Dams were traditionally built to impound rivers and rainwater that could be used later to irrigate agricultural fields. Today, dams are built not just for irrigation but for:
electricity generation,
water supply for domestic and industrial uses,
flood control,
recreation,
inland navigation,
fish breeding etc.
Hence dams are now referred to as multipurpose projects where the many uses of the impounded water are integrated with one another. For example, in the Satluj-Beas river basin, the Bhakra Nangal project water is being used both for hydel power production and irrigation. Similarly, the Hirakud project in the Mahanadi basin integrates conservation of water with flood control.
Multipurpose projects, launched after independence with their integrated water resources management approach, were thought of as the vehicle that would lead the nation to development and progress. But in the recent years, multipurpose projects and large dams have come under great scrutiny for a variety of reasons:
Regulating and damming of rivers affects their natural flow causing poor sediment flow and excessive sedimentation at the bottom of the reservoir, resulting in rockier stream beds and poorer habitats for the rivers’ aquatic life.
Dams also fragment rivers making it difficult for the aquatic fauna to migrate, especially for spawning.
The reservoirs that are created on floodplains also submerge the existing vegetation and soil leading to its decomposition over a period of time.
In geologically unstable areas, development of large dams can destabilise the land. The 2013 Uttarakhand Floods triggered a debate on whether the hydropower projects operational in Uttarakhand were responsible for the floods that killed more than 1000 people.
Inter-state water disputes are also becoming common with regard to sharing the costs and benefits of the multipurpose projects.
Source
A List of Important River Water Projects in India:
The monsoonal rainfall in India is concentrated only in four months and more than 50% of the net sown area is rainfed only. Irrigation is thus essential to overcome spatial and temporal variation of rainfall.
Archaeological and historical records show that from ancient times we have been constructing sophisticated hydraulic structures like dams built of stone rubble, reservoirs or lakes, embankments and canals for irrigation. Not surprisingly, we have continued this tradition in modern India by building dams in most of our river basins. Before we look at these methods of irrigation in detail, let’s have a look at some of the hydraulic structures used in ancient India!
Some Hydraulic Structures used in Ancient India:
In the first century BC, Sringaverapura near Allahabad had sophisticated water harvesting system channelling the flood water of the river Ganga.
During the time of Chandragupta Maurya, dams, lakes and irrigation systems were extensively built.
Evidences of sophisticated irrigation works have also been found in Kalinga (Orissa), Nagarjunakonda (Andhra Pradesh), Bennur (Karnataka), Kolhapur (Maharashtra), etc.
In the eleventh century, Bhopal Lake, one of the largest artificial lakes of its time was built.
In the 14th century, the tank in Hauz Khas, Delhi was constructed by Iltutmish for supplying water to the Siri Fort Area.
Coming back to irrigation in the present day India, let’s look at some important facts and figures before we move forward:
Some important facts and figures:
The net irrigated area = 66.1 million hectares.
Total/Gross Irrigated Area = 92.6 million hectares.
Irrigation Intensity in India = (Gross Irrigated Area ÷Gross Sown Area) * 100
= (92.6 ÷ 194.4) *100
= 47.6%
More than 50% of the country’s cropped area depends exclusively on rainfall, most of which is concentrated in a few months of the year. Even where the annual overall precipitation is high, the available moisture is not adequate to support multiple cropping.
Ultimate Irrigation Potential:
As seen in the above figures, only about 66mha i.e. 47.6% of the net sown area is estimated to be irrigated. There is a need to bring more cropped area under assured irrigation so as to increase agricultural productivity and production.
The total ultimate irrigation potential of the country has been estimated as 140mha, with about 76 mha from surface water sources and about 64mha from groundwater sources.
Irrigation – Sources and Methods
The main sources of irrigation in India are:
Canals
Wells (and tubewells)
Tanks
The relative importance of these has been changing from time to time. Let’s look at these in detail:
1. Canal Irrigation:
A canal is an artificial watercourse constructed for water supply and irrigation.
Inundation Canals – These are taken out from the rivers without any regulating system like weirs etc at their head. Such canals are useful only during the rainy season
Perennial Canals – These are those which are taken off from perennial rivers by constructing a barrage across the river. Most of the canals at present in India are perennial.
Canals can be an effective source of irrigation in areas of low relief, deep fertile soils, perennial source of water and an extensive command area. Therefore the main concentration of canal irrigation is in the northern plains.
The canals are practically absent from the peninsular plateau region because of rocky terrain. However, the coastal and the delta regions in South India have some canals for irrigation.
The percentage of canal irrigation area to total irrigated area in the country has fallen from about 40% in 1950-51 to less than 25% at present.
The states UP, Punjab, Haryana, Rajasthan and Bihar account for about 60% of the canal irrigated area in the country.
Merits of canal irrigation:
Perennial Source
Provides safety from droughts
Brings fertile sediments to the fields
Economical to serve a large area
Demerits:
Canal water soaks into the ground and leads to water logging, increases salinization, and leads to marshy conditions leading to malaria and flooding
Wastage of water.
2. Wells (and Tube Wells)
A well is a hole dug in the ground to obtain the subsoil water. An ordinary well is about 3-5 metres deep but deeper wells up to 15 metres are also dug.
This method of irrigation has been used in India from time immemorial. Various methods are used to lift the ground water from the well. Some of the widely used methods are the persian wheel, reht, charas or mot, and dhinghly (lever) etc.
A tube well is a deeper well (generally over 15 metres deep) from which water is lifted with the help of a pumping set operated by an electric motor or a diesel engine.
Well irrigation is gradually giving way to energized tube wells. But there are many wells still in use where electricity is not available or the farmers are too poor t0 afford diesel oil.
This method of irrigation is popular in those areas where sufficient sweet ground water is available.
It is particularly suitable in areas with permeable rock structure which allows accumulation of ground water through percolation. Therefore wells are seen more in areas with alluvial soil, regur soil, etc. and less seen in rocky terrain or mountainous regions.
These areas include a large part of the great northern plains, the deltaic regions of the Mahanadi, the Godavari, the Krishna and the Cauvery, parts of the Narmada and the Tapi valleys and the weathered layers of the Deccan trap and crystalline rocks and the sedimentary zones of the peninsula
However, the greater part of peninsular India is not suitable for well irrigation due to rocky structure, uneven surface and lack of underground water.
Large dry tracts of Rajasthan, the adjoining parts of Punjab, Haryana and Gujarat and some parts of Up have brackish ground water which is not fit for irrigation and human consumption and hence unsuitable for well irrigation
At present irrigation from wells and tubewells accounts for more than 60% of the net irrigated area in the country.
UP has the largest area under well irrigation which accounts for 28% of the well irrigated area of the country. U.P., Rajasthan, Punjab, Madhya Pradesh, Gujarat, Bihar and Andhra Pradesh account for about three-fourths of the total well-irrigated area
Well is an independent source of irrigation and can be used as and when the necessity arises. Canal irrigation, on the other hand, is controlled by other agencies and cannot be used at will.
Some ground water salts are useful for crops
Does not lead to salinization and flooding problems
There is a limit to the extent of canal irrigation beyond the tail end of the canal while a well can be dug at any convenient place.
Demerits
Only limited area can be irrigated. Normally, a well can irrigate 1 to 8 hectares of land.
Not suitable for dry regions
Overuse may lead to lowering of water table
3. Tank irrigation
A tank is a reservoir for irrigation, a small lake or pool made by damming the valley of a stream to retain the monsoon rain for later use.
It is practised mainly in the peninsular region due to the following reasons:
The undulating relief and hard rocks make it difficult to dig canals and wells
There is little percolation of water due to hard rock structure and ground water is not available in large quantities.
Most of the rivers are seasonal; there are many streams which become torrential during the rainy season – so the only way to use this water is to impound it by constructing bunds and building tanks. Also, it is easy to collect rainwater in natural or artificial pits because of impermeable rocks.
Scattered nature of agricultural fields
Merits
Most of the tanks are natural and do not involve cost for their construction
Independent source for an individual farmer or a small group of farmers
longer life span
can be used for fishing also
Demerits
Depends on rain and these tanks may dry up during the dry season
Silting of their beds
Require large areas
Evaporation losses
Sometimes there might be a need to lift the water to take it to the field
Knowing a soil’s water, mineral, and organic components and their proportions can help us determine its productivity and what the best use for that soil may be. Several soil properties that can be readily tested or examined are used to describe and differentiate soil types. The most important properties are discussed below:
1. Colour: A soil’s colour is generally related to its physical and chemical characteristics. E.g.
Soils rich in humus tend to be dark because decomposed organic matter is black or brown. Soils with high humus content are usually very fertile, so dark brown or black soils are often referred to as ‘rich’. [Note – Some dark soils may be dark because of other soil forming factors and may have little or no humus]
Red or yellow soils typically indicate the presence of iron.
2. Texture: The soil texture refers to the coarseness/fineness of the mineral matter in the soil. It is determined by the proportion of the sand, silt and clay particles:
Clay: Particle Size – diameters less than 0.002 millimetre
Silt: Particle Size – diameters between 0.002 millimetres to 0.05 millimetres.
Sand: Particle Size – diameters between 0.05 and 2 millimetres.
[Rocks larger than 2 millimetres are regarded as pebbles, gravel, or rock fragments and technically are not soil particles.]
Note:
Clay being the finest of all plays the most important role in soil chemistry (offers more surface area).
Loamy Soil: Loamy soil is the one in which none of the three (sand/silt/clay) dominates the other two. In particular, loamy soil has about 40% sand, 40%silt, and 20% clay.
Generally speaking, Good Soils = Clay + Humus. The clay-humus complex is essential for a fertile soil as it provides it with a high water and nutrient holding capacity. Humus acts as a cement binding the soil particles together and thus reducing the risk of erosion.
3. Structure :
While the soil texture describes the size of soil particles, soil structure refers to the arrangement of the soil particles. The way in which sand, silt, clay and humus bond together is called soil structure. Structure can partially modify the effects of soil texture.
Some structural characteristics of soil:
Permeability – The ease with which liquids/gases can pass through rocks or a layer of soil is called permeability. It depends on the size, shape and packing of particles. It is usually greatest in sandy soils and poor in clayey soils.
Porosity – The volume of water which can be held within a soil is called its porosity. It is expressed as a ratio of volume of voids (pores) to the total volume of the material.
Note: Most porous rocks are permeable with the exception of clay in which pore spaces are so small that they are often sealed with groundwater held by surface tension. Another exception – granite is non-porous but permeable. It is a crystalline rock and hence non-porous. Its individual crystals absorb little or no water but the rock may have numerous joints/ cracks through which the water can pass rendering it permeable.
A soil with high organic content also tends to have high porosity.
4. Soil Chemistry – Acidity or Alkalinity:
An important aspect of soil chemistry is acidity, alkalinity (baseness), or neutrality.
Low pH values indicate an acidic soil, and a high pH indicates alkaline conditions. Most complex plants grow only in the soils with levels between pH 4 and pH 10 but optimum pH varies with the plant species.
In arid and semi-arid regions, soils tend to be alkaline and soils in humid regions tend to be acidic.
To correct soil alkalinity and to make the soil more productive, the soil can be flushed with irrigation water.
Strongly acidic soils are also detrimental to plant growth, but soil acidity can generally be corrected by adding lime to the soil.
Now that we are done with the basics, let’s move on to the soils of India!
Soils of India
India has varied relief features, landforms, climatic realms and vegetation types. These have contributed to the development of various types of soils in India.
Various classifications adopted to study the Indian Soils:
1. In ancient times, soils used to be classified into two main groups:
Urvara (i.e. fertile), and
Usara (i.e. sterile)
2. In the 16th century A.D., soils were classified on the basis of their inherent characteristics and external features such as texture, colour, the slope of land and moisture content in the soil.
Based on texture, main soil types were identified as sandy, clayey, silty and loam, etc.
On the basis of colour, they were red, yellow, black, etc.
3. The National Bureau of Soil Survey and the Land Use Planning an Institute under the control of the Indian Council of Agricultural Research (ICAR) did a lot of studies on Indian soils. In their effort to study soil and to make it comparable at the international level, the ICAR has classified the Indian soils on the basis of their nature and character as per the United States Department of Agriculture (USDA) Soil Taxonomy.
Chief characteristics of these are:
Entisols – Immature soils that lack the vertical development of horizons. These soils are often associated with recently deposited sediments from wind, water, or ice erosion. Given more time, these soils will develop into another soil type.
Inceptisols – young soils that are more developed than entisols.
Vertisols – heavy clay soils that show significant expansion and contraction due to the presence or absence of moisture. These are common in areas that have shale parent material and heavy precipitation.
Aridisols – soils that develop in very dry environments.
Ultisols – associated with humid temperate to tropical climates. Warm temperatures and the abundant variability of moisture enhance the weathering process and increase the rate of leaching in these soils.
Mollisols – soils common to grassland environments
4. On the basis of genesis, colour, composition and location, the soils of India have been classified into:
(i) Alluvial soils
(ii) Black soils
(iii) Red and Yellow soils
(iv) Laterite soils
(v) Arid soils
(vi) Saline soils
(vii) Peaty soils
(viii) Forest soils.
5. Another way of classifying rocks is on the basis of dominant soil forming factors:
Zonal Soil – These soils occur in broad geographical areas or zones.
They are influenced more by the climate and vegetation of the area rather than the rock-type.
They are mature, as a result of stable conditions over a long period of time.
For example – red soils, black soils, laterite soils, desert soils etc.
Azonal Soil – It is that soil which has been developed by the process of deposition by the agents of erosion.
It means that it has been made by the fine rocky particles transported from the far-off regions.
These are immature soils and lack well-developed soil profiles. This may be due to the non-availability of sufficient time for them to develop fully or due to the location on very steep slopes which prohibits profile development.
For Example – alluvial and loess soils.
Intrazonal Soil – These soils occur within other zonal soils.
It is a well-developed soil reflecting the influence of some local factor of relief, parent material, or age rather than of climate and vegetation.
For example, calcerous soil (soils which develop from limestone), peat soil.
The major factors responsible for the formation of soil:
The major factors affecting the formation of soil are relief, parent material, climate, vegetation and other life-forms and time. Besides these, human activities also influence it to a large extent.
1. Parent Material
The parent material of soil may be deposited by streams or derived from in-situ weathering. Soil inherits many properties from the parent material from which it forms, for example, the mineral composition, the colour, the particle size and the chemical elements.
For Example,
The peninsular soils reflect the parent rock very much.
The ancient crystalline and metamorphic rocks which are basically granite, gneiss and schist form red soils on weathering because they contain iron oxide.
Soils derived from lava rocks are black coloured.
Sandy soils are derived from sandstone.
At the same time, the soils of the northern plains are transported and deposited from Himalayan and peninsular blocks, so they have little relation to rock material in-situ.
2. Climate
The role of climate is to vary the inputs of heat and moisture. It affects the rate of weathering of the parent rock. Hot and humid environments, in general, witness the most rapid weathering of parent materials.
Role of precipitation: In areas that experience a lot of rainfall, water percolating down through soil tends to leach nutrients and organic matter out of the upper layers, unless modified by other soil components like plant roots.
E.g. the soils underlying tropical rain forests tend to be nutrient-poor because of intensive leaching due to heavy rains; most of the nutrients are stored in the lush vegetation itself.
Conversely, in arid regions with little annual precipitation, high rates of evaporation encourage the accumulation of salts in the soil.
Role of temperature: Solar energy, usually expressed as temperature, controls the form of water falling onto the soil surface as well as in the soil. Also, it increases the rate of reactions, such as chemical reactions, evapotranspiration and biological processes. Wide fluctuations in temperature, especially in the presence of water cause shrinking and swelling, frost action and general weathering in soils.
E.g. Laterite soils are found in alternate wet and dry climate.
In Rajasthan, both granite and sandstone give birth to sandy soil irrespective of parent rock because of high temperature and wind erosion.
3. Biota (Flora, Fauna and Microorganisms):
Biota, in conjunction with climate, modifies parent material to produce soil.
The kind and amount of plants and animals that exist bring organic matter into the soil system as well as nutrient elements. This has a great effect on the kind of soil that will form.
E.g. Soils formed under trees are greatly different from soils formed under grass even though other soil-forming factors are similar.
The roots of plants also hold the soils and protect them from wind and water erosion. They shelter the soils from the sun and other environmental conditions, helping the soils to retain the needed moisture for chemical and biological reactions.
Topography is often considered a passive factor modifying the effects of climate.
Topography redistributes the water reaching the soil surface. Runoff from uplands creates wetter conditions on the lowlands, in some cases saline sloughs or organic soils. Thus, as a redistributor of the climate features, topography affects soil processes, soil distribution and the type of vegetation at the site.
Soils can take many years to form. Younger soils have some characteristics from their parent material, but as they age, the addition of organic matter, exposure to moisture and other environmental factors may change its features. With time, they settle and are buried deeper below the surface, taking time to transform. Eventually, they may change from one soil type to another.
Look at the following diagram for a quick revision of the above-discussed facts:
Note:
The above factors are not mutually exclusive but interdependent. For example, the kind of vegetation found at any one location on the earth’s surface is dependent on climate, parent material, topography, time and, in fact, soil. It is obvious that numerous combinations of the factors are possible. This leads to many different kinds of soils, each representing a certain combination of the factors of soil formation.
Soil Profile
As we discussed earlier, soil development begins when plants and animals colonize rocks or deposits of rock fragments. Once organic processes start among mineral particles or rock fragments, chemical and physical differences begin to develop from the surface down through the parent material.
Initially, vertical differences result from surface accumulations of organic litter and the removal of fine particles and dissolved minerals by percolating water that deposits these materials at a lower level.
Over time, as climate, vegetation, animal life, and the land surface affect soil development, this vertical differentiation becomes increasingly apparent.
If you could dig a massive trench, about 50-100ft vertically downwards into the ground, you will notice that you would have cut through various layers of soil types. A look at the layers from a distance gives one a cross-section view of the ground (beneath the surface) and the kind of soils and rocks it is made up of. This cross section view of soil from the surface down to the parent material is called a Soil Profile.
The Soil Profile is a product of the balance between the soil system inputs (i.e. additions) and outputs (i.e. losses) and the redistribution of (i.e. translocations), and chemical changes (transformations) in the various soil constituents.
The soil profile is made up of layers, running parallel to the surface, called Soil Horizons. These layers are distinguished by their physical and chemical properties.
Most soils have three major horizons. These are A Horizon, B Horizon and C Horizon. Aside these three, there are also the O, E and R horizons. How are they different? Let’s see!
O-Horizon: The O-horizon is very common to surfaces with lots of vegetative cover. It is the layer made up of organic materials such as dead leaves and surface organisms, twigs and fallen trees. In fact, the ‘O’ designation refers to this horizon’s high content of organic debris and humus. It is often black or dark brown in colour, because of its organic content. It is the layer in which the roots of small grass are found. The A-Horizon: The A horizon, immediately below the O horizon, is usually known as the topsoil. It is the top layer soil for many grasslands and agricultural lands. In general, A horizons are dark because they contain decomposed organic matter. The E-Horizon: The E horizon is usually lighter in colour, often below the O and A horizons. It is often rich in nutrients that are leached from the top A and O horizons. It has a lower clay content and is common in forested lands or areas with high-quality O and A horizons. The B-Horizon: Below the E-horizon is the B-horizon, a zone of accumulation, where much of the nutrients removed from the A and E horizons are deposited. It is the layer in which the roots of big trees end. There is a close relationship between the A and B horizons. Translocations, as well as, many biological and chemical reactions take place between them. The B horizon, however, tends to be more stable than the A for short term differences. The C-Horizon: The C horizon is the weathered parent material from which the soil has developed. This layer is the first stage in the soil formation process and eventually forms the above two layers. The C horizon is also known as saprolite. The R-Horizon: It is the unweathered parent material.
Before we discuss the various soil types and their distribution in India, it is imperative that we first go through the basics. Let’s begin with what soil is and how it is formed:
What is soil?
Soil is the loose material of the earth’s surface in which the terrestrial plants grow. It is usually formed from weathered rock or regolith changed by chemical, physical and biological process.
Thus the soil may be considered as an entity, quite apart from the rocks below it. It consists partly of mineral particles and partly, to a varying extent, of organic matter. Let’s look at the composition in detail:
Composition of soils:
Soils have four main constituents:
Mineral matter – It includes all minerals inherited from the parent material as well as those formed by recombination from substances in the soil solution.
Organic matter – It is derived mostly from decaying plant material broken down and decomposed by the actions of animals and microorganisms living in the soil. It is this organic portion that differentiates soil from geological material occurring below the earth’s surface which otherwise may have many of the properties of a soil. (Note: The end product of breakdown of dead organic material is called humus.)
Air
Water
Normally, both air and water fill the voids in soil. Air and water in the soil have a reciprocal relationship since both compete for the same pore spaces.
For example, after a rain or if the soil is poorly drained, the pores are filled with water and air is excluded. Conversely, as water moves out of a moist soil, the pore space is filled with air. Thus the relationship between air and water in soils is continually changing.
The ratio of the components by volume is generically indicated as:
Note: The exact ratio depends on various factors like geographical location and the historical treatment of soil – by humans, by climate, by time.
Why is soil so important?
Soils are essential for life, in the sense that they provide the medium for plant growth, habitat for many insects and other organisms, act as a filtration system for surface water, carbon store and maintenance of atmospheric gases. They also support buildings and highways and contribute to the economies of our cities.
E.g. the rich, deep fertile soils of the Ganga plain especially its delta and the coastal plains of Kerala support a high density of population through agricultural prosperity. On the other hand, the shallow and coarse-grained soils of Telangana and Rajasthan do not provide a base for prosperous agriculture and thus support only a small population.
At the same time, the soil must not be regarded as a passive and inert body on the earth’s surface. It is a continually changing system within the total environment. The nature of a soil reflects the ancient environments under which it formed as well as current environmental conditions. The soil forming process, also known as pedogenesis, is described below:
How is soil formed?
Soil formation is a process taking many thousands of years.
Formation of soil from rocks.
The Pedogenic Processes:
The above-explained conversion from rocks to soils happens via four basic processes:
Additions
Losses
Translocations
Transformations
Let’s look at these soil forming processes in detail:
Additions: Most additions occur at the surface. The most obvious ones include solar energy, water controlled by climate, and organic material derived principally from the vegetation.
Losses: Losses occur both from the surface and from the deep subsoil. For instance, water is lost by evapotranspiration and carbon dioxide by diffusion at the surface and, on a more catastrophic level, large masses of soil can be stripped by erosion. Materials suspended or dissolved in water are the main forms of losses from the subsoil e.g. leaching.
Translocation: It refers to the physical movement of material within the soil. The material can be in the solid, liquid or gaseous form, the movement can be in any direction from and to any horizon. For instance clay, organic matter and iron and aluminium hydrous oxides are commonly moved from the surface horizon to a subsurface horizon. Conversely, in very dry climates salts are moved upwards in solution by capillarity, and in very cold climates solid mineral fragments are moved upwards by frost action.
Transformation: Additions, losses and translocations all involve movement as shown in the above figure. Transformations, on the other hand, involve the change of some soil constituent without any physical displacement. Chemical and physical weathering and the decomposition of organic matter are included here.
All these processes occur to a greater or lesser extent in all soils. The properties that characterise one soil are the result of a particular balance among all the processes. Other soils will be different because they have been formed by groups of processes having different balances.
The two driving forces for these processes are:
climate (temperature and precipitation), and
organisms, (plants and animals).
Passive factors:
Parent material is usually a rather passive factor in affecting soil processes because parent materials are inherited from the geologic world.
Topography (or relief) is also rather passive in affecting soil processes, mainly modifying the climatic influences of temperature and precipitation.
The months of October-November form a period of transition from the hot rainy season to the dry winter conditions.
Surface Air Circulation during the Autumn Period. Source
The withdrawal of the south-west monsoon and the onset of north-east monsoon are both gradual phenomenon. They take place almost at the same time and tend to merge. This explains the popularity of the phrase “Retreating Monsoon”.
A Season of Retreating Monsoon
The retreat takes place due to the weakening of the low-pressure area over the north-western parts of India (and thus a gradual transition of ITCZ towards the south). This happens due to:
The apparent shift of sun towards the equator
Reduction in temperature due to widespread rains.
Consequently, the air pressure starts decreasing. Such changes in the atmospheric pressure cause the south-west monsoons to withdraw.
The Retreat of Monsoons is a process much slower than its arrival. It does not imply a right about turn but a gradual change of comparative pressure positions, thus gradually weakening and reducing the area of coverage and influence.
The retreat:
The south-west monsoons start retreating in the first week of September from Pakistan’s border in North-West India. Thus these winds withdraw earlier from the regions they reached the last.
The monsoon retreats from the western Rajasthan by the first week of September. It withdraws from Rajasthan, Gujarat, Western Ganga plain and the Central Highlands by the end of the month. By the beginning of October, the low pressure covers northern parts of the Bay of Bengal and by early November, it moves over Karnataka and Tamil Nadu. By the middle of December, the centre of low pressure is completely removed from the Peninsula.
This season is marked by clear skies and a rise in temperature. The land is still moist. Owing to the conditions of high temperatures (around 25°C) and humidity, the weather becomes rather oppressive and unbearable. This is commonly known as the ‘October heat’ or ‘Kwar ki Umas’.
In the second half of October, the mercury begins to fall rapidly, particularly in northern India. This continuous decrease in temperature after mid-October helps winter to set in by November or Early December.
Surface Winds and Precipitation:
By and large, the topography of the region influences the wind direction:
The winds 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 (thus the name North-East monsoon).
Precipitation:
Winter monsoons do not cause rainfall as they move from land to the sea. It is because:
They have little humidity; and
Due to anti-cyclonic circulation on land, the possibility of rainfall from them reduces.
However, there are some exceptions:
These months are the rainiest months of the year in coastal areas of Tamil Nadu. This is because the large indentation made by the Bay of Bengal into India’s eastern coast means that the flows are humidified before reaching Cape Comorin and rest of Tamil Nadu. Parts of West Bengal, Orissa, Andhra Pradesh, Karnataka and North-East India also receive minor precipitation from the northeast monsoons.
Central parts of India and northern parts of southern Peninsula also get winter rainfall occasionally.
Arunachal Pradesh and Assam in the northeastern parts of India also have rains between 25 mm and 50 mm during these winter months.
The low-pressure area lying over north-west India is transferred to the middle of Bay of Bengal by the end of October. As a result of these unstable conditions, severe cyclonic storms originate in this region.
These cyclonic storms strike along the eastern coast of India causing widespread rain in the coastal regions.
These tropical cyclones are very destructive. The thickly populated deltas of the Godavari, Krishna and Kaveri are their preferred targets. Every year cyclones bring disaster here. A few cyclonic storms also strike the coast of West Bengal, Bangladesh and Myanmar.
A bulk of the rainfall of the Coromondal coast is derived from these depressions and cyclones. Such cyclonic storms are less frequent in the Arabian Sea.
Now that we have studied all the seasons in detail, let’s have a look at the annual distribution and variability of rainfall in India:
Rainfall Distribution:
The distribution of rainfall in India is highly uneven. Its distribution is largely controlled by the nearness of the sea and orographic features. The average annual rainfall in India is shown in the following map. Notice that the regional variations in the distribution of rainfall over India are quite pronounced.
The rainfall in India is highly variable. The actual rainfall of a place in a year deviates from the average rainfall by 10-60%.The variability of rainfall is computed with the help of the following formula:
The variability of rainfall is computed with the help of the following formula:
C.V. = (Standard Deviation÷ Mean) × 100
where C.V. is the coefficient of variation.
RainfallVariability in India
Notice that the regions of inadequate rainfall are also the regions with the highest variability of rainfall. The variability of rainfall has a significant role in the agricultural operations and other economic activities of a country. The areas showing high variability of rainfall have a chronic deficiency of water.
Climatic Regions of India
As discussed in the beginning, India has a monsoon type of climate with many regional variations. These variations represent the subtypes of the monsoon climate. It is on this basis that the climatic regions can be identified.
A climatic region has a homogeneous climatic condition which is the result of a combination of factors. Temperature and rainfall are two important elements which are considered to be decisive in all the schemes of climatic classification.
The classification of climate, however, is a complex exercise. There are different schemes of classification of climate. Two important ones are discussed here:
A) Koeppen’s scheme of Climatic classification
It is based on monthly values of temperature and precipitation.
He identified five major climatic types and used letter symbols A, B, C, D and E to denote them:
Tropical climates (A): [where mean monthly temperature throughout the year >18°C]
Dry climates (B): where precipitation is very low in comparison to temperature.
If dryness is less, it is semiarid (S);
If it is more, the climate is arid(W).
Warm temperate climates (C): where mean temperature of the coldest month is between 18°C and minus 3°C.
Cool temperate climates (D): where mean temperature of the warmest month is over 10°C, and mean temperature of the coldest month is under minus 3°C.
Ice climates (E), where mean temperature of the warmest month is under 10°C.
These five types can be further subdivided into sub-types on the basis of seasonal variations in the distribution pattern of rainfall and temperature. Koppen used small letters such as m, w or h to define these sub-types:
f (sufficient precipitation)
m (rain forest despite a dry monsoon season),
w (dry season in winter)
h (dry and hot)
c (less than four months with mean temperature over 10°C)
g (Gangetic plain)
Accordingly, India can be divided into the following eight climatic regions:
Kendrew and Stamp on the basis of the 18°C isotherm for the month of January (which almost follows the Tropic of Cancer) divided India into two major climatic regions:
Subtropical India (Continental)
Tropical
These two major climatic regions have been further divided into eleven regions as follows:
As the sun shifts northward towards the Tropic of Cancer after the vernal Equinox, the whole India experiences an increase in temperature.
In most parts of India, temperatures recorded are between 30°-32°C.
North India:
April, May and June are the months of summer in north India.
In May, the heat belt moves further north, and in the north-western part of India, temperatures around 48°C are not uncommon.
South India:
The Peninsular situation of south India with moderating effect of the oceans keeps the temperatures lower than that prevailing in north India. So, temperatures remain between 26°C and 32°C.
Western Ghats – Due to altitude, the temperatures in the hills of Western Ghats remain below 25°C.
The temperature increases from the coast towards the interior areas.
Surface Pressure and Winds:
The atmospheric pressure is low all over the country due to high temperatures.
Since the sun goes gradually towards the north (summer solstice), the Inter Tropical Convergence Zone (ITCZ) begins to move towards the north (Eventually reaching up to 25° latitude in July).
The general direction of winds is from the north-west and west in north-western India, and from the south-west in the Arabian Sea and adjoining coasts.
In the months of May and June, the high temperature in north-western India builds steep pressure gradient.
Under such conditions, hot dust-laden strong winds known as ‘loo’ blow.
These strong dust storms result from the convective phenomenon and their intensity increases in the afternoon. These are locally known as Andhis.
These are essentially short-lived thunderstorms, which move like a solid wall of sand and dust.
These bring little rainfall and give much needed relief from heat.
Dust storms in the evening are very common during May in Punjab, Haryana, Eastern Rajasthan and Uttar Pradesh.
Occasionally, the moisture-laden winds are attracted towards the periphery of the trough. A sudden contact between dry and moist air masses gives rise to local storms of great intensity. These local storms are associated with violent winds, torrential rains and even hailstorms.
The thunderstorms which originate over Chotanagpur plateau are carried eastwards by westerly winds. The areas with the highest incidence of thunderstorms are the north-eastern states, West Bengal, and the adjoining areas of Orissa and Jharkhand.
In West Bengal and the adjoining areas of Assam, Orissa and Jharkhand, the direction of squalls is mainly from the northwest and they are called Norwesters (Squall – a sudden, violent gusty wind).
The rainfall brough by norwesters is called spring storm showers.
These are often very violent with squall speeds of 60-80km/hour.
Large sized hailstones sometimes accompany these showers and harm the animals and standing crops.
The period of maximum occurrence of these storms is the month of Baisakh. These are thus locally called ‘Kal Baisakh (a calamity of the month of Baisakh)’.
In Assam, these storms are known as “Bardoli Chheerhaor Bordochila”.
In the south, thunderstorms occur in Kerala and adjoining parts of Karnataka and Tamil Nadu particularly in the evenings and nights. These pre-monsoonal showers are called by various names:
Tea showers in Assam ( they are good for tea, jute and rice)
Mango showers in Kerala and coastal areas of Karnataka as they help in the early ripening of mangoes.
Cherry Blossoms/ Coffee showers in Kerala and nearby areas (good for coffee plantations)
Tropical Cyclones (TC) are intense low-pressure systems that develop over the seas or oceans in the tropical and subtropical regions. Tropical cyclones cause destruction in the coastal areas because of:
High wind velocities.
Storm Surge ( i.e. rise of coastal waters due to approaching cyclone)
Torrential rainfall which often lead to floods in the coastal areas.
Note: The interior regions do benefit from the torrential rain associated with a tropical cyclone for agriculture and other applications of water.
The Indian sub-continent having a coast line of 7516 km is the worst affected region of the world. It is exposed to nearly 10% of the world’s Tropical Cyclones.
Many low-pressure systems of varying stages of development form in the Bay of Bengal and in the Arabian Sea and move west or north-westwards, sometimes re-curving north or north-east at a later stage (See the following map ). Re-curvature usually occurs when these systems are between 16° and 18°N.
Only a few of them develop fully into the mature stage and the majority remain as depressions.
The fully developed low-pressure systems called cyclones generally form in the lower latitude belt (10° N – 14°N) before and after the SW monsoon. They are very intense systems and are responsible for the major portion of rainfall over the peninsula.
These systems reach their maximum intensity before/after the monsoon period.
During the SW monsoon season, these systems form in the Bay of Bengal and generally travel west or north-west along the monsoon trough. The rainfall over northern India is to a large extent dependent on the frequency, track and intensity of these depressions (called monsoon depressions). The frequency and direction of these cyclones also influence weather conditions along the eastern coast during retreating monsoon season i.e. in October and November.
An analysis of the frequencies of cyclones on the East and West coasts of India shows that the East Coast is more prone to tropical cyclones as compared to the West Coast.
Globalization has been defined as the process of rapid integration of countries and happenings through greater foreign trade and foreign investment. It is the process of international integration arising from the interchange of world views, products, ideas, and other aspects of culture.
What are the factors aiding globalization?
Factor
Description
Impact on India
Examples
Technology
Reduced communication speed drastically, making distance insignificant. Enabled faster access to information and social media.
Increased job opportunities requiring analytical, communication, and numerical skills.
Growth of IT sector, expansion of social media platforms.
LPG Reforms (1991)
Economic liberalization leading to increased interaction with the global economy.
Opened Indian markets to global trade, foreign investment, and competition.
Entry of global companies like Ford, Coca-Cola, and Microsoft.
Faster Transportation
Improved transport systems, especially air travel, facilitating easier global movement of people and goods.
Enhanced international tourism and trade; facilitated faster export and import processes.
Expansion of airports like Delhi and Mumbai for global travel.
Rise of WTO (1994)
Reduced tariffs and non-tariff barriers, promoting free trade agreements between nations.
Increased India’s involvement in global trade agreements, fostering economic growth.
India’s membership in WTO, trade agreements with other countries.
Improved Mobility of Capital
General reduction in capital barriers allowing easier flow of capital between economies. Increased interconnectedness of financial markets.
Indian companies gained better access to global financial markets, fostering investment in sectors like technology.
Indian firms raising capital abroad through IPOs and investments.
Rise of MNCs
Multinational corporations operating in multiple countries lead to the diffusion of best practices and global products.
Creation of jobs, transfer of technology, and integration of Indian firms into global value chains.
MNCs like Unilever, Amazon, and Tata Group operating globally.
1) Technology: has reduced the speed of communication manifolds. The phenomenon of social media in the recent world has made distance insignificant.
The integration of technology in India has transformed jobs that required specialized skills and lacked decision-making skills into extensively defined jobs with higher accountability that require new skills, such as numerical, analytical, communication, and interactive skills. As a result of this, more job opportunities are created for people.
2) LPG Reforms: The 1991 reforms in India have led to greater economic liberalization which has in turn increased India’s interaction with the rest of the world.
3) Faster Transportation: Improved transport, making global travel easier. For example, there has been a rapid growth in air-travel, enabling greater movement of people and goods across the globe.
4) Rise of WTO: The formation of WTO in 1994 led to reduction in tariffs and non-tariff barriers across the world. It also led to the increase in the free trade agreements among various countries.
5) Improved mobility of capital: In the past few decades there has been a general reduction in capital barriers, making it easier for capital to flow between different economies. This has increased the ability for firms to receive finance. It has also increased the global interconnectedness of global financial markets.
6) Rise of MNCs: Multinational corporations operating in different geographies have led to a diffusion of best practices. MNCs source resources from around the globe and sell their products in global markets leading to greater local interaction.
These factors have helped in economic liberalization and globalization and have facilitated the world in becoming a “global village”. Increasing interaction between people of different countries has led to internationalization of food habits, dress habits, lifestyle and views.
Globalization and India:
Developed countries have been trying to pursue developing countries to liberalize the trade and allow more flexibility in business policies to provide equal opportunities to multinational firms in their domestic market. International Monetary Fund (IMF) and World Bank helped them in this endeavour. Liberalization began to hold its foot on barren lands of developing countries like India by means of reduction in excise duties on electronic goods in a fixed time frame.
Indian government did the same and liberalized the trade and investment due to the pressure from World Trade Organization. Import duties were cut down phase-wise to allow MNC’s operate in India on equality basis. As a result globalization has brought to India new technologies, new products and also the economic opportunities.
Despite bureaucracy, lack of infrastructure, and an ambiguous policy framework that adversely impact MNCs operating in India, MNCs are looking at India in a big way, and are making huge investments to set up R&D centers in the country. India has made a lead over other growing economies for IT, business processing, and R&D investments. There have been both positive and negative impacts of globalization on social and cultural values in India.
IMPACTS OF GLOBALISATION IN INDIA
Economic Impact:
Greater Number of Jobs: The advent of foreign companies and growth in economy has led to job creation. However, these jobs are concentrated more in the services sector and this has led to rapid growth of service sector creating problems for individuals with low level of education. The last decade came to be known for its jobless growth as job creation was not proportionate to the level of economic growth.
More choice to consumers: Globalisation has led to a boom in consumer products market. We have a range of choice in selecting goods unlike the times where there were just a couple of manufacturers.
Higher Disposable Incomes: People in cities working in high paying jobs have greater income to spend on lifestyle goods. There has been an increase in the demand of products like meat, egg, pulses, organic food as a result. It has also led to protein inflation.
Protein food inflation contributes a large part to the food inflation in India. It is evident from the rising prices of pulses and animal proteins in the form of eggs, milk and meat.
With an improvement in standard of living and rising income level, the food habits of people change. People tend toward taking more protein intensive foods. This shift in dietary pattern, along with rising population results in an overwhelming demand for protein rich food, which the supply side could not meet. Thus resulting in a demand supply mismatch thereby, causing inflation.
In India, the Green Revolution and other technological advancements have primarily focused on enhancing cereals productivity and pulses and oilseeds have traditionally been neglected.
Shrinking Agricultural Sector: Agriculture now contributes only about 15% to GDP. The international norms imposed by WTO and other multilateral organizations have reduced government support to agriculture. Greater integration of global commodities markets leads to constant fluctuation in prices.
This has increased the vulnerability of Indian farmers. Farmers are also increasingly dependent on seeds and fertilizers sold by the MNCs.
Globalization does not have any positive impact on agriculture. On the contrary, it has few detrimental effects as government is always willing to import food grains, sugar etc. Whenever there is a price increase of these commodities.
Government never thinks to pay more to farmers so that they produce more food grains but resorts to imports. On the other hand, subsidies are declining so cost of production is increasing. Even farms producing fertilizers have to suffer due to imports. There are also threats like introduction of GM crops, herbicide resistant crops etc.
Increasing Health-Care costs: Greater interconnections of the world has also led to the increasing susceptibility to diseases. Whether it is the bird-flu virus or Ebola, the diseases have taken a global turn, spreading far and wide. This results in greater investment in healthcare system to fight such diseases.
Child Labour: Despite prohibition of child labor by the Indian constitution, over 60 to a 115 million children in India work. While most rural child workers are agricultural laborers, urban children work in manufacturing, processing, servicing and repairs. Globalization most directly exploits an estimated 300,000 Indian children who work in India’s hand-knotted carpet industry, which exports over $300 million worth of goods a year.
Socio-Cultural Impact on Indian Society
Nuclear families are emerging. Divorce rates are rising day by day. Men and women are gaining equal right to education, to earn, and to speak. ‘Hi’, ‘Hello’ is used to greet people in spite of Namaskar and Namaste. American festivals like Valentines’ day, Friendship day etc. are spreading across India.
Access to education: On one hand globalisation has aided in the explosion of information on the web that has helped in greater awareness among people. It has also led to greater need for specialisation and promotion of higher education in the country.
On the flip side the advent of private education, coaching classes and paid study material has created a gap between the haves and have-nots. It has become increasingly difficult for an individual to obtain higher education.
Growth of cities: It has been estimated that by 2050 more than 50% of India’s population will live in cities. The boom of services sector and city centric job creation has led to increasing rural to urban migration.
Indian cuisine: is one of the most popular cuisines across the globe. Historically, Indian spices and herbs were one of the most sought after trade commodities. Pizzas, burgers, Chinese foods and other Western foods have become quite popular.
Clothing: Traditional Indian clothes for women are the saris, suits, etc. and for men, traditional clothes are the dhoti, kurta. Hindu married women also adorned the red bindi and sindhur, but now, it is no more a compulsion. Rather, Indo-western clothing, the fusion of Western and Sub continental fashion is in trend. Wearing jeans, t-shirts, mini skirts have become common among Indian girls.
Indian Performing Arts: The music of India includes multiples varieties of religious, folk, popular, pop, and classical music. India’s classical music includes two distinct styles: Carnatic and Hindustani music. It remains instrumental to the religious inspiration, cultural expression and pure entertainment. Indian dance too has diverse folk and classical forms.
Bharatanatyam, Kathak, Kathakali, Mohiniattam, Kuchipudi, Odissi are popular dance forms in India. Kalarippayattu or Kalari for short is considered one of the world’s oldest martial art. There have been many great practitioners of Indian Martial Arts including Bodhidharma who supposedly brought Indian martial arts to China.
The Indian Classical music has gained worldwide recognition but recently, western music is too becoming very popular in our country. Fusing Indian music along with western music is encouraged among musicians. More Indian dance shows are held globally. The number of foreigners who are eager to learn Bharatanatyam is rising. Western dance forms such as Jazz, Hip hop, Salsa, Ballet have become common among Indian youngsters.
Nuclear Families: The increasing migration coupled with financial independence has led to the breaking of joint families into nuclear ones. The western influence of individualism has led to an aspirational generation of youth. Concepts of national identity, family, job and tradition are changing rapidly and significantly.
Old Age Vulnerability: The rise of nuclear families has reduced the social security that the joint family provided. This has led to greater economic, health and emotional vulnerability of old age individuals.
Pervasive Media: There is greater access to news, music, movies, videos from around the world. Foreign media houses have increased their presence in India. India is part of the global launch of Hollywood movies which is very well received here. It has a psychological, social and cultural influence on our society.
McDonaldization: A term denoting the increasing rationalization of the routine tasks of everyday life. It becomes manifested when a culture adopts the characteristics of a fast-food restaurant. McDonaldization is a reconceptualization of rationalization, or moving from traditional to rational modes of thought, and scientific management.
Walmartization: A term referring to profound transformations in regional and global economies through the sheer size, influence, and power of the big-box department store WalMart. It can be seen with the rise of big businesses which have nearly killed the small traditional businesses in our society.
Psychological Impact on Indian Society
Aspect
Description
Impact on Indian Society
Examples
Development of Bicultural Identity
A hybrid identity combining local cultural roots with a global awareness. Young individuals are now able to connect with both local and global cultures.
Educated youth may embrace global practices in their professional lives while adhering to traditional Indian values at home.
Preference for arranged marriages, while being tech-savvy and global.
Growth of Self-Selected Culture
People forming groups to maintain their identities separate from global culture, seeking to protect values that global culture may undermine.
Some individuals resist global consumerism and individualism, preferring local traditions and values.
Rural communities focusing on preserving local traditions.
Emerging Adulthood
Delay in taking on adult roles like work, marriage, and parenthood due to extended education and job preparation in the technological economy.
Youth are now taking more time to marry or start a family, focusing instead on career and education.
Young Indians opting for higher education and career before marriage.
Consumerism
A shift towards Western consumerist culture, particularly in urban areas, with increased consumption of goods and services influenced by the media.
Traditional dress and lifestyle patterns are being replaced by Western fashion and consumer habits.
Urban Indians adopting Western clothing and lifestyle brands.
Globalization’s Pace
Increased interaction between people worldwide due to technology and economic structures.
Greater exposure to global events, ideas, and values through media and the internet.
The rise of internet use and social media for global communication.
Development of Bicultural Identity: The first is the development of a bicultural identity or perhaps a hybrid identity, which means that part of one’s identity is rooted in the local culture while another part stems from an awareness of one’s relation to the global world.
The development of global identities is no longer just a part of immigrants and ethnic minorities. People today especially the young develop an identity that gives them a sense of belonging to a worldwide culture, which includes an awareness of events, practices, styles and information that are a part of the global culture. Media such as television and especially the Internet, which allows for instant communication with any place in the world, play an important part in developing a global identity.
A good example of bicultural identity is among the educated youth in India who despite being integrated into the global fast paced technological world, may continue to have deep rooted traditional Indian values with respect to their personal lives and choices such as preference for an arranged marriage, caring for parents in their old age.
Growth of Self-Selected Culture: means people choose to form groups with like-minded persons who wish to have an identity that is untainted by the global culture and its values. The values of the global culture, which are based on individualism, free market economics, and democracy and include freedom, of choice, individual rights, openness to change, and tolerance of differences are part of western values. For most people worldwide, what the global culture has to offer is appealing. One of the most vehement criticisms of globalization is that it threatens to create one homogeneous worldwide culture in which all children grow up wanting to be like the latest pop music star, eat Big Macs, vacation at Disney World, and wear blue jeans, and Nikes.
Emerging Adulthood: The timing of transitions to adult roles such as work, marriage and parenthood are occurring at later stages in most parts of the world as the need for preparing for jobs in an economy that is highly technological and information based is slowly extending from the late teens to the mid-twenties. Additionally, as the traditional hierarchies of authority weaken and break down under the pressure of globalization, the youth are forced to develop control over their own lives including marriage and parenthood. The spread of emerging adulthood is related to issues of identity.
Consumerism: Consumerism has permeated and changed the fabric of contemporary Indian society. Western fashions are coming to India: the traditional Indian dress is increasingly being displaced by western dresses especially in urban areas. Media- movies and serials- set a stage for patterns of behavior, dress codes and jargon. There is a changing need to consume more and more of everything.
Globalisation is an age old phenomenon which has been taking place for centuries now. We can experience it so profoundly these days because of its increased pace. The penetration of technology and new economic structures are leading to an increased interaction between people. As with other things there have been both positive and negative impacts on India due to it.
Conclusion:
Wecannot say that the impact of globalization has been totally positive or totally negative. It has been both. Each impact mentioned above can be seen as both positive as well as negative. However, it becomes a point of concern when, an overwhelming impact of globalization can be observed on the Indian culture.
Every educated Indian seems to believe that nothing in India, past or present, is to be approved unless recognized and recommended by an appropriate authority in the West. There is an all-pervading presence of a positive, if not worshipful, attitude towards everything in western society and culture, past as well as present in the name of progress, reason and science. Nothing from the West is to be rejected unless it has first been weighed and found wanting by a Western evaluation. This should be checked, to preserve the rich culture and diversity of India.
When done with basic book reading and Prelims is near, many aspirants face the dilemma of how to revise entire syllabus and then remember important points from it.
We understood this problem and our team worked together to compile all important topics at one place through excel sheets and Dr V compiled all important static syllabus points through Titbits.
The excel sheets prepared by us are available to view and download below (best viewed on desktop/ large screens):
Important Acts/bills- Bills/Acts/Amendments which have been in news from 2014-2017- Click2view
Declarations, conventions, protocols- Contains important IR pacts signed in the last few years- Click2view
Important Books/ Texts in Indian History – IAS Pre & beyond- Click2view
Satellites, Space Missions, Space Tech by India –Click2view
The island groups of Bay of Bengal: Andaman & Nicobar Islands
The island groups of Arabian Sea: Lakshadweep and Minicoy Islands
The Physiographic Divisions of India | The Islands
Let’s take these up one by one:
Andaman & Nicobar Islands:
Also called the emerald islands.
Location and Extent:
These are situated roughly between 6°N-14°N and 92°E -94°E.
The most visible feature of the alignment of these islands is their narrow longitudinal extent.
These islands extend from the Landfall Island in the north (in the Andamans) to the Indira Point (formerly known as Pygmalion Point and Parsons Point) in the south (In the Great Nicobar).
Origin: The Andaman and Nicobar islands have a geological affinity with the tertiary formation of the Himalayas, and form a part of its southern loop continuing southward from the Arakan Yoma.
The entire group of islands is divided into two broad categories:
The Andaman in the north, and
The Nicobar in the south.
They are separated by a water body which is called the Ten degree channel.
The Andaman islands are further divided into:
Great Andamans
North Andaman
Middle Andaman
South Andaman
Little Andaman
Little Andaman is separated from the Great Andamans by the Duncan Passage.
The Andaman and Nicobar Islands
Chief Characteristics:
These are actually a continuation of Arakan Yoma mountain range of Myanmar and are therefore characterized by hill ranges and valleys along with the development of some coral islands.
Some smaller islands are volcanic in origin e.g. the Barren island and the Narcondam Island. Narcondam is supposed to be a dormant volcano but Barren perhaps is still active.
These islands make an arcuate curve, convex to the west.
These islands are formed of granitic rocks.
The coastal line has some coral deposits, and beautiful beaches.
These islands receive convectional rainfall and have an equatorial type of vegetation.
These islands have a warm tropical climate all year round with two monsoons.
The Saddle peak (North Andaman – 738 m) is the highest peak of these islands.
The Great Nicobar is the largest island in the Nicobar group and is the southernmost island. It is just 147 km away from the Sumatra island of Indonesia.
Lakshadweep Islands:
These islands were earlier (before 1st November 1973) known as Laccadive, Minicoy and Amindivi Islands.
Location:
These are scattered in the Arabian Sea between 8°N-12°N and 71°E -74°E longitude.
These islands are located at a distance of 280 km-480 km off the Kerala coast.
Origin: The entire island group is built of coral deposits.
Important islands:
Amindivi and Cannanore islands in the north.
Minicoy (lies to the south of the nine degree channel) is the largest island with an area of 453 sq. km.
These consist of approximately 36 islands of which 11 are inhabited.
These islands, in general, have a north-south orientation (only Androth has an East-West orientation.
These islands are never more that 5 metres above sea level.
These islands have calcium rich soils- organic limestones and a scattered vegetation of palm species.
One typical feature of these islands is the formation of crescentic reef in the east and a lagoon in the west.
Their eastern seaboard is steeper.
The Islands of this archipelago have storm beaches consisting of unconsolidated pebbles, shingles, cobbles and boulders on the eastern seaboard.
The islands form the smallest Union Territory of India.
Other than the above mentioned two major groups, the important islands are:
Majauli: in Assam. It is:
The world’s largest freshwater (Brahmaputra river) island.
India’s first island district
Salsette: India’s most populous island. Mumbai city is located on this island.
Sriharikota: A barrier island. On this island is located the satellite launching station of ISRO.
Aliabet: India’s first off-shore oil well site (Gujarat); about 45 km from Bhavnagar, it is in the Gulf of Khambat.
New Moore Island: in the Ganga delta. It is also known as Purbasha island. It is an island in the Sunderban deltaic region and it was a bone of contention between India and Bangladesh. In 2010, it was reported to have been completely submerged by the rising sea water due to Global warming.
Pamban Island: lies between India and Sri Lanka.
Abdul Kalam Island: The Wheeler Island near the Odisha coast was renamed as Abdul Kalam island in 2015. It is a missile launching station in the Bay of Bengal. The first successful land-to-land test of the Prithvi Missile was conducted from the mainland and it landed on the then uninhabited ‘Wheeler Island’ on November 30, 1993.
Now that we are done with this part, let’s try to attempt some questions from the past UPSC examinations:
Prelims:
1996
Question: ‘Saddle Peak’ the highest peak of Andaman and Nicobar islands is located in
A. Great Nicobar
B. Middle Andaman
C. Little Andaman
D. North Andaman
Ans. D
Mains:
Question: Write a short note on New Moore Island. (2006/2M)
Question: Write a short note on Indira Point. (2007/2M)
Question: Name the main physiographic divisions of India and give the salient features of each division. (2000/15M).
Question: How do the Andaman and Nicobar Islands and the Lakshadweep differ in the geological evolution and topographical conditions? (1998/15M)
Source
