Evaluation of Active Tectonic Features of Nandakini River Basin, Lesser Himalaya, India by Using Morphometric Indices: A GIS Approach

Abstract

Tectonic geomorphology has been evidenced as an essential tool to define and measure recent tectonic deformation. The Nandakini River originates from Nanda Ghunti glacier at 6886 m in Lesser Himalaya. It covers about ~551 km2 basin area, with a fourth-order stream. It confluences with the Alaknanda River near Nand Prayag (at elevation 852 m), Chamoli district of Uttarakhand. The drainage pattern is predominantly dendritic in the study area. The morphotectonic indices are measured to know the tectonic activity of the drainage basin. Morphometric indices reflecting hypsometric Integral is 1.07, indicating a deeper incision and a slight erosion. The basin elongation ratio is 0.17, suggesting that the area is tectonically active. The drainage basin asymmetric factor (44) suggest tilting. In addition, the drainage basin shape (3.27) indicates the basin is tectonically strong, the transverse topographic symmetry factor (0.31) indicates the asymmetric nature, the valley floor width to valley height ratio is 0.54 shows the deep, narrow valleys, and Active V-shaped incision. Stream longitudinal profile showing the area tectonically influenced. The Sinuosity Index of 1.12 suggests that low sinuous nature. The Stream length-gradient Index is 10.64, indicating high tectonic activity in valleys and basin areas. The transverse profile helps to understand the tilting of the basin. The Surface profile shows irregularity, and the linear trend of the profile shows the tilting of the basin. River carrying capacity with large boulder-size sediment indicates youth stage and tectonically active environment. The morphotectonic indices suggest that the drainage basin was affected by the regional structures and the present tectonics.