Geological Controls of Dyke Networks on Drainage Morphometry: Evidence from the Bhad River Basin, North Maharashtra

Abstract Drainage morphometry provides vital insights into the interaction between geological structures and fluvial processes. The present study investigates the influence of mafic dyke intrusions on the drainage morphometric characteristics of the Bhad River basin, located within the Nandurbar–Dhule dyke swarm region of North Maharashtra, India. The basin covers an area of 164.32 km² and is structurally dissected by 27 prominent dykes, which exert a strong control on drainage orientation, basin geometry, and stream network development. Remote sensing data, topographic maps, and GIS-based techniques were employed to extract and analyze linear, areal, and relief morphometric parameters. The structural analysis reveals that the dykes display a dominant E-W orientation, with strike angles ranging between 10° and 110° and a mean strike of N80°, indicating strong regional structural control. Dyke lengths and thicknesses exhibit inverse and weak linear relationships, respectively, suggesting heterogeneous emplacement conditions. Morphometric evaluation shows that the Bhad River is a sixth-order basin with a total stream length of 450.19 km and a bifurcation ratio of 3.39, reflecting moderate structural disturbance. Drainage density (2.74 km/km²), stream frequency (3.15), and drainage texture (7.08) indicate a moderately dissected terrain with efficient surface runoff. Relief parameters such as basin relief (271 m), ruggedness number (0.74), and dissection index (0.68) suggest moderate relief and ongoing erosional activity influenced by dyke-controlled topography. The hypsometric integral value of 0.49 places the basin in a late youthful to early mature stage of geomorphic evolution. Overall, the study proves that dyke intrusions meaningfully influence drainage alignment, basin morphology, and hydrological response. These findings highlight the importance of structural controls in morphometric studies and provide valuable inputs for watershed management, geomorphic interpretation, and regional planning in dyke-dominated terrains.