Pente du Terrain

Utilisation des Solsv0

Responsable:Niccolò Calandri

Pente du terrain en degres (0-90) calculee a partir du modele numerique d'elevation USGS SRTM. La mission SRTM (Shuttle Radar Topography Mission) a acquis des donnees d'elevation quasi-mondiales en fevrier 2000 a une resolution de 1 seconde d'arc (~30m). La pente est derivee par la methode des differences finies sur la grille MNT (ee.Terrain.slope() dans Google Earth Engine).

Sources de Données et Références

Sources

USGS_SRTM_003

Méthodologie

Terrain Slope

Overview

The Terrain Slope layer computes the steepness of the ground surface in degrees (0-90) from the USGS Shuttle Radar Topography Mission (SRTM) digital elevation model at 30m resolution.

Calculation Methodology

DEM source - Load the SRTM GL1 elevation raster (USGS/SRTMGL1_003) from Google Earth Engine at 25m output resolution.
Slope computation - Apply ee.Terrain.slope() which computes the gradient magnitude using a 3x3 finite difference kernel (Horn's method) on the elevation grid, returning values in degrees.
Reprojection - Reproject to Web Mercator (EPSG:3857) at 25m pixel size.
Clipping - Clip to the area of interest with configurable buffer.
Quadrant splitting - For areas larger than 625 km2, the image is split into quadrants for parallel download and then merged.

Output unit: degrees (0 = flat, 90 = vertical)

Data Sources

Code	Name	Provider	Type	Coverage	Resolution	Reference Year
`USGS/SRTMGL1_003`	SRTM GL1	NASA/USGS	Elevation DEM	60N-56S	30m (~1 arc-second)	2000

Quality Range and Levels

Indicator	Unit	Range	Inverted
`terrain_slope`	degrees	[0, 5, 15, 25, 35, 90]	No

Level	Thresholds	Interpretation
A (Flat)	0-5 degrees	Plains, valley floors, plateaus
B (Gentle)	5-15 degrees	Gentle hills, suitable for most agriculture
C (Moderate)	15-25 degrees	Moderate slopes, terracing may be needed
D (Steep)	25-35 degrees	Steep terrain, erosion risk, limited agriculture
E (Very Steep)	> 35 degrees	Cliffs, mountain faces, high landslide risk

References

Farr, T.G. et al. (2007). The Shuttle Radar Topography Mission. Reviews of Geophysics, 45(2).
Horn, B.K.P. (1981). Hill shading and the reflectance map. Proceedings of the IEEE, 69(1).

Responsible: Claudio Barbieri