Reclamative grouping of ravines using Cartosat-1 PAN stereo data

Abstract

Information on the depth and bed width of ravines (network of gullies) at large scales is critical for their reclamation and management. Hitherto such information has been generated from aerial photo- graphs and space borne stereo images with medium to coarse 'z '- axis resolution. The present study, aims at demonstrating the potential of Cartosat � 1( an Indian Earth observations satellite) stereo images with 2.5 m spatial resolution in deriving morphometric information on ravines for their reclamative grouping. The study area is a part of Jhansi and Hamirpur dis- tricts of Uttar Pradesh, northern India. The approach involves acquiring precise ground control points using Differential GPS (DGPS), triangulation, DEM extrac- tion and generation of ortho image as well as ana- glyphs for stereo viewing. The depth and bed width of ravines were measured in the field for validation. A comparison with field observations reveal that the bed width of ravines and depth can be measured success- fully with Carto-1 stereo data. The anaglyph data was used to delineate various categories of ravines based on their depth and bed width. Results indicate that the Cartosat-1 stereo images are quite suitable for delin- eation of three categories of ravines, namely shallow ( 18 m bed width) and deep (>9 m deep) which are important for their reclamation.