Landscape Characterization of the Cauvery Basin, India using Geomorphic Indices Derived from the Digital Elevation Model

Landscape characterization is essential for deciphering geomorphic evolution, resource potential, and sustainable management in river basins. While geomorphic indices are commonly used for quantifying terrain and assessing erosion, their integrated application with landform features remains underexplored. This study offers a comprehensive landscape assessment of the Cauvery River Basin, India, by integrating geomorphic indices with landform features to study spatial patterns of fluvial erosion. Using Shuttle Radar Topography Mission (SRTM-30 m) data, three geomorphic indices-Hypsometric Integral (HI), Hack’s Stream-Length Gradient (SL) Index, and Normalized Channel Steepness (Ksn) Index-were computed across six sub-basins, along with landform classification. The HI values ranged from 0.11 to 0.27, indicating varied stages of landscape development, with the Shimsha sub-basin showing the highest HI (0.27), and the Kabini, Noyil, and lower Cauvery basins the lowest (0.11–0.12), suggesting mature, eroded terrains. Knickpoints analysis showed intense incision in the Bhavani basin (3162 knickpoints), supported by high Ksn values (90), and high SL values (up to 160,884 gradient meters), particularly around waterfalls and dams shaped by lithological controls. Clustering of knickpoints at elevations between 0-120 m above sea level, suggests that Quaternary eustatic base-level fall triggered a phase of river rejuvenation across the basin. Landform classification shows plains dominate (52-89 % areal coverage), especially in lower sub-basins, while ridge and deeply incised streams show more active erosion zones. This integration of geomorphic indices and landforms shows a framework for linking fluvial erosion to sea-level history, providing insights into past geomorphic responses, lithological controls over river basin evolution, and implications for sustainable land and water resource management.