-year peak discharge estimated for the Magpie Creek drainage ranges from a high of 4394 cfs calculated using TM-1 to a lw of 3156 cfs calculated by the MULTSED model. A peak discharge of 3885 cfs was calcuated using SRWARB. The peak discharge of 3156 cfs is at the outlet of the drainage basin. However, because the channel slope at the outlet is mild, the water spreads out more in the downstream channel enabling more water to in- filtrate into the ground through the channel bottom. Thus, tha peak discharge on Magpie Creek and the contributing drainagn area to the east occurs upstream of the Magpie Creek drainage outlet. In addition, the MULTSED model incor- porates a routing process which has an effect on the peak discharge. The MULTSED results are within 28 percent of TM-1 and 19 percent of SRwARB. The 100-year peak discharge estimated for the Newlin Creek drainage ranges from a high of 10,234 cfs calculated using SRwARB to a low of 9499 cfs calculated using TM-l. A peak discharge of 9789 cfs was calculated by the HULTSED model. The P;ULTSED results are within three percent of TM-1 and four percent of SRWARB. The 10-year, 24-hour peak discharge calculated by the MULTSED model for the Magpie Creek and Newlin Creek drainages is 897 cfs and 2325 cfs, respectively. Comparison to SANARB shows these values to be within ten percent for Magpie • Creek and one percent for Newlin Creek. The 10-year, 24-hour peak discharge calculated using TM-1 is much higher than that calculated by both SRwARB and MULTSED.