Use of SRTM data to calculate the (R)USLE topographic factor

ABSTRACT. The topographic factor of the Universal Soil Loss Equation and its revised version (R)USLE are currently calculated by Digital Elevation Models (DEM) integrated to Geographic Information Systems (GIS). However, some countries have no topographic information to calculate DEM. In this study we evaluated the use of the Shuttle Radar Topography Mission (SRTM) data for computing the (R)USLE topographic factor. Furthermore, 90 m SRTM DEM, refined 30 m SRTM DEM and DEMs 30 m and 90 m derived from official topographic maps (1:100,000 scale) were used. Using DEMs the topographic factor was calculated by USLE-2D software. The topographic factor calculated from SRTM data showed greater detail levels (especially in flat areas) than those obtained from topographic maps. The reduction of spatial resolution of DEM-SRTM provided the topographic factor’s average rate decrease. SRTM data may be employed in further studies for soil loss predictions. The methodology may be useful in Brazil for the development of soil and water conservation programs