Morphometric and Morpho-Tectonic Screening and Prioritisation of Sub-Basins in The Kabini River Basin, Kerala: Remote Sensing and GIS-Based Approach

The present study reports the morphometric and morpho-tectonic analysis of six sub-basins ‎‎(WS-1 to WS-6) of the Kabini River basin, Wayanad, Kerala, by considering different linear, ‎areal and relief parameters (Drainage density, Stream frequency, Drainage texture, Bifurcation ‎ratio, Circularity ratio, Elongation ratio, Shape factor, Total Relief, Relief ratio and Ruggedness ‎number) derived from CartoDEM data. An equal-weight compound ranking scheme was used ‎to rank the sub-basins to give a repeatable ranking. Three robustness checks were performed by ‎leaving one parameter out, leaving out relief and 10,000-run random weighting. The WS-3 and ‎WS-5 consistently ranked first (WS-3 ranked first in 86% of cases), whereas the WS-2 and ‎WS-4 ranked in medium priority and WS-1 and WS-6 ranked in low priority. Basin-level ‎morpho-tectonic indices (Transverse topographic symmetry factor, Hypsometric integral and ‎Asymmetry factor) are given for reference and are not diagnostic. The results indicate that the ‎trunk stream shows moderate asymmetry from TTSF. The asymmetry factor suggests it is ‎nearly symmetric (50.52%). The low value of the hypsometric integral indicates it is at a late ‎erosional stage. The Stream Length Gradient Index was inconsistent and so omitted. This study ‎does not allow any separation between lithological, climatic and erosional effects and tectonic ‎effects, as the indices are derived from DEM data; however, the ranking can be used as a ‎screening tool to identify sub-basins for structural, geophysical and field analysis‎.