Methodologies of preparing erosion features map by using RS and GIS

The erosion features map is one of the basic maps in erosion and sediment studies and watershed management programs.Some methodologies of preparing erosion features map by using RS and GIS were compared in research which took place in the Jajrood sub-basin in north-east Tehran,Iran.In the first phase,four working units' maps were prepared by integration a) plant cover,geology and slope b) land use,geology and slope c) land use,rocks sensitivity to erosion and slope and d) land use,rocks sensitivity to erosion and land units' layers.In addition to these four working units' maps,three more maps were also evaluated in separating erosion features including e) land units f) sensitivity of rocks to erosion and g) image photomorphic units.The efficiency of these seven working units' maps was evaluated by 314 control points.For this purpose,by using erosion features of control points regarding field views,surface,rill,gully and channel erosion maps were prepared and compared by crossing them with working units' maps.Results showed that method "d" was better than "a","b" and "c" in providing soil erosion features regarding economic and executive considerations.The accuracy of methods "e" and "f" was 53.0 and 42.9% and their Root Mean Squared Error was more than method "g" and methods "a" to "d".The coefficient of variation was highest for methods "e" and "f" and the least for method "e" and the greatest precision was related to image interpretation.