WSPC01928

• File Number: 8283.200
• Description: Colorado River Basin-Colorado River Computer Models-Colorado River Decision Support System-RAY
• State: CO
• Water Division: 5
• Date: 3/25/1991
• Title: HYDROSS-HYDROSS Version 4.10
• Water Supply Pro - Doc Type: Report/Study

Introduction

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Seepage appears immediately below the reservoir as project water. Seep"age can be defined as
a constant, as a monthly table, as a function of flow or as a function of mean reservoir content.

1.4.7 Power Generation: Monthly power generation is computed using discharge,
head and efficiency data. Power is computed at the downstream side of the reservoir station.

1.4.8 Diversions: A diversion may occur at any station, and there is no limit to the
number of diversions per station. A diversion may have a natural water right, or a project water
right or a natural water right supplemented with a project water right. The data used by a diversion
include a monthly delivery system (canal) efficiency table, a site efficiency percentage table, percent
of canal loss to return flow, percent of site loss to return flow, canal capacity, maximum annual
diversion, and a diversion requirement.
The diversion requirement may be one of five types:
Monthlv Table of gross diversion values.
Irril!ation Reouirement with an area to be irrigated and a monthly unit requirement
table.
Pooulation Reouirement with the number of units requiring water and a monthly unit
requirement table.
Offstream Storal!e Reouirement which attempts to keep an offstream storage facility at
a target content.
Monthly table of Byoass Diversion Values in which flows in excess of this value can
be diverted.
HYDROSS also allows a diversion capacity and a pump capacity. The diversion capacity and
pump capacity can be used to constrain diversions at a station.

1.4.9 Other Loss and Other Gain: HYDROSS allows the user to input an "Other
Loss" table. The "Other Loss" table is a way to arbitrarily remove water from the system. Other
Loss will use any water it can get (natural or project) and deny it to all users below the station
without reference to priority. "Other Gain" (negative "Other Loss") is a means of forcing project
water into the system, such as releases from upstream reservoirs upstream of the area of study.

1.4.10 Return Flow: Return flows originate from diversions or reach losses, may
return to the system as natural water or project water, and may be delayed for as long as eleven
months. Return flows can re-enter the system at any station.

1.4.11 Channel Caoacities and Flood Control: HYDROSS allows the user to specify
a channel capacity table at any station which is the flow at which the river enters flood stage.
HYDROSS will not voluntarily release stored water which will cause flooding. This is one case in
which the model will store water in a reservoir above maximum (see section 1.4.4 [Page 2]). In
effect, HYDROSS allows for flood control storage in a reservoir by using storage available between
the maximum and absolute maximum content levels.

1.4.12 Area-Caoacity-Elevation (ACE) Data: HYDROSS allows the user to input one
area-capacity relationship for each reservoir. HYDROSS can accept up to 99 data points from an
area-capacity-e!evation curve for a given reservoir.

1.4.13 Water Ouality: HYDROSS is not a water quality model but does have the
capability to produce an output report which prepares data files for input to water quality models.

March 25, 1991

HYDROSS 4.1

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