Remote Sensing and GIS Based Terrain Analysis: A Case Study of Bhera River Watershed, Ranchi- Ramgarh Districts, Jharkhand, India

Abstract

Remote sensing (RS) and geographic information system (GIS) based terrain analysis is essential for characterizing watershed dynamics and aids in sustainable land and water resource management, particularly in hard rock terrain where primary porosity is minimal, and topography and lithology pose challenges for groundwater and erosion control. Despite advancement in geospatial techniques, integrated terrain- hydrological evaluations remain limited for watersheds in hard rock terrain, particularly in Jharkhand because of its diverse physiography and effects of multiple tectonism. This study aims to highlights the potential of geomatic techniques in assessing seven key terrain parameters, lithology, geomorphology, lineaments, soil, slope, drainage, and hydrological indices (NDWI, NDMI, EWI) for sustainable management of Bhera River watershed, Ranchi- Ramgarh districts, Jharkhand. The Bhera watershed, having an area of 269 sq. km, lies within the Chotanagpur Plateau and is characterised by dissected plateaus, undulating hills, and diverse lithology ranging from Precambrian granites and gneisses to Gondwana sediments. The thematic maps were generated using Visual and Digital Image interpretation, using the sources from existing thematic maps, satellite imageries- Landsat 8 and 9 (Date of acquisition- 20th  and 22nd November 2023), SRTM (Date of acquisition- 1st November 2023), and survey of India toposheets at 1:50,000 scale. The study reveals geologically complex landscape with dominant pediplains (70% coverage) indicating moderate groundwater potential, moderate structural control, luvisols as the dominant soil type with good nutrient retention, dendritic to sub-dendritic drainage pattern indicating uniform lithology and varied slopes heightening runoff and erosion risks. Hydrological indices highlight sparse water bodies (NDWI: -0.43 to 0.11), moderate vegetation moisture (NDMI: -0.09 to 0.26), and predominantly dry to sparsely vegetated soils (EWI: -0.60 to -0.35). These findings underscore the watershed's vulnerability to erosion and groundwater overexploitation despite adequate rainfall (1100-1400 mm annually), emphasizing the need for integrated RS-GIS approaches for terrain evaluation to guide conservation strategies and sustainable management in similar hard rock regions.