### BLTM - Branched Lagrangian Transport Model

#### ABSTRACT

BLTM uses Lagrangian calculations that are unconditionally stable
and based upon a reference frame that moves at a velocity equal to
the mean channel flow velocity. BLTM results are within the
accuracy required by most water-quality studies. The BLTM is easily
applied to unsteady flows in networks of one-dimensional channels
with fixed geometry and tributary inflows. Reaction kinetics for up
to 10 constituents are provided in a user-written decay-coefficient
subroutine. Postprocessor plot programs improve the utility of the
model. The model routes any number of interacting constituents
through a system of one-dimensional channels.
The following programs are included in the BLTM distribution:

cbltm - branched Lagrangian transport model
qbltm - bltm with qual2e
tbltm - bltm with temperature
bbltm - builds the input file for BLTM
bqual2e - builds the input file for QBLTM
mrg - builds a table of data by adding or modifying a
column based on data in files old.bc and in,
writes file bc
ctplt - plots concentration vs time and compute the RMS error
cxplt - plots concentration vs distance
equltmp - computes the equilibrium temperature from daily extreme
temperatures
solar - computes the solar radiation from empirical equations
The following programs are included in the BLTM distribution and are
also available as a separate DAFLOW distribution:
daflow - diffusion analogy flow model
wdaflo - diffusion analogy flow model, uses either flat file or
wdm data base
flwopt - computes RMS errors to optimize hydraulic coefficients
bdaflow - builds the input file for DAFLOW
cel - computes coefficients for area and width equations
intrp - interpolates data to an even interval
unit - reads unit values from adaps and uses a rating table
to do something
flwplt - estimates ungaged inflow and plot
**METHOD**
The model solves the one-dimensional convective-diffusion equation
with reaction kinetics.
**DATA REQUIREMENTS**
Flow--areas, top widths, and velocities at each grid point are
needed for each time step. Initial conditions--concentration of
each constituent at each grid at time zero. Boundary
conditions--concentration of each constituent at upstream junctions
and in each tributary during each time step.
**OUTPUT OPTIONS**
Data are output in text files. Postprocessor programs are available
to produce graphical and tabular summaries.
**SYSTEM REQUIREMENTS**
BLTM and DAFLOW are written in Fortran 77 with the following
extensions: include files and variable program names longer than 6
characters. wdaflow uses the UTIL, ADWDM, and WDM libraries from
LIB. A subset of these libraries is provided with the code and may
be used instead of the libraries; this subset uses INTEGER*4 and
mixed type equivalence. For more information, see System
Requirements in LIB. ctplt, cxplt, and flwplt may be implemented
with a user-supported Computer Associates DISSPLA library or the LIB
libraries GRAPH, UTIL, and STATS.
**DOCUMENTATION**
Jobson, H.E., and Schoellhamer, D.H., 1987, Users manual for a
Branched Lagrangian transport model: U.S. Geological Survey
Water-Resources Investigations Report 87-4163, 73 p.
Jobson, H.E., 1997, Enhancements to the Branched Lagrangian
transport modeling system: U.S. Geological Survey Water-Resources
Investigations Report 97-4050, 57 p.
Schoellhamer, D.H., and Jobson, H.E., 1986, Programmers manual for a
one-dimensional Lagrangian transport model: U.S. Geological
Survey Water-Resources Investigations Report 86-4144, 101 p.
Schoellhamer, D.H., and Jobson, H.E., 1986, Users manual for a one-
dimensional Lagrangian transport model: U.S. Geological Survey
Water-Resources Investigations Report 86-4145, 95 p.
**REFERENCES**
Bulak, J.S., Hurley, N.M., Jr., and Crane, J.S., 1993, Production,
mortality, and transport of striped bass eggs in Congaree and
Wateree Rivers, South Carolina: American Fisheries Society
Symposium 14, 1993, p. 29-37.
Hurley, N.M., Jr., 1991, Transport simulation of striped bass eggs
in the Congaree, Wateree, and Santee Rivers, South Carolina:
U.S. Geological Survey Water-Resources Investigations Report
91-4088, 57 p.
Jobson, H.E., 1981, Temperature and solute-transport simulation in
streamflow using a Lagrangian reference frame: U.S. Geological
Survey Water-Resources Investigations Report 81-2, 165 p.
Jobson, H.E., 1985, Modeling temperature, BOD, DO and the nitrogen
cycle in the Chattahoochee River, Georgia, using the land flow
model: U.S. Geological Survey Water-Supply Paper 2264.
Jobson, H.E., 1987, Modeling dye and gas transport in the Missouri
River, Nebraska, the Madison effluent channel, Wisconsin, and
Trinity River, Texas: Water Resources Research, v. 23, no. 1.
**CONTACTS**
Operation:
U.S. Geological Survey
Office of Surface Water
Harvey Jobson
415 National Center
Reston, VA 20192
hejobson@usgs.gov