Morphometric Analysis and Soil Erosion Assessment Using Remote Sensing and Geographic Information System in Karauli Watershed of Rajasthan, India

Soil erosion deteriorates the land and creates environmental problems, and hence, its assessment is requisite for sustainable development and management of natural resources in a watershed. Also, knowledge about morphometric parameters is essential for understanding and managing watershed-scale soil erosion. In this study, soil erosion is estimated for Karauli watershed of Rajasthan, India, where semi-arid climate exacerbates soil degradation risks. In this study, morphometric parameters, i.e., stream order, stream length, bifurcation ratio, form factor, ruggedness number, drainage density, stream frequency, and relief were computed using high-resolution (12.5 m) Advanced Land Observing Satellite - Phased Array type L-band Synthetic Aperture Radar (ALOS PALSAR) digital elevation model (DEM). The results revealed that the watershed is of 7th order with total of 3635 streams. Further, the revised universal soil loss equation (RUSLE) model was employed to quantify soil erosion. All the RUSLE factors were determined based on the average annual rainfall map, soil properties, DEM, normalized difference vegetation index (NDVI), and land use/land cover (LULC). It was found that drainage density varied from 0.20-5.34 km km-2; the high values of drainage density and steep slopes (greater than 37%) suggested high runoff potential and increased soil erosion towards the southern and northern parts of the watershed. The value of crop management and conservation practice factor in the poorly vegetated area was close to one. All the factors were combined in geographic information system and a soil loss map was developed. It was observed that most of the watershed lands were under the soil loss category of less than 10 t ha-1 yr-1. Morphometric analysis along with the RUSLE modeling enhanced understanding of spatial soil erosion dynamics and provided a scientific basis for prioritizing sub-watersheds and implementing targeted soil and water conservation measures. This study delivered a comprehensive erosion risk assessment framework for semi-arid watershed management.