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<br />-, <br /> <br />N <br />--<1 <br />en . <br />OJ <br /> <br />f. For density determinations, systematic sampling of sedi- <br />ment deposits at depths up to about 10 feet will be made during the <br />next resurvey provided the reservoir is dry. The assumed initial <br />density of 75.7 pounds per cubic foot should only be applied to recently <br />deposited sediment. After applying a factor for compaction, the <br />volume of sediment from the resurvey approximates very closely the <br />sediment deposited as computed by suspended sediment inflow-outflow <br />relationship. <br /> <br />g. The original prov1s1on for sediment storage in the res- <br />ervoir is considered adequate based on the experienced rate of sediment <br />deposition during the 24.3 years of operation covered in this report. <br />The storage estimate for sediment deposition during design of the John <br />Martin project was 250,000 acre-feet, This was based on a SO-year <br />deposition period (5,000 acre-feet per year) and estimated average <br />yearly stream inflows of 350,000 acre-feet. Experienced loss of <br />storage is about 70,700 acre-feet for 24,3 years (2,910 acre-feet <br />per year) with average yearly stream inflow of about 277,100 acre-feet.. <br /> <br />h. It is proposed that the next resurvey of John Martin <br />Reservoir be a topographic survey. The last topographic survey was <br />made in 1948 and, as indicated in paragraph 41j, the areas computed <br />by Constant Factor computations tend to be erratic, This will neces- <br />sitate scheduling of the next resurvey when the reservoir is about <br />empty. Use of aerial topography will be considered for this purpose. <br /> <br />14 <br />