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<br />rainfall event to exceed the infiltration rates in the <br />majority of Clear Creek basin upstream from Lawson. <br />Infrequent rainfall events with intensities exceeding <br />infiltration rates for longer durations would result in <br />significantly higher runoff volumes and peak discharges. This <br />would result in a high positive skew which is not inherent in <br />the Clear Creek basin streamflow records. Therefore , it is <br />believed that the use of a rainfall/runoff model is a <br />reasonable method to refine the rainfall discharge frequency <br />relationship. <br /> <br />CWCB Comment #2. <br /> <br />How were snowmelt flows arrived at? Was a separation of <br />rainfall and snowmelt peaks performed for the two stream <br />gages? It was not documented whether all of the annual peaks <br />for the Lawson and Golden gages were taken to be snowmelt <br />peaks without questions or whether the gage records were <br />examined to determine which flows were snowmelt-caused and <br />which were rainfall-caused. One thought was that perhaps <br />there was no need to derive synthetic rainfall peaks if one <br />just used the rainfall peaks that resulted from separating <br />rainfall and snowmelt peaks in the gage records. Did you find <br />actual rainfall peaks in your review of the gage records? If <br />so, why were they not used, along with the separate snowmelt <br />peaks in your analysis? <br /> <br />Corps Response #2. <br /> <br />Snowmelt flows at various locations along Clear Creek <br />were based on relationships between drainage area and mean <br />flood logarithm and standard deviation of the logarithms. <br />Those relationships were derived by analysis of the streamflow <br />records at the Lawson and Golden gages. The streamflow <br />records were obtained from the USGS Open File Report 82-426 <br />which contained annual peak discharges separated for both <br />snowmelt and rainfall peaks. Appendix A, in our revised <br />report, contains the peak discharges used in our analysis. <br /> <br />CWCB Comment #3. <br /> <br />Were the data and the procedures used to separate <br />rainfall and snowmelt peaks those described by Elliot, Jarrett <br />and Ebling of the USGS in their report entitled "Annual <br />Snowmel t and Rainfall Peak Flow Data on Selected Foothills <br />Region Streams, South Platte River, Arkansas River, and <br />Colorado River Basins, Colorado." Open File Report 82-426? <br /> <br />2 <br />