Uncertainty is a very important concept in geomorphometry because it is a key component in quality assessments of any scientific study that utilizes topographic information. Uncertainty exists at all analysis steps of topographic data modeling and analysis including land surface data capture, model generation, preprocessing, and surface analysis and visualization. This study attempted to improve on our understanding of the uncertainties associated with land surface analysis. It focuses on the relative uncertainties caused by differences in the terrain techniques that are adopted by considering the consequences of choosing different flow routing algorithms, hydrological extraction methods, and terrain model parameters such as grid resolution, flow time, and soil properties using both synthetic constructed and real surfaces. The study found that model uncertainties in geomorphometry are significant and should be taken into account in studies that use the primary and secondary terrain attributes extracted from these terrain models. The findings suggest that an automated system to quantify geomorphometric uncertainties should be incorporated in all terrain analysis model workflows.