The influence of landslide morphology on erosion rate variability across western Himalayan catchments: Role of westerlies and summer monsoon interaction in the landscape characterization

Abstract

The tectonically active western Himalayan landscape evolved as a consequence of the interaction of major fluvial systems with long‐term erosional processes. To understand how landslide‐driven erosion impacts the geomorphic evolution of the terrain, we correlated the denudation rates and estimated exhumation ages with their conditioning factors, such as topographic matrices and precipitation intensity. We studied the occurrences of landslides as a function of the primary erosional drivers over precipitation variabilities, such as western disturbance (WD) and Indian summer monsoon (ISM), across the major river catchments in the western Himalayas. Our observation indicated that the phase of the differential precipitation pattern has a substantial impact on the variations in fluvial erosion rates over geological timescales, triggered by landslides. However, erosion patterns are more explicitly linked to tectonically driven topographic growth across the western Himalayan region. The result suggests that the WD precipitation pattern has a significant impact on landslide‐driven erosion across the Chenab, Beas and Sutlej catchments, which extend from the Tethyan to the higher Himalayas and can frequently contribute to increased denudation rates. The interaction of seismicity, litho‐tectonics (MCT–MBT), steep channel gradient (~ > 250) and high steepness (>252 m0.9) may be frequently contributing to an increase in rates of erosion (~ > 2 mm/y) throughout the catchments influenced by the WD, whereas the Yamuna, Ganga and Kali catchments, which are highly impacted by the ISM precipitation pattern and have comparable lower denudation rates (~ < 1.5–2 mm/y) and exhumation ages, are mostly triggered by elevated precipitation intensity (> ~ 2000 mm/y) associated with higher relief change (~3000–5000 m) over the lesser to southern Himalayan front.