Comprehensive analysis of the CATHY model sensitivity to soil hydrodynamic properties of a tile-drained, agricultural micro-watershed

A comprehensive sensitivity analysis study of an application of the catchment hydrology (CATHY) model on a tile-drained watershed was performed using the Morris, FAST99 (Fourier Amplitude Sensitivity Test) and Sobol2002 methods. The analysis focused on identifying the most influential parameters with respect to: (a) tile-drain flow and (b) edge-of-field flow of the Bras d'Henri, an agricultural micro-watershed (Quebec, Canada). Of the 24 parameters evaluated using the Morris method, nine and eight parameters, being the most influential on the two output variables, respectively, were used for analysis by the FAST99 and Sobol2002 approaches. The results indicate that the lateral saturated hydraulic conductivity of the layers underlying the tile drainage systems is the most influential parameter with respect to both output variables. Thus, characterization of soil anisotropy should not be neglected when applying a three-dimensional hydrological model.