The spatially distributed and process-oriented water and nutrient transport model JAMS/J2000-S was used to quantify nitrate transport process dynamics in the meso-scale, humid Duck catchment in Tasmania, Australia. As shown by previous studies, the model was successfully calibrated and validated based on the comparison of model results with observed water volumes and monthly monitored nutrient concentrations. However, model approaches using large numbers of calibration parameters imply parameter uncertainties which might affect model results significantly. In particular in catchments with relative low nutrient concentrations, parameterisation needs to be done carefully assuming that little changes in parameter settings have significant influence on the simulated outputs. Observations in Tasmanian catchments showed that nitrogen concentrations are considerably low, already catchments with concentrations of less than 1 mg/l NO3-N are being reported as ‘impacted.’ The fully distributed model JAMS/J2000s has been previously applied for the Tasmanian Duck catchment to assist water resources management and to improve the understanding of diffuse source pollution and its contribution from different pathways. One of the key questions of this study was to find out if the model is capable to simulate these low concentrations with a reasonable quality and to quantify. As a supplement to this first study now a regional parameter sensitivity analysis was applied for the Tasmanian Duck catchment to: (i) identify those parameters that significantly influence model results in terms of simulated nitrate concentration, at the catchment outlet, (ii) test the model’s suitability and applicability for the specific Tasmanian conditions, and (iii) provide feasible parameter ranges for Tasmanian test catchment conditions allowing the regionalized application of the developed model. The paper present the results obtained in the Duck catchment, the applied methodology for the sensitivity analysis along with the findings obtained with this procedure. The results of the study showed that JAMS/J2000s was able to accurately simulate the hydrological dynamics in the Duck catchment. The comparison of simulated and observed runoff in the validation period resulted in a Nash-Sutcliffe efficiency of 0.7 and a coefficient of determination of 0.91. The most obvious feature was a slight overprediction of the runoff volume in particular at the beginning of the wet period. The comparison of the simulated Nconcentration at the catchment outlet with a number of observations did also show the principle suitability of the model to reproduce the nitrogen turnaround processes in the basin. The sensitivity analysis of six model parameters, based on a Monte-Carlo-Analysis of 2400 model runs showed that only three parameters considerably affect the simulation of the N-concentration. These were the parameters which are responsible for the mobilization of nitrogen, whereas the three insensitive parameters are responsible for the distribution and mixing of nitrogen in the soil profile. An additional sensitivity analysis output was obtained for one parameter which was responsible for very poor model results when set to values which were exceeding a specific threshold. This behaviour gives an indication for a potential structural model problem for either the Tasmanian conditions or in general which needs to be addressed in further studies.The overall outcome of the study showed that the JAMS/J2000s model seems to be very suitable for the assessment and simulation of water and nutrient transport processes in the Tasmanian Duck catchment. Nevertheless, the study showed that the model still has some systematic shortcomings which need more research and testing in future projects in Tasmania and other regions.