MAPPING ATRAZINE LEACHING POTENTIAL WITH INTEGRATED ENVIRONMENTAL DATABASES AND SIMULATION-MODELS

A methodology was developed to integrate a simulation model and enviro nmental databases for mapping pesticide leaching potential at landscap e scale. A deterministic, one-dimensional solute transport model was a pplied using soil, land use, and climate data compiled for the northea st region of the United States. Landscape units that combined soil and climate variables were modeled to produce estimates of atrazine leach ing in agricultural lands. Model results were aggregated into class ra nges indicating the proportion of a landscape unit susceptible to pest icide leaching. Significant results were, first, that pesticide leachi ng potential was related to the amount and distribution of rainfall an d soil organic carbon, and second, that a functional deterministic sim ulation model and database were developed for use by environmental pro fessionals to model and visualize soil behavior at regional scale. Imp lications of this study indicate that aggregated leaching indices shou ld be mapped at scales no finer than 1:250,000 when using regional-sca le databases; and uncertainty associated with spatial and temporal var iability, model type, and environmental database quality limit interpr etations of regional model simulations and resultant map products to l andscape units similar in size to Major Land Resource Areas or individ ual states, whichever is larger.