Use of a landscape simulator in the validation of the SIBERIA catchment evolution model: Declining equilibrium landforms

This paper presents a study to test the ability of the current generation o f landscape evolution models to correctly predict landscape form from measu red erosion processes. Landscapes generated by the SIBERIA landscape evolut ion model were compared to experimental model landscapes in declining equil ibrium. The model simulations were compared using geomorphologically and hy drologically significant parameters. Comparisons of the simulated landscape s with the experimental landscapes were carried out using the hypsometric c urve, width function, cumulative area distribution, and area-slope relation ship. These comparisons demonstrate that SIBERIA can correctly simulate the experimental model landscape at declining equilibrium. The simulation show ed sensitivity to the spatial distribution of the rainfall, particularly wi th respect to hypsometry. Using the correct measured distribution of rainfa ll was necessary rather than using a spatially uniform rainfall distributio n. The results also highlighted the importance of digital terrain map (DTM) error in deriving geomorphic statistics. The observed landform had a consi stently larger width function than the simulation. Only when the simulation s were corrupted with elevation errors with statistical properties of the e rrors in the experimental landscape DTM, as measured by photogrammetry, did the observed and simulated width functions match.