WSP09055

• File Number: 8281.100
• Description: Colorado River Studies and Investigations -- Availability of Water-Hydrologic Determination
• Basin: Colorado Mainstem
• Water Division: 5
• Date: 1/1/1988
• Title: Hydrologic Determination - 1988 - Water Availability from Navajo Reservoir and the Upper Colorado River Basin for Use in New Mexico
• Water Supply Pro - Doc Type: Report/Study

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APPENDIX II

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USE OF
THE COLORADO RIVER SIMULATION SYSTEM (CRSS)
TO DETERMINE AVAILABLE STORAGE

Documentation ,of the CRSS model is found in the following _publicati.on~l, .!!-ll
published by the Bureau of Reclamation:

Colorado River Simulation System - An Executive Summary
Colorado River Simulation System - System Overview
CRSM User Manual

The model accounts for sedimentation in four reservoirs: Navajo, Flaming
Gorge, Lake Powell, and Lake Mead. Sedimentation is assumed to be a
constant annual amount that varies seasonally for each reservoir, but the
distribution of sediment between active and dead storage pools is a
function of the individual reservoir operation. The model continually
updates the elevation-capacity relationships for each of the four
reservoirs. Sedimentation is important in yield determination since over
the 81 year period of record used in modeling, total Upper Basin system
storage is decreased by over 5 MAF as a result of sediment.

Shortages are calculated locally in the model at individual demand points
and summed for the entire basin. The model output indicates total annual
shortages. It is recognized that inaccuracies in shortages are generated
by the model. This is due to modeling limitations such as not modeling
local storage facilities, as well as not recognizing water right prior-
ities. In some instances shortages are generated due to inadequacy of
hydrologic information in localized areas.

In current runs of the CRSS model, consideration of bank storage is given
to two reservoirs in the Upper Basin. The change in storage of Lake Powell
is modified by a bank storage factor of 0.08 and in Flaming Gorge the
change in storage is modified by a factor of 0.033. No consideration for

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