Availability of an Alternative One-Dimensional, Unsteady Flow Model; the Full Equations Model (FEQ)
To: "A - Division Chief and Staff",
"B - Branch Chiefs and Offices",
"FO - State, District, Subdistrict and other Field Offices",
"PO - Project Offices"
cc: " , WRD Archive File, Reston, VA ",
"L. Jane Rose, Secretary, Reston, VA "
Subject: OSW Technical Memorandum No. 98.03
Date: Wed, 18 Feb 1998 17:10:01 -0500
From: "L. Jane Rose, Secretary, Reston, VA "
In Reply Refer To: February 10, 1998
Mail Stop 415
OFFICE OF SURFACE WATER TECHNICAL MEMORANDUM NO. 98.03
Subject: Availability of an Alternative One-Dimensional, Unsteady Flow
Model; the Full Equations Model (FEQ)
The Illinois District recently distributed copies of WRIR 96-4240, entitled
"Full Equations (FEQ) Model for the Solution of the Full, Dynamic Equations of
Motion for One-Dimensional Unsteady Flow in Open Channels and Through
Control Structures" by Delbert D. Franz and Charles S. Melching. The purpose
of this memo is to confirm that the model has received sufficient testing to
be considered as an operational tool for use in WRD. The FEQ model and its
companion utility program, Full Equations UTiLities (FEQUTL) (Franz and
Melching, in press) are distributed by the Hydrologic Analysis and Support
Software (HASS) group and is included on the last WRDAPP tape release, as well
as the HASS software-distribution tape and internet site. Support for the
model is provided by the Illinois District (contact Steve Melching or
FEQ and FEQUTL are non-proprietary programs developed by Dr. Delbert Franz of
Linsley, Kraeger Associates in Mountain View, California. The
U.S. Geological Survey (USGS) involvement with FEQ began in the late 1980's at
the Illinois District when two major cooperators became interested in applying
FEQ for flood-plain delineation utilizing runoff input from the watershed
model, Hydrologic Simulation Program Fortran (HSPF), and operational
management of low-head dams. FEQ also has been applied in the State of
Washington, by the South Florida Water Management District, and by numerous
consulting firms. The FEQ output has been linked to the USGS GENerate
SCeNarios (GENSCN) software for post-processing analytical and graphical
tools. FEQ is capable of modeling a system constrained by a wide variety of
fixed and variable-geometry hydraulic controls such as bridges, culverts,
weirs, side weirs, and pumps. Specifying these controls is simplified in FEQ
by use of its companion program, FEQUTL, which is used to supply function
tables for cross-sections and hydraulic controls. FEQ is capable of modeling
dendritic flow networks that contain loops. It accounts for lateral-inflow and
wind and has a zero-inertia option for use on steeper streams. The accuracy of
FEQ in simulating field conditions has been documented in Turner and others
(1996) and Ishii and Turner (1997).
FEQ is a computer program that solves the one dimensional, unsteady flow
equations (St. Venant equations) for water-surface elevation and mean water
velocity. It uses the four point implicit finite difference numerical scheme
and solves the equations with an iterative method that uses interpolation
for functional values at computational nodes.
Other 1-D unsteady flow models available from the USGS are DAFLOW, BRANCH, and
DAFLOW is well suited to applications simulating steeper upland
channel networks in support of transport models, where limited
geometric data are available. DAFLOW does not support backwater
conditions or looped networks.
BRANCH has a long-proven history of successful application in WRD
projects and for computing discharge from slope measurement sites.
BRANCH is recommended for slope station applications. A solution of
the advection-dispersion transport equation has been incorporated in
the BRANCH model to facilitate simulations where density gradients
are important. BRANCH has also been coupled to the groundwater flow
model, MODFLOW, for simulating groundwater/surface water
interactions. The stream/aquifer linked version is referred to as
MODBRANCH. A window-based graphical user interface (GUI) for creation
and modification of model-input files, compatible with MicroSoft
Windows environment, has been developed for BRANCH and is available
via the WWW at the Internet site http://stress.er.usgs.gov.
The FOURPT has an excellent range of options for model start up in
either upland or tidally affected reaches. FOURPT or FEQ should be
considered for networks where subsectioning of cross-sections is
needed to improve behavior of the depth-conveyance relationship or
the behavior of hydraulic controls is important.
Any of the models can be used in conjunction with the BLTM transport model.
Users should consider the weaknesses and strengths of each of the available
models when selecting a model for a particular application. The Office of
Surface Water, either Janice Fulford or Harvey Jobson, will be happy to
discuss the strengths and weaknesses of each model and provide help in
selecting the model that is best suited for a particular application.
Training on the application of FEQ may be offered in FY98 at the National
Training Center or in the Northeastern Region (sponsored by Northeastern
Region) depending on interest within the USGS. For more information on FEQ
or to express interest in the training course, contact Steve Melching at
(217)344-0037, ext. 3031 (email: csmelchi) or Audrey Ishii at (217)344-0037,
ext 3026 (email: alishii). The training course, (ID2020TC) Modeling Flow and
Transport in a Riverine Environment, emphasizes the DAFLOW model; the
course, (G0913) Implementation and Calibration of Unsteady Open-Channel Flow
and Transport Models, emphasizes the BRANCH model; and the course, (G0403
One-Dimensional Streamflow Modeling Concepts, emphasizes the FourPt model.
Franz, D.D. and Melching. C.S., in press, Full Equations Utilities (FEQUTL)
model for the approximation of hydraulic characteristics of open channels
and control structures during unsteady flow: U.S. Geological Survey Water-
Resources Investigations Report 97-4037.
Ishii, A.L., and Turner, M.J., 1997, Verification of a one-dimensional,
unsteady-flow model for the Fox River in Illinois: U.S. Geological Survey
Water-Supply Paper 2477, 66p.
Turner, M.J., Pulokas, A.P., and Ishii, A.L., 1996, Implementation and
verification of a one-dimensional unsteady-flow model for Spring Brook near
Warrenville, Illinois: U.S. Geological Survey Water-Supply Paper
Thomas H. Yorke
Chief, Office of Surface Water
WRD Distribution: A, B, FO, PO