Performance assessment of topographic position index and geomorphon-based landform classification for geomorphic analysis of Indian Western Himalayas

Landform diversity in the Indian Western Himalaya (IWH) is the result of aggradational and degradational processes through the workings of tectonic, climatic, and anthropogenic forces. Understanding landuse management and disaster risk reduction makes better sense when the landform-distribution pattern is incorporated in the analysis. The IWH region is experiencing unplanned human settlement, increased frequency of natural hazards, degradation of land and natural resources, loss of habitat, and the impact of climate change. In our study, we aim at delineating landforms within the IWH and its sub-regions using the Topographic Position Index (TPI) and Geomorphon-based multi-scale approach. We further examined spatial correlation between landform classes achieved through TPI and Geomorphon approach and the patterns of slope (based on the definition of geomorphon) and Land Use/ Land Cover (LULC). The findings of the study indicate that tectonic, erosional, and depositional processes highly influence the rugged and diverse terrain of the region. According to the TPI-based landform classification, deep valleys occupy 27.84% of the study area, followed by high ridges covering 23.59% of the area. Geomorphon-based landform classification shows that slope is the dominant landform class, covering 38.76% of the total area. The performance of TPI and Geomorphons vary from each other as TPI-based classification can effectively capture slope transitions in larger geomorphic units while Geomorphons can differentiate localized landform features. According to the LULC distribution, plains and footslopes are primarily utilized for human settlements and agricultural activities, while barren land, scrubland, and dense vegetation occupy steep terrains. The results of the present study highlight the significance of suitable scale selection for geomorphological and landform classification studies. The TPI and Geomorphon-based landform classification support the integration of geomorphic data into land-use planning and provide a comprehensive understanding of terrain characteristics, which helps to carry out effective land-use planning, ecological conservation, and disaster risk mitigation.