Surveying activities of unstable material on high slopes is better done from above and with a drone rather than walking on it.
A “ravaneto“, in the Apuanian Alps quarries (where white marble from Carrara is extracted), is a part of the slope where waste of blocks’ extraction is discharged.
The grain size of the material is big and so it is the friction angle.
Slops could reach angles that go from 40° to 50°.
Moving around by feet, to measure points with a GPS or to carry around a reflected prisma on a pole (to be collimated by a total station), has two big issues:
- you move slowly and with difficulty, because your feet do not feel comfortable, and you can fall;
- it is not said that the material remains in place under the weight of a person.
In this picture the rocks stopped at the bottom and made a kind of barrier for the finer-grained one.
If something is moving down there, everything goes down!
To stay away if it rains hard …
If you use a drone (for photogrammetry or lidar) you don’t have to walk on it.
You’ll be faseter and you’ll be able to generate a really good and reliable 3D model.