Runoff of Pesticides:
Achievements and Limitations of Modelling Agrochemical Dislocation from Non-Point Sources at Various Landscape Related Scales

Abstract

In the absence of drainage systems, runoff is a major transport pathway of pesticides from agricultural areas to aquatic systems. We provide an overview of existing runoff models eligible to describe the transport and fate of pesticides in the terrestrial environment. We distinguish between leaching, erosion, and hydrological models. Recent developments in runoff modelling include the evolution of complex deterministic models, combinations of models and probabilistic approaches on a GIS-platform. The latter enable users to make geo-referenced predictions of diffuse pesticide emissions from small to large scales. Simulated loads mostly correlate well with measured pesticide loads and concentrations on a catchment scale, but often overestimate measured concentrations, because the edge-to-field approach applied does not consider any attenuation by degradation or sorption between the location of pesticide application and surface waters. Therefore, future developments of horizontal pesticide transport models should focus on detention and retention mechanisms during transport on highly resolved temporal and spatial scales. Additionally, for the simulation of realistic scenarios of pesticide emissions on a catchment scale, the evaluation and standardization of probabilistic approaches can be helpful.