This project studied hydrological models used in the catchment of the Petite Chamberonne north-west of Lausanne. In a first step, input data have been analysed and prepared for the spatially explicit, conceptual hydrological model SEHR-ECHO. It has been proved that rainfall data can be taken and homogeneously distributed over the catchment from a nearby rain gauge (Crissier). The 9 months of discharge data proved to be of good quality; 9 months of data however is rather short for automatic calibration. Unique annual events influence the calibration of the hydrological model strongly and had to be removed and tested manually. First results showed a mediocre performance of the standard version of SEHR-ECHO. In order to improve the results of the simulation, several adaptations of the model have been tested. The best variant showed to be SEHR-ECHO, using reservoirs in series (instead of parallel) and Horton’s mechanism for surface runoff production (instead of Dunne’s mechanism). A NSE of 0.77 has been achieved. Based on this hydrological model, two types of pesticide transport models have been developed and tested. Though not yet calibrated (due to the lack of data), it has been observed that the two models give results that are sensitive to the chemical properties of the simulated pesticide and that the results show similarities to what has been observed in previous studies (e.g. [Leu et al., 2004a]). A further effort in calibration using more date will have to be undertaken in order to improve and validate the hydrological simulations. At last, the pesticide transport model will have to be calibrated and its results interpreted once data is available.