9380

• UCREFRP Catalog Number: 9380
• Author: U.S. Bureau of Reclamation.
• Title: Grand Valley Irrigation Company Fish Screens ‎(Predesign)‎.
• USFW Year: 2000.
• USFW - Doc Type: Boise.
• Copyright Material: NO

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g = acceleration of gravity = 32.2 ftlsec2

Using the above equation, the resulting head loss through the louvers will be 0.18 feet.

The designed louver structure is slightly smaller than the typical screen structure. Therefore, the

approach velocity for a screen structure will be slightly less than the louver structure because of

its slightly larger size. It is anticipated the head losses through a screen structure will be similar

to the louver structure.

Total losses through the trashrack and screens will be approximately 0.2 feet (0.01 feet + 0.18

feet). Using the required elevation at the staff gage ofEl. 4679.6, the required elevation at the

downstream side of the headworks will be El. 4679.8. Assuming a minimum water surface

elevation on the upstream side of the headworks of El. 4681.0, the maximum loss through the

headworks would be 1.2 feet (El. 4681.0 - El. 4679.8). Two different bypass arrangements will

be discussed in later sections of this memorandum, however, they are mentioned here because of

the different impacts on the headworks head losses. The two potential bypass flows are 10 cfs

and 44 cfs. Using the 10 cfs bypass option, the total design flow through the headworks will be

650 cfs (640 cfs + 10 cfs). For this flow and a 1.2 feet head loss, Sheet 3 in Appendix C shows

the required gate opening to be 84 percent. Using the 44 cfs bypass option, the total design flow

through the headworks will be 684 cfs (640 cfs + 44 cfs). For this flow and a 1.2 feet head loss,

Sheet 3 shows the required gate opening to be 89 percent.

The above calculations show that under the low flow condition in the river, the water delivery

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