Author(s): M. Chen; G. R. Willgoose; P. M. Saco
Linked Author(s):
Keywords: Soil moisture; HYDRUS; IBIS
Abstract: Soil moisture is an important component of land surface schemes being incorporated into climate models. We conducted an intercomparison of two widely-accepted land surface models (HYDRUS-1D and IBIS) by simulating the daily soil moisture dynamics in one monitoring site at our Stanley site. Surface 30cm soil moisture can be satisfactorily calibrated using HYDRUS. The models differed significantly in their simulations when HYDRUS calibrated soil-and-vegetation parameters were used in IBIS. This results from 1) different soil hydraulic properties, derived from the same soil classes using different pedotransfer functions in the two models, and 2) different lower boundary conditions at the 30cm interface. Simulations of HYDRUS and IBIS were comparable after adjusting the two factors, but IBIS still predicted a slightly wetter soil conditions than HYDRUS during dry periods. Daily boundary drainage and evapotranspiration estimates were similar, but the timing and magnitude of simulated surface runoff differed significantly. This implies a larger uncertainty in modelling the surface runoff using these land surface schemes relative to evapotranspiration and soil moisture. These conclusions also held for different soil properties obtained from other Stanley sites, except for S3 (with a lower saturated hydraulic conductivity).
Year: 2011