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RIVWQ

RIVWQ was developed to evaluate time-varying water and chemical mass balance in river networks as a result of point-source and nonpoint-source chemical loadings. The model has been linked with PRZM and EXAMS for ecological and human health risk assessments under FIFRA.

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 not to require overly sophisticated algorithms for which input and validation data are seldom available.

Model Description

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 re-suspension from sediment. The model can simulate up to five chemical/metabolites.

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, which can change from time period to time period. Any change in the hydraulic regime is assumed instantaneous throughout the system. This allows flows to be calculated using the continuity equation.

Chemical input parameters 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, link volume, length, hydraulic radius, and dispersion coefficient. Sediment properties include initial suspended sediment settling velocity, re-suspension velocity, porosity of bed sediment, and bulk density of bed sediment.

Several output files are created. One file echoes the input data; a second file produces time-series flows and concentrations at user-specified points of interest; and a third file provides time snapshots of system discharges, velocities, and concentrations.

Obtaining the Model

The RIVWQ 2.0.2 model is available under a friendship/partnership concept. If the model is used for profit, please try to either involve us in your studies or otherwise compensate us for the use of the model. If the model is being used purely for research or academic purposes, please allow us to collaborate on publications or otherwise publicize the model or our company. As always, please reference the model when used in presentations or publications.

To obtain a copy of the model, please go to the model download page.