Read distance, elevation and units
The horizontal axis describes distance along the selected line; the vertical axis describes terrain elevation in the stated height reference system. Vertical exaggeration can make gentle slopes appear steep.
The established German preview uses metres and NHN/DHHN2016 heights. US inputs must retain their actual horizontal and vertical reference systems and units. Do not assume every elevation value is in feet or that regional height datums are interchangeable.
Slope percent and degrees are different
Slope percent equals height change divided by horizontal distance, multiplied by 100. A drop of two metres over ten horizontal metres is 20 percent. The same ratio works with feet when both measurements use feet.
Twenty percent is approximately 11.3 degrees, not twenty degrees. The average raster-cell slope of an area can differ from the end-to-end slope of a selected profile.
Grid spacing is not survey accuracy
A one-metre grid specifies sample spacing. Interpolating more profile points or displaying extra decimal places does not create new survey observations.
Source date, surface changes, vegetation filtering, missing cells and local acquisition quality affect what can be inferred. Small steps or channels can be smoothed or absent.
Check the location before starting
The US pilot accepts user-drawn study areas within the contiguous-US pilot extent. The worker checks for usable native USGS project-level 1 m elevation data. Coverage is incomplete and may fail for a selected area; no coarser dataset is silently substituted.
Baden-Württemberg remains a separate established German workflow with official ALKIS parcels. US address points and drawn areas are not official parcel boundaries.
What terrain screening cannot determine
Terrain screening does not simulate rainfall, infiltration, sewer capacity or the hydraulic effects of walls and culverts. It cannot predict flood depth, size a drainage system or confirm that a property is safe to build on.
A local catchment is limited to the analysed area. Contributions from beyond its boundary can be unknown. A modelled boundary crossing is not evidence of a real drain or drainage outlet.
Common questions
Does this predict flooding?
No. The screening describes terrain and potential surface flow paths. It does not simulate a storm or predict water levels.
Are PDF reports free?
No. PDFs are paid products. A free preview or analysis access key is not a purchase. Check the pricing page for current sales availability.
Editorial: Terraincheck · Updated 6 November 2026. See our methodology · data sources.
Terrain screening provides preliminary context. Site assessment, engineering design and construction decisions require appropriately qualified professionals.