Fall profile: Himmelbjerget to Julsø
A terrain profile is a series of levels along a line. With the first and last level you calculate fall, gradient and angle.
5 chapters · 5 questions
The line
The profile runs 630.11 m from the top at the place name Himmelbjerget down to the shore of Julsø, with a level every 2 m: 317 points.
Source: Dataforsyningen DHM via Grundfast · fetched
First and last point
The terrain is 133.41 m above sea level at the start and 20.97 m at the lake (height system DVR90). The fall is 133.41 − 20.97 = 112.44 m.
Source: Dataforsyningen DHM via Grundfast · fetched
Gradient and angle
The gradient is 112.44 / 630.11 = 17.84%, or 178.4‰. The angle is arctan(0.1784) = 10.12°. Percent and degrees are not the same.
Source: Dataforsyningen DHM via Grundfast · fetched
The trap: fald_m
The API also returns fald_m = 112.93 m. That is the highest minus the lowest level on the line (133.9 − 20.97), not the difference between the end points. For sewer falls and road gradients you use the first and last point yourself.
Source: Dataforsyningen DHM via Grundfast · fetched
Terrain and surface
At the top the terrain is 133.43 m, but the surface is 157.65 m. The surface model measures the top of what stands on the ground — buildings and trees. For falls you use the terrain.
Source: Dataforsyningen DHM via Grundfast · fetched
Questions 1 / 5
The terrain falls from 133.41 m to 20.97 m over 630.11 m. What is the gradient in percent?