1. General Model Information

Name: River Water Quality Model

Acronym: RIVWQ


Main medium: aquatic+terrestrial
Main subject: ecotoxicology, biogeochemistry, hydrology
Organization level: ecosystem
Type of model: not specified
Main application:
Keywords: water and chemical mass balance, river, water quality, point-source chemical loadings, non-point source chemical loadings

Contact:

Marty Williams, Amy Ritter

Waterborne Environmental, Inc.
897-B Harrison Street, S.E.
Leesburg, VA 20175
Tele: (703) 777-0005
FAX: (703) 777-0767

Phone: (703) 777-0005
Fax: (703) 777-0767
email: wei@waterborne-env.com
Homepage: http://www.waterborne-env.com/modeling/index.html

Author(s):

W. Martin Williams, Christienne O'Flaherty, J. Mark Cheplick, Piyush Singh, and Amy M. Ritter
Waterborne Environmental, Inc.
Leesburg, VA

Abstract:

Processes Simulated:
RIVWQ simulates water and chemical mass balance. Water mass balance accounts for conservation of mass from time varying discharges. Chemical mass balance can accommodate dilution, advection, volatilization, partitioning between water/sediment, decay in water and sediment, burial in sediment, and resuspension from sediment.

Model geometry is based on link-node approach in which the prototype system is divided into a number of discrete volumes (nodes or junctions) which are connected by flow channels (links).

Steady-state hydraulics are assumed that can change from time period to time period. Any change in the hydraulic regime is assumed to be instantaneous throughout the system. This allows flows to be calculated using the continuity equation alone and to neglect the momentum equation.

Dynamic constituent transport is a balance between river driven flows and dispersion processes. Dispersion processes are lumped together into one diffusion coefficient.

Chemical constituent mass balance can accommodate dilution, advection, volatilization, partitioning between water and sediment, decay in water and sediment, burial in sediment, and resuspension from sediment.

Boundary condition inflows are calculated by drainage area ratio to a user input stream flow record. Solution is based on explicit unwind technique requiring following stability criteria:

in which dt is the computational time step, V is the volume of a link, min is the minimum value of all link calculations, Q is the flow in the link, dx is the length of the link, and EL is the diffusion coefficient.

Input Parameters:
Chemical properties include water/sediment partition coefficient, degradation rate in water, degradation rate in sediment, mixing velocity (diffusion), and rate of volatilization.
Geometric input includes node number; incremental drainage area to node; link volume, length, hydraulic radius, and dispersion coefficient; and suspended sediment concentration.

Sediment properties include initial suspended sediment concentration, settling velocity, resuspension velocity, porosity of bed sediment, and bulk density of bed sediment.

A time history of unit drainage area discharges are also required.

Output Parameters:
For each selected point of interest, the output file contains daily time series of discharges, chemical concentration in water and sediment and the following time series accounting of chemical mass: degradation in water, volatilization, settled, resuspended, diffused between water and sediment, degraded in sediment, and lost from active sediment layer due to burial.

Critical Assessment:
Strengths of Model:
RIVWQ is extremely easy to use, relatively stable, and configured for statistical calculations of exposure concentrations through multiple runs and batch job processing. The model was intentionally designed to not be overly sophisticated with algorithms for which input and validation data are seldom available.

Weaknesses of Model:
Degradation is represented by lumped 1st-order kinetics. Distinct biological and chemical transformation processes are not included. Degradation products are currently not simulated. Suspended sediment is held constant in a link or is a function of discharge as specified in a user supplied rating curve. Unsteady flow hydrodynamics are not represented. Erroneous results can occur if stability criteria are violated.

Internal Diagnostics: Limited - will be increased in future versions.

Current Version No.: 1.42 (1997) ; 1.52 (1998, used for chem.specific analysis)

Format and Costs: IBM DOS. Private: $300, cost free help unitl it interferes with paid deliverables.

source of abstract: American Crop Protection Association (ACPA) model database (04/1998), EPA database: Comparison of Model Capabilities (PRZM/EXAMS; RIVWQ; HSPF; SWAT; AnnAGNPS)


II. Technical Information

II.1 Executables:

Operating System(s): Moderate - IBM compatible 80386 Pre-processors: For bulk file processing. Post-processors: For bulk file processing and statistical data reduction; automated graphics macros under Quattro Pro.

II.2 Source-code:

Programming Language(s): FORTRAN
Version Control: Modifications require express written consent of Waterborne Environmental, Inc.
Availability of Authors: Free if under an undefined deadline. Otherwise, under corporate fee structure.

II.3 Manuals:

Documentation: Not yet released, under development.

II.4 Data:



III. Mathematical Information


III.1 Mathematics


III.2 Quantities


III.2.1 Input

Input Parameters:
Chemical properties include water/sediment partition coefficient, degradation rate in water, degradation rate in sediment, mixing velocity (diffusion), and rate of volatilization.

Geometric input includes node number; incremental drainage area to node; link volume, length, hydraulic radius, and dispersion coefficient; and suspended sediment concentration.

Sediment properties include initial suspended sediment concentration, settling velocity, resuspension velocity, porosity of bed sediment, and bulk density of bed sediment.

A time history of unit drainage area discharges are also required.

III.2.2 Output

Output Parameters:
For each selected point of interest, the output file contains daily time series of discharges, chemical concentration in water and sediment and the following time series accounting of chemical mass: degradation in water, volatilization, settled, resuspended, diffused between water and sediment, degraded in sediment, and lost from active sediment layer due to burial.

Output Flexibility:
Time series output file created which can be linked to numerous processors for probability analyses.

Graphic Capability: Automated graphics macros under Quattro Pro.


IV. References

Documentation: Not yet released, under development.
RIVWQ is presently being validated on several systems varying from 10 to 100 square miles. Publications pending.




V. Further information in the World-Wide-Web



VI. Additional remarks

Validations Reported:
RIVWQ is presently being validated on several systems varying from 10 to 100 square miles. Publications pending.

Last review of this document by: Juergen Bierwirth Fri Oct 9 11:33:10 MET 1998
Status of the document:
last modified by Tobias Gabele Wed Aug 21 21:44:48 CEST 2002

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