Terrain Slope Analysis
Definition
Terrain slope analysis quantifies the steepness of the ground, typically as degrees or percent rise calculated from a DEM. Beyond simple slope, analysts examine slope distribution, breaklines, and relationships with aspect and curvature to understand stability, runoff, and accessibility. Accuracy hinges on DEM quality and window choice: small windows capture microrelief but amplify noise; larger windows smooth extremes. Slope analysis is a building block for risk maps, suitability models, and design constraints.
Application
Civil engineers test whether grading plans meet code; foresters and firefighters estimate fire spread potential; farmers plan contour cultivation; and outdoor recreation managers grade trails by difficulty. Urban planners use slope thresholds to guide hillside development policies.
FAQ
How do you translate slope into construction constraints?
Jurisdictions define thresholds (e.g., >25% requires engineering). Slope maps feed cut/fill estimates, retaining wall needs, and stormwater controls.
What artifacts suggest slope errors in a DEM?
Striping, stair-step patterns along tile edges, or steep slopes over water bodies indicate data or processing issues needing correction.
Why pair slope with aspect in hazard analysis?
Solar exposure and prevailing winds differ by aspect; together with slope they influence snowmelt, drying, and fire behavior.
How does resampling a DEM change slope outputs?
Downsampling reduces extremes, while bilinear resampling can blur edges; choosing the right method and documenting it prevents misinterpretation.