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<br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br /> <br />II. <br /> <br />B-2 <br /> <br />B. SUMMARY COMMENTS <br /> <br />1. The selected events, inflows, discharges, etc. are <br />summarized as follows: <br /> <br />PEAK <br />SNOW MELT <br />INFLOW <br /> <br />PEAK <br />RAINFALL <br />INFLOW <br /> <br />PEAK <br />DIS- <br />CHARGE <br /> <br />PEAK <br />FLOW AT <br />YMCA SITE <br /> <br />a. 100yr snow melt flood occurring at full reser- <br />voir, elevation 79.5 <br />4500cfs -0- 3800-4000cfs 3500-3700cfs <br /> <br />b. 100yr rainfall occurring after 100yr snow melt <br />peak has passed, reservoir full at elev. 79.7 <br />3200cfs 6480cfs 4800-5000cfs 4500-4700cfs <br /> <br />c. 25yr rainfall occurring simultaneously with 25yr <br />snow melt peak, reservoir full at elev. 79.5 <br />3600cfs 5l00cfs 5000-5200cfs 4700-4900cfs <br /> <br />d. loyr rainfall occurring simultaneously with 10yr <br />snow melt peak, reservoir full at elev. 79.5 <br />3200cfs 4200cfs 4400cfs 4l00cfs <br /> <br />The 25yr snow meltj25yr rainfall simultaneous occur- <br />rence theoretically has a probability of 1 in 625. <br />This seems too restrictive, especially when adding <br />the requirement of a full reservoir. A 10yr snow- <br />meltjlOyr rainfall simultaneous occurrence has a <br />theoretical probability of 1 in 100. <br /> <br />2. Therefore, in evaluating the above flow estimates, <br />we recommend using the 100yr rainfall occurring <br />after the peak of a 100yr snow melt. This yields a <br />flow of 4600cfs to determine the looyr flood level <br />at the Phase 2 site. <br /> <br />3. Projected water level depths of this flow are on the <br />order of 4.3ft to 7.4ft. <br /> <br />FLOOD FLOW DETERMINATION <br /> <br />A. FACTORS AFFECTING FLOOD FLOWS AT PHASE 2 LOCATION <br /> <br />There are several factors which affect flood flows at <br />the Phase 2 site. In general, they are as follows: <br /> <br />1. Natural inflows from the Granby Reservoir basin <br />2. Manmade inflows to Granby Reservoir <br />3. Transmountain releases from the reservoir <br />4. Reservoir level at time of flood occurrence <br />5. Operating guidelines and restrictions regarding <br />reservoir level and discharges <br /> <br /> <br />