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<br />. <br /> <br />. <br /> <br />. <br /> <br />coincident 100 cfs discharge fro,n the Chatfield project contributing to the <br /> <br /> <br />flood from th,e uncontrolled area below 3S was assumed in that report. <br /> <br /> <br />b. On Svstem Operation. A study 'was made of the Tri-Lakes syst.em using a <br /> <br /> <br />HEC-5 model t.o simulate conditions of \/ith and without storage conversion for <br /> <br /> <br />the period 1942 to 19311 along with changes in storage allocations at Chatfield <br /> <br /> <br />and B,ear Creek. Also considered was the effects of chcmging maximum Chatfield <br /> <br /> <br />releases from 5,000 cfs to 3,000 cfs. The 'naximum release rates from Bear <br /> <br /> <br />Creek and Cherry Creek were held constant at 2,000 cfs and 5,000 cfs, respect- <br /> <br /> <br />ively. Tne sensitivity of channel capacity constr~ints for the South Platte <br /> <br /> <br />River at the Henderson gage was also investigated. Toe most sensitive factor <br /> <br /> <br />in the operation of Tri-Lakes projects is the imposition of channel con- <br /> <br /> <br />straints at Henderson. This beca~e evident after using target flows of 3,000 <br /> <br /> <br />cfs, 5,000 cfs, and 7,000 cfs for this location in the model. It showed that <br /> <br /> <br />even for the nonconversion condition the 1942 mountain sno~nelt flood would <br /> <br /> <br />have encroached well into the upper half of the flood pools of Chatfield and <br /> <br /> <br />Bear Creek for either Chatfield release rate if the Henderson constraint would <br /> <br /> <br />have been 3,000 cfs. Tnis demonstrates the amount of flood storage that is <br /> <br /> <br />required to protect against minor erosion damages dmmstreil'll. A 5,000 cfs <br /> <br /> <br />constraint at Henderson would have held both 1942 maximun pool levels to less <br /> <br /> <br />than half full, ;/i1ich is about the level that >,;ould be expected for this type <br /> <br /> <br />of an event. <br /> <br />c. On Pool L~. Adding 22,700 Ac ft and 18,400 Ac Ft of \~ater supply <br />storage at Chatfield and Bear Creek, respectively, ',~ould obviously have a sig- <br />nificant i:npact on th.e conversation pool level at each proj ect. At C:l<3tfield, <br />it would increase the conservation pool elevation fro:n 5432 to 5445.2; ~1ile <br />at Be<3r Cree!( it \-Iould increase the pool from 5553 to 5619.5. It is not knO\Vll <br /> <br />4 <br />