The global terrain slope and aspect database has been compiled using elevation data from the Shuttle Radar Topography Mission (SRTM). The SRTM data is publicly available as 3 arc second (approximately 90 meters resolution at the equator) DEMs (CGIAR-CSI, 2006).

The high resolution SRTM data have been used for calculating:

1. Terrain slope gradients and classes for each 3 arc-sec grid cell;
2. Aspect of terrain slopes for each 3 arc-sec grid cell;
3. Distributions of slope gradient and slope aspect classes for 30 arc second grid.

The SRTM data cover globe areas up to 60° latitude. For the remaining area elevation data from GTOPO30 (USGS, 2002) were used.

A global terrain slope and aspect database comprises the following elements.

• Elevation (median)
• Slope gradient: Distributions of nine slope gradient classes are available for each grid-cell: 0–0.5%, 0.5–2%, 2–5%, 5–8%, 8–16%, 16–30%, 30–45%, and > 45%. 
• Slope aspects: Slope aspect data is stored in distributions of five classes namely: Class 1:  slopes below 2% undefined aspect; Class 2: slopes facing North (315°–45°); Class 3: East (45°–135°); Class 4: South (135°–225°), and Class 5: West (225°–315°).

Access data/Download

Data Citation
Fischer, G., F. Nachtergaele, S. Prieler, H.T. van Velthuizen, L. Verelst, D. Wiberg, 2007. Global Agro-ecological Zones Assessment for Agriculture (GAEZ 2007). IIASA, Laxenburg, Austria and FAO, Rome, Italy.

Responsible for this page: Elisabeth Kawczynski
Last updated: 09 Nov 2009