Geomorphic characteristics of a bedrock river inferred from drainage quantification, longitudinal profile, knickzone ide
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ORIGINAL PAPER
Geomorphic characteristics of a bedrock river inferred from drainage quantification, longitudinal profile, knickzone identification and concavity analysis: a DEM-based study Sumit Das 1 Received: 12 January 2018 / Accepted: 30 October 2018 # Saudi Society for Geosciences 2018
Abstract An examination of river channels has ability to provide substantial information regarding the geomorphic characteristics, control of lithology, tectonic uplift and geomorphic evolution during the geological past of an area. In this paper, a detailed study of geomorphic and structural investigation has been carried out for Pravara basin, Maharashtra, with the help of 90-m resolution SRTM DEM and geospatial techniques. Drainage network analysis performed in this paper demonstrates the general geomorphic characteristics, while the analysis of longitudinal profile synthesises lithological control over Pravara basin. Pravara is a 6th order drainage basin, encompassing an area of 2637 km2. Bifurcation ratio reveals low to moderate structural control. Due to the hard rock lithology, the drainage density and stream frequency are low, and it indicates higher permeability in the sub-surface layers. The shape parameters denote that Pravara is highly elongated and it is easier to control floods in this basin. Relief parameters show very steep slope and higher vulnerability to the slope failure in some areas. Upstream of Pravara river has shown that series of breaks and knickzones indicate active erosion and acute lithological control on the channel. Major breaks are observed only in the main channel whereas in two major tributaries, no such breaks found, instead these tributaries are characterised by several knickzones which indicate regional variation in the lithological physiognomies. Different lithological stages on knickpoint and channel incision substantiate rejuvenation of Pravara river in several phases during geological past. The geospatial methodology carried out in this study can be pragmatic elsewhere around this world to recognise the geomorphic appearances and lithological control of a drainage basin. Keywords Morphometric analysis . Longitudinal profile . Knickpoint . Western Ghat . SRTM DEM . Pravara
Introduction Fluvial landscape is the most common geomorphic phenomenon in this world, which occurs because of either rainfall or melted snow in an area (Das and Pardeshi 2018a). Fluvial processes can be seen anywhere except extreme polar regions as those regions are characterised by permafrost. Even, in desert region, fluvial processes take place occasionally (Das 2018). Drainage quantification is an essential method for assessing the basin morphology and the impact of lithology, geology, tectonics and climate in terrain evolution of a region. Hence, the * Sumit Das [email protected] 1
Department of Geography, Savitribai Phule Pune University, Pune 411007, India
past terrain deformation can easily be understood by evaluating these variables through morphometric analysis of an area. Drainage quantific
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