Pesticide leaching into field soils: sensitivity analysis of four mathematical models

In this study, four mathematical models were evaluated for their sensitivity with respect to both general and specific input parameters. The models compared were MOUSE, GLEAMS, TETRANS, and HYDRUS, which were also employed in a prior analysis of long-term atrazine leaching potential towards groundwater. MOUSE showed only high sensitivity to sorption parameter, but simulations dependend excessively on the soil depth. GLEAMS model sensitivity was moderate with respect to hydraulic conductivity and potential evapotranspiration, whereas it was high for the input parameters related to runoff, sorption, and degradation submodels, besides to the soil water content at the field capacity. TETRANS was sensitive to Kdʹs inputs whereas it was less to the bypass flow parameter. HYDRUS was sensitive to both Kd and μ parameter inputs, too. Comparisons of measured and simulated alachlor leaching data showed that the analyzed models differently predicted the pesticide transport and that, under some field soil conditions, their calibrations may improve simulations only partially. A general analysis on some pesticide leaching showed the models to give more differentiated performances for highly sorptive soils.