Quoted from: https://www.waterborne-env.com/model/rivwq-202/
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.
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.