Comparative Study of Morphometric and USDA SCS - CN Methods for Assessing Runoff Potential in Hazaribagh Plateau, India

Abstract

The assessment and management of surface runoff is important for watershed planning and water resource utilization, especially in areas where agriculture is mostly dependent on rainfall. This study aims to evaluate and compare the runoff potential of 98 delineated watersheds within the Hazaribagh Plateau region using two distinct approaches namely morphometric analysis and the Soil Conservation Service-Curve Number (SCS-CN) methods using Geographic Information System (GIS) and Remote Sensing (RS) techniques. A Compound Factor (CF), which represents the structural runoff potential of each watershed was computed using morphometric parameters under linear, areal, and relief aspects that were obtained from the Digital Elevation Model (DEM) and is categorised into five ranks. Similarly, runoff coefficients were estimated using the SCS-CN approach based on land use/land cover, hydrologic soil groups and antecedent moisture conditions, which are further categorised into five classes. Comparative analysis revealed that 46 watersheds exhibited matching ranks, while 35 showed lower SCS-CN ranking than morphometric parameter ranking and 17 showed higher. These variations highlight the combined influence of terrain characteristics, land use patterns, soil properties, and moisture conditions on runoff generation. The results demonstrate that morphometric analysis provides a preliminary assessment of runoff behaviour, while the SCS-CN method offers a more dynamic and quantitative evaluation, and their integration improves the reliability of runoff assessment for efficient watershed planning.