IDENTIFICATION OF GEOMORPHIC SIGNATURES OF NEOTECTONIC ACTIVITY USING DEM IN THE PRECAMBRIAN TERRAIN OF WESTERN GHATS, INDIA
Keywords: DEM, Geomorphology, GIS, Identification, Geology, Stream length gradient (SL) index
Abstract. To assess the relative tectonic activity classes, five geomorphic indices such as stream-gradient index (SL), drainage basin asymmetry (Af), hypsometric integral (Hi), valley floor width – valley height ratio (Vf) and drainage basin shape (Bs) of ninety-four sub-basins of Valapattanam river basin have been analysed by applying the standard formulae. Relative tectonic activity classes (Iat) obtained by the average (S/n) of different classes of geomorphic indices have been classified into three groups. Group I shows high tectonic activity with values of S/n < 2; group II shows moderate tectonic activity with S/n > 2 to < 2.5; and group III shows low tectonic activity with values of S/n ≥ 2.5. Field evidences such as deep valleys, sudden changes in the river course and waterfalls at fault planes clearly agree with the values and classes of tectonic geomorphic indices.