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RISK OF UNSATURATED/SATURATED TRANSPORT AND TRANSFORMATION OF CHEMICAL CONCENTRATIONS (RUSTIC): VOLUME 1. THEORY AND CODE VERIFICATION
Citation:
Dean, J., P. Huyakorn, A. Jr, K. Voos, R. Schanz, Y. Meeks, AND R. Carsel. RISK OF UNSATURATED/SATURATED TRANSPORT AND TRANSFORMATION OF CHEMICAL CONCENTRATIONS (RUSTIC): VOLUME 1. THEORY AND CODE VERIFICATION. U.S. Environmental Protection Agency, Washington, D.C., EPA/600/3-89/048a.
Description:
The RUSTIC program links three subordinate models--PRZM, VADOFT, and SAFTMOD--in order to predict pesticide transport and transformation through the crop root zone, the unsaturated zone, and the saturated zone to drinking water wells. PRZM is a one-dimensional finite-difference model that accounts for pesticide fate in the crop root zone. This release of PRZM incorporates several features added to the original code--soil temperature simulation, volatilization and vapor phase transport in soils, irrigation simulation, and a method of characteristics algorithm to eliminate numerical dispersion. PRZM now is capable of simulating the fate of the parent compound and up to two daughter species. VADOFT is a one-dimensional finite element code that solves the Richard's equation for flows in the unsaturated zone. The user may make use of constitutive relationships among pressure, water content, and hydraulic conductivity to solve the flow equations. VADOFT also may simulate the fate of two parent and two daughter products. SAFTMOD is a two-dimensional finite-element model that simulates saturated solute flow and transport in either an X-Y or X-Z configuration. The codes are linked with the aid of a flexible execution supervisor that allows the user to build models that are tailored to site-specific situations. To perform exposure assessments, the code is equipped with a Monte Carlo pre- and post-processor.