Write a note on the Coastal lowlands of India.

 The Plateau of Peninsular India is fringed with narrow coastal lowlands. Raised beaches and wave-cut platforms above the high water mark signify that these lowlands are essentially the emerged floors of the seas adjacent to the land. After the emergence of these lowlands, fluctuations in sealevel, though limited to small areas, have brought some changes in the general surface features of the littoral (shore areas). The west and east coastal lowlands are described below:

West Coastal Lowlands

The physiography of West coastal lowlands is varied. It contains marshes, lagoons, mud-flats, peninsulas, creeks, gulfs and islands. The Rann of Kutch, the peninsulas of Kutch and Kathiawar and the Gujarat Plain are the major physiographic regions.

The Rann of Kutch lies to the north of Kutch. Earlier a gulf and now a vast desolate lowland it was formed due to the deposition of silt brought mainly by the Indus in the past. Its surface is only slightly above sealevel and is interspersed with mudflats, marshes and creeks. It is covered with shallow water during the rainy season and is being continuously filled up by the silt brought by the rivers. There are a few islands in the Rann, with Bela, Khadir and Pachham islands as the only ones of significant size.

Kutch, once an island, lies to the south of the Rann of Kutch. It is an arid area with generally broad sandy terrain along the coast and the Rann of Kutch and bare low rocky ridges in the interior. Kathiawar is located to the south of Kutch. It is hilly in the central part and elsewhere it is a rolling plain. Gorakhnath in the Girnar Hills in Junagadh is the highest peak in Kathiawar. The Gir Hills extending in the east-west direction lie to the south of Kathiawar and are connected with a broad hill-mass lying further north in the central part of Kathiawar which runs north-south forming a low narrow dissected range. In the north-east there is a belt of low country which is marked by Lake Nal and Marshes.

Along with several small rivers, long rivers like, the Tapti, the Narmada, the Mahi and the Sabarmati deposit enormous load of sediments in the Gulf of Cambay leading to siltation of the gulf. This has resulted in the creation of a broad fertile alluvial plain north of Daman extending towards north up to the Aravalli Range and termed as the Gujarat Plain. South of Daman, the coastal lowland narrows to a width of around 50 km, which occasionally broadens by a few kilometres at places where streams have gnawed back into the steeply rising Western Ghats. Between Daman and Goa the western littoral is called the Konkan. Coastal lowlands of Goa and the Konkan, to the south of Bombay are marked with the low hills separated by river courses which form creeks near the sea. The fact that the drowning of the lower courses of the rivers has taken place clearly suggests that there has been some recent submergence, though on a small-scale, of the coast, north of Marmagao.

Coastal plain in the vicinity of the Palghat Gap and in the south of Kerala is relatively broad reaching to a width of 96 km. Off-shore bars have enclosed lagoons which run parallel to the coast in southern Kerala and are known as Kayals. These lagoons receive water of a large number of rivers before discharging that to the sea with which they are connected by narrow openings. Formation of lagoons and off-shore bars indicate that there has been a slight emergence of southern coastal plain not in the very distant past.

The West coastal lowland south of Surat is drained by several small rivers, which become torrents during the monsoon. In the normal course these torrents should have formed deltas. However, as at this time strong sea-waves also develop due to south-west monsoon winds and these waves having an unusually great scouring power, the mouths of the rivers are desilted and thereby impede the formation of deltas on the west coast. Instead of deltas, long off-shore bars which enclose lagoons, particularly in the south, develop as suggested above.

East Coastal Lowlands

East coastal lowlands is broad compared to the western lowlands and it is broadest in Tamil Nadu where its width ranges from 100 to 120 km. North of the Godawari Delta the coastal lowland is narrow as the Eastern Ghats closes on the sea. At some places it is as narrow as 32 km. in width. Since the Plateau of Penninsular India, especially of the Satpura Range, is tilted to the east, all rivers of the Deccan with the exception of the Tapti flow eastwards and reach the Bay of Bengal. These rivers have spread alluvium over almost whole of this plain and have built large deltas at several places. Sea waves being far less furious than those impinging on the west coast, the sediments brought by large rivers – the Mahanadi, the Godavari, the Krishna and the Kaveri have formed deltas. These deltas being fertile and properly irrigated are densely peopled. At some places spits, lagoons and off-shore bars have also developed along the coast. The coast is fringed at some places with dunes. Mangrove forests grown along the seaward front of the deltas have been a major characteristic. As the sea is shallow near the emerged lowland coasts, deep natural harbours except Bombay and Marmagao are absent along both the coasts.

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