Here is your short paragraph on the Indian coastal plains!
The narrow coastal strip between the edges of the Peninsular Plateau and the coastline of India running for a distance of about six thousand kilometres from the Rann of Kuchchh in the west to the Ganga-Brahmaputra delta in the east is called the coastal plains.
The area between the Western Ghats and the Arabian Sea coast is known a he West Coastal Plain and that between the Eastern Ghats and the Coast of the Bay of Bengal is died the East Coastal Plain. The two coastal plains meet each other at the southernmost tip i.e. Kanniyakumari.
The West Coastal Plains:
Stretching from Rann of Kuchchh in the north to Kanniyakumari in the South, there are narrow west coastal plains with an average width of about 65 km. It is quite narrow in the middle and a bit broader in the northern and southern parts. Depending upon relief and structure, it can be divided into following subdivisions.
The Kuchchh Peninsula was an island surrounded by seas and lagoons. These seas and lagoons were later filled by sediment brought by the Indus River which used to flow through this area. Thus, the island became a part of the mainland and comparatively broad plain was formed.
Some scholars do not consider it as part of the west coastal plains and treat it as a separate identity. There are other geographers who consider Kachchh and Kathiawar as part of the Peninsular plateau because Kathiawar is made of the Deccan Lava and there are tertiary rocks in the Kuchchh area.
The true west coastal plain, according to them, lies between Surat and Kanniyakumari for a distance of 1600 km. But the ground reality is that it is, more or less, a plain area and lies near the west coast of India. Hence it should be treated as an integral part of the West Coastal Plains.
Due to scarcity of rain and flowing surface water, the work of wind is felt everywhere and this has given rise to arid and semi-arid landscape. Coastal sand dunes, sandy plains, interrupted with bare rocky hills are the chief characteristic physiographic features.
All along the north of Kuchchh there lies a broad level salt-soaked plain. This is the Great Rann. Its southern continuation, known as the Little Rann lies on the coast and south-east of Kuchchh. The flat and unbroken Great Rann is about 320 km long with a maximum width of 160 km, covering an area of about 21,500 sq km. It rises only a few metres above the sea level and is flooded by the Banas and the Luni rivers during the rainy season.
Some places are actually below sea level and are inundated during high tides. Most of the area is formed of sun-baked dark silt encrusted with salt. A few patches of high ground are covered with grass and break the monotony of the otherwise flat plain.
The Kathiawar Peninsula lies to the south of the Kuchchh. It is encircled on the east and northeast by the Little Rann and the Nal Basin. The average elevation is less than 200 m. The central part is a highland of Mandav Hills from which small streams radiate in all directions.
Mt. Gimar (1,117 m), the highest point, is supposed to be of volcanic origin. The Gir Range is located in the southern part of the Kathiawar peninsula. It is covered with dense forests and is famous as the home of Gir lion.
The Gujarat Plain lying east of Kuchchh and Kathiawar slopes towards the west and south west. It may almost be described as an intrusion of Indo-Gangetic conditions into the Peninsula. Formed by the rivers Narmada, Tapi, Mahi and Sabarmati the plain includes the southern part of Gujarat and the coastal areas of the Gulf of Khambhat.
This is a low plain no part of which exceeds 150 m elevation. The eastern part of this plain is made of sediments and is fertile enough to support agriculture, but the greater part near the coast is covered by windblown loess which has given rise to semi-arid landscape. A chain of saline marshes near the coast is prone to floods during high tide.
The Konkan Plain south of the Gujarat plain extends from Daman to Goa for a distance of about 500 km with its width varying from 50 to 80 km. It has some features of marine erosion including cliffs, shoals, reefs and islands in the Arabian Sea.
Mumbai was an island but parts of the sea lying between the mainland and the island have been reclaimed in recent years to connect it with the mainland. The Thane creek of the Ulhas around Mumbai is an important embayment which provides an excellent natural harbour on the southern side of the island.
South of Mumbai, the Konkan coast has a series of small bays and coves lying between jutting head-lands containing beaches of sand. Behind the alluvial coastal belt, there is a series of parallel ridges reaching 450-600 m in which rivers like the Vaitami, Ulhas and Amba have lower courses more or less parallel to the coast before reaching it transversely. Some lateritic hillocks rise to 100 m above mean sea level.
The Karnataka Coastal Plain from Goa to Mangalore is about 225 km long. It is a narrow plain with an average width of 30-50 km, the maximum being 70 km near Mangalore. The central part of this plain is crossed by numerous spurs projecting from the Ghats.
These spurs approach so close to the coast that the breadth of the lowland is reduced to 5-7 km at 14°N latitude where the Ghat’s crest is only 13 km away from the sea. Running like ridges, the spurs attain heights of more than 600 m. near the Ghats.
At some places the streams originating in the Western Ghats descend along steep slopes and make waterfalls. The Sharavati while descending over such a steep slope makes an impressive waterfall known as Gersoppa (Jog) Falls which is 271 m high. Marine topography is quite marked on the coast.
The Kerala Plain also known as the Malabar Plain, between Mangalore and Kanniyakumari is about 500 km long. This is much wider than the Karnataka plain and at places it is 96 km wide. It is a low lying plain and at no place its height exceeds 30 m.
The existence of lakes, lagoons, backwaters, spits, etc. is a significant characteristic of the Kerala coast. The backwaters, locally known as kayals are the shallow lagoons or inlets of the sea, lying parallel to the coastline. The largest among these is the Vembanad lake which is about 75 km long and 5-10 km wide and gives rise to a 55 km long spit.
Kochi is situated on its opening into the sea. This and several other lagoons have been joined together by canals to provide excellent inland waterways from the mouth of the Ponnani to Thiru vananthapuram.
The East Coastal Plains:
Between the Eastern Ghats and the east coast of India are located the East Coastal Plains extending from the Subamarekha river along the West Bengal-Orissa border to Kanniyakumari. A major part of the plains is formed as a resuh of the alluvial fillings of the littoral zone by the rivers Mahanadi, Godavari, Krishna and Cauvery comprising some of the largest deltas.
Its western boundary is a discontinuous line of the Eastern Ghats, more precisely by the contours of 75 m in Orissa, 100 m in Andhra Pradesh and 150 m in Tamil Nadu. In contrast to the West Coastal Plains, these are extensive plains with an average width of 120 km although it may be as wide as 200 km in the deltaic regions and as narrow as 35 km in-between the deltas.
This plain is known as the Northern Circars between the Mahanadi and the Krishna rivers and Carnatic between the Krishna and the Cauvery rivers. Depending upon physiographic variations, the entire plain is divided into three regions.
The Utkal Plain comprising coastal areas of Orissa is about 400 km long. It includes the Mahanadi delta with Cuttack at its head. There is thick layer of alluvium covering this delta. The most prominent physiographic feature of this plain is the Chilka Lake in the south of the Mahanadi delta.
This lagoon on the Orissa coast is about 70 km long and its maximum width on the north-east is nearly 22 km narrowing to about 7 km on its south-western end. It is the biggest lake in the country and its area varies between 780 sq km in winter to 1,144 sq km in the monsoon months. South of Chilika Lake, low hills dot the plain.
The Andhra Plain lies south of the Utkal Plain and extends upto Pulicat Lake, some 40 km north of Chennai. This lake has been barred by a long sand spit known as Sriharikota Island, on which is located the satellite launching station of the Indian Space Research Organisation.
The lagoon is about 60 km long and about 16 km wide in its widest part. The most significant feature of this plain is the delta formation by the rivers Godavari and Krishna. In fact, the two deltas have merged with each other and formed a single physiographic unit.
The combined delta has advanced by about 35 km towards the sea during the recent years. This is clear from the present location of the Kolleru Lake which was once a lagoon at the shore but now lies far inland. This part of the Andhra plain is quite wide. Andhra plain has straight coast and badly lacks good harbours with the exception of Vishakhapatnam and Machilipatnam.
The Tamil Nadu Plain stretches for 675 km from Pulicat lake to Kanniyakumari along the coast of Tamil Nadu. Its average width is 100 km. The most important feature of this plain is the Cauvery delta where the plain is 130 km wide. The fertile soil and large scale irrigation facilities have made the Cauvery delta the granary of South India.
Significance of the Coastal Plains:
Large parts of the coastal plains of India are covered by fertile soils on which different crops are grown. Rice is the main crop of these areas. Coconut trees grow all along the coast. The entire length of the coast is dotted with big and small ports which help in carrying out trade.
About 98% of our international trade is carried through these ports. The sedimentary rocks of these plains are said to contain large deposits of mineral oil. The sands of Kerala coast have large quantity of monazite which is used for nuclear power. Fishing is an important occupation of the people living in the coastal areas. Low lying areas of Gujarat are famous for producing salt.