Mains Practice Questions

Introduction

Himalayan rivers, such as the Ganga, Yamuna, and Brahmaputra, maintain perennial flow, whereas Peninsular rivers like the Godavari, Krishna, and Mahanadi exhibit seasonal variations in their discharge. These differences arise due to distinct geographical, climatic, and hydrological factors that influence their regimes.

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Geographical Factors: Himalayan vs Peninsular Rivers' Flow:

• Source of Origin and Water Supply
  • Himalayan Rivers: These rivers originate from glaciers and snow-fed regions in the Himalayas, ensuring a continuous water supply throughout the year.
    • Examples: The Ganga originates from the Gangotri Glacier, and the Brahmaputra from the Chemayungdung Glacier in Tibet.
    • During summer, melting glaciers significantly contribute to their flow, compensating for reduced rainfall.
  • Peninsular Rivers: Most peninsular rivers are rain-fed, relying heavily on the southwest monsoon for their water supply.
    • Examples: The Godavari originate from Trimbakeshwar in the Western Ghats, and the Krishna from Mahabaleshwar in Maharashtra.
    • In non-monsoon months, these rivers often dry up or experience reduced flow due to the absence of alternative water sources.
• Climatic Influence
  • Himalayan Rivers: The humid and subtropical climate in the Himalayan region ensures a steady supply of precipitation, including snowfall in winter and rainfall during the monsoon.
    • Examples: Tributaries of the Ganga, such as the Kosi receive rainfall from the high-rainfall areas of the Terai region.
  • Peninsular Rivers: The semi-arid to tropical climate in peninsular India results in pronounced seasonality.
    • Examples: Rivers like the Cauvery and Tungabhadra experience high discharge during the southwest monsoon but show significant reductions in the dry seasons.
• Catchment and Geology
  • Himalayan Rivers: The large catchment areas of these rivers and their extensive tributary networks allow for efficient water collection.
    • Examples: The Brahmaputra has large tributaries like the Dibang and Lohit, ensuring a vast catchment area.
    • The young and tectonically active Himalayas are prone to erosion, contributing to high sediment loads that sustain flow.
  • Peninsular Rivers: These rivers have smaller catchments and originate from ancient, stable geological formations with hard crystalline rocks, limiting groundwater recharge.
    • Seasonal rainfall drains quickly due to the hard terrain and limited permeability.
• Human Interventions
  • Himalayan Rivers: The perennial nature of Himalayan rivers makes them suitable for irrigation and hydroelectric projects, helping to regulate flow.
    • Examples: The Tehri Dam on the Bhagirathi and the Farakka Barrage on the Ganga manage flow for irrigation and navigation.
  • Peninsular Rivers: Over-reliance on monsoon-fed rivers for irrigation and drinking water exacerbates their seasonal nature.
    • Examples: The Hirakud Dam on the Mahanadi often faces low storage levels during dry seasons.

Conclusion

Himalayan rivers maintain their perennial nature due to glacial melt, large catchments, and favorable climatic conditions, while peninsular rivers face seasonal variations due to monsoon dependence, geological constraints, and smaller catchments. These differences underline the need for effective water resource management, such as river interlinking, to mitigate disparities and ensure sustainable water availability.

Alternatively, the body section can be presented in tabular format: