Quoted from: https://water.usgs.gov/cgi-bin/man_wrdapp?daflow(1) 

      DAFLOW is a digital model for routing streamflow using the diffusion analogy form of the flow equations in conjunction with a Lagrangian solution scheme.  The flow model is designed to provide reasonable predictions of discharge and transport velocity using a minimum of field data and calibration.  The use of hydraulic geometry coefficients for area and top width is believed to contribute to the model's predictive capability.  The flow model is designed to support the BLTM transport model documented by Jobson and Schoellhamer (1987), which simulated the fate and movement of dissolved water-quality constituents through a network of upland streams and rivers.  It also should be useful for routine flow routing applications.

      DAFLOW is included in the BLTM distribution and also available separately as a DAFLOW distribution containing the following programs:

          daflow  - diffusion analogy flow model

          wdaflo  - diffusion analogy flow model, use either flat file or wdm data base

          flwopt  - computes RMS errors to optimize hydraulic coefficients

          bdaflow - build the input file for DAFLOW

          cel     - compute 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  - estimate ungaged inflow and plot

METHOD

       DAFLOW routes flow through a system of open channels and generates output that can be used to drive a transport model such as LTM or BLTM.  The program solves the diffusion analogy form of the flow equations and therefore should not be used where backwater effects are significant or where flow reversals occur.  The program is very simple and stable.  The model has only two adjustable coefficients per branch (the wave celerity and wave attenuation coefficient), and these must remain constant.  DAFLOW input and output is to flat files, but auxiliary programs to input data and plot results are available.  The program generates a file containing the discharge, cross-sectional area, top width, and tributary inflow at each grid point and time step.

       DAFLOW uses a flat file format for the input and output of time-series data. A modified version of the program WDAFLO supports both the flat file formats and the Watershed Data Management (WDM) file.

HISTORY

       Version 1.2 1996/11/04 - In daflow.f, the code was incorrectly checking the value of IERR for 1 rather than 21, causing the code to fail to print the error message for too many waves in a branch.  Code was corrected.

       Version 1.1 1995/04/11 - The daflow program was changed to read in slope instead of wave dispersion coefficient.  This allows the program to vary the wave attenuation with discharge; the bdaflow program was changed to ask for slope values rather than dispersion.

          The cel program was modified to add a new option to adjust W2 holding the width constant.  For the first two options it also computes coefficients based on channel forming discharge.  It no longer asks for a characteristic discharge.  It also computes a representative wave length and a wave length value needed for smooth results.

       Version 1.0 1995/02/08 - The cel program was modified to include two methods for computing W1:  from measured width (option 0) or from channel forming discharge (option 1, the original method).

          The daflow program was changed to correct a problem that occurred in selecting the range of flows for estimation in the trial error solutions for the discharge in the mixed wave.  The problem occurred when you had a tributary extracting more flow than exists in the smallest wave.

       1993/06 - The program wdaflo (a modified version of daflow) was developed to support the use of the Watershed Data Management (WDM) file for storage and management of input and output time-series data.

DATA REQUIREMENTS

       (1) Network description including branch lengths, wave celerity, and wave attenuation. (2) Inflow hydro graphs at the upstream boundaries and at tributaries input from either a flat file (DAFLOW or WDAFLO or from a WDM file (WDAFLO).

OUTPUT OPTIONS

       DAFLOW and WDAFLO both generate a flat file containing the discharge, cross-sectional area, top width, and tributary inflow at each grid point and time step; this format is compatible with BLTM input require ments. WDAFLO will also write the discharge to a WDM file.

SYSTEM REQUIREMENTS

       DAFLOW is written in Fortran 77 with the following extensions: include files and variable program names longer than 6 characters. WDAFLO 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. FLWPLT may be implemented with a user-supported Computer Associates DISSPLA library or the LIB libraries GRAPH, UTIL, and STATS.

DOCUMENTATION

       Jobson, H.E., 1989, Users manual for an open-channel streamflow model based on the diffusion analogy:  U.S. Geological Survey Water-Resources Investigations Report 89-4133, 73 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., 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.

       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.

       Wiley, J.B., 1992, Flow and solute-transport models for the New

          River in the New River Gorge National River:  U.S. Geological

          Survey Open-File Report 92-65, 53 p.

       Wiley, J.B., 1993, Simulated flow and solute transport and

          mitigation of a hypothetical soluble-contaminant spill for the

          New River in the New River Gorge National River, West Virginia:

          U.S. Geological Survey Water-Resources Investigations Report

          93-4105, 39 p.