Vishwas S Kale
Articles written in Journal of Earth System Science
Volume 117 Issue 6 December 2008 pp 959-971
In line with the passive margin landscape evolutionary model in vogue, sustained erosion and long-distance retreat of the Western Ghat escarpment are widely considered to be the results of erosionally-driven isostatic uplift since Tertiary by many workers. Others have postulated or adduced evidence for strong neotectonic activity in the Ghat region. An obvious question in this regard is whether there is any geomorphometric evidence in support of this widespread view? In order to test the hypothesis of ongoing post-rift fexural uplift or neotectonic activity in the western Deccan Basalt Province (DBP), geomorphometric analysis was carried out and commonly used geomorphic indices of active tectonics (GAT)were derived for 30 selected river basins on both sides of the Western Ghat. SRTM-DEM data and ArcGIS were used to derive the indices. Tectonic geomorphic analysis based on ﬁve proxy indicators suggests that the differences in GAT indices, both along strike and across the Western Ghat,are statistically insigniﬁcant. The index values are nowhere close to the GAT values typically associated with drainage basins affected by active tectonics and deformation.Mapping of the indices reveals lack of discernable trends. The adduced results indicate that the western DBP belongs to the class of relatively low tectonic activity.
Volume 120 Issue 1 February 2011 pp 157-165
The most conspicuous erosional features associated with constricted bedrock channel reaches and knickpoints are potholes. The presence and morphology of potholes have been attributed to a number of factors by earlier researchers. Amongst these factors, the role of substrate rock properties has received very little quantitative attention. The main objective of this study is to quantitatively evaluate the physical properties of bedrock in order to test the possible influences of rock properties on the occurrence and morphology of potholes. The area selected for this study is a large scabland area developed by the Indrayani river at Shelarwadi near Pune. This site is ideally suited for the study since it is featured by wide straths, multiple inner channels and several hundred potholes. A transect-based quadrat method was used in this study. Within each quadrat, the pothole dimensions, the joint length, joint direction, the rock mass strength and the distance from active channel were measured. The analysis reveals a weak correlation between pothole size and rock properties. The distance from the active channel emerges as the most significant factor, suggesting that the hydraulics of flows is the key factor and substrate characteristics play only a secondary role.