WSP04354

• File Number: 8102
• Description: Arkansas River Hydrology
• State: CO
• Basin: Arkansas
• Water Division: 2
• Date: 1/1/1997
• Author: USGS
• Title: Description of the Program Changes 1989 97 and a User Manual for a Transit Loss Accounting Program Applied to Fountain Creek Between Colorado Springs and the Arkansas River Colorado
• Water Supply Pro - Doc Type: Report/Study

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Once initiated, the accounting program queries
the user for the required input data: (I) The TRF and
the native return-flow quantities discharged at the CCS
WWTF, (2) the discharge at each gaging station
(table I, fig. 3), and (3) \he diversion at each ditch
(table 1). These data are input manually to the
program for each day of transit-loss computations:
however, the diversion data, once input, only need to
be reentered when the diversions change from the
previous day. All input data, \he accounting program
computations, and the output results are expressed in
cubic feet per second, unless noted otherwise.

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Program Computations

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In computing the estimated quantities of TRF in
Fountain Creek and the associated transit losses, the
accounting program uses two sets of computations.
The first set of computations is made between any two
adjacent gaging stations (stream-segment computa-
tions); these computations estimate the loss or gain in
NSF between the two adjacent gaging stations. The
second set of computations is made between any two
adjacent nodes (subreach computations); the actual
transit-loss computations are made in the subreach
computations, using the result from the stream-
segment computations. The stream-segment computa-
tions are completed for a stream segment, then the
subreach computations are completed for each
subreach within the stream segment. When the
subreach computations are completed for all
subreaches within a stream segment, \he stream-
segment computations are repeated for \he next stream
segment, followed again by the subreach computa-
tions; the process continues until computations are
completed downstream through subreach 14.

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Assumptions Used in the Computations

To compute estimated transit losses using the
accounting program, an assumption must be made in
the stream-segment computations that the quantity of
TRF at the downstream gaging station is the same as at
the upstream gaging station. This assumption is neces-
sary because, at this point in the computations, the
quantity of TRF at the downstream gaging station is
not known. Although this assumption results in some
error in estimating the loss or gain in NSF between the
gaging stations, these errors are not substantial (Kuhn,

1988, p. 88). Because of this assumption, the
computed quantity of NSF at the end of the down-
stream subreach within a stream segment is somewhat
different from the NSF at the beginning of \he next
stream-segment computations (see the "Program
Output" section, p. 12). This discrepancy in NSF
computation has been corrected in the program
version currently (1997) in use (see \he "Changes to
Program Output" section, p. 22). To perform the
transit-loss computations, the input data also are
assumed to be accurate.

Stream-Segment Computations

After the data are input, the accounting-program
computations begin wi\h the stream-segment compu-
tations, which are diagramed in figure 4. To perform
the stream-segment computations, the following
stream-segment known quantities (SS_Kx, where x is
a number) need to be defined:

I. SS_KI (fig. 4), which is the total streamflow at the
upstream gaging station. If the upstream gaging
station is station 07105500, then SS_KI is equal
to the sum of the daily mean discharge at station
07105500 and the total return flow (sum of TRF
and native return flow) discharged into Fountain
Creek at the CCS WWTF; otherwise, SS_KI is
equal to \he daily mean discharge at the upstream
gaging station.

2. SS_K2 (fig. 4), which is the TRF at the upstream
gaging station. If the upstream gaging station is
station 07105500, then SS_K2 is equal to the
TRF discharged at the CCS WWTF; otherwise,
SS_K2 is equal to SR_U3 (the TRF at the down-
stream node) from the last subreach computation
of the previous stream segment (see fig. 5 and the
"Subreach Computations" section, p. 9-12).

3. SS_K3 (fig. 4), which is the NSF at the upstream
gaging station. SS_K3 is equal to SS_KI ntinus
SS_K2.

4. SS_K4 (fig. 4), which is the total streamflow at the
downstream gaging station. SS_K4 is equal to
the daily mean discharge at the downstream
gaging station,

5. SS_K5 (fig. 4), which is the total NSF diversion in
the stream segment. The NSF diversions are
input individually for each ditch and the program

8 Descriptions of the Program Changes (1989-97) and a User Manual for a Transit-Loss Accounting Program
Applied to Fountain Creek Between Colorado Springs 8nd the Arkansas River, Colorado