Three-dimensional landscape process modelling: The effect of DEM resolution

Many landscape models have been developed over the past decades; however, r elatively little is known about handling the effects of changing spatial an d temporal resolutions. Therefore, resolution effects remain a factor of un certainty in many hydrological and geomorphological modelling approaches. I n this paper we present an experimental multi-scale study of landscape proc ess modelling. Emphasis was laid on quantifying the effect of changing the spatial resolution upon modelling the processes of erosion and sedimentatio n. A simple single process model was constructed and equal boundary conditi ons were created. Using artificial digital elevation models (DEMs) eliminat ed effects of landscape representation. The only variable factors were DEM resolution and the method of flow routing, both steepest descent and multip le flow directions. Our experiments revealed an important dependency of mod elled erosion and sedimentation rates on these main variables. The general trend is an increase of erosion predictions with coarser resolutions. An ar tificial mathematical overestimation of erosion and a realistic natural mod elling effect of underestimating resedimentation cause this. Increasing the spatial extent eliminates the artificial effect while at the same time the realistic effect is enhanced. Both effects can be quantified and are expec ted to increase within natural landscapes. The modelling of landscape proce sses will benefit from integrating these types of results at different reso lutions. Copyright (C) 2000 John Wiley & Sons, Ltd.