Coastal Plains, Desert and Islands
NCERT Class 9 - Contemporary India I, Chapter 2 • NCERT Class 11 - India Physical Environment
Coastal Plains, Desert and Islands
Between the plateau and the sea lie two coastal plains, very different in width and character. Beyond them lie two island groups of entirely different origin, and to the north-west of the Aravalli lies the Thar desert.
The two coastal plains
| Point | Western coastal plain | Eastern coastal plain |
|---|---|---|
| Width | Narrow, squeezed between the Ghats and the sea | Broad and level |
| Origin | Largely a submerged coast | Largely an emergent coast |
| Rivers | Short, swift streams with no deltas | Large rivers forming wide deltas |
| Ports | Natural harbours are possible because the water is deep | Fewer natural harbours; ports often need dredging |
| Divisions | Kachchh and Kathiawar, Konkan, Kannad and Malabar | Northern Circar in the north, Coromandel in the south |
- The Malabar coast in the far south is famous for its backwaters, called kayals, which are used for fishing, inland navigation and tourism.
- The eastern plain carries the deltas of the Mahanadi, Godavari, Krishna and Kaveri, which are among India's most productive agricultural regions.
- Chilika lake, on the Odisha coast, is the largest brackish water lake in India.
- Because the western coast is submerged and the eastern emergent, the west has better natural harbour sites despite being narrow.
The Indian Desert
- The Thar desert lies west and north-west of the Aravalli, mainly in Rajasthan.
- Rainfall is very low and erratic, generally below about 150 millimetres a year, and the climate is arid with a large temperature range.
- Its landforms include barchan and longitudinal sand dunes, and the surface streams that appear briefly after rain are called nalas.
- The Luni is the only river of any size, and it too is seasonal and drains into the Rann of Kachchh.
- The Aravalli lies across the path of the monsoon rather than facing it, so it fails to force the moist air upward and the region remains dry.
The islands
- Lakshadweep lies in the Arabian Sea, close to the Malabar coast. Its islands are of coral origin, built on submerged volcanic foundations, and are small, low and surrounded by reefs. Minicoy is the largest of the group.
- Andaman and Nicobar lie in the Bay of Bengal and are far larger and more scattered. They are the exposed tops of a submerged mountain range, and one of them, Barren Island, holds India's only active volcano.
- The Ten Degree Channel separates the Andaman group from the Nicobar group.
- Indira Point, on Great Nicobar, is the southernmost point of Indian territory.
- The islands are covered with dense equatorial forest, have great biodiversity, and are home to several protected tribal communities.
- Their strategic importance is high, since they command the approaches to the Strait of Malacca and extend India's exclusive economic zone far into the Bay of Bengal.
हिंदी संकेत: लक्षद्वीप प्रवाल मूल का है और अंडमान-निकोबार जलमग्न पर्वत शृंखला के शीर्ष हैं। दोनों की उत्पत्ति बिल्कुल अलग है - यही सबसे अधिक पूछा जाता है।
Exam me kaise aata hai
Match-the-following on coastal section and its region is standard. Factual questions ask which channel separates the Andaman from the Nicobar group, where Barren Island lies, and which is the largest brackish water lake. Statement-based questions compare the two coastal plains.
UPSC / State PSC ke liye
Note the strategic and economic dimension of the islands - they extend India's maritime zone, sit near one of the world's busiest shipping straits, and support fragile coral and forest ecosystems that limit how far they can be developed. This tension between strategy, ecology and tribal rights is the standard analytical frame.
Yahan confuse hote hain
✗ The Andaman islands are of coral origin | ✓ Lakshadweep is coral; the Andamans are the tops of a submerged mountain range
✗ The eastern coastal plain is narrower than the western | ✓ The eastern plain is broader
✗ The Luni flows into the Arabian Sea directly | ✓ It is seasonal and drains into the Rann of Kachchh
Ek nazar me
- Western coastal plain is narrow and submerged; the eastern is broad and emergent.
- Western divisions - Kachchh and Kathiawar, Konkan, Kannad and Malabar with its kayals.
- Eastern divisions - Northern Circar and Coromandel, with the great east flowing deltas.
- Chilika is the largest brackish water lake in India.
- The Thar lies west of the Aravalli, has very low rainfall, and the Luni is its only large river.
- Lakshadweep is of coral origin; the Andaman and Nicobar islands are a submerged mountain range.
- Ten Degree Channel separates the two island groups; Indira Point is the southernmost territory.
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