System Modeling Approach for Solute Transport Through Upper Soils

Abstract

Solute transport through upper soils has been traditionally simulated by following a physically based modeling approach. Unfortunately, the application of physically based models is often limited by difficulties in solving interrelated problems of parameter identification, system boundary definition, and mathematical solution. These problems can be largely alleviated by an alternative modeling approach based on the system theory. In the system approach, dynamic relations between the input of the chemical at the soil surface and its subsequent downward movement are represented by system response functions that do not require knowledge of the intimate structure of relevant transport mechanisms. System modeling techniques were developed and applied in this study to simulate the transport of the pesticide fenamiphos in Hawaiian soils. A comparison of the calculated concentration distributions with field measurements shows that the system model provides satisfactory transport simulation.