PERMFILE106431

• Permit No: C1980005
• IBM Index Class Name: Permit File
• Doc Date: 12/11/2001
• Doc Name: HYMO MODEL
• Section_Exhibit Name: TAB 07 APPENDIX 7-6 ATTACHMENT 7-6-1
• Media Type: D
• Archive: No

• HYMO:
PROBLEM-ORIENTED COMPUTER LANGUAGE
FOR HYDROLOGIC MODELING
Users Manual
By Jimmy R. Williams3 and Roy W. Hann, Jr.2
INTRODUCTION
;•
HYMO (7)3 is a problemoriented computer
language for modeling surface runoff and sedi-
ment yield from watersheds. The language is
called HYMO from the words "hydrologic
model." HYMO was designed for planning flood
prevention projects, forecasting floods, and re-
seazch studies. It consists of a main program and
16 subroutines written in FORTRAN IV, but it
can be used by hydrologists with little knowl-
edge, of computer programing. The language
provides I7 commands for the hydrologist to
use in any sequence for application to any
watershed.
HYMO was designed to transform rainfall
data into runoff hydrographs and to route these
hydrographs through streams and valleys or
reservoirs. It will also compute the amount of
sediment produced by a storm at any point on a
watershed. It will be useful to reseazch hydrolo-
gists in studying the effects of watershed and
storm chazacteristics on the flood hydrograph.
HYMO is also a good reseazch tool for testing
hydrologic procedures; for example, a new
flood-touting method could be added to HYMO
and tested easily, because the inflow hydro-
graphs and the rating curves aze available in a
HYMO program.
HYMO is flexible. Present hydrologic proce-
dures can be modified or deleted, and other
hydrologic procedures can be added by hydrolo-
gists familiaz with FORTRAN IV programing.
Adding a new command simply requires the
addition of a new subroutine.
HYMO is efficient, practical, and generally
applicable. HYMO programs can be written and
the results interpreted by hydrologists who have
no conventional computer programing experi-
ence. The hydrologic procedures used in HYMO
aze practical -required inputs aze easy to obtain
for most watersheds.
HYMO, was written for the IBM 360-65
computer, but it could be run on an IBhI 1130
with little modification. The storage require-
ment is about 73 K.
OPERATION OF HYMO
•
HYMO consists of a main program and 16
subroutines. The HYMO cazd deck is set up in
the following order:
'Hydraulic engineer, College Station Area, Southern Reqion,
Agricultural Research Service, U. 5. Department of Agri-
culture, Riesel, Tex.
'Head, Ervironmentol Engineering Division, Civil Engineer-
ing, Texas A8M University, College Station, Tex.
'Italicized number in parentheses refer to items in "Liter-
ature Cited" preceding the appendix.
1. Main program.
2. Subroutines.
3. A data cazd containing the number of
commands in the command table.
4. A data cazd containing the ZALFA array.
5. Seventeen data cazds containing the com-
mand table.
6. The, users program deck consisting of
program and data cazds.
A printout of the main program, subroutines,
ZALFA array, and command table is given in
the appendix.
7-6-1-2