Digital Hillslope Position GIS Data
Author: Bradley Miller
The Digital Hillslope Position (DHP) model classifies the Iowa landscape into five terrain-based categories: summit, shoulder, backslope, footslope, and toeslope. The classification is based on terrain derivatives (i.e., slope gradient, profile curvature, and relative elevation), calculated from a fine-resolution (3-meter) LiDAR-based digital elevation model (DEM). These topographic categories represent functional segments of hillslopes that influence water movement, physical and chemical transport, and soil formation.
Applied Relevance
DHP can be used to infer patterns of soil drainage, erosion risk, and landscape stability. For example, summits often support well-developed, stable soils, while shoulders and backslopes are more prone to erosion and transport. Toeslopes typically contain poorly drained, frequently saturated soils. This classification supports conservation planning, digital soil mapping, hydrologic modeling, and precision agriculture.
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Limitations
Hillslope positions are a description of process zones along the profile of a hillslope and have tradition been applied as transects in research studying toposequences. Applying those concepts to a DEM in a GIS makes the classification into more of a 2.5-dimensional representation of the landscape that provides special insights into the topographic patterns of different regions. However, hillslope position does not consider the effect of plan curvature, which influences the convergence or divergence of water flow.
Reference
Miller, B.A. and R.J. Schaetzl. 2015. Digital classification of hillslope position. Soil Science Society of America Journal 79(1):132-145. doi: 10.2136/sssaj2014.07.0287.