Morphotectonic study of the Brahmaputra basin using geoinformatics

The Brahmaputra river basin occupies an area of 580,000 km2 lying in Tibet (China), Bhutan, India and Bangladesh. It is bounded on the north by the Nyen-Chen-Tanghla mountains, on the east by the Salween river basin and Patkai range of hills, on the south by Nepal Himalayas and the Naga hills and on the west by the Ganga sub-basin. Brahmaputra river originates at an elevation of about 5150 m in southwest Tibet and flows for about 2900 km through Tibet (China), India and Bangladesh to its mouth in the Bay of Bengal. The Brahmaputra river basin is investigated to examine the influence of active structures by applying an integrated study on morphotectonics, SRTM, and seismic data. The indices for morphotectonic analysis, viz. basin elongation ratio (Re) indicated tectonically active, transverse topographic symmetry (T = 0.018–0.664) indicated asymmetric nature, asymmetric factor (AF=33) suggested tilt, valley floor width to valley height ratio (Vf = 0.0013–2.945) indicated active incision and mountain-front sinuosity (Smf = 1.11-1.68) values indicated active tectonics in the area. Two prominent knicks on the long profile at distances of about 1600 km and 1900 km closely correlate to the two prominent peaks on the SL index. The first one represents the Indus - Tsangpo suture zone after crossing which the Brahmaputra (Tsangpo) enters the Himalayas and the second one represents the zone where the Dihang (Brahmaputra) comes out of the Himalayas after crossing the Main Boundary Thrust. A great or major earthquake in the modern times, in this region may create havoc with huge loss of life and property due to high population density and rapidly developing infrastructure. Keywords