ABSTRACT
Considerable progress has been made in modeling the movement and degradation of agricultural chemicals in the environment. Three factors affect the movement of a non-volatile agricultural chemical in both soil and ground water. One of these factors is the degradation rate which is usually dependent on soil or aquifer properties and temperature. Simulations of the degradation and movement of agricultural chemicals in ground water can vary significantly in complexity, depending on the objectives and available data. Saturated zone modeling, especially when combined with unsaturated zone modeling, can be an important tool in understanding the movement and degradation of agricultural chemicals in soil and ground water. The Environmental Protection Agency model Risk of Unsaturated/Saturated Transport and Transformation of Chemical Concentrations (RUSTIC), issued in 1989 does contain a saturated zone module which can be linked to other modules simulating movement of agricultural chemicals in the unsaturated zone.
