Sambhav-2025

Approach / Explaination / Answer

Approach Briefly introduce the geological structure and topography of Peninsular India. Discuss how these factors influence the drainage pattern with specific points, examples, and data. In conclusion, summarize the interdependence of geological structure, topography, and drainage patterns.

Introduction

The drainage patterns in Peninsular India are a product of its ancient geological structure and varied topography, which have guided the flow and evolution of its rivers over millions of years. The geological structure and topography of Peninsular India, characterized by hard crystalline rocks like granite and gneiss, ridges, and plateau, significantly influence the drainage pattern. The patterns reflect the interaction between structural features and landforms.

Body

Geological Structure:

• Ancient Cratonic Stability: The Peninsular region is part of the Indian Shield, made up of hard, crystalline igneous and metamorphic rocks. These rocks resist erosion, forming stable, well-defined river courses.
  • Example: Godavari and Krishna flow through stable plateaus.
• Tectonic Activity and Rift Valleys: Rivers like the Narmada and Tapi flow through rift valleys caused by faulting, resulting in straight courses and unique drainage patterns.
• Deccan Traps: The basaltic lava plateau of the Deccan Traps creates radial drainage, where rivers originate from central high points and flow outward.
  • Example: Narmada’s radial pattern near Amarkantak Plateau.

Topography:

• Western and Eastern Ghats:
  • Western Ghats act as a natural water divide, forcing rivers like Godavari, Krishna, and Kaveri to flow eastward.
  • Eastern Ghats, with their lower elevation, allow rivers to meander and form deltaic systems.
• Plateaus and Elevation Gradients:
  • The Chotanagpur Plateau has a dissected topography, resulting in complex drainage networks.
  • The sloping gradient towards the east promotes dendritic drainage for major rivers.

Drainage Patterns and Examples:

• Dendritic Pattern: Resembles tree branches, formed in areas with uniform geological structures.
  • Examples: Godavari, Mahanadi, and Krishna Rivers.
• Trellis Pattern: Parallel streams joined by tributaries at nearly right angles, occurring in regions with alternating hard and soft rock layers.
  • Examples: Chambal and Subarnarekha Rivers.
• Radial Pattern: Rivers flow outward from a central high point.
  • Examples: Rivers originating from the Amarkantak Plateau such as Narmada, Son, and Mahanadi.
• Rectilinear/Angular Pattern: Rivers follow fault lines or joints, creating sharp angular courses.
  • Examples: Narmada and Tapi Rivers flowing through rift valleys.
• Centripetal Pattern: Rivers flow inward, converging toward a central depression or basin.
  • Examples: Manjara River Basin, a tributary of Godavari.

Conclusion

The geological structure and topography of Peninsular India have intricately shaped its drainage systems, giving rise to diverse patterns. These rivers not only reflect the region’s geological past but also play a critical role in sustaining its ecosystems and human settlements.