Simulating pesticide transport via preferential flow: A current perspective

Preferential flow is often an important process for pesticide transport thr ough a wide range of soils. Accurate simulation of preferential flow is thu s a prerequisite for correct description of the behaviour of pesticides in soil under a. variety of conditions. The role of preferential flow modellin g in regulatory risk assessment is less clear because of misgivings over th e accuracy and robustness of models. Even so, a number of authorities are r equesting the use of preferential flow models on a routine basis to assess the risk of contamination of ground and surface waters. It is thus importan t to consider the benefits and constraints on use of preferential flow mode ls. This paper assesses the current state-of-the-art by bringing together a number of studies to: evaluate the predictive ability of preferential now models; understand and compare descriptions of key processes; and undertake sensitivity and uncertainty analyses. A series of priorities for future re search are proposed.