Characterizing Gully Morphology using Structure from Motion-Multi-View Stereo (SfM-MVS) technique in Garhbeta Badlands, West Bengal, India..

One of the principal causes of geo-environmental degradation in the humid tropics is gully erosion, reducing the productivity of land and increasing sediment discharge in rivers. Although there is extensive literature on gully erosion, less attention has been given to the study of gully morphology than to the factors responsible for gully initiation. The present work aims to analyze the effectiveness of modelling a single gully channel in Garhbeta badlands of West Bengal, India, with high-resolution topographic data derived from Structure from Motion-Multi View Stereo (SfM-MVS) using Canon EOS 60D camera and simultaneously extract cross-sectional properties of gullies. This close-range photogrammetric technique uses an image-matching process, whereby multiple overlapping offset images of the same surface is taken from different positions to generate a 3D object system. Markers were distributed along the gully length and the coordinates of these ground control points (GCPs) were established using Total Station and GPS. The 3D dense, point cloud obtained from SfM-MVS was used to create a high-quality DEM data and cross-sectional profiles were extracted at regular intervals along the gully length to measure morphometric parameters of the gully. Such close-range photogrammetry provides a very cost-efficient means of acquiring high-resolution topographic data, essential in the analysis of gully morphology and its response to the underlying lithological properties as this is crucial to the understanding of the gully development processes.