IPTM-CS: A windows-based integrated pesticide transport model for a canopy–soil system

A Windows-based integrated pesticide transport modeling system (IPTM-CS) has been developed for simulating three-phase (dissolved, adsorbed, and vapor phases) pesticide environmental fate in a canopy–soil system (or in the vadose zone alone). The modeling system integrates pre-processing of data (parameters estimation and input), model run, and post-processing of simulation results (summary tables, Excel spreadsheets, and graphs) in a user-friendly Windows interface. To facilitate parameter estimation, an extensive data supporting system that includes convenient parameter calculators and databases has also been developed and incorporated in the IPTM-CS. The data supporting system also provides links to a number of web-based databases maintained by government agencies and institutions. A time-continuous and space-discrete (TC-SD) method is employed to solve the transport problem and five different solution schemes of varying accuracy and features have been incorporated in the interfaced IPTM-CS. Finally, testing of the IPTM-CS at a field site in Chico, California is presented. Comparison of the simulated and observed diazinon concentrations is conducted for three selected depths (0.15, 0.25, and 0.5 m) and the results are further evaluated by using three methods (linear regression, normalized objective function, and modeling efficiency). The quantitative evaluation indicates that the IPTM-CS yields fairly good simulations.