WSP03830

• File Number: 8271.200
• Description: Colorado River Basin Salinity Control Program - Development and History - UCRB 13a Assessment
• Basin: Colorado Mainstem
• Water Division: 5
• Date: 1/1/1978
• Author: Huntly - Main - Lane
• Title: Streamflow Simulation with the Colorado River Simulation Model
• Water Supply Pro - Doc Type: Report/Study

.

e--

.'

The {ollowing table summarizes the potential number of node.,
inflow sequence points, demand sequence points, and user. and shows
the number of each presently used.

.'Table I. Node setup.

Item

Number
Potential Useda.

Nodes
)nflow sequence points
Demand &equence point"
Uaers

25 25
250 154
250 78
2,500 129

&Currently used for Colorado Rive r model runs.

The _hode, control structure includes three seta of control informa-
tion. The.first set derines node order, node identifica.tion, and destina_
tion of node outflow. Node order is sel up 80 that calculations begin ~t
the top of ,the river basin and proceed down the basin to the bottom. Cal-
culatiohs' also proceed from the top of a node to the bottom of the node.
Thus, flow at all upstream nodes is handled prior to any downstream
node it may a{[ect.
The 6econd set defines the sequence of inflow points, demand
points, and the reservoir point within the node. Sequence numbers are
assig.ned point by point from top to bottom; positive for inflows, nega-
tive for d~mands, and zero for a reservoir. .Care must be taken in
assigning inflow and demand points so that basin structure is modeled
as closely as pouible. This will help to prevent the calculat.ion of
negative flows in the J.:iver.
The third ~et of control information defines the upstream node
numbers which can provide water lor dern.a.nds within the node.

146

.

Reservoir Operational Input

!:6tJ

Reservoir operational relationships represehted by-polynomial
equations in this model are as follows: (I) Reservbir elevatio'n-area-
capacity; (2) horsepower at lull gate ver6US head; (3) flow rate versus
head; and (4) tailwater elevation versus flow rate.
The polynomial is of the form

2 3
Y~aOtalx+a2.x ta3x

n
+... + a x
n

The a coefficients are determined by least squares fit a'rid entered as
n
input data.
Other reservoir operational inputs are: (1) Target capacity value.
for each month called rule curves; (Z) bank storage coefficient; (3) evap-
oration rates for each month; (4) capacity at normal water; (5) maximum
and minimum reservoir capacities; (6) maximum and minimum outlet
capacities; and (7), beginning reservoir storage and salinities.

Demand Input

The simulation model requires input data. on a node and demand
sequence point arrangement as described in the section on node control
structure. However, demand input is usually set up on a detailed
"uscrll basis and put through a separat.e program which prepa res the
information for the simulation model. The user basis model is called

Simulation Model Demand Input Data (SMDID).
The use r basis allows a more detailed breakdown of demands and

allows them to be identified by state and function. SJ..fDID can take de-
mand information from up to 10 users and combine it into the total de-
mand at a single demand sequen'ee point within Lhe node.
Types of information required in setting up the demand data lor
a node are listed as follow8: (1) Withdrawals for a given user at a de-
mand point; (Z) depletions (or return flow); (3) year of withdra.wal and
depletion; (4) base year (coordinated with hydrology modified flow base);

147

I
.i
i1
I