# Water Resources Applications Software

## Summary of SEDDISCH

```NAME
seddisch - Computation of fluvial sediment discharge

ABSTRACT
SEDDISCH computes fluvial sediment discharge by allowing the user to
choose between five described bedload formulas and eight described
bed-material formulas.  The bedload discharge formulas are those of
Schoklitsch (1934), Kalinske, Meyer-Peter and Muller (1948),
Rottner, and Einstein.  The bed-material formulas are those of
Laursen, Engelund and Hansen, Colby, Ackers and White, Yang sand
formula, Yang gravel formula, Einstein, and Toffaleti.

METHOD
Numerous sediment-discharge formulas have been proposed in
literature.  Selection of the thirteen formulas used in SEDDISCH was
based on: (1) theoretical background, (2) extent of testing by
original author and independent investigator(s), and (3) extent of
use by engineers and researchers.  The user is asked to choose from
these formulas based on which field data are available.

Bedload discharge is the discharge of sediment that moves in
essentially continuous contact with the bed.

Schoklitsch developed a bedload formula based mainly on Gilbert's
(1914) flume data with median sediment sizes ranging from 0.3 to
5 mm.  The basis for this formula is that bed material begins to
move at some critical discharge and that the bedload discharge is
proportional to the rate of work done by the part of the tractive
force in excess of that needed to overcome the resistance along
the wetted perimeter.

The formula developed by Kalinske for computing bedload discharge
of unigranular material is based on the continuity equation which
states that the bedload discharge is equal to the product of the
average velocity of the particles in motion, the weight of each
particle, and the number of particles.

Meyer-Peter and Muller developed an empirical formula for the
bedload discharge in natural streams.  The computer program
computes the effective diameter of the bed-material mixture from
the entered sediment size-fraction data.  However, the program
does not compute the bedload discharge by size fractions.

Rottner developed an equation to express bedload discharge in
terms of the flow parameters based on dimensional considerations
and empirical coefficients.  In his derivation, wall and bed form
effects were excluded, and Rottner stated that the equation may
not be applicable when small quantities of bed material are being
moved.

The bedload relation developed by Einstein is derived from the
concept of probabilities of particle motion.
Bed-Materal Discharge Formulas

Bed-material discharge is the discharge of sediment which is derived
from and readily exchanges with the particles in the bed material;
particles comprising the bed-material discharge move both as bedload
and in suspension.
The equation developed by Laursen to compute the mean
concentration of bed-material discharge is based on empirical
relations using natural sediments with a specific gravity of
2.65, and medium diameters that range from 0.011 to 4.08 mm.

Engelund and Hansen applied Bagnold's (1966) stream power concept
and the similarity principle to derive a sediment transport
equation.  This equation can be used with moderately sorted bed
materials having mean fall diameters larger than 0.15 mm.

Colby presented a graphical method to determine the discharge of
sand-size bed material that ranged from 0.1 to 0.8 mm in water at
a temperature of 15.6 degrees Celsius.  This program uses a set
of equations derived by Carl Nordin (U.S. Geological Survey) that
represent Colby's curves at 0, 5, 10, 15.6, 20, 30, and 40
degrees Celsius.

Ackers and White developed a general sediment-discharge function
in terms of three dimensionless groups: size, mobility, and
discharge.

Yang derived an equation to compute concentration of the bed-
material discharge, for sand-bed streams, based on dimensional
analysis and the concept of unit stream power.  He defined unit
stream power as the rate of potential energy dissipated per unit
weight of water, which is expressed by the velocity and slope
product.

Yang, using the same dimensional analysis and multiple regression
methods as was used to derive discharge rates in sand-bed
streams, derived an equation to compute the bed-material
discharge concentration, in gravel-bed streams.  The same
definition of unit stream power is used in both the sand and
gravel transport equations.

Einstein's method combines his computed bedload discharge with a
computed suspended bed-material discharge to yield the total bed-
material discharge.

Toffaleti's method is based on the concepts of Einstein with
three modifications: (1) velocity distribution in the vertical is
obtained from an expression different from that used by Einstein;
(2) several of Einstein's correction factors are adjusted and
combined; and (3) the height of the zone of bedload transport is
changed from Einstein's two grain diameters.  Toffaleti defines
his bed-material discharge as total river sand discharge even
though he defines the range of bed-size material from 0.062 to 16
mm.

HISTORY
Version 1.2 1998/01/16 - First release of original program as ported
and after code clean-up for use on UNIX workstations.

DATA REQUIREMENTS
Input for SEDDISCH is generated during an interactive session using
the program DISDATA.  DISDATA generates a direct access file that is
read by SEDDISCH.  The following data are prompted for by DISDATA to
form the SEDDISCH data set:
measurement location
top width
mean depth
mean velocity
water-surface slope
water temperature
particle size, in millimeters, at which the 35, 50, 65, and 90
percent by weight is finer (enter zero if not required)

Bed-material particle size data are entered depending on the value
of the option code selected at the start of the run.  One option is
that no size distribution data are to be entered.  Zero values are
given to the percent-in-class variables for the size fractions.  The
other two options are to enter the size data as percent-finer values
or as percent-in-class values.

SYSTEM REQUIREMENTS
SEDDISCH is written in Fortran 77.  Generally, the program is easily
installed on most computer systems.  The code has been used on UNIX-
based computers and DOS-based 386 or greater computers having a math
coprocessor and 1 mb of memory.

DOCUMENTATION
Stevens, H.H., and Yang, Chih Ted, 1989, Summary and use of selected
fluvial sediment-discharge formulas: U.S. Geological Survey
Water-Resources Investigations Report 89-4026, 121 p.

CONTACTS
Operation and Distribution:
U.S. Geological Survey
Hydrologic Analysis Software Support Program
437 National Center
Reston, VA 20192

h2osoft@usgs.gov

Official versions of U.S. Geological Survey water-resources analysis
software are available for electronic retrieval via the World Wide
Web (WWW) at:

http://water.usgs.gov/software/

and via anonymous File Transfer Protocol (FTP) from:

water.usgs.gov (path: /pub/software).

The WWW page and anonymous FTP directory from which the SEDDISCH
software can be retrieved are, respectively:

http://water.usgs.gov/software/seddisch.html
--and--
/pub/software/surface_water/seddisch