The Variability of Geomorphic Descriptors to Change in Aspect Ratio

Over recent years a number of geomorphic measures have been used to test the ability of landscape evolution models to simulate field catchments. These statistics are the hypsometric curve, area-slope relationship, width function and cumulative area diagram. We are only now developing the statistical tools to assess whether these geomorphic measures are sufficiently discriminatory for use as tools of comparison between models and field data. To examine this question and the effect of catchment geometry, a series of catchments with varying aspect ratio were created with area matching that of a well understood field catchment. This field catchment has been used in previous studies to test the ability of the SIBERIA landscape evolution model to model field catchments. These catchments with differing aspect ratio were then allowed to evolve using the calibrated SIBERIA model and the hypsometric curve, area-slope relationship, width function and cumulative area compared with field catchment data. The results demonstrate the strengths and weaknesses of each geomorphic measure when used as a means of comparison between model and field data. They also indicate that the effect of aspect ratio on these properties is small.