CHAPTER 1: India: Physical Aspects

CHAPTER 1: India: Physical Aspects

Geographic Profile

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. 

Gondwana System   

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.  

The Trans-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. 

Doab  

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.  

Punjab-Haryana Plain  

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.  

Ganga Plain 

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.  

Rajasthan Plain  

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.  

Brahmaputra Plain  

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   

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  

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. 

Inland Drainage  

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. 

T

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. 

Physiography  

The physical features influence the air temperature, atmospheric  pressure, direction of winds and the amount of rainfall in  different parts of the country.  

Monsoon Winds  

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. 

El-Nino Effect   

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 

Winter Season  

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.  

Summer Season   

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   

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.  

Winter Monsoon  

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.  

Summer Monsoon  

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.  

Jet Streams  

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. 

Mangroves  

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.  

Wildlife  

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  

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. 

Indian Soils  

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.  

Red Soils  

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.  

Mountain Soils  

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.  

Karewa Soils  

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.  

Forest Soils 

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). 

Soil Erosion  

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.  

Sheet erosion.  

Splash erosion. 

Soil Conservation  

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.  

Deforestation  

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. 

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