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[FEQ Update Contents]
Enhancements and Modifications to
the Full Equations (FEQ) Model, March 1995 to August 1999.
Note: This document is separate from the U.S. Geological Survey report by Franz and Melching (1997). This description of enhancements and modifications to the Full Equations Utilities Model has not been approved by the Director of the U.S. Geological Survey.
Input description update for
section 13.3, Tributary Area Block--Tributary Area Tables, Franz and Melching
(1997a), p. 164
Section 13.3 Tributary Area Block--Tributary
Area Tables
To
RELEASE.TXT
The tributary area is only required when the model is to compute lateral
inflows to branches or level-pool reservoirs. FEQ computes the lateral
inflows from the product of an area tributary to a computational element
and a unit-area runoff intensity for that area. The input described below
must define where FEQ is to find the data for the unit-area runoff intensities,
what is the distribution of tributary area among the computational elements,
and which unit-area runoff intensities is to be used for each element's
tributary area.
For conceptual convenience the tributary area in an unsteady flow model
for FEQ is broken into subareas based on the rainfall data used to estimate
the unit-area runoff intensities. This reflects the reality that a single
rain gage must be used to represent the temporal rainfall pattern over
an extensive land area even though the surface conditions vary widely.
Each surface condition will have a different time series of unit-area runoff
intensity even though the same time series of rainfall data is used in
the rainfall-runoff computations. FEQ groups the various time series of
unit-area runoff intensity derived from a rain gage under the concept of
a gage number, assigned by the user to the rain gage. For example, if two
rain gages, say one at Wheaton and the other at O'Hare airport are used,
the user could assign gage 1 to Wheaton and gage 2 to O'Hare. The watershed
area assigned to Wheaton might have three different time series of runoff,
one for impervious surfaces, one for forested surfaces, and the last for
surfaces covered with grass. All three time series are implied by gage
number 1 when the number is used in subsequent input. Although the user
assigns gage numbers they must start at 1 and be consecutive thereafter.
The first part of the tributary area input relates gage numbers to
the source of the time series data in the computer system. Two sources
for the unit-area runoff intensities are supported by FEQ. They are selected
by the value given to DIFFUS
in
the Run Control Block.
If DIFFUS=YES,
then the source of the unit-area runoff intensity time series is a Diffuse
Time-Series File (DTSF) that contains the time series for all land use
and gage combinations. A DTSF stores multiple runoff events each with its
own starting and ending times. These values over ride the starting and
ending times given in the Run Control Block. Furthermore, FEQ will automatically
compute the conditions in a dummy event, the first event stored in the
DTSF. This event will always be computed to set the initial conditions
to be used by all subsequent events in the DTSF. Provision is made for
storing summary results from each event in a flood frequency file for later
analysis.
On the other hand if DIFFUS=DSS,
then the source of the unit-area runoff intensities is one or more HEC
DSS files. A HEC DSS pathname defines one time series so that if there
are 20 land-use and gage combinations there will be 20 different path names
required to define the unit-area runoff intensities. The data type for
these path names must be PER-CUM. The time series must be regular-interval
time series and all time series must have the same time step. The units
of the data are assumed to be in inches per interval but FEQ does not make
use of the HEC DSS UNITS field at this time. The structure of the HEC DSS
does not permit storage of starting and ending times as does the DTSF.
Therefore the starting and ending times given in the Run Control Block
are retained and only one event is run. No flood frequency file is used
because only one event is run at a time.
The second part of the tributary area
input defines the distribution of tributary area across computational elements.
This distribution is independent of the source of the runoff intensities
and is discussed after the two alternative sources for runoff intensity
are described.
If DIFFUS=YES
Return to section 13.3
Tributary Area Block--Tributary
Area Tables, and Melching
(1997a), p. 164
LINE 1
Variable: |
TSFDSN, TSFNAM |
Format: |
7X, I5, A64 |
Example: |
TSFDSN=00012\SALT\TSFLONG |
Explanation: |
Supplies the FORTRAN unit number and
name for the DTSF giving the unit-area runoff intensities on the tributary
areas. If TSFNAM
is
non-blank, FEQ will attempt to open a file with name given by the contents
of TSFNAM (most
micro-computers) as the DTSF. On IBM mainframes the name given by TSFNAM
will
be the ddname for the DD statement defining the dataset. If the TSFNAM
is
blank IBM mainframes will attempt an implicit open if the proper DD statement
defining the unit number given by TSFDSN
is
present. Some micro-computer environments will prompt the user for the
file name in this case and some will abort execution. The unit number can
be omitted and if it is given FEQ will not use the value. The unit number
field is retained for consistency with old input files. Only the file name
needs to be given. |
LINE 2
Variable: |
FFFDSN, FFFNAM |
Format: |
7X, I5, A32 |
Example: |
FFFDSN=00011\SALT\UPMS\FFF |
Explanation: |
Supplies the FORTRAN unit number for
the file to be used to store the flows and stages required for making a
flood frequency analysis. If FFFNAM
is
non-blank, FEQ will attempt to open a file with name given by the contents
of FFFNAM (most
micro-computers) to store the values needed for flood frequency analysis.
On IBM mainframes the name given by FFFNAM
will
be the ddname for the DD statement defining the dataset. If the FFFNAM
is
blank IBM mainframes will attempt an implicit open if the proper DD statement
defining the unit number given by FFFDSN
is
present. Some micro-computer environments will prompt the user for the
file name in this case and some will abort execution. The unit number can
be omitted and if it is given FEQ will not use the value. The unit number
field is retained for consistency with old input files. Only the file name
needs to be given. |
LINE 3
Variable: |
NLUSE |
Format: |
6X, I5 |
Example: |
NLUSE=00006 |
Explanation: |
Gives the number of cover type/land
uses and rain gage combinations represented by the tributary areas. For
example, if there are three land uses in each of two segments in the hydrologic
simulation then NLUSE=6.
The maximum number of diffuse tributary areas allowed in FEQ is specified
in the parameter MNDIFA and MXGLU in the INCLUDE file ARSIZE.PRM. The current
number of land uses per gage is 12. |
LINE 4
Variable: |
NGAGE |
Format: |
6X,
I5 |
Example: |
NGAGE=00003 |
Explanation: |
Gives the number of gages used to
define the runoff intensities on the tributary area for the watershed. |
LINE 5
Variable: |
HEAD |
Format: |
A80 |
Example: |
GAGE NCOV |
Explanation: |
Heading for the gage number cover
type table. |
LINE 6 (one for each raingage)
Variable: |
GAGE, NCOV |
Format: |
2I5 |
Explanation: |
Gives the gage number (in ascending
order) and its number of cover types. There must be a line for each gage
and the sum of the number of cover types must be the same as the value
of NLUSE given
on line 3. Line 6 is repeated as required to specify the number of cover
types for each gage subarea in the watershed. |
FEQ assumes that the runoff intensities
in each record of the DTSF are stored in the order given here. The order
is under the control of the user but a logical ordering should be used
because the order of input for tributary area is tied to the order of appearance
of the runoff values in the DTSF. Giving the runoff values in land-cover-type
order for each gage has worked well in the past. |
Back
to Franz and Melching (1997a), p. 166 for lines 7-9