APTITUDE AND FOUNDATIONAL VALUES FOR CIVIL SERVICE , INTEGRITY, IMPARTIALITY AND NON-PARTISANSHIP, OBJECTIVITY, DEDICATION TO PUBLIC SERVICE, EMPATHY, TOLERANCE AND COMPASSION TOWARDS THE WEAKER-SECTIONS.
Q.4) A new civil service incumbent in IPS, after completion of his training, joins his first posting in a district.
(I) Some influential people, outside his office as well as subordinates in his office come and meet him and offer him valuable gifts in welcome gesture.
(II) He is also told by his subordinates that there is a channel of money collection by the police of the area from commercial vehicles, shanty vendors and shopkeepers as well as spurious liquor lobby etc, share of which would automatically reach to the new officer. This money is unaccounted and does not go to the establishment.
(a) The officer is in dilemma. Whether he should accept the gifts in welcome gesture from influential people outside office or only from his official colleagues or from both? Give reasons.
(b) Should he take the share from unaccounted money mentioned above? If not what would be professionally and ethically correct decision for him.
MAJOR CROPS CROPPING PATTERNS IN VARIOUS PARTS OF THE COUNTRY, DIFFERENT TYPES OF IRRIGATION AND IRRIGATION SYSTEMS STORAGE, TRANSPORT AND MARKETING OF AGRICULTURAL PRODUCE AND ISSUES AND RELATED CONSTRAINTS
Q.3) Advancing rights of women farmers can revolutionize the rural ecosystem.” Discuss the relevance of this statement in the current Indian context.
SALIENT ASPECTS OF ART FORMS, LITERATURE AND ARCHITECTURE FROM ANCIENT TO MODERN TIMES
Q.1) Ashoka’s Dhamma is a superb document of his essential humanity and an answer to the socio-political needs of the contemporaneous situation. Comment.
Agroforestry is a sustainable management mechanism for land that:
increases overall production,
combines agricultural crops, tree crops, forest plants and animals simultaneously, and
applies management practices that are compatible with cultural practices of the local population.
It is a type of social forestry in which an individual farmer undertakes tree farming and grows fodder plants, grasses and legumes on his own land. In agroforestry trees are considered a crop and become a part of crop combinations.
Some Patterns of Agroforestry
There is an increasing number of farmers who plant trees either along the boundaries or in the whole field/farm as a crop. In fact, in the northern plains of India, trees are planted by most of the farmers irrespective of the size of their holdings. The large farmers and absentee landlords generally put a part of their holdings or total agricultural area under tree crops.
The main advantage of agroforestry is considered to be its positive impact on the soil. Let’s understand the impact of trees on the soil.
How trees improve soils:
Litter or Mulch:
During the lifetime of a tree, leaves, twigs and branches die and fall to the ground as litter. Litter contributes to the organic-matter content of the soil after it decomposes. A soil that is rich in organic matter has a better capacity to absorb and retain water and thus is also more resistant to erosion. A good cover of litter or mulch can also be very effective in suppressing weeds.
2. Increase nutrient content of soil:
Nutrient Uptake from deeper layers of soil: Tree roots normally penetrate deeper into the soil than the roots of crops. Though not experimentally verified, trees are generally considered more efficient than crops in taking up nutrients released by weathering deep in the soil.
Nutrients from the atmosphere: The presence of a tree reduces the wind speed and creates good conditions for the deposition of dust. Nutrients in the atmosphere are conveyed to the soil when they are dissolved in rain or settle with dust. Rain water dripping from leaves and flowing along the branches carries the nutrients to the ground, together with those released from the tree itself and associated plants growing on it. It is known that the amounts of nutrients reaching the ground in this way are substantial.
Nitrogen Fixation: Many leguminous trees and a few non-leguminous ones have the ability to fix atmospheric nitrogen through symbiosis with bacteria or fungi in root nodules. The fixation of nitrogen has been proven and found to be a significant factor in soil fertility. Also, the litter from nitrogen-fixing plants is often rich in nitrogen which is added to the soil when the litter or mulch decomposes.
3. Protection from soil erosion
Tree roots and stems reduce surface run-off, nutrient leaching and soil erosion.
Reduction of pressure on natural forests. It is also recognized that Agroforestry is perhaps the only alternative to meeting the target of increasing forest or tree cover to 33 percent from the present level of less than 25 per cent, as envisaged in the National Forest Policy (1988).
Agroforestry is known to have the potential to mitigate the climate change effects through:
microclimate moderation and natural resources conservation in the short run, and
carbon sequestration in the long run. Agroforestry species are known to sequester as much carbon in below-ground biomass as the primary forests, and far greater than the crop and grass systems.
When strategically applied on a large scale, with an appropriate mix of species, agro-forestry enables agricultural land to withstand extreme weather events, such as floods and droughts, and climate change.
2. Economic benefits:
A greater output of food, fuel wood, fodder and timber.
Increase in levels of farm income due to improved and sustained productivity.
Agroforestry leads to a reduction in the incidence of total crop failure, which is common to single cropping or monoculture systems. This is because such systems are structurally and functionally more complex than monoculture.
The absentee landlords go for agroforestry to retain the title of the land and to increase their income. It provides an alternative to land owners to manage their agricultural land in absence of family labour.
Agroforestry has significant potential to provide employment to the rural and urban population through production, industrial application and value addition ventures. Current estimates show that about 65 % of the country’s timber requirement is met from the trees grown on farms.
3. Social benefits :
Improvement in rural living standards from sustained employment and higher income.
Makes the villagers self-dependent at the village-level.
Despite the numerous material and geo-climatic benefits, agroforestry if not carefully planned can have some adverse effects on agricultural land. Some of these are:
In the fields along which trees have been planted, the productivity per unit area decreases, as in at least about two meters from the trees the moisture content in the soil is significantly reduced. Also, the combination of trees and crops must be so chosen so as to minimise the competition between their roots for moisture.
Unscientific planning can also negatively impact the agricultural productivity of the land. E.g. growing trees with photophilic i.e. light-loving plants.
Pests and Diseases: Mixtures of trees and crops make a more diverse environment than monocropping. A diverse environment enables a greater variety of species of all kinds of organisms — both desirable and less desirable — to thrive. With increased diversity, the risks of pests and diseases may also increase. On the other hand, a greater diversity of species also allows for better regulatory mechanisms which may reduce the seriousness of the pests and diseases. Careful planning is necessary so that the organisms promoted by one component in the system and are not harmful to the other component or components.
Thus, for an agroforestry system to be successful, a careful and scientific approach is required which incorporates knowledge from both agriculture and forestry.
Apart from these, certain shortcomings have been observed in the case of agroforestry programs in India:
The tendency of farmers to opt for market-oriented trees rather than the trees which are more ecologically suited or are locally needed (fuelwood/fodder).
Agroforestry has benefitted the big farmers more than the marginal and small farmers. Many of the absentee landlords plant commercial trees in their agricultural landholdings to save their land from dispossession. This programme is said to have encouraged absentee landlordship.
The diversion of good agricultural land from cereal and commercial crops may create the scarcity of food and industrial raw material.
Possible negative impact on crop production because of planting trees on fertile lands.
Thus, while the potential benefits of agroforestry are well documented, particular aspects of these systems need to be adapted to suit the areas where they are introduced. These adaptations primarily involve the selection of the ideal combinations of trees, shrubs and crops that will benefit each other, the environment and the income of the small-scale farmers.
National Agroforestry Policy 2014:
In February 2014, India became the first nation in the world to adopt an agroforestry policy. Agroforestry was earlier covered as a part of other policies e.g. the National Forest Policy, the Green India Mission etc.
The Policy aims to improve coordination, convergence and synergy between various elements of agroforestry, scattered across various existing missions, programme and schemes under different ministries—agriculture, rural development and environment.
Objectives of the National Agroforestry Policy 2014:
Promote agroforestry to increase farm income and livelihoods of rural households, especially the small and marginal farmers.
Protect and stabilise ecosystems, and promote resilient cropping and farming systems to minimise the risk during extreme climatic events.
Simultaneously provide raw material to wood based industries. Thus create new avenues for rural employment, and reduce pressure on the forests.
To develop capacity and strengthen research in agroforestry and create a massive people’s movement for achieving these objectives.
Cropping Pattern refers to a yearly sequence and spatial arrangement of crops and fallow in a given area
Cropping pattern used on a farm and its interaction with farm resources, other farm enterprises and available technology that determines its make up, is called a cropping system.
A farmer’s choice of crops is governed by several sets of factors: Physical, Social and Economic. But, by and large, most of the Indian farmers go for cultivation of a number of crops at their farms and rotate a particular crop combination over a period of 3-4 years. It results in a multiplicity of cropping systems, which remains dynamic in time and space making it difficult to precisely determine the spread of different cropping systems.
Scientists have identified more than 250 cropping systems being followed throughout the country but it is estimated that only 30 major cropping systems are prevalent (except the areas under monocropping due to moisture or heat conditions)
A large diversity of cropping systems exists under rainfed and dryland areas with an overriding practice of intercropping. This is because of greater risks involved in cultivating a large area under a particular crop. While in areas with assured irrigation only a few cropping systems are followed and they have a considerable coverage across the region and contribute significantly to foodgrains production at the national level.
Types of Cropping Systems in India:
Broadly speaking there are 3 types of cropping systems in India:
1. Sequential – In sequential multiple cropping, farmers use short duration crops and intensive input management practices. E.g.
In Maharashtra:- Rice-Frenchbean-Groundnut
In Rainfed Areas:- Pigeon Pea – Wheat
2. Inter-Cropping – Growing two or more crops simultaneously on the same field is called intercropping. In this case, crop intensification is in both temporal and spatial dimension. There is an inter-crop competition during all or in part of crop growth. E.g.
Maize and Groundnut in Ranchi
Cotton and Groundnut in Junagarh
3. Alley Cropping System – Growing of annual crops with multipurpose perennial shrubs/trees is called alley cropping. It is a way of increasing production potential under fragile environments. It is recommended to meet food, fodder and fuel needs besides improving soil fertility e.g. In the salt affected alluvial soil areas of Modipuram, alley cropping of rice-wheat sequence is done with trees like babool.
Major Cropping Systems in India:
The crop occupying the highest percentage of sown area of the region is taken as the base crop and all the other possible alternative crops sown in the region as substitutes (i.e. spatial variation) for the base crop in the same season or as the crops that fit in with the rotation in the subsequent seasons (i.e. temporal variations) are considered in the pattern.
1. Rainy Season Cropping Systems: Among the Kharif Crops – Rice, Sorghum, Pearl Millet (Bajra), Maize, Groundnut and Cotton are the prominent crops to be considered as the base crops for describing the Kharif Cropping Patterns.
Rice Based Cropping Patterns: Rice is grown in the high rainfall area or in the areas where supplemental irrigation is available to ensure good yields. At an all India Basis, nearly 80% of rice is sown during June to September and the rest during the remaining season. E.g.
With rice, other crops being cotton, vegetables and fruits (in Meghalaya)
Jute as an alternative to rice (in Orissa, coastal Andhra Pradesh, Bihar, Jharkhand, Assam etc.)
In Bihar, the alternative crops being pulses, wheat, maize, jute, sugarcane and oilseeds
Kharif Cereals other than rice:
Maize-based cropping systems: Maize is grown in high rainfall areas or on soil with a better capacity for retaining moisture, but with a good drainage.
Sorghum based cropping system: Grown in medium rainfall regions. These systems are popular in Maharashtra and Madhya Pradesh. The alternative crops being cotton, pulses, groundnut, and small millets in Maharashtra.
Pearl-Millet based cropping system –Pearl millet is a more drought resistant crop than several other cereal crops and is generally preferred in low or less dependable rainfall and on light textured soils. These are popular in Rajasthan, Maharashtra, Gujarat and Uttar Pradesh. E.g. in Rajasthan with pulses, groundnut, oilseeds, etc.
Groundnut based cropping systems: These are popular in Andhra Pradesh, Gujarat, Karnataka, Tamil Nadu and Maharashtra. E.g. In Andhra Pradesh and Tamil Nadu, rice forms an alternative; in Karnataka, Sorghum is the main alternative crop, whereas cotton, tobacco, sugarcane and wheat are also grown here.
Cotton based cropping systems: These are popular in Maharashtra, Gujarat, Andhra Pradesh and Punjab. E.g. Cotton with other crops:
Sorghum (Kharif and rabi), groundnut, pulses and wheat etc;
With irrigation in some places sugarcane and rice are also grown with cotton.
2. Winter Cropping Systems: Among the Rabi Crops, wheat together with barley and oats, sorghum and chickpea are the main base crops. Generally, wheat and chickpea are concentrated in the subtropical region in northern India, whereas Rabi sorghum is grown mostly in the Deccan.
Wheat and Chickpea based cropping systems: Wheat and Chickpea are grown under identical climate and can be substituted for each other. E.g. alternative crops in Madhya Pradesh being Kharif sorghum groundnut, oilseeds, cotton, small millets etc. In Punjab, the alternative crops are rice, mailze, cotton, pearl-millet etc.
Rabi Sorghum based cropping systems: These are popular in Maharashtra, Karnataka and Andhra Pradesh. E.g. in Maharashtra, the alternative crops are pearl millet, pulses, oilseeds and tobacco etc.
3. Plantation and other commercial crops:
Sugarcane, Tobacco, Potato, Jute, Tea, Coffee, Coconut, Rubber, Spices and condiments are important crops. Some of these are seasonal, some annual, some perennial.
Generally, the areas occupied by these crops are very limited compared with those of food and other crops. Nevertheless, they are important from commerce point of view.
Besides the above-mentioned crops, there are certain horticultural crops like apple, mango and citrus fruits.
E.g. in the jute growing areas, rice is the usual alternative crop; in Punjab, Bihar, Haryana and Uttar Pradesh, wheat and maize are rotation crops with sugarcane.
4. Mixed Cropping:
Crop Mixtures, for example, pulses and some oilseeds are grown with maize, sorghum and pearl millet.
Lowland Rice is invariably grown unmixed, but in upland rice, several mixtures are prevalent. E.g. In un-irrigated areas of the north, during rabi season, wheat, barley and chickpea are the mixtures of grain crops.
Note: Mixed Cropping was considered by some researchers a primitive practice, but now many researchers regard it as a more efficient way of using the land. [Mixed cropping ≠Mixed Farming; Mixed Farming = Farming + Animal Rearing. Note the difference!]
Note4students: With this article, we conclude our discussion on Indian Agriculture. However, these articles only cover the geographical aspect of agriculture in India. For a comprehensive understanding and coverage of other aspects like economic, government schemes etc., do read our comprehensive article series on Indian Agriculture (Click here to read).
Rice grows best in areas of warm, humid climate; rice requires temperatures between 20°C and 35°C and a well-distributed rainfall of about 100 cm or irrigation facilities.
Fertile soil. Delta and valley soils are the most suitable. Soils with higher clay content are preferred for its cultivation due to their better moisture retention capacity.
Important Producing Areas:
West Bengal (highest producer), Uttar Pradesh, Andhra Pradesh, Punjab (highest per hectare yield), Bihar, Orissa, Chhattisgarh, Assam, Tamil Nadu, Haryana.
About 25% of the arable land is used for the cultivation of rice.
On the basis of climatic conditions, three varieties of rice are found in India:
Winter/ Agahani/ Aman – Planted in July-August and harvested in October-December. 86% of the total rice cultivation comes under this variety.
Autumnal/ Kuari/Aus – Sown in May-June and harvested in September – October.
Summer/Boro – It is sown in November – December and harvested in March-April. It is grown on 1% of the total rice area.
Note: All the above mentioned 3 varieties (aman, aus, boro) are grown in West Bengal and Assam.
Important varieties: IR-8, Jaya, Padma, Hamsa, Krishna, Sabarmati, and IET 1039.
India is the 2nd largest producer in the world after China.
2. Wheat
Geographical Conditions of Growth:
It is a crop of temperate climate. The ideal temperature for its cultivation is about 15°-20°C and requires a moderate amount of rainfall of 25-75 cms. It can be grown in the drier areas with the help of irrigation.
Well drained loamy and clayey soils are ideal.
Important Producing Areas:
Wheat is cultivated on about 14% of the total arable area of the country.
There are two important wheat producing zones in the country – the Ganga-Satluj plains in the north-west and the black soil region in the Deccan.
In north India, wheat is sown in October – November and harvested in March – April. In south India, it is sown in September-October and harvested in December – January. Wheat takes lesser time in ripening in south India than that in the north because of hotter climatic conditions in the south.
Uttar Pradesh (highest producer), Punjab (highest yield per hectare), Madhya Pradesh, Haryana, Rajasthan, Bihar, Gujarat, Maharashtra, West Bengal, Uttarakhand.
It is a crop of semi-arid climate and is used both as food and fodder.
A temperature of 21°C- 27°C and 50-100cm rainfall is suitable for its cultivation.
Alternate spells of rains and sunny weather are ideal for maize.
It is a Kharif Crop but in some states like Bihar, it is grown in the rabi season also.
It grows well in alluvial and red soils with good drainage. It can also be grown in mountainous soils.
Important Producing Areas:
It is grown on 3.6% of the total sown area in the country.
Karnataka, Uttar Pradesh, Bihar, Rajasthan and Andhra Pradesh are important maize producing states.
Important Varieties: Sartaz, Ganga, Deccan-103, Deccan-105, Dhawal, Prabhat, Arun, Kiran etc.
4. Millets:
Jowar, Bajra and Ragi are the important millets grown in India. Though these are known as coarse grains, these have high nutritional value. These are grown on 16.5% of the total sown area in the country.
Bajra
Geographical Conditions of Growth:
It thrives in areas of warm, dry climate.
It requires an annual rainfall of 45cm and temperature ranging between 25 to 30°C.
It grows well on sandy soils and shallow black soil.
Important Producing Areas:
Rajasthan is the largest producer of bajra followed by Uttar Pradesh, Maharashtra, Gujarat and Haryana.
Jowar
Geographical Conditions of Growth:
It is a rainfed crop mostly grown in moist areas which hardly needs irrigation.
This crop requires moderate rainfall of 30-100cms and high temperatures ranging from 20 to 32°C.
Both excessive moisture and prolonged drought are harmful.
Well drained light soils are ideal.
Important Producing Areas:
It is the third most important food crop with respect to area and production.
It is cultivated as the major food crop in semi-arid areas of the central and south India.
In north India, Jowar is mainly a Kharif crop whereas it is sown as both Kharif and Rabi in the southern states.
Maharashtra is the largest producer of jowar followed by Karnataka, Andhra Pradesh and Madhya Pradesh.
India is the largest producer of jowar in the world.
Ragi
Ragi is very rich in iron, calcium, other micro-nutrients and roughage.
Geographical Conditions of Growth: It is a crop of dry regions and grows well on red, black, sandy, loamy and shallow black soils.
Important Producing Areas: Karnataka is the largest producer of Ragi followed by Tamil Nadu. Other states important for the production of ragi are Himachal Pradesh, Uttaranchal, Sikkim, Jharkhand and Arunachal Pradesh.
4. Pulses
Major pulses that are grown in India: tur, urad, moong, masur, peas and gram.
Chief Characteristics:
India is the largest producer as well as consumer of pulses in the world. About 20% of the pulses of the world are produced here.
These are the major sources of protein in a vegetarian diet.
Being leguminous crops, all the above-mentioned pulses (except tur) help in restoring soil fertility by fixing nitrogen from the air. Therefore these crops are mostly grown in rotation with other crops.
Geographical Conditions of Growth:
Pulses need less moisture and survive even in dry conditions
Important Producing Areas: The major pulse producing areas are Madhya Pradesh, Uttar Pradesh, Rajasthan, Maharashtra and Karnataka. It is grown on about 11% of the total sown area in India.
5. Barley
Geographical Conditions of Growth:
This is grown mainly as a dry crop.
This is the crop grown in the wheat producing area on the poor soil and in area of lower precipitation.
Although the geographical conditions required for its cultivation are similar to those for wheat, it has more tolerance for adverse environmental conditions.
Important Producing Areas: The major producers are Uttar Pradesh, Bihar and Madhya Pradesh.
Formation: These are derived from the disintegration of adjacent rocks and are largely blown from coastal regions and Indus valley.
Areas: Arid soils are characteristically developed in western Rajasthan, which exhibit characteristic arid topography.
Soil Colour: Arid soils range from red to brown in colour.
Soil Texture: They are generally sandy to gravelly in texture and have a high percentage of soluble salts.
Other characteristic features:
These are saline in nature. In some areas, the salt content is so high that common salt is obtained by evaporating the saline water.
Due to the dry climate, high temperature and accelerated evaporation, they lack moisture and humus.
These soils are deficient in nitrogen and humus. The phosphate and iron content is normal. These soils are rich in minerals but the main limitation is the lack of water.
The soils exhibit poorly developed horizons.
Plants are widely spaced.
Chemical weathering is limited.
Lower horizons of the soil are occupied by ‘kankar’ layers because of the increasing calcium content downwards. The ‘Kankar’ layer formation in the bottom horizons restricts the infiltration of water, and as such when irrigation is made available, the soil moisture is readily available for a sustainable plant growth.
Suitable crops: If irrigated these soils give high agricultural returns. The availability of water from the Indira Gandhi canal has transformed the agricultural landscape of desert soils of western Rajasthan. These soils are mainly devoted to bajra, pulses, guar, fodder and less water requiring crops.
6. Saline and Alkaline Soils
They are also known as Usara soils. Various local names for saline soils are Reh, Kallar, and Chopan, Rakar, Thur, Karl etc.
Formation:
These soils have developed in areas with dry climatic conditions (in areas having a little more rainfall than the areas of desert soils) accompanied by lack of proper drainage. In this situation, salts of sodium, calcium and magnesium are deposited on the upper layer of the soil by capillary action.
In the Rann of Kuchchh, the Southwest Monsoon brings salt particles and deposits there as a crust.
These soils are also formed when saline water spreads on the land at the time of high tide in coastal areas. Also, seawater intrusions in the deltas promote the occurrence of saline soils.
Salinization also occurs because of over-irrigation (canal irrigation/groundwater use) and in areas of high water table (as in the coastal areas of Maharashtra and Tamil Nadu).Salinity from irrigation can occur over time wherever irrigation occurs. This is because almost all water (even natural rainfall) contains some dissolved salts. When the plants use the water, the salts are left behind in the soil and eventually begin to accumulate. Also, excessive irrigation with dry climatic conditions promotes capillary action, which results in the deposition of salt on the top layer of the soil (See the following figure).
Areas: They occur in arid and semi-arid regions, and in waterlogged and swampy areas. These are more widespread in western Gujarat, deltas of the eastern coast and in Sunderban areas of West Bengal.
Soil Texture: Their texture ranges from sandy to loamy.
Other characteristic features:
Because of capillary action, the salts are sucked up in solution to the surface and form white encrustations on the surface (See the picture below).
The salt efflorescence of calcium, magnesium and sodium makes these soils infertile.
Saline soils contain an excess of neutral soluble salts of chlorides and sulphates whereas sodic or alkali soils contain sodium carbonates/ sodium bicarbonates.
They lack in nitrogen and calcium and have low water bearing capacity.
These soils can be reclaimed by improving drainage, by applying gypsum and/or lime, and by cultivating salt resistant crops like barseem, dhaincha and other leguminous crops.
The saline and alkaline soils may occur in any group of soils.
Crops grown: In coastal areas, coconut trees are found in plenty in these soils. As discussed above, cultivating salt resistant crops like barseem, dhaincha and other leguminous crops can help in reclaiming these soils.
Note: In the areas of intensive cultivation with excessive use of irrigation, especially in areas of green revolution, the fertile alluvial soils are becoming saline. In such areas, especially in Punjab and Haryana, farmers are advised to add gypsum to solve the problem of salinity in the soil.
7. Peaty Soils
These soils are locally called Kari in Kottayam and Alleppey districts of Kerala.
Formation: These are marshy soils and are a result of water logging and anaerobic conditions (which leads to partial decomposition of organic matter).
Areas: They are found in the areas of heavy rainfall and high humidity, where there is a good growth of vegetation. It occurs widely in the northern part of Bihar, the southern part of Uttaranchal and the coastal areas of West Bengal, Orissa and Tamil Nadu.
Soil Colour and Texture: These soils are normally heavy and black in colour
Other characteristic features:
These soils are characterised by a rich humus and organic content.
There is a presence of iron and varying amounts of organic matter (10-40%). The organic matter in these soils may go even up to 40-50 per cent.
These soils are generally acidic in nature. But at many places, they are alkaline also.
Suitable crops: These are generally submerged during the rainy season and utilised for the cultivation of rice.
8. Forest Soils
Formation: As the name suggests, forest soils are formed in the forest areas where sufficient rainfall is available.
Areas: These are found in the forest areas of Himalayas, Sahyadris, Eastern Ghats and terai region.
Soil colour and texture: The soils vary in structure and texture depending on the mountain environment where they are formed. They are loamy and silty on valley sides and coarse-grained in the upper slopes. Their colour is dark brown.
Other Characteristics:
In the snow-bound areas of the Himalayas, they are acidic with low humus content. This is because humus is rawer at higher levels. Also, these soils are subjected to denudation due to landslides and snowfall.
The soils found in the lower valleys are fertile and rich in organic content.
Owing to sharp differences of hill slopes and climates, these soils may differ greatly even when in proximity. [Recall here the discussion on the impact of topography on soils!]
Also, these soils exist in thin layers because of their development on the mountain slopes.
These soils are poor in potash, phosphorus and lime.
Soil erosion is a major problem in these areas.
Crops grown: The slopes are used for horticulture and plantations crops like tea, coffee, spices, apple, peach etc. Rice and wheat are grown in valleys. Potatoes are grown in mostly all areas.
Now that we are done with all the soil types, expand the following image for a quick revision!
Major Soil Types of India (Classification by ICAR)
We learnt about the various ways to classify soils. In this article, we will look at the various types of Indian soils in detail (According to ICAR’s classification). Let’s begin!
Formation: They are mainly derived from the debris brought down from the Himalayas or the silt left out by the retreating sea. Thus they are azonal soils.
Areas: Alluvial soils are widespread in the northern plains and the river valleys. Through a narrow corridor in Rajasthan, they extend into the plains of Gujarat. In the Peninsular region, they are found in deltas of the east coast and in the river valleys.
Soil texture: The alluvial soils vary in nature from sandy loam to clay. These soils are more loamy and clayey in the lower and middle Ganga plain and the Brahmaputra valley. The sand content decreases from the west to east.
Soil Colour: The colour of the alluvial soils varies from the light grey to ash grey depending on the depth of the deposition, the texture of the materials, and the time taken for attaining maturity.
Other Characteristic Features:
In the Upper and Middle Ganga plain, two different types of alluvial soils have developed, viz. Khadar and Bhangar.
Khadar and Bhangar
Khadar: the newer alluvium deposited by floods annually, enriches the soil by depositing fine silts, light colour, found near river beds, porous in nature.Bhangar: older alluvium, clayey, darker, has lime nodules called Kankars, found in doabs (inter-fluve areas).
Alluvial soils of the northern plains —> transported soils —> therefore lack humus —> lack nitrogen [That is why we need to use nitrogenous fertilisers in the northern plains!]. Exception: the Ganga-Brahmaputra delta region is rich in humus.
These soils lack in nitrogen, phosphorus and humus. However, they are generally rich in potash and lime.
The soil profile has no stratification.
Alluvial soils are intensively cultivated.
In certain areas, these soils are covered with unproductive wind-borne soil called Loess.
Limitations:
Allow water to sink into lower strata, and
Lack nitrogen (But these soils are capable of fixing nitrogen very rapidly through leguminous crops (peas, beans, cloves etc.)
These soils are locally known as the ‘Regur Soil’ or the ‘Black Cotton Soil’. Internationally, these are known as ‘tropical chernozems’. These soils are famous for the cultivation of cotton.
Formation: These have mainly formed from the Deccan Trap rocks —> Zonal Soils
Areas: These are found in the Deccan trap region. Black soil covers most of the Deccan Plateau which includes parts of:
Maharashtra,
Madhya Pradesh,
Gujarat,
Andhra Pradesh and some parts of
Tamil Nadu.
Soil Texture: Black cotton soil (regur soil) is highly argillaceous i.e. clayey. It is deep and impermeable and thus has high water retention capacity.
Soil Colour: These soils are black in colour due to the presence of iron, aluminium compounds and humus.
Other Characteristic Features:
These soils are rich in minerals and known for their fertility.
The soil depth varies from place to place. It is very thick in lowlands but very thin on highlands. Also, in the upper reaches of the Godavari and the Krishna, and the northwestern part of the Deccan Plateau, the black soil is very deep.
These soils swell and become sticky when wet and develop deep wide cracks when dry. This helps in self-aeration, which leads to absorption of nitrogen from atmosphere. Thus, there occurs a kind of ‘self ploughing’. This aeration and oxidisation to deep levels contributes to maintenance of fertility of these soils. This continued fertility is favourable in the area of low rainfall for cotton cultivation even without irrigation.
Due to slow absorption and loss of moisture, the black soil retains the moisture for a very long time, which helps the crops, especially, the rain fed ones, to sustain even during the dry season.
Chemically, the black soils are rich in lime, iron, magnesia and alumina. They also contain potash. But they lack in phosphorous, nitrogen and organic matter.
Suitable Crops: These soils are highly productive and well suited to the cultivation of cotton, pulses, millets, linseed, tobacco, sugarcane, vegetables and citrus fruits.
Note: In the southern and eastern parts of the country where rainfall is heavy, black soils often occur in close proximity to red soils. Black soils occupy valleys and low-level areas whereas the red soils occur on higher slopes and hill tops. Mixed black and red soils occur in Coimbatore, Madurai, Tirunelveli (Tamil Nadu) and Bundelkhand region.
3. Red and Yellow Soils
Locally called ‘Chalka’ in Andhra Pradesh.
Formation: These are derived from granites, gneisses and other metamorphic rocks —> Zonal Soils. These are formed under well-drained conditions.
Areas: Along the piedmont zone of the Western Ghat, a long stretch of area is occupied by red loamy soil. Yellow and red soils are also found in parts of Orissa and Chattisgarh and in the southern parts of the middle Ganga plain. They encircle the black cotton soil zone.
Soil Colour: The soil develops a reddish colour due to a wide diffusion of iron in crystalline and metamorphic rocks. It looks yellow when it occurs in a hydrated form. Often, their upper layer is red and the lower layer is yellow.
Soil Texture: Varies from sand to clay and loam.
Other Characteristic Features:
The fine-grained red and yellow soils are normally fertile, whereas coarse-grained soils found in dry upland areas are poor in fertility.
Have a porous and friable structure.
They are generally poor in nitrogen, phosphorous and humus.
These soils are airy and need irrigation for cultivation.
Intense leaching is a menace in these soil areas.
Suitable Crops: In places where irrigation facilities are available, the crops cultivated are wheat, cotton, pulses, tobacco, millets, oilseeds, potato, maize, groundnut and orchards.
4. Laterite Soil
The word laterite has been derived from the Latin word ‘Later’ which means brick. These soils when wet are as soft as butter but become hard and cloddy on drying. Therefore, these are widely cut as bricks for use in house construction.
Formation: The lateritic soils are particularly found on high flat erosion surfaces in areas of high(>200cm) and seasonal rainfall. The alternating wet and dry seasons lead to the leaching away of the siliceous matter of the rocks leaving behind the compounds of iron and aluminium. These are zonal soils.
Areas: These soils have mainly developed in the higher areas of the Peninsular plateau. The laterite soils are commonly found in Karnataka, Kerala, Tamil Nadu, Madhya Pradesh and the hilly areas of Orissa and Assam.
Soil Colour: Reddish brown in colour due to the presence of iron oxide.
Other characteristic features:
With rain, lime and silica are leached away, and soils rich in iron oxide and aluminium compound are left behind(thus the reddish brown colour). Also, humus content of the soil is removed fast by bacteria that thrives well in high temperature.
These soils represent the end product of decomposition and are generally low in fertility.
The pebbly crust is the important feature of laterites which is formed due to alteration of wet and dry periods.
These soils are acidic in character due to leaching. Application of manures and fertilisers is required for making these soils fertile for cultivation.
These soils are poor in organic matter, nitrogen, phosphate and calcium, while iron oxide and potash are in excess.
Suitable crops: Red laterite soils in Tamil Nadu, Andhra Pradesh and Kerala are more suitable for tree crops like cashewnut. These soils are also suitable for tea plantations.
India is one of the 17 mega diverse countries of the world. With only 2.4% of the world’s land area, 16.7% of the world’s human population and 18% livestock, it contributes about 8% of the known global biodiversity, however, putting enormous demands on our natural resources. India is home to world’s largest wild tigers population and has a unique assemblage of globally important endangered species like Asiatic lion, Asian Elephant, One-horned Rhinoceros, Gangetic River Dolphin, Snow Leopard, Kashmir Stag, Dugong, Gharial, Great Indian Bustard, Lion Tailed Macaque etc. The following steps have thus been taken to protect and manage the wildlife of the country:
Conservation of Wildlife:
1. The Government of India enacted Wild Life (Protection) Act 1972 with the objective of effectively protecting the wild life of this country and to control poaching, smuggling and illegal trade in wildlife and its derivatives.
The act extends to the whole of India except J&K which has its own wildlife act.
It has 6 schedules which give varying degrees of protection.
Schedule I and part II of Schedule II provide absolute protection and offences under these are prescribed the highest penalties.
The penalties for Schedule III and Schedule IV are less and these animals are protected.
Schedule V includes the animals which may be hunted. These are the Common crow, Fruit bats, Mice & Rats only.
Schedule VI contains the plants, which are prohibited from cultivation and planting.
2. A National Board for Wildlife (NBWL), chaired by the Prime Minister of India provides for policy framework for wildlife conservation in the country.
3. The National Wildlife Action Plan (2002-2016) was adopted in 2002, emphasizing the people’s participation and their support for wildlife conservation. The Draft National Wildlife Action Plan (NWAP) 2017-31 envisages 17 focus areas, including a new area linking wildlife planning to climate change.
4. The Indian Constitution entails the subject of forests and wildlife in the Concurrent list thus laying the responsibility of wildlife conservation on both the Centre and the State. The Federal Ministry acts as a guiding torch dealing with the policies and planning on wildlife conservation, while the provincial Forest Departments are vested with the responsibility of implementation of national policies and plans.
5. Specialized projects: To save the endangered species of animals, specialised projects are being implemented with international cooperation (WWF, UNDP, UNEP, IUCN) as well as on a stand-alone basis e.g.
Project Tiger 1973 [Follow the news story here for latest developments]
Operation Crocodile 1975
Project Rhinoceros 1987
Project Snow Leopard
Project Elephant 1988
More recently, the Black Buck (chinkara), the Great Indian Bustard (godawan) and the snow leopard etc. have been given full or partial legal protection against hunting and trade throughout India.
6. The Protected Areas of India:
Protected areas are those in which human occupation or at least the exploitation of resources is limited. These are defined according to the categorization guidelines for protected areas by the International Union for Conservation of Nature (IUCN). There are several kinds of protected areas, which vary by level of protection depending on the enabling laws of each country or the regulations of the international organizations involved.
There are 4 categories of the Protected Areas in India viz,
A National park is an area with enough ecological, geo-morphological and natural significance with rich fauna and flora, which is designed to protect and to develop wildlife or its environment.
National parks in India are IUCN category II protected areas.
Activities like grazing, hunting, forestry or cultivation etc. are strictly prohibited. No human activity is permitted inside the national park except for the ones permitted by the Chief Wildlife Warden of the state.
India’s first national park was established in 1936 as Hailey National Park, now known as Jim Corbett National Park, Uttarakhand.
There are 103 existing national parks in India covering an area of 40,500 km2, which is 1.23% of the geographical area of the country (National Wildlife Database, April 2015). [For a complete list of national parks in India and their associated fauna, click here.]
Wildlife Sanctuary:
Any area other than area comprised with any reserve forest or the territorial waters can be notified by the State Government to constitute as a sanctuary if such area is of adequate ecological, faunal, floral, geomorphological, natural. or zoological significance, for the purpose of protecting, propagating or developing wildlife or its environment.
The difference between a Sanctuary and a National Park mainly lies in the vesting of rights of people living inside. Unlike a Sanctuary, where certain rights can be allowed, in a National Park, no rights are allowed. No grazing of any livestock is permitted inside a National Park while in a Sanctuary, the Chief Wildlife Warden may regulate, control or prohibit it.
There are a total of 537 wildlife sanctuaries in India.
Conservation reserves and community reserves in India:
These terms denote the protected areas of India which typically act as buffer zones to or connectors and migration corridors between established national parks, wildlife sanctuaries and reserved and protected forests of India.
Such areas are designated as Conservation Reserves if they are uninhabited and completely owned by the Government of India but used for subsistence by communities and Community Reserves if a part of the lands is privately owned.
These protected area categories were first introduced in the Wildlife (Protection) Amendment Act of 2002 − the amendment to the Wildlife Protection Act of 1972.
These categories were added because of reduced protection in and around existing or proposed protected areas due to private ownership of land, and land use.
7. Biosphere Reserves: A biosphere reserve is an area of land or water that is protected by law in order to support the conservation of ecosystems, as well as the sustainability of mankind’s impact on the environment.
Each reserve aims to help scientists and the environmental community figure out how to protect the world’s plant and animal species while dealing with a growing population and its resource needs.
To carry out the complementary activities of biodiversity conservation and sustainable use of natural resources, biosphere reserves are traditionally organized into 3 interrelated zones, known as:
The purpose of the formation of the biosphere reserve is to conserve in situ all forms of life, along with its support system, in its totality, so that it could serve as a referral system for monitoring and evaluating changes in natural ecosystems.
Presently, there are 18 notified biosphere reserves in India. Ten out of the eighteen biosphere reserves are a part of the World Network of Biosphere Reserves, based on the UNESCO Man and the Biosphere (MAB) Programme list. [Related Reading: Everything about biosphere reserves explained here. A complete list of biosphere reserves in India and their fauna types can be found here!]
How is a biosphere reserve different from a national park/ wildlife sanctuary?
Biosphere Reserves of India protect larger areas of natural habitat (than a National Park or Wildlife Sanctuary). Biosphere Reserves may cover multiple National Parks, Sanctuaries and reserves as well.
Ex. the Nilgiri Biosphere covers: Bandipur National park, Mudumalai Tiger Reserve, Silent Valley National Park, Nagarhole National Park, Mukurthi National Park and is usually a contiguous area.
Some of the other differences are listed in the image below:
Tiger reserves – Project Tiger was launched by the Government of India in the year 1973 to save the endangered species of tiger in the country. Starting from nine (9) reserves in 1973 the number has now grown up to fifty (50) in 2016.
UNESCO World Heritage Sites (Natural, Cultural and Mixed) – Places listed by the United Nations Educational, Scientific and Cultural Organization as of special cultural or physical significance.
9. Role of communities: Communities have played a vital role in the conservation and protection of wildlife in India. E.g.
Sariska Tiger Reserve: In Sariska tiger reserve Rajasthan villagers have fought against mining by citing the wildlife protection act. In many areas, villagers themselves are protecting habitats and explicitly rejecting government involvement.
Bhairodev Dakav Sonchuri: The inhabitants of five villages in the Alwar district of Rajasthan have declared 1200 hectares of forests as the Bhairodev Dakav Sonchuri declaring their own set of riles and regulation which do not allow hunting, and are protecting the wildlife against any outside encroachments.
Bishnoi villages: In and around Bishnoi villages in Rajasthan, herds of blackbuck, Nilgai and peacocks can be seen as an integral part of the community and nobody harms them.
In this article, we continue the discussion and look at various conservation attempts made to protect the Indian forests.
Conservation of Forests:
1. The National Forest Policy:
The National Forest Policy 1952 aimed at bringing one-third of the total land area with 65% in hilly and 25% in plains under the forest cover. It suggested the extension of tree lands on river/canal banks, roads, railways, cultivable waste and degraded lands.
A new forest policy was adopted in 1988 the main emphasis of which was on the protection, conservation, regeneration, and development of forests.
2. Social Forestry:
The term, social forestry, was first used in India in 1976 by The National Commission on Agriculture. It was then that India embarked upon a social forestry project with the objective of taking the pressure off the traditional forests by the plantation of fuelwood, fodder, timber and grasses on unused and fallow land.
What social forestry means – Social Forestry refers to the forests (trees) planted by the people of a society. It has been defined as ‘the forestry of the people, for the people, by the people’.
Although a wide range of activities are included in social forestry, these mainly have the following components:
Agro Forestry – Encouraging Farmers to plant trees on their farms. Read more about it here.
Extension Forestry – Woodlots planted by forest departments for the needs of the community especially along roads, canals, railways, and other public lands
Community Forestry – Trees planted by the community themselves, on community lands, to be shared equally by them.
Reforestation or rehabilitation of degraded forest areas.
The social forestry projects, however, failed because:
They did not involve women who were the main beneficiaries.
Market-oriented trees were planted. Thus communities and farmers saw it as a cash generating rather than basic need generating exercise. The wood ended up for urban and industrial use rather than fuel and fodder needs of the rural people.
Agro-forestry reduced land employment while absentee landlordism increased.
3.Severallaws have been passed by legislatures to regulate the use of forests, ban on cutting of trees and encroachment on forest lands:
Forest Conservation Act, 1980 was passed for reserved forest areas.
Environmental Protection Act gave the Central Government powers to protect and improve the quality of the environment and preventing pollution.
The Scheduled Tribes and Other Traditional Forest Dwellers (Recognition of Forest Rights) Act, 2006, recognises the rights of forest-dwelling Scheduled Tribes and other traditional forest dwellers over the forest areas inhabited by them and provides a framework for according the same.
Besides, international conventions like Reducing Emissions through Deforestation and Degradation plus (REDD+) help to set guidelines.
4.At present there are two major afforestation schemes namely:
National Afforestation Programme – NAP (Aimed at afforestation and eco-restoration of degraded forests and adjoining areas with emphasis on community participation)
National Mission for a Green India (Aimed at increasing the forest cover of country along with improving its quality)
Commonly called the Green India Mission (GIM)
Launched in February 2014
It is one of the eight Missions outlined under India’s action plan for addressing the challenge of climate change -the National Action Plan on Climate Change (NAPCC). GIM.
There is a component under GIM to support forestry on farm lands for taking up Agro-forestry and Social forestry.
[Note: Generally a “mission mode” project implies a project that has clearly defined objectives, scopes, implementation timelines and milestones, as well as measurable outcomes and service levels.]
5. Other Government Initiatives:
National Green Highways Mission
Launched in July 2016
The mission aims to provide a green canopy along 100,000km of highways and create jobs for 1 million youth.
Under the mission, the government has made it mandatory to set aside 1% of the total project cost of any national highway contract to a Green Fund for plantation.
Nagar Van-udyan Yojana
A programme for climate smart green cities.
It is a Pilot scheme recently launched for implementation for a period of five Years.
The scheme aims at developing 200 Nagar Van (City Forests) across the country in cities having Municipal Corporation or Municipalities.
A Nagar Van-Udyan is a forested area in the vicinity of a city accessible to the city dwellers suitably managed for providing a wholesome natural environment for recreation, conservation education, biodiversity conservation etc.
School Nursery Yojana
It seeks to bring students closer to nature and inculcate in them a sense of urgency to protect the environment.
Under the scheme, students will sow seeds and grow saplings in the school nursery as part of their practical exercise for Biology classes or as their extra-curricular activities.
The students will also carry out a tree census in their school and the locality.
6. The Role of communities: Communities have played a vital role in the conservation and protection of forests in India. E.g.
Chipko movement: – Chipko Movement, started in 1970’s, was a non-violent movement aimed at protection and conservation of trees and forests from being destroyed. The name of the Chipko moment originated from the word ’embrace’ as the villagers used to hug the trees and protect them from wood cutters from cutting them. This movement headed by Shri Sunderlal Bahaguna in the Himalayas not only successfully resisted deforestation in several areas but also showed that community afforestation with indigenous species can be enormously successful.
Appiko Movement – On the lines of Chipko movement, Pandurang Hegde launched the Appiko Movement in Karnataka in 1983 (Appiko – to express one’s affection for a tree by embracing it). Its objectives were afforestation as well as development, conservation and proper utilization of forests in the best manner.
Silent Valley Movement – The silent valley is an area of tropical evergreen forests in Kerala. It is among the last tracts of virgin tropical evergreen forest in India and is very rich in bio-diversity. The environmentalists and the local people strongly objected to the hydel power project being set up here in 1973. Under pressure, the government had to declare it a national reserve forest in 1985.
Joint forest management: – this programme furnishes a good example for involving local communities in the management and restoration of degraded forests. The programme has been in formal existence since 1988 when the state of Orissa passed the first resolution for joint forest management. JFM depends on the formation of local (village) institutions that undertake protection activities mostly on degrade forest land managed by the forest department. In return, the members of these communities are entitled to intermediary benefits like non – timber forests produce and share in the timber harvested by successful protection.
Certain societies revere a particular tree which they have preserved from time immemorial. E.g. the Mundas and the Santhals of Chhotanagpur region worship Mahua and Kadamba trees and the tubes of Orissa and Bihar worship theTamarind and many trees during weddings.
The Himalayan ranges show a succession of vegetation from the tropical to the tundra, which changes with altitude. When we look at the vegetational zones, the eastern Himalayas are similar to the western Himalayas.
But on the whole, the eastern Himalayas have more tropical elements, a greater variety of Oaks and Rhododendrons and less of conifers than the western Himalayas.
Some other differences are:
The higher rainfall and warmer conditions in this part of the Himalayas.
Also, the tree line and the snow line are higher in the eastern Himalayas than the corresponding lines in the western Himalayas (Recall the discussion on snowline? Click here to quickly revise!).
Species diversity and vegetation density are also higher in the East.
Also, the southern slopes of the Himalayas carry a thicker vegetation cover because of relatively higher precipitation than the drier north-facing slopes.
Some other ways of classifying forests:
1. Classification according to composition:
Coniferous Forests: These are temperate forests occupying about 6.50% of the total forest area of the country. These are confined to the Himalayan ranges and provide soft wood timber.
Broad-Leaved Forests: These are tropical and subtropical monsoon forests. These are widely spread and cover 94% of the total forest area of the country. These are found in the plains, plateaus and mountainous areas of the country. Sal, Teak and Bamboo are important varieties.
2. Legal or Administrative Classification:
Broadly speaking, reserved, protected and unclassed are the three major legal classes of forest in India. A legal notification in a government gazette under Indian Forest Act creates or defines the boundaries of “reserved and “protected” forests in India. These forests by definition are owned by government. The rest of forests areas or waste land or any other land “recorded” in land records as “forest” but not notified in government gazette as “reserved” or “protected” forests under Indian Forest Act, are called unclassed forests. The status of their ownership and control varies among various States in India.
Reserved Forests:
These forests are under the direct supervision of the government and no public entry is allowed for the collection of timber or grazing of cattle.
About 53 % of total forest area falls in this category.
Reserved forests are regarded as the most valuable as far as the conservation of forests and wildlife is concerned.
In such forests, most of the activities are prohibited unless allowed.
Protected Forests:
These forests are looked after by the government but the local people are allowed to collect fuelwood/timber and graze their cattle without causing serious damage to the forests.
These occupy 29% of the total forest area of the country.
In such forests, most of the activities are allowed unless prohibited.
Unclassed/Unclassified Forests:
There is no restriction on cutting of trees and cattle grazing.
These occupy 18% of the total forest area of the country.
These are the other forests and wastelands belonging to both government and private individuals and communities.
All north-eastern states and parts of Gujarat have a very high percentage of their forests as unclassed forests managed by local communities.
Reserved and protected forests are referred to as permanent forest estates because they are maintained for the purpose of producing timber and other forest produce, and for protective reasons
3. The Forest Survey of India classifies forest cover in 4 classes:
Very Dense forest: All lands with tree cover (including mangrove cover) of canopy density of 70% and above.
Moderately dense forest: All lands with tree cover (including mangrove cover) of canopy density between 40% and 70%.
Open forests: All lands with tree cover (including mangrove cover) of canopy density between 10% and 40%.
Scrubs: All forest lands with poor tree growth mainly of small or stunted trees having canopy density less than 10%
The moderately dense and very dense forests are called Prime forests. Non-Forests are the lands not included in any of the above classes.
Source – India State of Forest Report (ISFR) 2015
Forest Cover in India:
According to the India State of Forest Report 2015, forests cover 21.34% of the total geographical area of the country (Road more about the report here!).
Some other facts:
Out of the total forest cover, the maximum share is of Moderate Dense Forests, followed by Open Forests.
Also, Madhya Pradesh has the largest total forest cover, followed by Arunachal Pradesh and Chhattisgarh.
Mizoram, with 88.93 % of forest cover has the highest forest cover in percentage terms, followed by Lakshadweep.
Source – India State of Forest Report (ISFR) 2015The Forest Cover map of India. Source: India State of Forest Report (ISFR) 2015
The Problems of Indian Forestry:
The specific problems of the Indian Forestry are the following:
1. Low Forest Cover
The forest cover in India is only 21.34% against the world average of about 35% and the stipulated 33% under the National Forest Policy 1952. The states of Punjab, Haryana and Rajasthan have less than 5% of their areas under forests. Forest area is decreasing due to deforestation on account of:
Growing demand for agricultural land.
Urbanisation and industrialisation
Construction of multipurpose projects
Commercial activities like mining, quarrying, oil extraction, orchard development etc.
Shifting cultivation – Increasing pressure of population has reduced the jhum cycle to only 5 years in many parts of Nagaland, Meghalaya, Mizoram, Tripura and Manipur. Consequently, the forests do not have sufficient time to regenerate.
Overgrazing by cattle
Transhumance i.e. seasonal migration by nomadic tribes up and down the mountains.
2. Uneconomic utilisation of forests:
Most of the forests are not gregarious i.e. usable plants not growing close enough. This creates a problem in their exploitation.
40% of the total forest area is inaccessible.
Lumbering, transport and sawing of timber is still done by primitive techniques.
Lack of scientific techniques of growing forests as in Canada, Russia. Only natural growth of forests takes place in India
Distribution: These forests occur on the lower slopes of the Himalaya in Bengal and Assam and on other hill ranges such as Khasi, Nilgiri, Mahabaleshwar, Pachmarhi, Amarkantak and Parasnath.
Important Species: In the eastern Himalayas, Oak, Chestnut, Ash, Birch, Pine are common species.
B. Sub-tropical Pine Forest
Distribution: Subtropical chir pine forest occurs throughout the central and western Himalaya, and Khasi pine forest occurs in Khasi hills.
Important Species: In the western Himalayas Chir Pine is the most important tree while Oak occurs in the wetter areas. In drier areas of Kashmir (rainfall 50-100cm) wild Olives are common with varieties of scrub.
Chief Characteristics:
These forests are almost pure throughout their zone of distribution.
The understorey is also not pronounced.
C. Sub-tropical Dry Evergreen Forest
Distribution: These forests occur in areas with low rainfall and consist of xerophytic, thorny and small-leaved evergreen species. Such forests are localised in the north-west corner of the country.
5. Temperate Vegetation
A. Himalayan Dry Temperate Vegetation
Distribution: It is found in the inner dry ranges of the western Himalayas.
Characteristic Features: It is predominantly a coniferous forest with xerophytic scrubs. Epiphytes and climbers are rare. [Coniferous trees are tall, straight with narrow needle like leaves. Most of the coniferous trees are evergreen but some like Larch are deciduous in nature]
Important Species are Chilgoza, Deodar, Oak, Maple, Ash, Olive etc.
B. Himalayan Moist Temperate Vegetation
Distribution: In the western Himalayas between 1500m and 3000m.
Characteristic Features: The trees are 30 to 50m tall and undergrowth is mostly evergreen. Mosses and ferns grow freely on trees.
Important Species: Deodar, Spruce, Maple, Walnut, Poplar, Cedar, Chestnut, Birch, Oak etc.
C. Montane Wet Temperate Vegetation
Distribution: In the eastern Himalayas, evergreen wet temperate forests occur between 1800m and 2700m of altitude. Nilgiris, the Annamalai and the Palni hills of south India also have this kind of forests above 1500m of altitude. The trees there are shorter, and the undergrowth is denser with abundance of epiphytes, mosses and ferns.
Characteristic Features: Rainfall is high, temperature is moderate in summer, and winter is cold. Rate of evaporation is not high. So trees do not shed their leaves annually, at least not at the same time.
Important Species: Oak, Poplar, Elm, Laurel, Maple, Birch, Alder, Magnolia
6. Sub-Alpine and Alpine Vegetation
Distribution: It occurs above 2700m of altitude in the eastern Himalayas and above 3000m in the western Himalayas.
Important Species: It is a dense scrubby forest of Silver Fur, Juniper, Pine, Birch and Rhododendron.
Characteristic Features:
The alpine forests give way to alpine grasslands through shrubs and scrub. These extend upwards up to the snowline.
Bugyals: Bugyals are high altitude alpine grasslands or meadows in Uttaranchal (at an elevation between 3400m and 4000m). These are referred to as ‘nature’s own gardens’. The topography of the terrain is either flat or sloped. The surface of these bugyals is covered with natural green grass and seasonal flowers. They are used by tribal herdsmen to graze their cattle. During the winter season the alpine meadows remain snow-covered. During summer months, the Bugyals present a riot of beautiful flowers and grass. Bugyals have a very fragile ecosystem. Some examples of Bugyals:
Auli (near Joshimath) – A premier skii range is located here.
7. Littoral and Swamp Vegetation ( Mangrove Vegetation/ Tidal Forests)
Distribution: In the tidal deltas of Ganga, Mahanadi, Godavari and Krishna rivers, evergreen mangrove vegetation thrives. These areas have rainfall of more than 200cm.
Important Tree Species: Sundari, Agar, Bhendi, Keora, Nipa
Important Animal Species: Turtles, crocodiles, gharials and snakes are the common animals found in these forests. Royal Bengal Tiger is found in the tidal forests of Ganga delta.
Characteristic Features:
The trees are mainly evergreen. Typically they produce tangled webs of arching roots that are exposed during low tides.
This vegetation is an adaptation to two conditions:
High water salinity
Flooded at regular intervals
Prominent among these adaptations are the presence of stilt roots, buttress, pneumatophores etc.
Stilt roots (also called prop roots)- Stilt roots outgrow the trunk of the mangrove, branches or already existing stilt roots. As soon as stilt roots reach the ground the tip of the stilt root develops an underground root system with which it connects the stilt root into the ground and then develops one or more further stilt roots which grow arcuately into the air to again run into the ground to develop an underground root system, this process repeats several times.
Buttress Roots – Buttress roots, developed by many trees concerning mangroves, provide stability to huge trees. The buttress roots can grow up to 10 meters in height. Buttress roots, also called buttresses do not continue their growth underground as they do above, underground buttresses develop a huge amount of small roots that grow in the soil under the buttress root.
Pneumatophores – Because of waterlogged conditions, the roots are deprived of oxygen during high tides. Some mangrove roots extend vertically above the ground. These specialised roots are known as pneumatophores. These have pores which enable the trees to breathe when other roots are submerged under water during high tide.
Mangrove shrubs, known best for a thriving aquatic life nurtured within their mesh of stilt-roots also serve a vital socio-economic function. They act as “green shields” buffering the coastline against sea erosion, and the potentially devastating impacts of cyclones and tsunami.
Mangroves support livelihood, essentially aquaculture, they supply medicinal plants, and fuel wood and construction materials. And in terms of ecological services, they stabilise shorelines, are nurseries for fishbreeding and filter heavy metals.
Note:
A study in November 2014 found mangrove patches in Karnataka. The Forest Survey of India missed recording these mangrove patches earlier as they were not large. According to the study, Karnataka has 300 hectares of mangrove forests spread over 3 coastal districts and a vibrant saline water ecosystem generally associated with India’s east coast. At the confluence of 4 rivers – Aghanashini, Gangavali, Sharavati and Venkatpura; and the Arabian Sea, is a long stretch of dense and tall mangrove vegetation locally known as Kandla or Sundar (Sundar is a well-known species of trees in mangrove forests after which the Sunderbans have been named). The study notes that while mangroves have been declining in several parts of the world from timber harvesting and pollution, these forests in Karnataka have in fact grown spatially over the last two decades.
Grasslands in India:
Owing to a short monsoon season followed by a long hot dry season, grasslands equivalent to Steppe/Pampas/Savanna are absent in India. The closed deciduous forest grades into thorny forest without an intermediate park like stage, and there is no steppe type of Grassland between the woodland and the desert.
But locally available types of grassland are:
Hilly/Upland Grassland:
Himalayas (generally above 1000m height)
Deccan Plateau Hills (Western Ghats in Karnataka where forests have been cleared)
Nilgiris have extensive grassy slopes (grass is often found interspersed with small isolated ‘shola’ forests*).
Low Lands: in the plains of Punjab, Haryana, UP, Assam and Bihar.
Riverine Grasses: These are found along the banks of the rivers which provide grazing facilities to cattle especially the bhabar pastures in northern India.
*‘Sholas’ are the mixed dense forests of tropical evergreen and temperate evergreen rainforest species in the Nilgiri Hills. The patches of shola forests are found mainly in valleys and are usually separated from one another by undulating montane grassland. The shola and grassland together form the shola-grassland complex or mosaic.
Now that we are done with the vegetation types of India, expand the following image for a quick revision!
Moving on, let’s discuss the various natural vegetation types of India in detail:
Natural Vegetation Types of India
1. Tropical Evergreen Forests
‘Evergreen’ because there is no definite time for trees to shed their leaves, flowering and fruition. As such these forests appear green all the year round.
The common animals found in these forests are elephants, monkey, lemur and deer. The one-horned rhinoceros are found in the jungles of Assam and West Bengal. Besides these animals, plenty of birds, bats, sloth, scorpions and snails are also found in these jungles.
A. Tropical Wet Evergreen Vegetation:
Distribution: These forests are found on the western slope of the Western Ghats, upper Assam through Cachar and the Andaman and Nicobar Islands.
Climatic Conditions: They are found in warm and humid areas with an annual precipitation of over 250 cm and a short dry season. The mean annual temperature here is above 22°C.
Characteristic Features:
Tropical evergreen forests are well stratified, with layers closer to the ground covered with shrubs and creepers, followed by short structured trees, further followed by tall variety of trees.
In these forests, trees reach great heights up to 60 m or above.
Bounded by semi-evergreen forests on drier margins.
Very rich biodiversity.
Timber produced in these forests is fine-grained and durable.
Important Species found in these forests: Rosewood, Mahogony, Aini, Ebony, etc. Important species in Kerala are Mesa, White cedar, Jamun, Canes etc. Common species found in Assam forests are Gurjan, Jamun, Agar, Bamboo etc.
B. Tropical Semi-Evergreen Vegetation:
Distribution: These forests occur in areas adjoining tropical wet evergreen, and form a transition between evergreen and moist deciduous forests. These forests occur on the western coast, in Assam, on the lower slopes of the eastern Himalayas and in the Andamans in the areas where precipitation and atmospheric humidity is slightly less than that in tropical evergreen vegetation area.
Characteristic Features:
Such forests have a mixture of evergreen and moist deciduous trees. The undergrowing climbers provide an evergreen character to these forests.
The climbers are heavy, bamboos are less prevalent and epiphytes are abundant. [Epiphytes – The plants which depend on other plants for mechanical support (and not for nutrients). e.g. lichens, mosses, orchids etc.]
The forest is dominated by a variety of large trees with a tendency to gregariousness (i.e. growing in groups that are close together)
Plant Adaptations in these areas:
Buttresses – Many large trees have huge ridges called buttresses near the base that can rise 30 feet high before blending into the trunk. Buttress roots provide extra stability and increase the surface area of a tree so that it can ‘breathe in’ more carbon dioxide and ‘breathe out’ more oxygen. Typically, they are found in nutrient-poor rainforest soils and do not penetrate to deeper layers.
Source. A buttress root system provides structural support.
Big trees with buttress roots in tropical evergreen forest, India, Andaman Islands, Havelock Island. Source.
The bark is thicker and rougher, and the canopy is less dense than that in the previous type. Also, the canopies are not continuous and species richness is lower
Main species are white cedar, hollock and kail. Important Species in Kerala are Aini, Laurel, Rosewood, thorny bamboo, etc. Important species of northeastern India are White Cedar, Indian Chestnut, Champa and Mango.
C. Tropical Dry Evergreen Vegetation:
Distribution: This type is confined to the Tamil Nadu coast and the areas which receive rainfall of about 100cm mostly from the north-east monsoon/winter monsoon (October-December).
The growth of evergreen forests in areas of such low rainfall arouses great botanical interest. This vegetation may be due to the seasonal distribution of rainfall (winter rainfall).
Characteristic Features of this vegetation:
Short height trees (<12m)
A closed but low canopy of grasses and shrubs.
No canopy layer differentiation.
Bamboos are rare /absent.
Important Species found in these forests: Neem, Jamun, Tamarind, Machkund, Khirni, Kokko, Ritha, Gamari Canes.
Most of the land under these forests has been cleared for agriculture or casuarinas plantations (Eucalyptus tree plantations)
2. Tropical Deciduous Vegetation
Also called the monsoon forests, these are the most widespread forests in India. The term ‘Deciduous’ refers to the ability of some plants to lose their leaves annually. They are spread over regions which receive rainfall between 70 and 200 cm.
In these forests, the common animals found are lion, tiger, pig, deer and elephant. A huge variety of birds, lizards, snakes, and tortoises are also found here. [Currently, India is the only country on Earth confirmed to have both lions and tigers in its wilderness.]
On the basis of the availability of water, these forests are further divided into:
A.Tropical Moist Deciduous Vegetation
Climatic Conditions: It thrives in areas having of moderate rainfall of 150-200 cm with a dry season of 4 to 6 months, a mean annual temperature of 26°C to 27°C and an average relative humidity of 60-80%. On the wetter margins, it has a transition to the tropical Semi-Evergreen Vegetation, while on the drier margins to the Tropical Dry Deciduous.
Distribution: It is found on the eastern slopes of the Western Ghats, eastern coastal plains, eastern plateaus, Himalayan foothills and in some parts of the Satluj-Ganga plains.
Characteristic Features:
The trees shed their leaves during the dry season.
These forests are usually 2 to 3 layered.
Dense undergrowth
Important Species: The common trees are Sal, Teak, Sandalwood, Ajun, Ebony, Shisham, Hurra, Mahua, Amla, Semul, Mulberry and Kusum.
B. Tropical Dry Deciduous Vegetation
Climatic Conditions: The dry deciduous trees grow in areas where rainfall is less than 150cm and the dry period is relatively long. On the wetter margins, it has a transition to the moist deciduous, while on the drier margins to thorn forests.
Distribution: It is found in Eastern Rajasthan, Kathiawar, rain-shadow areas of the Deccan plateau, central India and Punjab.
Characteristic Features:
These forests consist of trees less than 25m high, with a light canopy consisting of deciduous trees. The undergrowth is shrubby and grassy.
As the hot dry season begins (March-May), the trees shed their leaves completely and the forest appears like a vast grassland with naked trees all around.
In the higher rainfall regions of the Peninsular plateau and the northern Indian plain, these forests have a parkland landscape i.e. trees are more stunted and widely spaced and are interspersed with patches of grass.
In the western and southern part of Rajasthan, vegetation cover is very scanty due to low rainfall and overgrazing.
Important Species: Common plants are Teak, Sal, Laurel, Palas, Khair, Tendu, Amaltas, Bel, Axlewood etc.
3. Tropical Thorny Vegetation
Climatic Conditions: In areas with 50-70cm of rainfall
Distribution: It is found in south-western Punjab, western Haryana, western Uttar Pradesh, central and eastern Rajasthan, western Madhya Pradesh, Kachchhand, neighbouring parts of Saurashtra, leeward areas of Sahyadris.
Characteristic Features:
Plant life is highly specialized to adapt to the coarse and dry conditions in this area, with long roots, small leaves, stems that store water, and prickly spines that discourage animals from touching or eating them.
The natural vegetation consists of open stunted (trees with 6-9m height) forest breaking down into xerophytic bush and western Rajasthan grading into deserts.
In these forests, plants remain leafless for the most part of the year and give an expression of scrub vegetation.
Plant adaptations:
These xerophytic plants combat drought with certain devices of water preservation like partial or complete replacement of leaves by thorns, waxy leaves, water storing cells, hair on the stalk etc.
Tussocky grass grows up to a height of 2 m as the undergrowth.
Trees are scattered and have long roots penetrating deep into the soil in order to get moisture.
The stems are succulent to conserve water.
Leaves are mostly thick and small to minimize evaporation.
Before we discuss the natural vegetation types found in India, let’s get acquainted with some basic terms:
Flora, Vegetation and Forests:
Flora refers to plants of a particular region or period, listed as a species and considered as a group. Likewise, fauna refers to the animal life, considered collectively, of any given period, environment or region.
Vegetation, on the other hand, refers to the assemblage of plant species in a given environmental frame or ecological frame. It is broader than the term flora which refers to species composition. Further:
Natural vegetation includes that part of the plant life which grows in wild without human aid and adapts to constraints of the natural environment in size, structure and requirements. Thus cultivated crops and fruit orchards form a part of the vegetation but not natural vegetation.
That part of natural vegetation which has remained undisturbed by humans is referred to as virgin vegetation. It can be found in India in the inaccessible parts of the Himalayas, the Thar Desert and the Sunderbans. Elsewhere, human occupation has either transformed natural vegetation into cultivated vegetation or degraded the natural vegetation.
The virgin vegetation, which is purely Indian is known as endemic or indigenous species but that which has come from outside India is termed as exotic.
Forest: The term forest implies ‘natural vegetation’ of the area, existing from thousands of years and supporting a variety of biodiversity, forming a complex ecosystem.
Depending on the physical, geographical, climatic and ecological factors, there are different types of forests like evergreen forest (mainly composed of evergreen tree species i.e. species having leaves all throughout the year) and deciduous forest (mainly composed of deciduous tree species i.e. species which lose their leaves during particular months of the year). Each forest type forms a habitat for a specific community of animals that are adapted to live in it.
Various factors which influence the type and distribution of natural vegetation and wildlife:
Land
The nature of land affects the natural vegetation directly and indirectly. E.g. the type of vegetation in the mountainous regions is different than that in the plateau and plain areas. The fertile land is generally devoted to agriculture, while the undulating and rough terrains are areas where grassland and woodlands develop and give shelter to a variety of wildlife.
Soil
Different types of soils provide basis for different types of vegetation. The sandy soils of the desert support cactus and thorny bushes while wet, marshy, deltaic soils support mangroves and deltaic vegetation. The hill slopes with some depth of soil have conical trees.
Temperature and Humidity
Temperature and humidity are the main factors which determine the character and extent of vegetation. E.g. an area with high temperature and high humidity supports evergreen forest, while an area with high temperature and low humidity supports thorny bushes (desert).
Precipitation
Areas of heavy rainfall have more dense vegetation as compared to other areas of less rainfall.
See the following diagram to understand the combined effect of temperature and annual precipitation on the vegetation type of an area:
Photoperiod, also called the light duration or day length, refers to the length of the light period as compared to the darkness within a day. The variation in photoperiod at different places is due to the differences in latitude, altitude, season and duration of the day. Due to longer duration of sunlight, trees grow faster in summer.
Altitude
Increasing elevation causes a distribution of vegetation similar to that of increasing latitude. In general, ‘altitude mimics latitude’ and there occurs a close parallel between latitudinal and altitudinal zonation of climate and thus natural vegetation too. E.g. Mount Kenya in east Africa and Mount Chimborozo in Equador have their feet on the equator but their peaks are snow covered.
It was Alexander Von Humboldt who first recognised the relationship between vegetation and altitude.
Since India is a land of various climatic regions, varied kinds of natural vegetation have developed here. Having said that, rainfall is more important than temperature (except in the Himalayas) in determining the vegetation distribution in India. The seasonal rainfall distribution/the length of the dry season also affect the vegetation distribution in an important way.
In general, the following inter-relationship is observed in India:
Observe this broad relationship as highlighted in the following map:
High rainfall areas (>200cm) —> Evergreen forests grow in the high rainfall areas of the Western Ghats, North –eastern India and the Andaman and Nicobar Islands. These forests grow in areas where the monsoon period lasts for several months. There is no definite time for trees to shed their leaves, flowering and fruition. As such these forests appear green all the year round, hence the name evergreen.
Moderate Rainfall Areas (70-200cm) —>Deciduous forests are found in regions with a moderate amount of seasonal rainfall that lasts for only a few months. Most of the forests in which Teak trees grow are of this type. The deciduous trees shed their leaves during the winter and hot summer months.
Low Rainfall areas/ Semi-arid areas (<70cm) —> Thorn forests are found in the semi-arid regions of India. The trees, which are sparsely distributed, are surrounded by open grassy areas.
Apart from these, mangroves forests grow along the coast, especially in the river deltas. These plants are uniquely adapted to be able to grow in a mix of saline and freshwater (will be taken up in detail in the following sections.)
India’s Climatic Calendar: The Southwest Monsoon Season
Chief Characteristics of Monsoonal Rainfall:
Monsoonal rainfall is largely governed by relief or topography. For example:
The windward side of the Western Ghats registers a rainfall of over 250 cm.
The heavy rainfall in the north-eastern states can be attributed to their hill ranges and the Eastern Himalayas.
The monsoon rainfall has a declining trend with increasing distance from the sea. E.g. consider the amount of rainfall received during the south-west monsoon period at the following places:
The rain comes in spells and displays a declining trend from west to east over the west coast, and from the south-east towards the north-west over the North Indian Plain and the northern part of the Peninsula.
Its spatial distribution is also uneven which ranges from 12 cm to more than 250 cm.
Image Source: NCERT
What causes monsoons?
Monsoon is a familiar though a little known climatic phenomenon. Despite the observations spread over centuries, the monsoon continues to puzzle the scientists. Many attempts have been made to discover the exact nature and causation of monsoon, but so far, no single theory has been able to explain the monsoon fully.
Let’s look at some of the important concepts about the origin of monsoons. We will study these along the following lines:
The Classical Hypothesis
Halley(1690’s)
Hadley (1730’s)
The role of moisture.
The shifting of ITCZ – Flohn
Recent theories:
The role of Tibetan plateau
As a mechanical barrier
As a high-level heat source
The role of jetstreams
The Sub-tropical/ tropical westerly jetstream
The tropical/ equatorial easterly jetstream
1. The Classical Hypothesis
Halley hypothesized that the primary cause of the annual cycle of Indian monsoon circulation was a differential heating effect between the ocean and land in South Asia.
During April and May when the sun shines vertically over the Tropic of Cancer, the large landmass in the north of Indian ocean gets intensely heated. This causes the formation of an intense low pressure in the northwestern part of the subcontinent.
The pressure in the Indian Ocean in the south of the landmass is high as water gets heated slowly.
This pressure differences causes the flow of winds from the high pressure to low pressure areas
Thus the first model ever proposed about the mechanism of the Indian monsoon was Haley’s planetary scale sea-breeze – land breeze system in 1690’s.
Image SourceIndian Monsoon: Haley’s Planetary Scale Sea Breeze–Land Breeze Model
Hadley later argued that Haley’s model was lacking in the physical ingredient of the effect of rotation of earth about its axis. Hadley reasoned that the monsoon originates in the SE trades of the southern hemisphere and as it flows across the equator towards the heated landmass, the coriolis force causes it to turn to right, thereby forming the summer monsoon or the SW monsoon.
Moisture plays an important role in the atmospheric circulation which was not appreciated by either Halley or Hadley.
In this respect, the release of latent heat augments the differential heating produced by the land-sea contrast by providing a mechanism for the solar energy received over the vast stretches of the Indian Ocean to be collected, stored, concentrated and later released over the parched landscape of India by a massive atmospheric motion (See the following image to understand this transfer of solar energy) . As the moisture laden air comes over India, with its upliftment there takes place condensation releasing latent heat – augmenting the low pressure conditions i.e. the cause getting augmented by its effect.
The existence of Asian monsoon according to Dr. Flohn is not due to the temperature contrast between land and sea but primarily due to the annual migration of thermally induced planetary winds and pressure belts. For Flohn, the winter monsoon is nothing but the tropical easterlies or the northern trade winds. According to Flohn, the SW monsoon is constituted by the equatorial westerlies which have been displaced northward (because of shift of ITCZ by 20° or more).
Shifting of the ITCZ and the Indian Monsoon – Dr. Flohn
Recent Theories:
1. The role of Tibetan Plateau:
A remarkable aspect of the large scale circulation during the summer monsoon season over south-Asia is the upper tropospheric anti-cyclone situated over the Tibetan Plateau.
The Tibetan Plateau located more than 4500m above mean sea-level with a length of 2000km and width of 600km in the west and 1000km in the east, is considered to be one of the key factors in the development of monsoon circulation in the region.
The Tibetan plateau exerts its influence both as a mechanical barrier in the atmospheric flow as well as a high level heat source.
An anti-cyclone appears in the upper troposphere over Tibet during the Indian monsoon season primarily due to latent and sensible heating over the plateau.
This anti cyclone appears over south-east Asia in the month of May and then moves north-westwards, reaching Tibetan plateau around the height of the summer monsoon season.
From about September, the anticyclone migrates south-eastward towards Indonesia and loses definition after October.
Variations in the intensity and position of this High and its orientation have been found to be closely related to the monsoon circulation over South Asia.
The role of Jet streams:
Jet streams which affect India’s monsoon:
1. Sub tropical/ Tropical Westerly Jet stream (TWJS) ~27°N
(Covered in detail in the discussion on winter season. Need to revise? Click here!)
According to Dr. Koteshwaram, the disappearance of this jet from the south of the Himalayas paves the way for the burst of South-West Monsoon along the coast of Kerala.
This jet is a prominent feature of the upper air circulation during the Indian summer monsoon season (June – September). It appears as a band of strong easterlies extending from SE Asia across the Indian Ocean and Africa to the Atlantic, generally at a height of about 14 kms. It is present over south Indian peninsula between 12° and 15°N with a mean position of 14°N. This easterly jet stream is held responsible for the burst of the monsoon in India.
The position and speed of this jet have been found to have significant spatial and temporal fluctuations, which in turn correlate with monsoon rainfall distribution over peninsular India.
The Subtropical Westerly Jetstream and the Tropical Easterly Jetstream
Factors which influence the South-West monsoon intensity and rainfall distribution:
Mascarene High and the Somali Jetstream: It is the high pressure area at sea level south of the equator in the Indian Ocean near Mascarene Islands. The position and intensity of this high are considered to be closely linked to the south summer monsoon activity.
According to scientists, the broad belt of high pressure around the Mascarene Islands generates a cross-equatorial flow known as the Somali Jet which brings heavy rain to India’s west coast. A strong, low level jet usually means a strong monsoon over peninsular India.
Variation in the axis of the monsoon trough: The monsoon trough axis experiences considerable day to day variation in its position, which has a vital bearing on the monsoon rainfall distribution in the region. During the break monsoon periods, when there is a temporary lull in monsoon activity, the trough line shifts to the foothills of the Himalayas. Rainfall over the central parts of India decreases considerably and there is an increase in rainfall over northern India along the Himalayan foothills.
Teleconnections (ENSO – El–Nino and Southern Oscillation Index):
A. Southern Oscillation Index (SOI)
A curious see-saw pattern of meteorological changes has been observed b/w Indian Ocean & Pacific ocean. Whenever pressure is higher over Indian Ocean, low pressure prevails over Pacific Ocean & vice versa. This see-saw relationship is referred to as the Southern Oscillations.
To measure this pressure difference, a SOI has been developed based on the pressure data at certain representative stations (e.g. the SOI between Tahiti island and Darwin is the most widely used)
It is an anomalous warming of the Eastern Tropical Pacific Ocean that occurs at 2 – 10 years intervals and is frequently associated with far reaching climatic and oceanic impacts around the world.
These two are believed to be inter-connected – the southern oscillation has been identified as the atmospheric counterpart to El-Nino. Both are together referred to as ENSO.
During the high southern oscillation phase (Normal situation), precipitation tends to be abundant in the Indonesian – Australian region, most of the south Asian region, SE Africa and northern coast of South America. Relatively dry conditions prevail over the equatorial pacific, east central Africa and northern Mexico.
During the low phase of the southern oscillation (El-Nino), the rainfall anomalies are approximately opposite. The El-Nino is found to be adversely correlated with the SW monsoon rain.
La-Nina (Spanish for girl child) refers to the reinforced normal situation and is found to be positively correlated with the SW monsoon rain.
India’s Climatic Calendar: the South-West Monsoon Season
Temperature Conditions during this season:
As the sun shifts northwards, the temperature rapidly increases especially in the northern India.
The wind circulation over the subcontinent undergoes a complete reversal at both, the lower as well as the upper levels. Let’s see how:
Distribution of air pressure and winds on the surface of the earth:
As a result of rapid increase in temperature in May over the north-western plains, the low-pressure conditions over there get further intensified.
Because of the heating of the subcontinent, by the middle of July, the low-pressure belt near the surface [termed as Inter Tropical Convergence Zone (ITCZ)] shifts northwards, roughly parallel to the Himalayas between 20° N and 25° N. The ITCZ in this position is sometimes called the monsoon trough.
[Revision Note: ITCZ is the low-pressure zone located at the equator where the trade winds converge. It is also referred to as the thermal equator. It is a zone of generally calm, hot, rising air and low pressure.]
Roughly, this elongated low-pressure monsoon trough extends over the Thar desert in the north-west to Patna and Chotanagpur plateau in the east-southeast.
Meanwhile, the sea surrounding India heats up slowly, creating a zone of relatively high pressure off India’s Southern Coastline.
Next, because winds blow from high to low pressure, warm moisture-laden air moves south-westerly direction from the sea over to India in the north and North East and is deflected by the Coriolis force as the Earth spins. It is this moist air current which is popularly known as the south-west monsoon.
By this time, the westerly jet stream withdraws from the Indian region. In fact, meteorologists have found an interrelationship between the northward shift of the equatorial trough (ITCZ) and the withdrawal of the westerly jet stream from over the North Indian Plain. It is generally believed that there is a cause and effect relationship between the two.
Indian Monsoons: Jetstreams and the Shifting of ITCZ
An easterly jet stream flows over the southern part of the Peninsula in June and has a maximum speed of 90 km per hour. In August, it is confined to 15°N latitude, and in September up to 22° N latitudes. The easterlies normally do not extend to the north of 30° N latitude in the upper atmosphere.
Image Source: NCERT
Easterly Jet Stream and Tropical Cyclones: [The tropical cyclones were discussed in detail in the discussion on summer season. Remember? Revise here before moving forward!]
The easterly jet stream steers the tropical depressions into India.
These depressions play a significant role in the distribution of monsoon rainfall over the Indian subcontinent. The tracks of these depressions are the areas of highest rainfall in India.
The frequency at which these depressions visit India, their direction and intensity, all go a long way in determining the rainfall pattern during the south-west monsoon period.
The onset and progress of South-West Monsoon in India:
1. Entry of Monsoon into India:
The rain in the south-west monsoon season begins rather abruptly. This sudden onset of the moisture-laden winds associated with violent thunder and lightning is often termed as the “break” or “burst” of the monsoons.
The mean date for the burst of monsoon along the coast of Kerala is 1 first June with a coefficient of variation of a week. It reaches the interior parts of the country by the first week of July. By mid-July, south-west monsoon engulfs the entire subcontinent.
Impact of this rainfall: One result of the first rain is that it brings down the temperature substantially. The day temperature registers a decline of 5°C to 8°C between mid-June and mid-July.
2. The progress of monsoons: As these winds approach the land, their south-westerly direction is modified by:
The relief, and
The thermal low pressure over the north-west India.
The monsoon approaches the landmass in two branches:
The Arabian Sea branch
The Bay of Bengal branch.
Indian Monsoons: the Arabian Sea Branch and the Bay of Bengal Branch
The Arabian Sea branch:
The monsoon winds originating over the Arabian Sea further split into three branches:
One branch is obstructed by the Western Ghats.
As these winds climb the slopes of the Western Ghats, they become cooler, their moisture retention capacity reduces and as a result, the windward side of the Sahyadris and Western Coastal Plain receive very heavy rainfall ranging between 250 cm and 400 cm.
Much of the rainfall along the Western Ghats is thus orographic, as the moist air is obstructed and forced to rise along the Ghats.
After crossing the Western Ghats, these winds descend and get heated up. This reduces humidity in the winds. As a result, these winds cause little rainfall east of the Western Ghats. This region of low rainfall is known as the rain-shadow area.
Another branch of the Arabian Sea monsoon strikes the coast north of Mumbai. Moving along the Narmada and Tapi river valleys, these winds cause rainfall in extensive areas of central India. The Chotanagpur plateau gets 15 cm rainfall from this part of the branch. Thereafter, they enter the Ganga plains and mingle with the Bay of Bengal branch.
The third branch of this monsoon wind strikes the Saurashtra Peninsula and the Kachchh. It then passes over west Rajasthan and along the Aravallis, causing only a scanty rainfall. In Punjab and Haryana, it too joins the Bay of Bengal branch. These two branches, reinforced by each other, cause rains in the western Himalayas.
Note: Though this branch passes through Rajasthan, it does not cause rainfall there. This is because:
The direction of Aravallis is parallel to these monsoon winds.
The dry and hot winds from the Sindh region of Pakistan lessen the relative humidity of these monsoon winds and do not allow them to get saturated.
The Bay of Bengal branch:
The Bay of Bengal branch strikes the coast of Myanmar and parts of south-east Bangladesh. But the Arakan Hills along the coast of Myanmar deflect a big portion of this branch towards the Indian subcontinent.
The monsoon, therefore, enters West Bengal and Bangladesh from the south and south-east instead of from the south-westerly direction.
From here, this branch splits into two under the influence of the Himalayas and the thermal low in north-west India.
One branch moves westward along the Ganga plains reaching as far as the Punjab plains.
The other branch moves up the Brahmaputra valley in the north and the northeast, causing widespread rains.
Its sub-branch strikes the Garo and Khasi hills of Meghalaya. The hills of Garo, Khasi and Jaintia are expanded in a funnel shape with an opening towards the sea. So the moist winds coming from the Bay of Bengal undergo a sudden rise here and cause excessive rainfall. Mawsynram, located on the crest of Khasi hills, receives the highest average annual rainfall in the world (1141cm).
There is relatively less rainfall on the leeward slope of the Meghalaya Plateau e.g. 143 cm in Shillong and 161 cm in Guwahati which is very less in comparison to that in Mawsynram.
The Brahmaputra valley to the north also experiences a rain-shadow effect; the problem is mitigated, however, by the adjacent Himalayas, which cause the winds to rise again, thereby establishing a parallel belt of heavy precipitation.
Note:
The Arabian Sea branch is stronger than the Bay of Bengal branch. 65% of the humidity brought by the monsoon comes from the Arabian Sea whereas the monsoon coming from the Bay of Bengal contributes only 35% to the humidity.
In the Gangetic Plains, the two branches merge into one. By the time they reach the Punjab their moisture is largely spent. The gradual reduction in the amount of rainfall toward the west is evidenced by the decline from 162 cm at Kolkata to 66 cm at Delhi and to desert conditions still farther west.
Over the north-eastern portion of peninsular India, the two branches also intermittently collide, creating weak weather fronts with sufficient rainfall to produce patches of fairly high precipitation (more than 152 cm) in the Chotanagpur plateau.
Here it is important to know why the Tamil Nadu coast remains dry during this season.
It is because:
The Tamil Nadu coast is situated parallel to the Bay of Bengal branch of south-west monsoon.
It lies in the rain-shadow area of the Arabian Sea branch of the south-west monsoon.
3. Break in the Monsoon
During the south-west monsoon period after having rains for a few days, if rain fails to occur for one or more weeks, it is known as ‘break’ in the monsoon. These dry spells are quite common during the rainy season.
Reasons:
These breaks in rainfall are related to the cyclonic depressions mainly formed at the head of the Bay of Bengal, and their crossing into the mainland. Besides the frequency and intensity of these depressions, the passage followed by them determines the spatial distribution of rainfall.
In northern India rains are likely to fail if the rain-bearing storms are not very frequent along the monsoon trough or the ITCZ over this region.
Over the west coast, the dry spells are associated with days when winds blow parallel to the coast.
4. The Withdrawal of the SW monsoon:
The withdrawal of the SW monsoon and the onset of the NE monsoon in the end of September are a gradual phenomenon. They take place almost at the same time and tend to merge. This explains the popularity of the phrase “Retreating Monsoon”. This will be taken up in detail in the discussion on Autumn Season.
By the end of December (22nd December), the sun shines vertically over the Tropic of Capricorn in the southern hemisphere. So, India which is located in the northern hemisphere experiences low temperatures. January and February are the coldest months over most parts of the country.
The isotherm of 20°C runs roughly parallel to the Tropic of Cancer.
The northern region:
This season usually begins in late-November in northern India. Lowest temperatures are observed in Punjab and Rajasthan. December and January are the coldest months in the northern plain. The night temperature may be quite low, sometimes going below freezing point in Punjab and Rajasthan.
There are three main reasons for the excessive cold in north India during this season:
States like Punjab, Haryana and Rajasthan being far away from the moderating influence of sea experience continental climate.
The snowfall in the nearby Himalayan ranges creates cold wave situation; and
Around February, the cold winds coming from the Caspian Sea and Turkmenistan bring cold wave along with frost and fog over the northwestern parts of India.
The peninsular region:
The Peninsular region of India, however, does not have any well-defined cold weather season. There is hardly any seasonal change in the distribution pattern of the temperature in coastal areas because of:
Moderating influence of the sea, and
Proximity to the equator.
Distribution of air pressure and winds on the surface of the earth:
In winter months, the weather conditions over India are generally influenced by the distribution of pressure in the Central and Western Asia.
A high-pressure centre in the region lying to the north of the Himalayas develops during winter.
This centre of high pressure gives rise to the flow of air from the north towards the Indian subcontinent, south of the mountain range.
These surface winds blowing out of the high-pressure centre over Central Asia reach India in the form of a dry continental air mass.
These continental winds come in contact with trade winds over northwestern India. The position of this contact zone is not, however, stable. Occasionally, it may shift its position as far east as the middle Ganga valley with the result that the whole of the northwestern and northern India up to the middle Ganga valley comes under the influence of dry northwestern winds.
In south India, the air pressure is slightly lower (due to higher temperatures). As a result, winds start blowing from northwestern high-pressure zone to the low air pressure zone over the Indian Ocean in the south. Due to a low pressure gradient, the light winds blow outwards with a low velocity of about 3-5 km per hour.
By and large, the topography of the region influences the wind direction (See the following map):
They are westerly or northwesterly down the Ganga Valley.
They become northerly in the Ganga-Brahmaputra delta.
Free from the influence of topography, they are clearly north-easterly over the Bay of Bengal.
These land bearing winds being cold and dry don’t give rain over most parts of the country. However, these winds cause rain along the Coromandel Coast since they collect moisture on their way over the Bay of Bengal.
Image Source – NCERT ClassXI
Jet Stream and Upper Air Circulation:
Higher up in the atmosphere, a different pattern of air circulation is observed during the winter months:
All of Western and Central Asia remains under the influence of westerly winds along the altitude of 9-13 km from west to east. These winds blow across the Asian continent at latitudes north of the Himalayas roughly parallel to the Tibetan highlands. These are known as the sub-tropical/tropical westerlyjet stream.
Tibetan highlands act as a barrier in the path of these jet streams. As a result, jet streams get bifurcated. One of its branches blows to the north of the Tibetan highlands, while the southern branch blows in an eastward direction, south of the Himalayas, later recombining into a single stream over China.
It is believed that this southern branch of the jet stream exercises an important influence on the winter weather in India.
The mean position of this jetstream is about 25°N.
Image Source: NCERT Class 9
This jetstream first appears over the northern parts of the Indian subcontinent in the month of October after the withdrawal of the summer monsoon and shifts progressively southwards with the advance of the winter season. Thereafter, it shifts back towards the north, weakens and disappears from the South Asian region with the establishment of the South-West monsoon in June. According to Dr.Koteshwaram, the disappearance of this jet from the south of the Himalayas paves the way for the burst of South-West Monsoon along the coast of Kerala.
Indian Climate and the role of Jetstreams.
Western Disturbances:
During the winters, the weather in India is pleasant. The pleasant weather conditions, however, at intervals, get disturbed by shallow cyclonic depressions originating over the east Mediterranean Sea.
These temperate cyclones travel eastwards across West Asia, Iran, Afghanistan and Pakistan and enter the north-western parts of India with the help of the westerly jetstream (discussed above).
On their way, the moisture content gets augmented from the Caspian Sea in the north and the Persian Gulf in the south. Since these extratropical cyclones reach India from the West, they are usually referred to as the western disturbances over the Indian region.
Because of the high terrain, mountain ranges, most of these disturbances are in the mature stage and hence weak or irregular by the time they reach India.
Reaching Rajasthan, Haryana and Punjab, these disturbances slow down and stagnate due the nearly closed in nature of the region with high hills.
With moisture feed from the Arabian Sea, these disturbances may intensify and move north-east. The tracks of these disturbances come farthest south to latitudes 22/23°N in the month of February.
An increase in the prevailing night temperature generally indicates an advance in the arrival of these disturbances.
The western disturbances result in:
A cold spell in north-western India as these depressions are followed by cold waves.
Winter rainfall in Punjab, Haryana, Delhi and western Uttar Pradesh, locally known as ‘mahawat’. Although the amount is meagre, it is highly beneficial for Rabi crops.
Snowfall in the higher altitudes of Kashmir and Himachal Pradesh and sometimes hail too. It is this snow that sustains the flow of water in the Himalayan rivers during the summer months.
The precipitation goes on decreasing from west to east in the plains and from north to south in the mountains.
Note: The term western disturbance is generally applied to all disturbances which come from the West, even when a “low” may not be seen on the synoptic charts.
India’s climate can be described as hot monsoonal type. The word monsoon comes from the Arabic word ‘Mausim’ which means ‘season’. Monsoon, by definition, is a wind system that changes wind direction seasonally. The four principal monsoon regions in the world are:
South Asia
East Asia
Northern Australia
West Africa
Let’s take the case of South Asia:
During winter, the large continent of Asia gets extremely cold and the Siberian high pressure develops. Air flow is offshore and dry. During the summer, the continent develops low pressure in response to heating and the airflow reverses. Moisture-laden air from the ocean is brought inland where it rises over the terrain and produces extremely large amounts of rainfall. See the following diagram and observed the marked shift in the wind direction.
But at the same time, we know that there are great regional differences and variations experienced in India with respect to temperature rainfall etc. Let’s look at some of these regional variations:
Variations in 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. On a December night, the temperature in Drass (Jammu and Kashmir) may drop down to minus 45°C while Thiruvananthapuram or Chennai on the same night record 20°C or 22°C.
Daily temperature range: In Kerala and in the Andaman Islands, the difference between day and night temperatures may be hardly seven or eight degree Celsius. But in the Thar desert, if the day temperature is around 50°C, at night, it may drop down considerably up to 15°-20°C.
Regional variations in type and amount of precipitation: While snowfall occurs in the Himalayas, it only rains over the rest of the country. Similarly, while Cherrapunji and Mawsynram in the Khasi Hills of Meghalaya receive rainfall over 1,080 cm in a year, Jaisalmer in Rajasthan rarely gets more than 9 cm of rainfall during the same period. Most parts of the country get rainfall during June-September, but in the coastal areas of Tamil Nadu, it rains in the beginning of the winter season.
These regional variations differentiate the weather and climate of different regions of India.
This brings us to the difference between weather and climate:
Weather is the momentary state of the atmosphere while climate refers to the average of the weather conditions over a longer period of time. Weather changes quickly, maybe within a day or week but climate changes imperceptively and may be noted after 50 years or even more.
Factors Determining the Climate of India:
India’s climate is controlled by a number of factors which can be broadly divided into two groups — factors related to location and relief, and factors related to air pressure and winds.
Factors related to Location and Relief
1. Latitude: The Tropic of Cancer passes through the central part of India in the east-west direction. Thus, the northern part of the India lies in the sub-tropical and temperate zone and the part lying south of the Tropic of Cancer falls in the tropical zone. The tropical zone being nearer to the equator experiences high temperatures throughout the year with small daily and annual range. Areas north of the Tropic of Cancer being away from the equator, experience extreme climate with high daily and annual range of temperature.
Impact of Latitude on India’s Climate
1. The Himalayan Mountains:
The lofty Himalayas in the north along with its extensions act as an effective climatic divide.
The Himalayas act as an invincible shield to protect the subcontinent from the cold northern winds. These cold and chilly winds originate near the Arctic circle and blow across central and eastern Asia.
The Himalayas also trap the monsoon winds, forcing them to shed their moisture within the subcontinent.
3. Distribution of Land and Water: India is flanked by the Indian Ocean on three sides in the south and girdled by a high and continuous mountain-wall in the north. As compared to the landmass, water heats up or cools down slowly. This differential heating of land and sea creates different air pressure zones in different seasons in and around the Indian subcontinent. The difference in air pressure causes a reversal in the direction of monsoon winds.
4. Distance from the Sea: With a long coastline, large coastal areas have an equable climate. Areas in the interior of India are far away from the moderating influence of the sea. Such areas have extremes of climate. That is why the people of Mumbai and the Konkan coast have hardly any idea of extremes of temperature and the seasonal rhythm of weather. On the other hand, the seasonal contrasts in weather at places in the interior of the country such as Delhi, Kanpur and Amritsar affect the entire sphere of life.
5. Altitude: Temperature decreases with height. Due to thin air, places in the mountains are cooler than places on the plains. For example, Agra and Darjeeling are located on the same latitude, but the temperature of January in Agra is 16°C whereas it is only 4°C in Darjeeling.
6. Relief: The physiography or relief of India also affects the temperature, air pressure, direction and speed of the wind and the amount and distribution of rainfall. The windward sides of Western Ghats and Assam receive high rainfall during June-September whereas the southern plateau remains dry due to its leeward situation along the Western Ghats.
Factors Related to Air Pressure and Wind
The following three factors are responsible for the differences in local climates of India:
Distribution of air pressure and winds on the surface of the earth.
Upper air circulation caused by factors controlling the global weather and the inflow of different air masses and jet streams.
The inflow of western cyclones generally known as disturbances during the winter season and tropical depressions during the south-west monsoon period into India.
Note: The variations in the atmospheric pressure closer to the surface of the earth have no role to play in the making of upper air circulation.
The mechanism of these three factors and their impact on the Indian climate will be understood with reference to specific seasons of the year in the following sections.
India’s Climatic Calendar
The climatic conditions of India can best be described in terms of an annual cycle of seasons.
The India Meteorological Department (IMD) recognises the following four seasons:
The Winter Season (January – February)
The Pre-monsoon Season or summer season (March – May)
The Southwest Monsoon Season or rainy season (June – September)
The Post Monsoon Season or autumn season (October – December)
The flow of water through well-defined channels is known as ‘drainage’ and the network of such channels is called a ‘drainage system’.
Types of Drainage Patterns
Discordant drainage
A pattern of drainage that bears no relation to the structure of the underlying rock. This may be because:
The drainage pattern developed on rock strata that have since been removed by erosion; a process known as superimposition. The drainage pattern thus developed is called superimposed drainage (or Epigenetic or Superinduced Drainage). Examples: The Damodar, the Subarnarekha, the Chambal, the Banas and the rivers flowing at the Rewa Plateau, rivers of eastern USA and southern France.
The drainage pattern was already present before a period of uplift and folding that formed the present structure. As the uplift took place, the rivers were able to cut down at approximately the same rate and so maintain their courses. This process is called antecedence and the drainage system thus developed is called antecedent drainage.
Many of the Himalayan rivers have antecedent origin i.e. these rivers existed even before the Himalayan ranges were uplifted. These rivers originate in the Tibetan side beyond the mountain ranges of Himalayas. The Indus, Satluj, Alaknanda, Gandak, Kosi, Brahmaputra all have an antecedent origin. Since these rivers are antecedent, they run transverse to the mountain ranges cutting deep V-shaped, steep-sided valleys (deep gorges).
Concordant Drainage (also called accordant drainage)
The pattern of drainage which arises from and closely follows the trends of the underlying strata is called concordant drainage.
Consequent Streams: Those streams whose courses are the direct consequence of the initial topography are called consequent streams.
Subsequent Streams: These are developed after the master consequent.
Obsequent streams: These flow in opposite direction to the master consequent.
Resequent Streams: A resequent stream flows in the same direction as that of the initial consequent stream, but which develops in response to a new base level formed due to inversion of relief.
Concordant Drainage Patterns
Drainage pattern:
Drainage pattern refers to a design which a river and its tributaries form together from its source to its mouth. The drainage pattern of an area is the outcome of:
The geological time period,
Nature and structure of rocks,
Topography,
Slope,
Amount of water flowing, and
The periodicity of the flow.
Some Important Drainage Patterns:
A combination of several patterns may be found in the same drainage basin.
Dendritic: The dendritic pattern develops where the river channel follows the slope of the terrain. The drainage pattern resembling the branches of a tree is known as “dendritic” the examples of which are the rivers of northern plain. It is the most common stream pattern. A dendritic pattern develops in a terrain which has uniform lithology, and where faulting and jointing are insignificant.
Radial: The radial pattern develops when streams flow in different directions from a central peak or a dome-like structure. E.g. the rivers like the Narmada, Son and Mahanadi originating from Maikal Hills flow in different directions and are good examples of a radial pattern.
Radial drainage patterns are also found/in the Girnar Hills (Kathiwar, Gujarat), and Mikir Hills of Assam.
Trellis: When the primary tributaries of rivers flow parallel to each other and secondary tributaries join them at right angles, the pattern is known as ‘trellis’. A trellis drainage pattern develops where hard and soft rocks lie parallel to each other. For example, rivers in the upper part of the Himalayan region and in the old folded mountains of the Singhbhum (Chotanagpur Plateau) have drainage of trellis pattern. The trellis drainage pattern can also be seen in the Appalachian region of the U.S.A., where hard and soft rocks occur in parallel bands.
Centripetal: When the rivers discharge their waters from all directions in a lake or depression, the pattern is known as ‘centripetal’. This drainage pattern is also called endorheic drainage. For example, Loktak lake in Manipur.
Rectangular: In this drainage, both the main stream and its tributaries show right-angled bends. A rectangular drainage pattern develops on a strongly jointed rocky terrain. It differs from trellis pattern drainage, since it is more irregular and its tributary streams are not as long or as parallel as in trellis drainage. Example: Colorado river (USA), streams found is the Vindhyan Mountains of India.
Barbed: If you look at the way that tributaries empty into larger rivers, you will notice that most of them flow in the same direction as the rivers they empty into. But quite a large number flow the other way. In fact, you will find stretches of some rivers where every tributary empties into the river in the “wrong” direction! Such an occurrence is known as a barbed drainage pattern.
Most barbed drainage patterns are the result of river-capture which reverses the direction of flow. However, the tributary channels continue to flow in their original direction.
The Arun River (Nepal), a tributary of the Kosi is an interesting example of barbed drainage pattern.
A Barbed Drainage Pattern
Annular: Annular pattern represents that part of a drainage pattern in which the subsequent streams follow the curving or arcuate courses before joining the consequent stream. These results from a partial adaptation to an underground circular structure i.e. batholiths. This is not a very common drainage pattern in India. Some examples of this are however found in Pithoragarh (Uttarakhand), Nilgiri Hills in Tamil Nadu and Kerala.
Parallel drainage: The drainage pattern in which the rivers flow almost parallel to each other is known as parallel drainage. The small and swift rivers originating in the Western Ghats and discharging their water into the Arabian Sea provide a good example of parallel drainage pattern in India.
Deranged pattern: This is an uncoordinated pattern of drainage characteristic of a region recently vacated by an ice-sheet. The picture is one of numerous water courses, lakes and marshes; some inter-connected and some in local drainage basins of their own. This type of drainage is found in the glaciated valleys of Karakoram.
