WSPC04476

• File Number: 8283.200
• Description: Colorado River Basin-Colorado River Computer Models-Colorado River Decision Support System-RAY
• State: CO
• Water Division: 5
• Date: 12/29/1993
• Title: Hydrosphere-Colorado River Model-Technical Overview
• Water Supply Pro - Doc Type: Report/Study

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Hydrosphere's Colorado River Model

December 29, 1993
Page II

Future versions of the model may include the capability to simulate lagged return flows
to remote river reaches. This upgrade will depend on the feedback we receive from our
customers.

Monthly Distribution of Depletions

The monthly depletions used in the model were derived by multiplying the annual
depletion by a distribution factor for each month. Each use can have a different distribution
factor. The distribution factors used in the baseline configuration of the model are taken from
the USBR 1991 AOP data set. These factors may be modified in the model.

Future Projected Depletions

The future depletion estimates used in Hydrosphere's Colorado River Model have been
obtained, in most part, from the USBR's 1991 AOP. These were developed by the Bureau
through model studies that included consideration of water supply, legal entitlement, current
and expected delivery capacity, and expected development of water-using projects.

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The model will accommodate modifications to the depletion estimates to simulate any
demand scenario. Depletions can be simulated at a constant level or as a time series of
increasing values. Constant depletions are used to evaluate scenarios which assume that full
depletion capabilities are attained starting from the first year of simulation (such as a
"buildout" scenario). Increasing future depletion estimates can be used to evaluate scenarios
where depletions are expected to increase due to increasing delivery capacities or other
reasons, usually defined over a planning horizon that extends 20 to 40 years into the future.

When short term dynamic analyses are made, depletions in the initial year of the model
simulation are usually set to current conditions as defined by the last year for which observed
depletions are available, which in the current data set is 1992. Depletion estimates then change
in the following years through 2040 according to the USBR 1991 AOP data set:

1992 (initial year)
1993
1994
1995
2000
2010
2020
2030
2040

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Depletions may be held constant between the years in which changes are specified or
they may be interpolated.

Previous analyses with Hydrosphere's Colorado River Model have adapted the USBR
1991 AOP depletions to represent three levels of projected depletions -- "low", "medium" and
"high" (Booker, 1992). The low depletion level assumes constantdemand (no growth) as
represented by the USBR schedule for 1992, and deliveries to CAP limited at 745 kaf for most
years. The medium depletion level assumes demand growth is represented by the USBR
schedule for years 1992 to 2030, but with agricultural uses fixed at 1992 levels. The total
CAP depletion is assumed to start with 543 kaf, increase quickly to 900-950 kaf, and jump to
1,116 kaf in 2010. The high depletion level assumes demand growth represented by the USBR
schedule for years 1992 to 2030. CAP demands grow to 1,666 kaf in the 3rd year, and to the

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