Resumen en español

This paper presents a methodology to assess explicitly the optimal value of the numerical parameters in a hydrodynamic model, such as the grid resolution (horizontal and vertical direction) and the calculation time interval. The methodology is based on a cost-benefit analysis which seeks a desirable balance between the quality of the numerical solution and the required computational time. The spatial nature of the sensitivity analysis presented allows us to determine in each calculation grid cell the alteration of the numerical solution due to changes in the numerical or physical parameters in the model. According to this, it was possible to determine within the Punchiná reservoir where and to what extent are relevant the grid resolution, the time interval, the bed roughness, and the eddy viscosity coefficient.