Coastal Plains: Western Coastal Plains and Eastern Coastal Plains, Broader

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Coastal Plains

Two divisions:

  • Western coastal plains
  • Eastern Coastal Plains

Western Coastal Plains

  • Submerged coastal plain. Hence, a narrow belt. Narrow in middle and broader towards north and south.
  • Ports: Provides natural conditions for the development of ports and harbours due to submergence. Kandla, Mazagaon (Mumbai) , JLN port Navha Sheva, Maramagao, Mangalore, Cochin etc.
  • Mumbai has the world՚s largest natural harbour.
  • May be divided into: Kachchh and Kathiawar coast in Gujarat, Konkan coast, Goan coast and Malabar coast.
  • Rivers don՚t form delta.
  • Kayals (Backwaters) : Found in the Malabar coast. Used for fishing and inland navigation. Every year Nehru Trophy Vallamkali (boat race) is held in Punnamada Kayal in Kerala.

Eastern Coastal Plains


  • Emergent coast. Hence, a smaller number of ports and harbours. Chennai, Vizag, Paradwip, Haldia.
  • Delta formation

The Islands

Two major Divisions:

  • Andaman and Nicobar
  • Lakshwadeep & Minicoy

Andaman and Nicobar

  • Two major island groups: Ritchie՚s archipelago and the Labrynth island.
  • The group is divided into: Andaman in the North and Nicobar in the South.
  • Andaman and Nicobar separated by the Ten Degree channel.

Barren Island

  • Peaks: Saddle Peak (N. Andaman – 738 m) , Mt. Diavolo (Middle Andaman – 515 m) , Mt. Koyob (S Andaman – 460 m) and Mt. Thuiller (Great Nicobar – 642 m)
  • Coral deposits found
  • Convectional rainfalls and equatorial type of vegetation.

Lakshadweep and Minicoy

  • Entire group built of coral deposits.
  • Total of 36 islands of which 11 are inhabited.

Smallest UT

  • Minicoy is the largest island.
  • Separated by the 9 Degree Channel, north of which is the Amini Island and to the south Canannore island.
  • These islands have storm beaches consisting of unconsolidated pebbles, shingles, cobbles and boulders.

Drainage System

  • Drainage: Flow of water through well-defined channels. Network of such channels is called a drainage system .
  • Drainage basin: An area drained by a river and its tributaries.
  • Watershed: Boundary line separating one drainage basin from other.
  • River basins are larger watersheds.
  • Drainage pattern of an area depends on the geological time period, nature and structure of rocks, topography, rocks, slope, amount of water and periodicity of flow.

Important drainage patterns:

  • Dendritic: Resembling the branches of a tree. E. g. Northern Plain rivers
  • Radial: Originate from a hill and flow in all directions. E. g. Rivers in Amarkantak
  • Trellis: Primary tributaries parallel to each other and secondary tributaries join them at right angles.
  • Centripetal: Rivers discharge waters from all directions in a lake or depression

A river drains the water collected from a specific area, which is called its catchment area.

Nearly 77 pc of drainage is towards the Bay of Bengal while about 23 pc is towards the Arabian Sea.

The Himalayan Drainage System

  • Mainly includes the Ganga, Indus and Brahmaputra river basins.
  • Over the plains, rivers of this system change the course often. River Kosi is also known as the ‘sorrow of Bihar’ due to flooding by its frequent change of course by deposition of sediments.

Developed by: