During the recent Rhone-AGGregation GLASS intercomparison project, several SVAT models have been integrated over a 4-year period and at various horizontal resolutions (from 8km to 1°) over the Rhone river basin. Due to its relatively dense observational network (of both atmospheric forcing and river discharge), this French basin provides an ideal testing ground for the ability of SVAT models to simulate the regional scale water balance. In the present study, additional off-line simulations are performed with a new version of the CNRM SVAT model called ISBA-SGH (Interaction between Soil, Biosphere and Atmosphere with SubGrid Hydrology). This model includes a more physical parametrization of surface hydrology based on the well-known Topmodel approach, in which subgrid variability of soil moisture is related to that of a compound topographic index. Moreover, sensitivity experiments are conducted at the 1° horizontal resolution, in which the observed atmospheric forcing and/or land surface parameters are replaced by the ISLSCP2 dataset to be used in the GSWP2 global intercomparison project. While ISBA-SGH generally shows an improved simulation of the daily and monthly discharge at most gauging stations compared to the former version of the model, the results are fairly sensitive to changes in the atmospheric forcing and/or in the soil and vegetation boundary conditions.