Pesticide uses in rice cultivation take generally place during the ponded period. Their persistence in paddy field is the origin of pollution risk according two main ways : directly in the runoff, moving and leachate in soil. To forecast pesticide behavior and hydraulic pathways in paddy field appear crucial in order to define non point pollution adapted management and to preserve water resources. The study presents an original coupling model approach to take into account pesticide transport in both compartments : surface water and soil. We focus on reproducing hydrological functioning and determining hydrodispersive parameters by using a tracer experiment data set.