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<br />4.9 <br /> <br />represents the best avail abl e ml~thod for rE! 1 at i ng mud f"lows with a return <br />period. <br />In the following sections, a. review is made of prev-ious hydrologic studies <br />for Cornet Creek, an analysis of clear-water hydrographs for 10-, 50-, 100-, and <br />500-year return peri od thunderstorms is prE!sented, and mud flow hydrographs based <br />on a variable sediment concentration are developed. The mud flow hydrographs <br />are compared to recorded hi stori c floods on the Cornet Creek alluvi a 1 fan. <br /> <br />4.4.2 Previous Flood Studies <br />Five previous studies have been conducted related to the flooding potential <br />along Cornet Creek. In the following section, the methods and results of each <br />study are discussed. <br />Debris Flow Hazard on CornE!t Creek ,It Tenuride. Colorildo Institute of <br />Arctic and Alpine Research, University of Colorado (Mears et al., 1974). <br />This report presents an analysis of the 1914 and 1969 floods along Cornet <br />Creek. The study was undertaken to determine the causes and characteristics of <br />past fl oods in order to develop rat i ona,l dE!S i gn criteri a for future fl ood- <br />protection works. The study reviewed the general nature of Cornet Creek floods <br />in 1914 and 1969. It stated that both floods were caused by short-duration, <br />high-intensity rainfall which occurred after a period of wet weather. Deposits <br />of the 1969 flood were analyzed to determine the potential range of flows <br />experienced. Cross sections of the lower one-half mile of the stream above the <br />town were taken for est imat i ng the potent i a 1 di scharge range. A maxi mum <br />discharge rate of 14,100 cfs was determined for the 1969 event. <br />Older debris flood deposits were identified during the field work for the <br />study. The old deposits were believed to indicate that larger discharges have <br />occurred along Cornet Creek in the past. The weathered and eroded nature of the <br />older deposits, however, prevented estimation of the prehistoric discharges. <br />The mud flows of this century wel,e judged to not be exceptionally rare events <br />in the history of Cornet Creek. <br />The recommend at ions for fl ood protect ion developed from the study <br />identified a discharge of 14,000 cfs for use in design of flood-control <br />structures along the stream. <br />