Q.Name some rivers of the Peninsular plateau which have their confluence in the Bay of Bengal and the Arabian sea, and mention some landforms which are typical to the east-flowing rivers but are absent in the west-flowing rivers.

The Peninsular rivers exhibit distinct drainage patterns and associated landforms based on their confluence.

Major east-flowing rivers such as the Mahanadi, Godavari, Krishna, and Kaveri have their confluence in the Bay of Bengal. Conversely, prominent west-flowing rivers like the Narmada, Tapi, Sabarmati, and Periyar drain into the Arabian Sea.

A significant landform difference is that east-flowing rivers typically form well-developed deltas at their mouths. This occurs due to their longer courses, gentler gradients, and the substantial sediment load they deposit in the relatively calm Bay of Bengal. In contrast, west-flowing rivers, particularly the Narmada and Tapi, flow through rift valleys and have shorter, swifter courses, leading them to form estuaries instead of deltas at their confluence with the Arabian Sea.

The Peninsular plateau of India is drained by a distinct set of rivers, fundamentally different from the Himalayan rivers. These Peninsular rivers are generally older, have fixed courses, are non-perennial (rain-fed), and have relatively shallower valleys. The Western Ghats, running parallel to the west coast, serve as a major water divide, influencing the direction of flow for most Peninsular rivers. Consequently, these rivers largely flow either eastward into the Bay of Bengal or westward into the Arabian Sea.

Rivers Confluencing in the Bay of Bengal

The majority of the large Peninsular rivers flow eastward and drain into the Bay of Bengal. These rivers generally originate in the Western Ghats or the central highlands and traverse the plateau before reaching the east coast. They have longer courses and larger drainage basins compared to their west-flowing counterparts.

Some prominent rivers that have their confluence in the Bay of Bengal include:

• Mahanadi: Originating in the highlands of Chhattisgarh, it flows through Odisha.
• Godavari: The largest Peninsular river, often called the 'Dakshin Ganga', it rises in the Nashik district of Maharashtra and flows through Maharashtra, Telangana, and Andhra Pradesh.
• Krishna: Originating near Mahabaleshwar in Maharashtra, it flows through Maharashtra, Karnataka, Telangana, and Andhra Pradesh.
• Kaveri: Rising in the Brahmagiri range of the Western Ghats in Karnataka, it flows through Karnataka and Tamil Nadu.
• Subarnarekha: Flows through Jharkhand, West Bengal, and Odisha.
• Brahmani: Formed by the confluence of Sankh and Koel rivers in Odisha.
• Penner: Flows through Karnataka and Andhra Pradesh.

Rivers Confluencing in the Arabian Sea

A smaller number of significant Peninsular rivers flow westward into the Arabian Sea. These rivers are generally shorter, have smaller drainage basins, and often flow through rift valleys or over hard, resistant rocks.

Some prominent rivers that have their confluence in the Arabian Sea include:

• Narmada: Originating from the Amarkantak Plateau in Madhya Pradesh, it flows westward through a rift valley between the Vindhya and Satpura ranges.
• Tapi: Also flowing through a rift valley, it originates in the Satpura range in Madhya Pradesh and flows parallel to the Narmada.
• Sabarmati: Rises in the Aravalli Range of Rajasthan.
• Mahi: Rises in the Vindhya Range in Madhya Pradesh.
• Periyar: A major river in Kerala.
• Sharavathi: A river in Karnataka, famous for the Jog Falls.
• Mandovi: A significant river in Goa.

Typical Landforms of East-Flowing Rivers Absent in West-Flowing Rivers

The most distinctive landforms typical to the east-flowing rivers, but largely absent in the west-flowing rivers, are deltas.

• Deltas in East-Flowing Rivers:

  • East-flowing rivers, such as the Mahanadi, Godavari, Krishna, and Kaveri, have long courses and flow over relatively gentler slopes as they approach the coast. This allows them to carry vast quantities of fine sediment eroded from the plateau.
  • As these rivers reach the Bay of Bengal, the coastal plains are wide and the sea is relatively shallow with weaker tidal currents. This combination of factors facilitates the deposition of the accumulated sediment at their mouths, leading to the formation of large, fertile deltas.
  • These deltas are highly productive agricultural regions, supporting dense populations and rich biodiversity, often characterized by intricate networks of distributaries.

• Absence of Deltas in West-Flowing Rivers:

  • In contrast, west-flowing rivers like the Narmada and Tapi flow through narrow rift valleys, over hard rocks, and have relatively steeper gradients. Their courses are shorter, and they carry less sediment.
  • The west coast of India is narrower, steeper, and characterized by a submerged topography. The Arabian Sea experiences stronger tidal currents and wave action.
  • Due to these factors, west-flowing rivers do not form deltas. Instead, they form estuaries. An estuary is a funnel-shaped mouth of a river where freshwater from the river mixes with saltwater from the sea, creating a brackish environment. The strong tidal currents effectively flush out any sediment, preventing delta formation.