Mapping of erosion risk zones in the Lake Tana region of Ethiopia

摘要

Abstract: The imaging mode 3 of the Modular OptoelectronicMultispectral Scanner (MOMS-02) combines twoalong-track panchromatic stereo bands (520 - 760 nm)with two multispectral bands in the red (645 - 680 nm)and near infrared (770 - 810 nm) wavelength spectrum.This special design offers the opportunity to combinethe stereoscopic evaluation of relief parameters withthematic information on actual landuse frommultispectral bands. Using FAO's Universal Soil LossEquation (USLE) for a test site in the EthiopianHighlands actual relief and thematic information isneeded in order to derive an actual erosion risk map.MOMS-02 multispectral data was used as a data sourcefor soil type mapping, the actual landcover andmanagement intensity estimations. Potential naturalvegetation cover and agroclimitical data were digitizedfrom official large scale maps. Relief parameters likeslope gradient and length were derived from a digitalterrain model (DTM). DTM's were generated out of aerialphotographs (1:50,000) and MOMS stereo data. They havebeen geocoded and validated by differential GPSmeasurements. Both DTM's were compared in order to showthe potential of DTM's derived from MOMS. GIS basedevaluations of the extracted parameters finally lead toan actual erosion risk map of the test site Dir Dira.Using landuse information from old topographic maps asan parameter for the USLE result in an historicalerosion risk map. The comparison between both resultsshows a considerable increase of the endangered areaswithin 10 years.!13