CHAPTER 1: India: Physical Aspects
India is a country of great geographical extent. It stretches from the snow-capped Himalayas in the North to Sun-drenched coastal villages of the South, the humid tropical forests on the South-West coast, the fertile Brahmaputra valley on its East to the Thar desert in the West.
Lying entirely in the Northern hemisphere, the mainland extends between 8°4’ N and 37°6’ N latitudes and 68°7’ E and 97°25 ’ E longitudes and measures about 3214 km between North and South extreme latitudes and about 2933 km between East and West extreme longitudes. It has a land frontier of about 15200 km. The total length of the coastline of the mainland, Lakshadweep islands and Andaman and Nicobar islands is 7516.6 km.
Countries having a common border with India are Afghanistan and Pakistan to the North-West, China, Bhutan and Nepal to the North, Myanmar to the far East and Bangladesh to the East of West Bengal. Sri Lanka is separated from India by a narrow channel of sea formed by the Palk Strait and the Gulf of Mannar.
The country can be divided into six zones, mainly North, South, East, West, Central and North-East zone. It has 28 states and 8 Union territories.
The terms ‘Indian sub-continent’ and ‘South Asia’ are often used interchangeably. It includes India, Pakistan, Bangladesh, Nepal, Maldives, Bhutan, Sri Lanka and sometimes, even Afghanistan. Indian Standard Time is calculated on the basis of 82.5° E longitude. It passes near Allahabad. It is 5 hours 30 minutes ahead of Greenwich Mean Time (GMT). Geological Structure
The geological structure, which includes the arrangement and deposition of rocks in the Earth’s crust, plays a dominant role in determining the relief of land and nature of soil.
It also helps in knowing about the vast mineral wealth buried beneath the Earth’s surface. Some rocks are badly deformed and metamorphosed, while others are recently deposited alluvium that has yet to undergo diagenesis.
Indian rocks can be divided into following categories based on their formation in different periods of the Geological Time Scale (GTS):
The Archaean Rock System
These are the oldest rocks of the Earth crust. They have been found at the bottom of the stratified (sedimentary) deposits in all countries of the world.
They are often called as the fundamental complex or the basement complex. They form the foundation of all ancient plateaus and core of all remove folded mountain ranges of the world, including Great Himalayas.
Distribution in India The Archaean rocks are found enormously in the Peninsular India— Odisha, Madhya Pradesh, Chhattisgarh, Chota Nagpur plateau, Meghalaya plateau, Bundelkhand from North of Vadodra (Baroda) to the Aravallis of Rajasthan and the whole length of the Himalayas with the exception of Sikkim.
Archaean systems are devoid of any form of life, they are all azoic or unfossiliferous.
The Dharwar System
In The state of Karnataka is the district of Dharwar where these rocks were first studied.
These are the most ancient metamorphosed sedimentary rocks.
he major rocks of the Dharwar system are hornblende, schist, quartzite, slates and dolomite.
They are highly metalliferous and rich in iron ore, manganese, lead, zinc, gold, silver, mica, copper, precious stones and building material. The Dharwar rocks are also found in Bellary and Mysore (Karnataka).
Kolar Gold Fields are located in Kolar district of Karnataka, where mining is done to the depth of more than 3.5 km, which is one of the deepest in world.
These rocks are also found in Jharkhand, Bastar (Chhattisgarh), Sundergarh, Keonjhar (Odisha), Jaipur, Palanpur (Rajasthan) and Meghalaya plateau.
The Cuddapah System
These rocks are typically found in the Cuddapah district of Andhra Pradesh. Apart from Cuddapah district, they are also found in Kurnool district (Andhra Pradesh), Chhattisgarh, Singhbhum (Jharkhand), Kalahandi and Keonjhar (Odisha) and Aravallis.
The Cuddapah rocks are rich in iron, copper, manganese, cobalt, nickel, asbestos, jasper and quartzites.
These rocks are also generally without fossils. The metallic contents in the ores of Cuddapah are low and at places uneconomical for extraction.
The Vindhyan System
The Vindhyan system extends from Sasaram and Rohtas in Bihar to Chittorgarh in Rajasthan. The mountains form the boundary line between the Ganga plain and the Deccan plateau.
They are also found in Bastar, Bhima valley (Karnataka) and Kurnool district (Andhra Pradesh).
The metallic minerals are not found in them, but are rich in durable stones like flagstone, ornamental stones, diamondiferous (well known diamond mines of Panna and Golconda), limestone, pure glass making sand, red sandstone, sandstone, building material and raw material for cement and chemical industries.
The Dravidian Rock System (Palaeozoic: 600-300 Million Years Age)
This system consists of the following: — Cambrian rocks Best developed in North-West Himalayas, Spiti valley, Kullu and Lahaul (Himachal Pradesh) Baramulla (Kashmir) and Kumaun hills (Uttaranchal). Sandstone, shales and dolomite are the main rocks.
— Ordovician rocks Developed in spiti valley, Lidder valley, Kumaon region. Quartzite, sandstone, grits and limestones are the main rocks.
— Devonion rocks Developed in Spiti valley and Kumaon. Quartzite is the main rock.
— Carboniferous rocks Developed Spiti valley, Kashmir, Shimla, Pir-Panjal, Kumaon, Chotanagpur plateau and Chhattisgarh. Sandstone, limestone, clay, shale and coal are the main rocks.
First discovered in Gond region of Madhya Pradesh, consists of sandstones, shales and clay. They also have rich deposits of iron ore, copper, uranium, antimony, sandstone, slate and conglomerates.
The Gondwana rocks are found in the Damodar valley, Mahanadi valley and along Godavari from Nagpur to its delta. Most of the good quality of coal deposits (bituminous and anthracite) are found in this area. About 98% of the coal of India is found in them. In the Himalayas, they are found in Kashmir, Darjeeling and Sikkim.
The Deccan Trap (Cretaceous Period)
Sprawling over Kachchh, Kathiawar, Gujarat, Madhya Pradesh, Maharashtra and parts of Andhra Pradesh, Telangana. It is made of lava deposits and has a thickness of about, 3000 m and covers over 5 lakh sq km of area.
It is the result of intense volcanic activity, in which large quantity of basaltic lava outpoured slowly (placid or Hawaiian type), which assumed such a great thickness. Basalt obtained from here are used for building road.
The regur soil developed on it, Which is good for cotton cultivation.
Recent Formations (Pleistocene)
The Indo-Gangetic plain, Valley of Kashmir, Dun valley, Brahmaputra valley (massive beds of clay, sandy or calcareous silt, mud and sand). Recent formations are divided into Bhangar-old alluvium and Khadar–new alluvium.
Physiography of India
The Indian mainland can be divided into five physiographic units as follows:
(i) The Great Himalayas of North
(ii) The Great Plains of North India
(iii) The Peninsular Plateau
(iv) The Coastal Plains
(v) The Islands
The Great Himalayas of North
Regarding the evolution of Himalayas, the Geosynclinal Theory of Kober and the Plate Tectonics Theory of Harry Hess are considered most acceptable. According to the Plate Tectonic Theory of Harry Hess — There was a marginal sea called Tethys sea in place of the Himalayas and it separated the Angara land in the North and Gondwana land in the South. The Indian plate was attached to the Gondwana land. About 70 million years ago, the Indian plate in the South moved in the North-Eastern direction towards the Eurasian plate. About 20-30 million years ago, these two landmasses got very close, due to which the sediments in the Tethys sea got folded and Himalayas were evolved.
— By about 10 million years before present, all the ranges of Himalayas got fully developed. The Greater Himalayas were formed in the Eocene and Oligocene periods of the Cenozoic era. The Lesser Himalayas were formed due to folding of the Potwar sediments in the Miocene period. The Shiwaliks were formed in the Pliocene period due to the sediments brought from the Greater and the Lesser Himalayas.
— The evolution process continued in the Pleistocene and Holocene period of the Neozoic or Quaternary era. Himalayas are in fact young mountains, which are still in the evolutionary process. The earthquakes in this region, continuous change of course by the Himalayan rivers and the lake deposits called Karewas found in the Pir Panjal range at a height of 1500-1850 m indicate towards the on-going process of the evolution of Himalayas.
These ranges have been formed even before the formation of Himalayas. These are especially found in the Western part of Himalayas.
It includes the Karakoram, Ladakh, Zanskar ranges etc. Mount K2 or Mount Godwin Austen (8611 m) is the highest peak of India, situated in the Karakoram range. Moreover, Trans-Himalaya is separated from the Great Himalaya by the Suture zone.
The Himalayas extends from Nanga Parbat in the West to Namcha Barwa or Mishmi hills in the East. There are two syntaxial bends like Hair-pin Turns.
These bends have been formed due to the pressure exerted by the Peninsular plateau in the North-Eastern direction. These ranges have convex slope towards the Peninsular Plateau and concave slope towards the Tibetan Plateau.
The width of the mountain chain decreases from the West to East, but its height goes on increasing in the same direction. The Greater Himalayas or the Higher Himalayas
This is the highest range of Himalayas. The average height of this range is 6000 m whereas its width is 120-190 km. Most of the world’s important peaks are located in this range. Major peaks are Mount Everest (8848.86 m), Kanchenjunga (8586 m), Mount Nanga Parbat, Nanda Devi, Kamet and Namcha Barwa. The highest peak of the world is Mount Everest, located in this range (in Nepal).
Moreover, the Greater Himalayas are separated from the Lesser Himalayas by the main central thrust.
The Lesser Himalayas or the Lower Himalayas
The average height of this range is 3700 – 4500 m and its average width is 80-100 km. This range includes the peaks such as Pir Panjal, Dhauladhar, Mussoorie, Nag Tibba and Mahabharat.
The Lesser Himalaya is famous for its scenic and healthy hill stations, e.g. Shimla, Kullu-Manali, Mussoorie and Darjeeling etc. Moreover, the Lesser Himalayas are separated from the Shiwaliks by the main boundary fault.
Shiwaliks (The Outer Himalayas or the Sub-Himalayas)
This range is 10-50 km wide and 900-1200 m high. Unlike above two ranges, this range is not continuous. This is the most recent part of Himalayas.
Between Shiwalik and Himachal, there are several valleys, e.g. Kathmandu valley. In the Western side, these valleys are called as Duns and Duars in Eastern side. e.g. Dehradun and Haridwar. Since, these valleys have fertile soils, so they are densely populated. The lower parts of Shiwalik are called Terai. It is a marshy area covered with thick forest covers. To the South of the Terai region is found the Great Boundary Fault, which extends from Kashmir to Assam.
The Eastern Hills or Purvanchal
These highlands consists of hill ranges which passes through Eastern Arunachal Pradesh and states having common border with Myanmar (Burma).
In the North, lies a high mountainous land called Dapha Bum (highest point 4578 mts). The Patkai Bum starts from the Southern end of the Dapha Bum, after running for some distance along the Indo-Burma boundary. It merges into Naga range. Saramati (3826 mount) is the highest peak of the Naga range.
The Patkai Bum and Naga Range forms the water shed between India and Burma.
Further South, this mountainous belt is called Manipur Hills (generally less than 2500 m in elevation) in Manipur state, the Mizo Hills (previously known as Lushai hills) in Mizoram and Tripura hills in Tripura. Height of the range falls gradually Southwards. The range and the valleys runs generally in North-South direction.
The Great Plains of North India
It is also called the Indus-Ganga Brahmaputra plain. It extends for a distance of about 3200 km and its width varies from 150 km to 300 km. The Great Plains of North India were formed in the Pleistocene and Holocene periods of the Neozoic or Quaternary era. This is the most recent geographical unit of India. These plains have been formed by the process of Tethys sea becoming narrower and shallower and by the deposition of sediments brought by the peninsular rivers.
These plains are almost featureless and attains a maximum height of 204 m. The land around Ambala acts as the water divide in this plain, because the rivers on its Eastern side drain into the Bay of Bengal and those on its Western side drain into the Arabian sea.
On the basis of characteristics of the alluvium, surface gradient, drainage channels and regional traits, this plain is divided into the following four parts:
(i) Bhabar region This region is found along the foothills of Shivaliks from Indus to Tista without any break. Its width is 8-16 km. Since, it is made up of stones and pebbles, it is highly porous which make rivers disappear beneath the ground in this region.
(ii) Terai region This region is found to the South of the Bhabhar region. The underground streams of the Bhabar re-emerge on the surface and give birth to marshy area. The speed of river flow in this region is slow. This is the region of dense forests and high biological diversity.
(iii) Khadar region It is made up of new alluvium. In this region, floods bring new alluvium every year. Khadar region is generally found in the delta regions. e.g. the Ganga-Brahmaputra delta spread in India and Bangladesh is a Khadar region.
(iv) Bhangar region It is that higher part of the plains, where the flood water cannot reach. It is made up of old alluvium. It is often seen in the structure of a terrace.
It refers to a tract of land lying between two converging or confluent rivers. In the Western region of seven rivers, where Aryan settled first, the sequence of doabs from West to East are is Sindhu Sagar doab of Indus and Jhelum, Chhaj doab of Jhelum and Chenab, Rechna doab of Chenab and Ravi, Bari doab of Ravi and Beas, Bist doab of Beas and Sutlej.
The Northern Plain
This lies to the West of the Indus river. It is mainly made up of the old alluvium i.e. Bhangar. Dhoros and Dhands are important feature here. Dhoros are depressions formed by the former rivers and Dhands are alkaline lakes.
This plain is located to the East and North-East of the Great Indian Desert (Thar) and West of the Yamuna river. A part of this plain is made-up of doabs from East to West. Intensive agriculture is practiced in this region.
It is very vast and the largest unit of the Great Plain of India. According to conveniece it is divided into three sub-divisions, namely, Upper Ganga Plain, Middle Ganga Plain and Lower Ganga Plain. Upper Ganga Plain comprises course of Yamuna river, Middle Ganga Plain comprises Eastern Uttar Pradesh and Bihar and Lower Ganga Plain covers some districts of Bihar and whole of West Bengal.
Thar or Great Indian Desert covered by sand dunes is the Westernmost region of Great Indian Plains in the Western Rajasthan. A semi-arid plain, lying to the East of Thar desert is known as Rajasthan Bagar. The Luni is the only South-West flowing river of this region. The Sambhar (largest), the Kuchaman and the Didwana are important lakes situated to the North of Luni Basin.
The low plains formed by the Brahmaputra river system is situated between Eastern Himalaya (Arunachal Pradesh) in the North, Patkai and Naga hills in the East, Garo-Khasi-Jaintia and Mikir hills and lower Ganga plain and Indo-Bangladesh border in the West.
The Peninsular Plateau
Covering an area of about 16 lakh sq km, the peninsular uplands form the largest physiographic divisions of India. It is a part of the ancient Gondwanaland and is triangular in shape. With a general elevation between 600-900 m, the region constitute an irregular. traingle with its base lying between Delhi ridge in the West and Rajmahal hills in the East, with a part of its Northern portion buried under the alluvilium of Ganga and Yamuna.
It is bounded by the Aravallis in the North-West, Hazaribagh and Rajmahal in the North-East, the Western ghats (Sahayadri) in the West and Eastern ghats in the East.
The Peninsular plateau of India is divided into several parts Central highlands, Deccan plateau, Eastern plateau, Western ghats and Eastern ghats.
The Central highlands are a wide tract of hilly country that includes the Rajasthan uplands, the Madhya Bharat plateau, the Bundelkhand uplands, the Malwa plateau bounded by Aravalli range in the West and the Satpura range in the South. The highest peak of Aravallis is Gurushikhar (1722 m) near Mount Abu (1158), being the only hill station of Rajasthan.
Vindhyan range flanking the Narmada-Son Rift is an escarpment trending East-West, acts as a watershed between the Ganga system and the river system of South-India and forms the Northern boundary of Deccan.
Satpura range lies between the valley of Narmada in the North and the Tapti in the South. Dhupgarh (1350 m, near Pachmarhi) is the highest peak of Satpura. Amarkantak (1064 m) is another important peak of Satpura.
Eastern plateau consists of Chota Nagpur plateau, Meghalya plateau, Mahanadi basin and Dandakarnya. The rivers, which drain the Chotanagpur plateau are Damodar, Subarnarekha, Barkar and Koel (North Koel and South Koel).
The Damodar river divide the plateau into two parts: Northern part is called Hazaribagh plateau and the Southern part is called Ranchi plateau. Highest point of the Hazaribagh plateau is Parasnath (1366 m).
Meghalaya plateau the Western part is called the Garo hills and the Central part—the Khasi-Jantia hills. In the North, it is bounded by Mikir and the Rengma hills. Shillong (1961 m) is the highest elevation of this plateau. Nokrek peak (1515 m) is the highest of Garo Hills.
Sahyadris or the Western Ghats occupy most of the Maharashtra plateau while Archean crystalline are spread over rest of the Deccan. The entire region of Karnataka plateau except for a small portion is included in the Deccan Lava region.
The Eastern part of the Karnataka plateau region is moderately large in size and low in elevation. It is known as Maidan whereas the Western part, which is lying close to the Western ghats is known as Malnad.
Western ghats run in North-South direction, parallel and close to Arabian sea coast from the Tapi valley to a little North of Kanniya kumari.
The important peaks of Western ghats include Kalsubai (1646 m), Salher (156 m)’ Kudermukh, Doda Betta (Nilgiri hills), Anaimudi (Annamalai Hills).
Eastern ghats bordering the Eastern edge of the Deccan plateau, runs. almost parallel to the East coast of India leaving broad plains between their base and the coast. It is a chain of highly broken and detached hills starting from the Mahanadi in Odisha to the Vaigai in Tamil Nadu. It is only in the Northern part, between the Mahanadi and the Godavari, that the Eastern ghats exhibit true mountain character. Difference Between Western and Eastern Ghats
The Coastal Plains
The Indian Peninsular plateau is fringed with narrow coastal plains. Eastern coastal plains runs from Tamil Nadu to West Bengal in the East. Western coastal plains extends from Gujarat in the West to Maharashtra, Goa and Kerala. Eastern coastal plains lies between the Eastern ghats and the Bay of Bengal, and is more extensive and wider than its Western counterpart. They represent an emergent coast, while its Western counterpart is an example of submergent coast.
The Northern Circars, amidst the Krishna river and the Mahanadi river is the Northern part of Eastern coastal plains. While the Southern part, the Coromandel coast, runs between the Cauvery and Krishna river. Utkal plains include Mahanadi delta and Chilika lake. Andhra plain extends from South of Utkal plain and continue upto Pulicat lake. Tamil Nadu plain extends from Pulicat lake to Kanniyakumari.
The Western coastal plain lies between Kerala and Gujarat and stretches from the Arabian sea to the Western ghats. These plains feature plentiful rivers and backwaters which result in forming estuaries. The Gulf of Kachchh and the Gulf of Khambat lie on the Northern part. The Western coastal plain is separated into three major parts: the Malabar coast, the Konkan coast and the Gujarat coast.
Difference between western coastal plains and eastern coastal plains
Great Rann (broad level salt soaked plain in the North of Kachchh) and Little Rann (Southern continuation of Great Rann) border the Kachchh on all sides except in the West and the South. The Luni and Banas rivers discharge into Rann forming inland drainage during rainy season.
Kathiawar peninsula lies South of Kachchh with the central part consisting of highland (Mandav hills). Mount Girnar (1117 m) is the highest point. Gujarat alluvial plain is formed by the rivers Narmada, Tapi, Mahi and Sabarmati.
From South of Gujarat plain, Konkan coastal plain extends from Daman to Goa. It is widest near Mumbai. Karnataka coastal plain extends from Goa to Mangalore. Kerala plain (Malabar plain) extends from Mangalore to Kanniya kumari.
The islands of India constitute Andaman and Nicobar group of islands (Bay of Bengal), Lakshadweep islands (Arabian sea), riverine and off-shore islands.
Majuli, the world’s largest river island, is present in Jorhat district in the Brahmaputra river, Assam.
Andaman and Nicobar group of islands are thought to be part of Himalayan system and extension of the Arakan Yoma range. The Andaman Islands and the Nicobar Islands are separated by the 10°N latitude (10° channel). The tribes of the Andaman group of islands includes the Great Andamanese, Onges, Jarawas and Sentinelese, all of Negrito origin, while the tribes of Nicobars are the Nicobarese and Shompens, both of Mongoloid stock.
Saddle Peak is the maximum elevated point of the island group, 750 m; located in North Andaman island. Indira Point is the Southernmost point of Indian territory, located in Great Nicobar Island 6.7° N 93.8°E. Barren island, the only active volcano in South Asia, is a part of Andaman group of island.
Narcondam island, a dormant volcano, is a part of Andman group of island. Great Andaman is separated from little Andaman by Duncan passage.
The Arabian sea islands constitutes Amindivi group islands (consisting of Amini, Keltan, Chetlat, Kadmat, Bitra and Perumal Par) and the Laccadive group islands (comprising mainly Abdroth, Kalpeni, Kavaretti, Pitti and Suheli Par).
Minicoy island, the largest of the Arabian sea group of islands and Southernmost of the union territory of Lakshadweep, is separated from the rest by 9° Channel. Lakshadweep islands are of coral origin, which have been developed around volcanic peaks.
Drainage basins are those areas, in which water is concentrated and flows into the drainage network. The drainage system of India may be divided into the Peninsular drainage and the Extra-Peninsular drainage or the Himalayan drainage system.
The Himalayan Drainage System
The Himalayan drainage system comprises all the international rivers of India, i.e. the Indus, the Ganga and the Brahmaputra.
Most of these rivers and their major tributaries are perennial in character, obtaining their water from the glaciers, springs and rains.
These rivers are in their youthful stage carving out a number of erosional landforms like waterfalls, cataracts, rapids, gorges, steep-sided valleys, alluvial fans and river terraces.
The regimes of these rivers exhibit wide seasonal fluctuations, causing devastating floods, especially during the season of general rains.
Most of the rivers, which rise in the Himalayas are antecedent in nature. These antecedent rivers existed and flowed before the Himalayas were formed.
The Peninsular Drainage System
The Peninsular drainage system comprises the Mahanadi, the Godavari, the Krishna, the Cauvery and other numerous West flowing rivers.
The drainage of the Peninsular India is much older than that of the Himalayan drainage system. They are mostly seasonal. Their erosional and carrying capacity is low. Their channels are more defined and are close to the base level.
The Indus System
The Indus also known as Sindhu has one of the largest river basins of the world, covering an area of 1165000 sq km. In India, it is 321289 sq km and a total length of 2880 km (in India 1114 km). It originates from a glacier near Bokhar Chu in the Tibetan region, in the Kailash mountain range.
It cuts across the Ladakh range and formed a gorge near Gilgit in Jammu and Kashmir.
The Shyok, Gilgit, Zaskar, Nubra, Shigar and Dras are the major tributaries in the upward region. Afterward, Indus flows Southward and receives Panjnad a little above Mithankot. The Panjnad is the name given to the five rivers of Punjab, namely Stlej, Beas, Ravi, Chenab and Jhelum.
It finally discharges into the Arabian sea, East of Karachi. The Indus flows in India only through the Leh district in Jammu and Kashmir.
Jhelum rises from verinag at Pir Panjal range. It flows through Srinagar and Wular lake. It joins Chenab near Jhang in Pakistan.
Chenab (1180 km) is the largest tributary of Indus. It is formed by two streams: Chandra and Bhaga, which joins at Tandi near Keylong in Himachal Pradesh. It also receives water from Bara Shigri glacier.
Ravi originates from Rohtang pass in Kullu hills of Himachal Pradesh and flows through the Chamba valley before joining Chenab near Sarai Sidhu in Pakistan.
Beas originates from the Beas Kund near Rohtang pass. The river flows through the Kulllu valley in the Dhauladhar range. It meets Sutlej near Harike in the Punjab plain.
Sutlej originates in the Rakas lake near Mansarovar in Tibet. It passes through the Shipki La in the Himalayan range. It is an antecedent river, it feeds the canal system of the Bhakra Nagal project.
Some rivers of India do not reach up to the sea and constitute inland drainage. These rivers are mostly present in the drier regions of the country like Western Rajasthan, Ladakh and Aksai Chin etc. Ghaggar river is the most important example of inland drainage. It is a seasonal stream rising from the lower slopes of Himalayas and is said to flow on the dried bed of ancient river Saraswati. It forms boundary between Punjab and Haryana for much of its length and gets subsumed in Rajasthan desert.
Inter-State River Water Disputes
Though India has vast water resources, but these are unevenly distributed. Most of the Himalayan rivers are large, are fed from glaciers and thus, perennial whereas Peninsular rivers are seasonal and unable to fulfil overwhelming demands of its riparian states during dry seasons.
Excessive demand lack of proper supply of waters and their utilisation in, different sectors such as irrigation and hydropower projects is what causes disputes between riparian states of a river.
National Water Grid
It has been proposed in order to cure the woes of disputing states. Such a grid of implemented, will connect the major Himalayan rivers with the Peninsular rivers by means of a network of canals. It envisages connecting 26 rivers by constructing 30 different link canals.
The surplus water of Himalayan, rivers which causes flooding in Northern plains would be carried over to the water starved drier Peninsular counterparts. But such a project faces environmental concerns and political difficulties.
Climate of India
The climate of India is described as monsoon type. Despite an overall unity in the general pattern, there are perceptible regional variations in climatic conditions within the country. It varies from very cold conditions of the Northern Himalayan belt to hot climate of Rajasthan desert to moderate of equable climate of the coastal areas. Some regional variations in temperature, winds and rainfall are as follows:
— Temperature While in the summer the mercury occasionally touches 55°C in the Western Rajasthan, it drops down to as low as minus 45°C in winter around Leh. In general, coastal areas experience less contrast in temperature conditions. Seasonal contrasts are more in the interior of the country.
— In certain places, there is wide difference between day and night temperatures. In the Thar desert, the day temperature may rise to 50°C and drop down to near freezing point the same night. On the other hand, there is hardly any difference in day and night temperatures in the Andaman and Nicobar islands and the coastal regions.
— Winds and Rainfall Variations are noticeable not only in the amount of precipitation but also in the type of precipitation. The annual precipitation in Meghalaya exceeds 1080 cm whereas it is less than 10 cm in Rajasthan desert and on the North-West Himalayas, such as in the Ladakh region of Jammu and Kashmir and Western Rajasthan.
— The Ganga delta and the coastal plains of Odisha are hit by strong rain-bearing storms almost every third or fifth day in July and August, while the Coromandel coast, a thousand km to the South, goes generally dry during these months.
— Most parts of the country receive rainfall in June-September. But some parts like Tamil Nadu coasts get most of its rains during autumn and early winter. While the Western disturbances bring rainfall to the Northern part of the country during winter, in Tamil Nadu, it is the North-East monsoons that cause rains.
— There is decrease in rainfall generally from East to West in the Northern plains. In some parts of the country, the precipitation is in the form of snowfall whereas in greater part of the country it takes place as rainfall.
Factors Influencing Indian Climate
Location and Latitudinal Extent
The Tropic of Cancer passes through the middle of the country. The Southern parts being closer to the Equator, experience high temperatures throughout the year. The Northern parts on the other hand lie in the warm temperate zone. Hence, they experience low temperature particularly, in winter.
Distance from the Sea
Areas near the coast have moderating influence of sea. On the contrary interior, location are deprived of the same and experience extreme or continental climate.
The Northern Mountain Ranges
These ranges protect India from the bitterly cold and dry winds of Central Asia during winter. Furthermore, they act as an effective physical barrier for the rain bearing South-West monsoons winds to cross the Northern frontiers of India.
The physical features influence the air temperature, atmospheric pressure, direction of winds and the amount of rainfall in different parts of the country.
The complete reversal in the direction of winds in India brings about a sudden change in seasons. The harsh summer season suddenly giving way to the eagerly awaited monsoon or rainy season. These winds have such a far reaching influence on India’s climate that it is termed as monsoon type of climate.
Western Disturbances and Tropical Cyclones
The inflow of Western disturbances which move under the influence of Westerly jet streams from the Mediterranean sea influence winter weather conditions over most of Northern plains and Western Himalayan region.
The tropical cyclones also develop in the Bay of Bengal. The frequency and direction of these cyclones influence weather conditions during South-West monsoons over most parts of India and along the Eastern coast during retreating monsoon season.
Weather conditions in India are also influenced by El-Nino which causes widespread floods and droughts in tropical regions of the world. This warming of tropical pacific waters affects the global pattern of pressure and wind systems including the monsoon winds in the Indian ocean. It is believed that the severest drought of 1987 in India was caused by El-Nino.
Seasons of India
This season starts by late November representing clear skies, fine weather, light Northerly winds, low humidity and temperatures and large daytime variations of temperature. The cold air mass extending from the Siberian region, has profound influence on the Indian sub continent (at least all of the North and most of Central India) during these months.
The mean air temperatures usually increase from North to South. The mean temperatures vary from 14°C to 27°C during January. The rains during this season generally occur over the Western Himalayas, the extreme North-Eastern parts of Tamil Nadu and Kerala. Western disturbances and associated trough in Westerlies are main rain bearing system in Northern and Eastern parts of the country.
The temperature start to increase all over the country in March and by April, the interior parts of the Peninsula record mean daily temperature of 30-35°C.
Central Indian land mass becomes hot with daytime maximum temperature reaching about 40°C at many locations.
Many places in Gujarat, North Maharashtra, Rajasthan and North Madhya Pradesh exhibit high day-time and low night-time temperatures during this season.
Maximum temperature rise sharply exceeding 45°C by the end of May and early June resulting in harsh summers in the North and North-West regions of the country. However, weather remains mild in coastal areas of the country owing to the influence of land and sea breezes.
The season is characterised by cyclonic storms, which are intense low pressure systems over hundreds to thousands of km associated with surface winds more than 33 knots over the Indian sea viz Bay of Bengal and the Arabian sea.
These systems generally, move towards a North-Westerly direction and some of them recurve to Northerly or North-Easterly path. Storms forming over the Bay of Bengal are more frequent than the ones originating over the Arabian sea.
On an average, frequency of these storms is about 7.4 per year. Weather over land areas is influenced by thunderstorms associated with rain and sometimes with hail in this season.
Local Winds of Hot Weather Season
Mango Showers Towards the end of summer, there are pre-monsoon showers, which are common phenomena in Kerala and coastal areas of Karnataka. Locally, they are known as mango showers, since, they help in the early ripening of mangoes.
Cherry Blossom With this shower, coffee flowers blossom in Kerala and nearby areas.
Kalbaisakhi These are dreaded evening thunderstorms in West Bengal and Assam. Their notorious nature can be understood from the local nomenclature of Kalbaisakhi, a calamity of the month of Baisakh. These showers are useful for tea, jute and rice cultivation. In Assam, these storms are known as Bardoli Chheerha.
Loo Hot and dry winds accompanied with dust winds blow frequently over the plains of North-West India. These are oppressive in nature and blow in the Northern plains from Punjab to Bihar with higher intensity between Delhi and Patna.
South-West Monsoon Season
The onset of the South-West monsoon normally starts over the Kerala coast, the Southern tip of the country by 1st June, advances along the Konkan coast in early June and covers the whole country by middle of July. However, onset occurs about a week earlier over islands in the Bay of Bengal.
Retreating/North-East Monsoon Season
North-East (NE) monsoon or post-monsoon season is transition season associated with the establishment of the North-Easterly wind regime over the Indian sub-continent.
Meteorological sub-divisions namely coastal Andhra Pradesh, Rayalaseema, Tamil Nadu, Kerala and South interior of Karnataka, receive good amount of rainfall accounting for about 35% of their annual total in these months.
Monsoon retreat from North to South in India following Southward shifting of low pressure led by Southward movement of Sun. This wind crosses through Bay of Bengal and collect moisture to pour over Tamil Nadu and adjoining areas.
Monsoon, derived from mausim is nothing, but the seasonal reversal of winds. In the winter, for six months wind blows from land to sea and in summer, for six months it blows from sea to lands.
The Indian agriculture is considered a gamble against monsoon because agricultural activities over almost all the parts of India are very much dependent upon the monsoon rainfall. In fact, monsoon is the axis around which the Indian economy revolves.
The nature of the monsoon winds can be described with reference to the surface distribution of pressure in different regions of India during winter and summer seasons.
During winter, the weather conditions are generally influenced by the high pressure area developed over North-Western part of the sub-continent. This results in the blowing of cold dry winds from these regions towards Southern low pressure areas lying over water bodies surrounding peninsular India.
Since, these winds are cold and dry, they do not cause rainfall and weather conditions under their influence remain cold and dry. However, these North-East monsoon winds while passing over the Bay of Bengal, collect moisture and bring rain along Coromandel coast.
During summer, the North-Western parts of India become very hot due to very high temperature. This is ascribed to the apparent shift of the Sun in Northern hemisphere. This results in the reversal of pressure conditions not only in North-Western India, but also on water bodies surrounding the peninsula.
As a result, North-East trade winds are replaced by South-West monsoon winds. Since, these winds are sea bearing and blow over warm water bodies before reaching land they are moisture laden, causing wide spread rain over the most parts of India.
This period of South-West monsoon from June to September is known as the rainy season for most parts of the country.
The jet streams are strong flowing masses of air that flows around high up in the Earth’s atmosphere, at around the level of the tropopause (situated between the troposphere and the stratosphere).
The changes in the upper air circulation over Indian landmass are yet another cause for sudden outbreak of monsoons in India. Jet streams in the upper air system influence the climate of India in the following ways:
Westerly Jet Stream and its Impact
During winter, at about 8 km above sea level, a westerly jet stream blows at a very high speed over the sub-tropical zone. This jet stream is bifurcated by the Himalayan ranges. The Northern branch of this jet stream blows along the Northern edge of this barrier. The Southern branch blows Eastwards South of the Himalayan ranges along 25° N latitude.
It is believed by meteorologists that this branch of jet stream exercises a significant influence on the winter weather conditions in India.
This jet stream is responsible for bringing Western disturbances from the Mediterranean region into Indian sub-continent. Winter rain and hail storms in North-Western plains and occasional heavy snowfall in hilly regions are caused by these Western disturbances. These are generally followed by cold waves in whole of Northern plains.
Easterly Jet Stream and its Influence
During summer, due to the apparent shift of the Sun in Northern hemisphere, the reversal in upper air circulation takes place.
The Westerly stream is replaced by Easterly jet stream which owes its origin to the heating of the Tibetan plateau. This leads to the development of an Easterly cold jet stream centered around 15°N latitude and blowing over peninsular India. This helps in the sudden onset of South-West monsoons.
Rainfall Distribution in India
The distribution of rainfall in India is quite uneven and the regional variations are apparent. The average annual rainfall is about 125 cm, but has great spatial variations. The highest rainfall occurs along the West coast, on the Western Ghats, as well as in the sub-Himalayan areas in the North-East and the hills of Meghalaya (Khasi, Jaintia and Garo).
Though, the Southern part of Meghalayan plateau gets more than 1000 cm, but its Northern frontier along with Brahmaputra valley gets less than 200 cm rainfall.
The Western part of Jaisalmer (Rajasthan) is one of the driest part of the world having only about 9 cm rainfall. Total rainfall increases generally Eastwards and with height.
The larger part of the Gangetic plain and the central uplands receive a moderate amount of rainfall. The rainfall over parts of Punjab-Haryana, Kachchh and Kathiawar region of Gujarat is below 60 cm. A narrow strip of land in the lee side of sahyadris is lying in the rain shadow area and has below 60 cm of rainfall.
Reason Behind Formation of Thar Desert
This desert is under the spell of the Arabian sea branch of the monsoon from the month of July to September, a humid air stream, but marked by the absence of Rain Generating Weather System. The monsoon circulation is marked by a region of ascent over North-East India and a zone of subsidence over North-West India. This pattern of subsidence is responsible for formation of desert condition in Rajasthan. There is a deep and dense layer of dust over the arid region of Rajasthan, transported from the desert of Arabian that makes net cooling over the region.
The cooling in turn promotes subsidence and formation of an inversion layer which prevents vertical ascent and consequently, rain formation inspite of the presence of a moisture laden air.
Climatic Regions of India
India’s climate is of tropical monsoon type but large size of the country, topographical contrasts, impact of sea, shifting pressure and wind belts have cumulative impact on climatic elements to exhibit variations and thereby create climatic variety at sub-regional level.
Variations may also be observed in respect of other climatic elements like temperature, pressure, wind direction and movements, cloudiness, humidity etc.
W Koeppen, CW Thornthwaite and Triwartha’s classification of climate are important, but Koeppen’s classification is widely used in India for its simplicity.
A systematic study of the Indian, climate was made by Koeppen in 1918, who divided the country into three broad climatic zones:
arid, semi-arid and humid.
These are further sub-divided into sub-types on the basis of seasonal variations in the distribution pattern of rainfall and temperature. India can be divided into following climatic regions on the basis of Koeppen’s scheme. Climatic Regions of India on the Basis of Koeppen’s Scheme
Tropical Savanna Type (Aw)
This is a climate associated with tropical Savanna grasslands and monsoon deciduous vegetation. May is the hottest month and the temperature of the coldest month is more than 18°C. Rainfall is seasonal with winter, dry and the range of temperature is high. Such type of climate is found over major parts of the peninsular India including Southern West Bengal and Bihar.
Tropical Monsoon Type (Amw)
It has a short winter dry season. The rainfall is heavy leading to the growth of evergreen rain forests. It occupies parts of Southern Konkan, Malabar coast, adjoining Western Ghats, Tamil Nadu plateau and Southern areas of Tripura and Mizoram.
Tropical Moist Type (As)
It is characterised by dry summer season, about 75% of rainfall obtained during September to December. It occupies a narrow zone along the Coromandel coast.
Semi-Arid (Steppe) Climate
Here, the mean annual temperature is above 18°C and the rainfall is seasonal (in summer). The rainfall of the rainiest month is roughly ten times higher than of the driest month. It covers rain shadow zone of Karnataka and Tamil Nadu, Eastern Rajasthan and some parts of Punjab and Haryana.
Hot Desert Type (BWhw)
This is an arid climate characterised by high temperature (maximum in June), scanty rainfall and higher range of temperature. This type of climate prevails over the Western parts of Rajasthan (Thar desert) including the districts of Jaisalmer, Barmer and Bikaner. Here, the monsoonal winds flow parallel to Aravalli hills and thus, no orographic rainfall occurs.
Monsoon Type (Cwg)
This climate is characterised by winter dry. The rainfall received in the rainiest month is 10 times of the driest month. The average temperature of the coldest month is less than 18°C, but the average temperature of the warmest month is above 10°C. It depicts Gangetic temperature regime wherein maximum temperature is recorded before summer solstice. It spreads over the entire stretch of the Great Plains of India.
Cold Humid Winter Type (Dfc)
This is a climate characterised by short summer and cold, humid winter. Average temperature of the coldest month is less than 3°C, but the average temperature of the warmest month is above 10°C. It includes Sikkim and Arunachal Pradesh.
Polar or Mountain Type (E)
This climate type extends over Jammu and Kashmir and Himachal Pradesh. Here, the temperature of summer is less than 10°C.
Natural Vegetation and Wildlife
India is a land of great variety of natural vegetation. Himalayan heights are marked with temperate vegetation; the Western Ghats and the Andaman and Nicobar islands have tropical rain forests; the deltaic regions have tropical forests and mangroves; the desert and semi-desert areas of Rajasthan are known for Cacti, a wide variety of bushes and thorny vegetation.
The total geographical area of India is 3287263 sq km of which about 675500 sq km equal to 22.50% is under forests.
Classification of Vegetation
On the basis of certain common features such as predominant vegetation type and climatic regions, Indian forests can be divided into the following groups:
India State of Forest Report 2017
The India State of Forest Report (ISFR) 2017 states that India’s forest and tree cover has increased by 8,021 sq km. The majority of the increase in forest cover has been observed in open forest category (mainly outside forest areas), followed by Very Dense Forests.
India follows a policy of keeping one-third of the country’s total land area under forest and tree cover.
Various Class of Forest – Very dense forest 2.99%, Moderate dense forest – 9.38%, Open forest – 9.8%, Shrub-1.48% and Non-forest – 77.06%.
Among all the States and Union Territories, Lakshadweep (90.33%) has the highest forest cover in terms of percentage of its geographical area, followed by Mizoram (86.27%) and Andaman and Nicobar Islands (81.73%). However, North-Eastern states of Mizoram, Nagaland, Arunachal Pradesh, Tripura and Meghalaya have experienced a decline in forest cover.
The mangrove cover in India has increased by 112 sq km following acute conservation in the Sundarbans and Bhitarkanika forest.
Mangrove forests are present all along the Indian coastline in sheltered estuaries, creeks, back waters, salt marshes and mudflats that are specifically the areas of Indian wetlands. Mangrove cover in India accounts for around 3% of the world’s total mangrove cover and is spread over an area of 4628 sq km in the coastal States/Union Territories of the country. Prominent mangrove covers are located in the Andaman and Nicobar islands, the Sunderbans delta, the Gulf of Kutch and the deltas of the Mahanadi river, Godavari river and the Krishna river. Certain regions of the State of Maharashtra, Karnataka and Kerala also have large mangrove covers and Indian wetlands. West Bengal has the maximum mangrove cover in the country, followed by Gujarat and Andaman and Nicobar islands of the country’s total mangrove cover. The Sunderbans delta, one of the world-renowned Indian wetlands is home to the largest mangrove forest in the world. It lies at the mouth of the Ganga river and spreads across areas of Bangladesh and West Bengal. The Sunderbans is a UNESCO World Heritage Site, but is recognised separately as the Sunderbans (Bangladesh) and the Sunderbans National Park (India). ‘Kharai came’ is found in the mangroves areas of India specially in Gujarat’s Bhuj area. It is capable of swimming upto 3 km is seawater.
With a great variety in physiographic, climate and habitat, India has a wide range of animals and birds in different parts. Total number of species of animals, birds and insects in India runs into several thousand. Species of birds alone number more than 1200.
Among mammal species in India, the elephant is the largest. Elephants are found in Assam, West Bengal, Uttarakhand, Central India and the Southern States of Karnataka, Kerala and Tamil Nadu.
Rhinoceros, the second largest mammal found in India once inhabited most of the Ganga valley. However, their numbers today have been reduced to less than 1500.
They are found in a few areas in West Bengal and Assam today. Most of them survive under protection in the Manas and Kaziranga reserves in Assam and Jaldapara sanctuary in West Bengal.
Among the large carnivores, tiger is an important animal. Most of the tigers survive in wildlife reserves – tiger sanctuaries and national parks. They inhabit the foothills of the Himalayan region, parts of West Bengal, Karnataka Madhya Pradesh and adjoining areas.
India had a large population of lions also. However, their numbers had declined and today they are confined to the Gir forest in Gujarat.
Indian forests are home to a number of other animals including different varieties of bears, panthers, leopards and deers, antelopes, hyenas, jackals, wild dogs, monkeys, langurs and a number of species of cats of different varieties. The Himalayan region is home to yak also.
Tortoises and turtles of different varieties abound in water bodies including rivers, seas and lakes etc. The breading area of the famous Olive Ridley’s turtles is the coast of Odisha while the Hawksbill turtles breed on the coast of Tamil Nadu.
The first National Park in India was established in 1936 under the name Hailey National Park. It is now known as Corbett National Park. India had only 5 National Parks till 1970. More than 165 National Parks have been sanctioned in the country and about 100 have already been established.
Biosphere reserves are areas of terrestrial and coastal ecosystems, which are internationally recognised within the framework of UNESCO’s Man and Biosphere (MAB) Programme.
They are required to meet a minimal set of criteria and adhere to a minimal set of conditions before being admitted to the World Network of Biosphere Reserves designated by UNESCO.
The programme was initiated in 1986 and till date 18 sites have been designated as Biosphere Reserve (BR) in different parts of the country. Endemic Species Found Only in India Endemic species are plants and animals that exist only in one geographic region. Species endemic to India include Asiatic Lion, Sangai Deer, Lion Tailed Macaque, Kashmir Stag, Nilgiri Tahr, Purple Frog, Pygmyhog, Namdapha Flying Squirrrel.
India is primarily an agricultural country. The success of agriculture depends upon the fertility of soils. Indian soils have been used for cultivation for hundreds of years and have lost much of their fertility. As such, there is urgent need of giving scientific treatment to our soils.
Soil is the mixture of rock debris and organic materials which develop on the Earth’s surface. The major factors affecting the formation of soil are relief, parent material, climate, vegetation and other life-forms and time. Besides these, human activities also influence it to a large extent.
Characteristics of Indian Soils
The Indian soils have been formed under varied geographical conditions and differ widely in their physical properties, chemical composition and fertility level. Most soils are old and mature. Soils of the Peninsular plateau are much older than the soils of the Northern plains.
Indian soils are largely deficient in nitrogen, mineral salts, humus and other organic materials. Plains and valleys have thick layers of soils while hilly and plateau areas depict thin soil cover. Some soils like alluvial and black soils are fertile while some other soils such as laterite, desert and alkaline soils lack in fertility and do not yield good harvest. Indian climate is characterised by seasonal rainfall and our soils need irrigation during the dry period. Indian soils suffer from soil erosion and other allied problems.
Distribution of Indian Soils Alluvial Soils
These soils occupy over 40% of the total soil area of the country and are formed through the process of deposition of sediments (sand, silt, clay etc) in layers. Alluvial soils are classified into newer alluvium (Khadar) and the older alluvium (Bhangar). The Bhangar lands are generally above the flood levels.
The Bhangar lands are however, characterised with Bhurs (winds deposits) and Usar soils. They are mainly devoted to rice, wheat, oilseeds, sugarcane, jute, pulses, maize, millets and fodder. Alluvial soil is found extensively in Northern plains, River Valley plains and Coastal plains.
These soils develop over the old crystalline and metamorphic rocks. These soils occupy over 18% of the total soil area of the country. The colour of the soils is generally red due to high iron content.
These are found in the hot and humid regions. Red soils cover a large part of Tamil Nadu, Karnataka, Andhra Pradesh, Telangana, Chhattisgarh, Jharkhand, Madhya Pradesh and Odisha. These soils are poor in phosphorus, nitrogen and lime content, but are fairly rich in potash. Rice, maize, millets, pulses and small grains are the main crops grown in them.
Black or Regur Soils
These soils cover about 15% of the total soil area of the country, the black soils are generally known as regur on blank cotton soils. Getting their parent material from the weathered rocks of lava, they stretch over Maharashtra plateau, region of Andhra Pradesh, Northern parts of Karnataka, Western parts of Madhya Pradesh and South-Eastern parts of Gujarat.
These are mature soils, having a high water retaining capacity. They are extremely compact and tenacious when wet and develop wide cracks when dry. When the soil is wet, it becomes difficult to plough the field as the plough gets stuck in mud. These soils are utilised mainly for the cultivation of cotton, millets, maize, pulses and citrus fruits-oranges, lemons etc.
Arid and Desert Soils
These soils are characterised by sandy texture. They are rich in mineral salts, but poor in organic matter. The pH value is high. These are typical of Rajasthan desert, parts of Gujarat, South-West Haryana, South-West Punjab, where the average annual rainfall is less than 40 cm.
These soils cover an area of 1.42 lakh sq km. This soil is reddish brown in colour and sandy soils are called bhur.
These soils can be reclaimed with the proper development of irrigation facilities. These soils are generally devoted to bajra, pulses (green-gram, blackgram) guar, fodder, millets, jowar etc.
These soils are found in the sub-mountain tracts of the Himalayas, on the hills of drier regions of the peninsula and in parts of Andaman and Nicobar islands.
The terai soils of the Himalayan foothills are rich in nitrogen and organic matter. In coniferous forest belt of Jammu and Kashmir, Himachal Pradesh, Uttarakhand and Sikkim, brown podzol soils are found.
Mountain soils having a good vegetation cover are rich in organic matter, but their base-status varies, depending on the degree of leaching.
This soil is suitable for plantation of tea, coffee, spices and tropical fruits in Southern regions and wheat, maize and barley in Northern regions.
Laterite or Lateritic Soils
The name of the lateritic soils has been derived from the Latin word later which means brick. These are the typical soils of the monsoon and humid tropical or equatorial zones characterised by deep weathered layer from silica, which has been leached.
These soils are rich in iron and aluminium, but poor in humus, phosphorus, potassium, lime and nitrogen. The reddish colour of these soils is imparted by the iron and aluminium residue.
Lateritic soils are found in Odisha, West Bengal, in some parts of Andhra Pradesh, Tamil Nadu, Kerala, Jharkhand, Chhattisgarh Maharashtra and Madhya Pradesh.
Karewas are the lacustrine deposits (lake deposits) in the Valley of Kashmir, Bhadarwah Valley of the Jammu and division of Jammu and Kashmir. They are composed of finesilt, clay, sand and boulder gravel.
Karewa soils are devoted mainly to the cultivation of saffron, almond, walnut, apricot, apple and peach orchards. Karewas of Palmpur, Pulwama and Kulgam (Kashmir valley) are famous for the cultivation of superior quality of saffron, walnut and almond.
Saline and Alkaline Soils
These soils contain huge quantity of salt and are known as alkaline soils. It is known by different names thur, kari, chopan, reh, kallar and usar. They are sandy to loamy sand in texture and their pH value is 8.5. This type of soil is often found in the tracts of Rann of Kachchh, Bihar, Uttar Pradesh, Haryana, Punjab, Rajasthan and Maharashtra.
There are many undecomposed rock and mineral fragments which on weathering liberate sodium, magnesium and calcium salts and sulphurous acid. These soils can be reclaimed by providing good irrigation, applying lime or gypsum and cultivating salt resistant crops. This soil is utilised in the cultivation of rice, wheat, cotton, sugarcane, tobacco etc.
This soil has originated from the mechanical disintegration of the ground rocks or is blown from the Indus basin and the coast by the prevailing South-West monsoon winds.
As the name suggests, forest soils formed in the forest areas, where sufficient rainfall is available. The structure and texture of the soil depend on the mountain environment where they are formed.
In the snow-bound areas of the Himalayas, they experience denudation and are acidic with low humus content. These soils are found in the lower valleys and are fertile.
Peaty and Marshy Soils
They originate in humid regions as a result of accumulation of large amounts of organic matter in the soil. This soil is heavy, black and highly acidic, but is deficient in phosphate and potash.
Marshy soils are the result of water logging, anaerobic condition of the soil and the presence of iron and varying amount of organic matter. These are found in West Bengal in Tamil Nadu, Central Bihar and Almora (Uttarakhand).
It is the removal of soil by the forces of nature more rapidly than the soil forming processes can replace it. Two natural agents i.e. water and wind are constantly at work indulging in soil erosion. Factors which can influence soil erosion in India are rainfall, vegetation, nature of the soil, wind velocity, tillage, soil moisture and slope topography.
Factors which causes soil erosion includes deforestation, faulty cultivation methods, over grazing, forest fires, shifting cultivation, climate change, urban sprawl and diversion of natural drainage channels by railway embankments and roads.
Types of Soil Erosion
Wind erosion is significant in arid and semiarid regions.
Run-off erosion in due to rills and gullies.
Biological methods include improving the existing surface cover, strip cropping, stubble mulching, vegetative binding and using organic manures. Other measures can be checking over grazing, reducing surplus cattle, stripping shifting cultivation and taking preventive measures against forest fires.
Mechanical measures include contour tillage, contour bunding, terracing, constructing proper drainage channels and plugging the gullies, basin listing, water harvesting and scientific slope management.
It is one of the major causes of soil erosion. Plants keep soils bound in locks of roots and thus, prevent erosion. Soil in irrigated zones of India is becoming saline because of over irrigation. Chemical fertilizers in the absence of organic manures are also harmful to the soil fertility. Unless the soil gets enoughs humus, chemicals harden it and reduce its fertility in the long run.