Climate and Soil in India PDF

India has a tropical monsoon type of climate because India lies in the tropical belt and its climate is influenced by the monsoon winds. The main characteristics of this type of climate are relatively high temperatures and dry winters. REGIONAL VARIATIONS Example, the climatic conditions of Bihar a...

India has a tropical monsoon type of climate because India lies in the tropical belt and its climate is influenced by the monsoon winds. The main characteristics of this type of climate are relatively high temperatures and dry winters. REGIONAL VARIATIONS Example, the climatic conditions of Bihar and Uttar Pradesh in the north differ from that of Kerala and Tamil Nadu in the south; yet all of these States have a similar monsoon type of climate. PRECIPITATION Variations occur not only in the type of precipitation but also in its amount and the seasonal distribution. Snowfall occurs in the Himalayas, whereas it only rains over the rest of the country. 1.Cherrapunji and Mawsynram in Meghalaya get about 1100 cm rains in the year, whereas Jaisalmer in Rajasthan hardly receives 9 cm of rainfall in a year. 2.Tura in Meghalaya gets an amount of rainfall in a single day which is equal to 10 years of rainfall at Jaisalmer in Rajasthan. 3.The Coromandel Coast remains dry in the months of July and August, whereas the Ganga delta and the coastal plains of Odisha are hit by strong storms almost every third or fifth day during these months. 4.Most parts of India receive rainfall during June-September, but the coastal areas of Tamil Nadu get rains in the beginning of the winter season. TEMPERATURE: Seasonal variations in temperature occur from place to place and from region to region. Variations in temperature are found also at Click here to buy Latest ICSE Class 10 Books-https://amzn.to/3xib8Bu a single place and in a single day. Examples of these variations are: 1. Barmer in Rajasthan may record a temperature of 48°C or 50°C on a June day, while it hardly reaches 22°C at Pahalgam or Gulmarg in Kashmir on the same day. However, in Dras near Kargil, the temperatures may go down to -40°C during winter. 2. Kerala has tropical climate with warm and moist air, whereas Punjab has continental climate with severe heat alternating with severe cold. 3. The temperature touches - 40°C in Kargil in the month of December whereas Kerala records 20°C or 22°C in the same month. FACTORS AFFECTING THE CLIMATE OF INDIA 1. The Himalayas: The Himalayas form a climatic barrier separating the Indian sub-continent from the rest of Asia. They not only prevent the cold Siberian winds from entering the Indian region and from India becoming a cold desert but they also force the moisture laden South West Monsoon winds to shed rainfall in India or else India would be a dry region. 2. The Monsoon Winds: During summers, the moisture carried by these south-westerly winds from the -Arabian Sea and Bay of Bengal bring rain to the entire subcontinent. Retreating monsoon brings rain in eastern coastal region. During winter, dry offshore, North-East Monsoon winds blow from high pressure to low pressure region. As they blow over a vast landmass, they are cold and dry. They pick moisture from the Bay of Bengal to bring rain to Tamil Nadu in winters. 3. Latitude: The Indian subcontinent is divided into two parts by the Tropic of Cancer. The northern portion lies in the temperate Click here to buy Latest ICSE Class 10 Books-https://amzn.to/3xib8Bu zone and the southern portion lies in the tropical zone.India is warmer than the north and does not have a clear-cut winter season. The northern zone does not have the mid-day Sun almost vertically overhead during any part of the year, while the southern zone has the mid-day Sun almost vertically overhead at least twice every year. 4. Varied Relief: Relief plays ar an important role in the climatic conditions of India, The Western Ghats get heavy rainfall on western side because cause they stand in the way of South West Monsoon winds which come from the Arabian Sea. On the other hand, the Deccan Plateau gets less rainfall as it lies in the rain shadow area of the Western Ghats. In Rajasthan, the Aravali Range is parallel to the direction of the South West Monsoon winds. So it is unable to stop the moisture laden winds. This makes Rajasthan a dry area. 5. Altitude: There is a decrease of 1°C for every 166 m rise in height, because temperature decreases as you move to higher altitudes. So, the mountains are cooler than the plains. 6. Influence of the Surrounding Areas: Nearness to the sea that these areas have a moderate climate. 7. Western Disturbances: In the winter season due to the shifting of the pressure belts. These cyclones bring rain to Northern Plains and snow in Jammu and Kashmir in India. 8. Jet Streams: Jet streams are cold fast blowing winds that develop in the upper layers of the atmosphere. They influence the climate of India. These depressions play a very significant role in the distribution pattern of the monsoon rainfall in the Click here to buy Latest ICSE Class 10 Books-https://amzn.to/3xib8Bu subcontinent. The highest rainfall occurs along the track of these depressions. 9. Distance from the Sea: Areas in the interiors of India have extreme type of climate or continental climate whereas coastal areas have equable or maritime climate! The effect of land breeze and sea breeze caused by differential rate of heating and cooling of land and sea are responsible for moderate climate in coastal areas. 10. El-Nino Effect: El-Nino is a warm ocean current which sometimes appears off the coast of Peru in South America during the month of December. It increases the surface temperature of the sea and affects the movement of monsoon winds in the Indian Ocean and causes weak drought-like situation in the Indian sub- continent. MONSOON PHENOMENA AND ITS MECHANISM Monsoons are periodic or seasonal winds. They develop because of differential heating as well as cooling of the land and sea. They are divided into two wind systems-the Summer Monsoon and the Winter Monsoon. SUMMER MONSOONS In summer, the land gets heated more than the sea. Hence there develops a centre of low pressure on the land. Over the adjoining sea, the air is comparatively cool, and a high pressure develops there. This causes the winds to blow from the sea to the land. It is the 'Summer Monsoon.' In May, June and July, the plains of the Indian subcontinent are heated by the vertical rays of the sun. The intense heat develops Click here to buy Latest ICSE Class 10 Books-https://amzn.to/3xib8Bu a low pressure. During these months, over the Indian Ocean, a high pressure area develops. So, the winds blow from the Indian Ocean northward and north-westward into Asia. As they blow from the sea to the land, they bring heavy rainfall in some parts of the Indian subcontinent. The summer monsoon winds blow south-west; so they are known as the 'South-West Summer Monsoon." WINTER MONSOONS During winter season, the conditions are just reverse of those in summers. A high pressure develops over a big landmass stretching from Central Asia upto north-west Indian plains. At the same time a low pressure zone develops in the Indian Ocean. As the winds blow from the land to the sea, they bring cold dry weather. They are incapable of producing rain. When these winds blow over seas and pass over the adjoining land, they bring some rainfall. The Southern Coromandel Coast (Tamil Nadu and southern tip of Andhra Pradesh) in India get rain from winter monsoons. The winter monsoon winds blow north- east; so the monsoon is known as the 'North-East Winter Monsoon.' FOUR SEASONS: The Monsoon type of climate has distinct seasonal pattern marked by significant change from one season to the other. These changes are clearly visible in the interior parts of the country. The coastal areas, due to the influence of the seas do not experience much variation in temperature though there occurs variation in the pattern of rainfall. Thus, the year may be divided into four principal seasons on the basis of monsoon variations: 1. The Hot and Dry summer (March to May). 2. The Hot and Wet or Rainy Season or the South-West Monsoon (June to September). Click here to buy Latest ICSE Class 10 Books-https://amzn.to/3xib8Bu 3. The Retreating South-West Monsoon (October-November). 4. The Cold and Dry Winter Season or North East Monsoon (December-February). 1. THE HOT DRY SUMMER In India, the hot season begins in March and lasts until June. The vertical rays of the Sun fall directly over the Tropic of Cancer during this period.. TEMPERATURE From March to May, due to the northward movement of the path of the Sun's vertical rays, the length of the day increases. It results in the increase in solar radiation which moves northward over the tropical areas of South Asia and the temperature starts rising. In most parts of India, temperature ranges between 30° and 32°C. The highest day temperatures increase as the heat belt moves further north. In north-western part of India, temperatures around 48°C are not uncommon. In south India, the hot weather is not as intense as in north India. The moderating influence of the oceans together with the Peninsular situation of south India keeps the temperatures lower than that in north India. The temperatures, therefore, remain between 26°C and 32°C in south India. PRESSURE CONDITIONS The warmest area slowly shifts from the Deccan to northwest India. The high temperature in the subcontinent causes a low pressure between Thar Desert and Chota Nagpur Plateau. The surrounding seas are cooler and develop high pressure conditions in the Indian Ocean. Click here to buy Latest ICSE Class 10 Books-https://amzn.to/3xib8Bu STORMS AND RAINFALL The hot-dry weather is marked by weak winds and dryness over the area. The low pressure over the Northern plains draws winds from the surrounding areas and gives rise to thunderstorms with strong dusty winds. LOCAL WINDS: (a) A striking feature of the hot weather season is the strong and dusty winds, called loo, which blow during day time over northern and north-western India. These winds have temperature range between 45°C and 50°C which is hot enough to cause heatstrokes. (b) There are occasional tornado-like dust storms in Punjab and Haryana and Uttar Pradesh. (c) The thunderstorms accompanied with strong winds and heavy rainfall occur in Assam and West Bengal. These local winds are known as Kalbaisakhi which means the calamity of the month of Baisakh'. In Assam, these storms are known as Bardoli Chheerha. They originate over the Chotanagpur Plateau and are carried eastward by westerly winds. They bring rainfall in Assam, West Bengal and Odisha. This rainfall is quite beneficial for growing jute and rice in West Bengal and tea in Assam. (d) Thunderstorms cause rainfall along the Kerala and Karnataka coasts. The little rainfall that they bring is important for mango, tea and coffee plants. Such rains are called mango showers as they help in the early ripening of the mango crop. They are also called cherry blossoms in Karnataka. 2. THE SOUTH-WEST MONSOON SEASON These winds bring heavy rainfall accompanied by violent thunder and lightning. This sudden violent onset of rainfall in the first Click here to buy Latest ICSE Class 10 Books-https://amzn.to/3xib8Bu week of June is termed as the Burst of the Monsoon. However, when the South-West Monsoon fails to bring rainfall for two or more weeks and there is a dry period in the rainy season it is called the Break of Monsoon. The first State to receive the monsoon showers is Kerala and also the last to see its withdrawal. As a result of the tapering topography of peninsular India the South-West Monsoon winds divides into two branches: (a) The Arabian Sea Branch; and (b) The Bay of Bengal Branch THE ARABIAN SEA BRANCH The monsoon winds originating over the Arabian Sea further split into three branches: (a) Its one branch is obstructed by the Western Ghats. These winds go up the slopes of the Western Ghats, become cool and bring heavy rains in the windward side of the Sahyadris and the Western Coastal Plains. (b) The second branch of the Arabian Sea monsoon winds strikes the coast north of Mumbai. (c) The third branch strikes the Saurashtra Peninsula and the Kutch. THE BAY OF BENGAL BRANCH The Bay of Bengal branch is directed towards the coast of Myanmar and part of south-east Bangladesh. However, owing to the presence of the Arakan Hills along the coast of Myanmar, a large part of this branch of monsoon is deflected towards the Indian subcontinent. The monsoons, therefore, enter West Bengal and Bangladesh from south and south-east instead of the south westerly direction. Cherrapunji and Mawsynram, located on the Click here to buy Latest ICSE Class 10 Books-https://amzn.to/3xib8Bu crest of the southern range of Khasi Hills, receive the highest average annual rainfall in the world. 3. The Retreating Monsoon The South-West Monsoon starts retreating from northern India in early October. Hence, the months of October and November are known for the retreating monsoon. The combination of high temperature and humidity gives rise to an oppressive weather. This is commonly known as 'October heat'. Day temperature rises due to clear skies. TROPICAL CYCLONES There are tropical depressions (low-pressure systems) originating in the Bay of Bengal caused by local variations of heat and moisture. They lead to tropical cyclones in November and December. Such cyclones generally originate in the neighbourhood of the Andaman Islands between 12°N and 17°N and travel west or northwest over the Bay of Bengal. Whenever they occur, they cause great loss of life and property due to heavy rains on the eastern coastal regions of India. OCTOBER HEAT October is marked by clear cloudless sky, high temperature and high humidity. 4. THE NORTH-EAST MONSOON SEASON The cold weather season commences at the end of November and continues till March. The skies are relatively clear with dry weather. Night temperatures are low, specially in northern India, but the days are pleasantly warm. The mean temperature in the northern plains is below 20°C and gets even lower in Himachal Pradesh, Jammu and Kashmir, Punjab and Haryana. Click here to buy Latest ICSE Class 10 Books-https://amzn.to/3xib8Bu TEMPERATURE In winter season, January is usually the coldest month. The temperature remains quite low during the winter months over the Indian sub- continent. The temperatures decrease from south to north. Dras Valley in Kashmir near Kargil records minimum temperature of -45°C. It is the coldest place in India). The excessive cold in north India during this season is due to the following reasons: (a) In the month of February, the cold winds from the Caspian Sea and Turkmenistan bring cold wave over the northwestern parts of India; (b) Punjab, Haryana and Rajasthan experience continental type of climates as they are located far away from the sea to experience its moderating influence; and (c) The snowfall in the nearby Himalayan ranges creates cold wave situation. PRESSURE The weather in this season is characterised by feeble high pressure conditions over the north-western part of the plain. This is because of the oblique rays of the Sun which reach the subcontinent as the Sun moves to the Southern hemisphere. During this season, the north east trade winds prevail over the country. These winds blow from land to sea and hence, for most parts of the country it is dry season. When these winds pass over Bay of Bengal they pick up some moisture and cause some amount of rainfall on the Coromandel Coast. As these winds blow from north-east to south- west, they are called the North-East Monsoon Winds. Click here to buy Latest ICSE Class 10 Books-https://amzn.to/3xib8Bu TEMPERATE CYCLONES (Western Disturbances) A characteristic feature of the cold weather season is the inflow of depressions from the west and the north-west. These low pressure systems, called the western disturbances, originate in West Asia and the regions near the Mediterranean Sea. They travel eastwards across Iran and Pakistan and reach. India during the winter season. They bring the much-needed winter rains over the plains and snowfall in the mountains. RAINFALL: Most parts of India do not receive rainfall in the winter season. This is because the winter monsoons have little humidity and due to anti-cyclonic circulation on land, the possibility of rain from them decreases. However, there are some areas which do receive rainfall in the winter season. Distribution of Rainfall: India can be divided into four rainfall regions: 1) Heavy Rainfall Region: more than 200 cm. 2) Moderate Rainfall Region: 100 cm to 200 cm. 3) Low Rainfall Region: 50 to 100 cm. 4) Scanty Rainfall Region: less than 50 cm. Features of the Rainfall: Main features of the Rainfall in India are: 1. There is rainfall over three months and the rest of the year is mostly dry. Seventy per cent of annual rainfall occurs in the rainy season. Click here to buy Latest ICSE Class 10 Books-https://amzn.to/3xib8Bu 2. The rains are mainly of relief type. The windward slopes of the mountains get more rainfall than the leeward side. 3. Only a small portion of the rainfall is received from sources other than the monsoon. like cyclonic rainfall and convectional rainfall. 4. The quantity and the time of occurrence of rainfall cannot be predicted as the rainfall is erratic. 5. India has an agrarian economy dependent on rainfall. As such rainfall affects the economy of the country. SOIL RESOURCES Soil forms the topmost layer of the Earth's land surface. It is the thin layer of loose mixture of small rock particles and rotting a matter that covers much of the land. Constituents of Soil: Soils are derived from parent rock material through a process of breakup or wear and tear. Soil Fertility: Soil fertility refers to the strength of the soil to support plant life. Fertile soil has the following characteristics: (i) It contains adequate amount of moisture to supply essential nutrients to the plants. (ii) It has sufficient depth to enable the plants to grow their roots as per their requirements. (iii) It is rich in nutrients such as nitrogen, phosphorus and potassium. (iv) It contains organic matter that improves the structure of soil. Click here to buy Latest ICSE Class 10 Books-https://amzn.to/3xib8Bu Soil Classification: According to its location, soil can be classified as: (i) Residual or Sedimentary Soil: Almost all soils are formed ‘in situ', that is, they are formed in their original position by the breaking up of parent rocks. They include black soil, red soil, laterite soil, desert soil, etc. (ii) Transported Soil: These soils are ex situ', that is, transported by various agents of erosion and consist of sediments carried and deposited by rivers and winds. TYPES OF SOILS: The soils of India are classified on the basis of their origin and formation as follows: 1. ALLUVIAL SOILS: These soils are formed by the sediments brought down by rivers. They are also rich in chemical ingredients. The rivers deposit very fine particles. of soil called alluvium in their plains during the course of their long journey. Alluvial soil is also known as riverine soil because it is mainly found in the river basins. It is a mixture of sand, clay and silt, called loam. These have been deposited by three important river systems-the Indus,the Ganga and the Brahmaputra. These soils occupy 40 per cent of the land area. The entire Northern Plains are made up of these soils. These soils are also predominant in coastal plains and deltas particularly in the deltas of the Mahanadi, the Godavari, the Krishna and the Kaveri rivers. Click here to buy Latest ICSE Class 10 Books-https://amzn.to/3xib8Bu On the basis of its age, the alluvial soil is of two types-bhangar and khadar The bhangra or the older alluvium is composed of lime nodules or kanker and has a clayey composition. The khadar is light in colour and is composed of newer deposits. Khadar is more fertile than bhangar soil as new layers are deposited year after year during monsoon floods. Crops can be grown on old alluvial soils by using manure. They form the largest and most important group as they contribute the largest share to the agricultural wealth of India. Distribution: I. Inland Alluvium: These soils are found on the plains of the Indus, the Ganga and the Brahmaputra rivers. Punjab, Haryana, Uttarakhand, Uttar Pradesh, Bihar, West Bengal have alluvial soils. II. Deltaic Alluvium: The Deltaic alluvium is found in the deltas of the Ganga- Brahmaputra, Mahanadi, Godavari, Krishna and Kaveri rivers. III. Coastal Alluvium: It is of tidal origin. It is found in the coastal strips of Peninsular India. It is also found in the plains of Gujarat. Characteristics of Alluvial Soil: (i) It is formed by the deposition of the river load as it flows from its upper to its lower course. (ii) The soil is coarse. Soil particles are large and non uniform. Such soil is prettominant in piedmont plains (plains near the foot Click here to buy Latest ICSE Class 10 Books-https://amzn.to/3xib8Bu of mountains). As we move further down a river valley, the soil particles become smaller and more uniform. They are found upto a depth of 500 metres. (iii) The alluvial soil of the Upper Ganga Valley is dry, porous, sandy, faint yellow and consists of clay and organic matter, while the soil of lower Ganga Valley, ie., of West Bengal and Bangladesh is more compact, less coarse and more moist. (iv) It is light and porous, therefore easily Tillable. (v) It is a fertile soil and it is rich in minerals, especially potash and lime. (vi) It is deficient in nitrogen and humus, except the alluvium of the Ganga deltaic region which is rich in humus. (vii) It is suitable for the growth of a large variety of rabi and kharif crops. (viii) Soil in the drier areas is more alkaline. Crops: Alluvial soil is fertile and suitable for cultivation of rice, wheat, sugarcane, cotton, tobacco, gram and oilseeds. In the lower Ganga-Brahmaputra Valley it is useful for jute cultivation. 2. BLACK SOIL: This soil is black in colour and is also known as the Requr soil or Black Cotton Soil. It is dark in colour and is suitable for cotton cultivation. This soil is the residual soil, i.e., it is formed at the place of its origin over the underlying rocks. Since it is formed by the denudation of volcanic rocks, it is also known as lava soil. Distribution: Maharashtra, Gujarat. Click here to buy Latest ICSE Class 10 Books-https://amzn.to/3xib8Bu Characteristics of Regur (Black) Soil:- (i) It is fine textured and clayey in nature. (ii) It has high quantities of lime, iron, magnesium and generally poor percentage of phosphorous, nitrogen and organic matter. (iii) It is black in colour as it is formed from weathered lava rocks. (iv) It is very clayey (up to 50% clay content) and, therefore, highly retentive of water. Because of high clay content, this soil expands when wet and become difficult to plough, During the dry season, black soil shrinks and develops big cracks. which help in air circulation (v) The soil is very fertile in most of the places. (vi) It is suitable for cultivation of cotton, jowar, wheat, sugarcane, linseed and gram. (vii) In any season it has moisture stored in its subsoil. Crops The moisture retentiveness of black soil makes it suitable for dry farming. 3. RED SOIL: It is a category of soil which develops on old crystalline rocks. Under prolonged weathering by rainfall, ancient crystalline and metamorphic rocks of the Peninsular plateau break up to form this soil. This soil differs from place to place on the basis of the parental rock material and climatic conditions. It is red in colour as it contains large amounts of iron oxide. At several places, its colour slightly changes and it appears brown or grey. It looks yellow when it occurs in a hydrated form. Distribution: Tamil Nadu in the south to Bundelkhand in the north and Rajmahal Hills in the east to Kutch in the west. Click here to buy Latest ICSE Class 10 Books-https://amzn.to/3xib8Bu Characteristics of Red Soil: (i) Red soil has got its name from its colour. (ii) It is porous and has high percentage of iron oxide. (iii) It is generally shallow and its pH value ranges from 6.6 to 8.0. (iv) It is loose and aerated. (v) It is poor in nitrogen, phosphorus, potassium and organic matter. (vi) It is ideal for dry farming as it is formed in poor rainfall areas. (vii) It is not fertile but responds to fertilizers. (viii) It needs irrigation support for cultivation. (ix) It contains soluble salts in small quantities. Crops Though red soil is suitable for cultivating almost all crop types, it is most suitable for growing vegetables, rice, ragi and tobacco. Groundnut and potatoes can be grown on coarse soils at higher levels and sugarcane on heavy clays at lower levels. 4. LATERITE SOIL: This soil type is formed as a result of atmospheric weathering of rocks under conditions of high rainfall and temperature with alternate wet and dry periods. It is the residual soil formed by leaching due to tropical rains. Leaching is the process in which the nutrients get percolated down below the soil due to heavy rainfall; thus leaving the top soil infertile. This is also called desilication. Due to heavy rains, lime and silica are leached away and aluminium compounds are left behind. Humus content of the soil is removed by bacteria that survives well in high temperature. Click here to buy Latest ICSE Class 10 Books-https://amzn.to/3xib8Bu There are two types of laterite soils: Upland Laterites and Lowland Laterites. Upland laterites are formed over hills and uplands. From there they are transported by streams towards lowlands. Such transported soils are known as Lowland Laterites. Distribution: Western & Eastern Ghats Characteristics of Laterite Soil: (i) It is of a coarse texture, soft and friable. (ii) It is red due to the presence of iron oxide which is formed by leaching. The soluble plant foods like potash are removed from the top soil leaving alumina and iron oxide. (iii) It is a porous soil; silica is removed from it by chemical action. It is poor in lime and magnesium and deficient in nitrogen (iv) It does not retain moisture and hence is not fertile. It suits only special crops like tapioca, cashewnuts, tea, coffee, etc. (v) It is acidic in nature as alkalis are leached. (vi) It is considered suitable for building purposes. Crops: As the laterite soil has low fertility because of high acidity and low moisture retention, manuring and other activities are required to make it suitable for growing crops such as ragi, rice and sugarcane. Paddy is grown on lower elevations, whereas tea, cinchona, rubber and coffee are grown on higher elevations. SOIL EROSION The removal of the top soil cover by water, wind and human activities is called soil erosion. Click here to buy Latest ICSE Class 10 Books-https://amzn.to/3xib8Bu 1. SOIL EROSION BY WATER:- (i) Sheet Erosion: It occurs on gentle slopes and is the slow removal of a thin layer of soil when vegetation is destroyed. Rainwater washes. away the thin layer of bare soils. (ii) Rill Erosion: When sheet erosion continues for long, the silt- laden run-off forms many finger-shaped rills or grooves over a large area. This is called rill erosion it is the intermediate stage between sheet erosion and gully erosion. (iii) Gully Erosion: During heavy downpour, deep gullies are made on bare soils on account of water run-off. Gully erosion removes nutrients and heavy load of loose soils, making the soil unproductive. It makes water very muddy. This is seen in the Chambal Valley region (iv) Leaching: After harvesting, farmers leave the soils bare for some time. During rainfall the nutrients in the soil are leached or percolated below the top layer. (v) Sea or Shore Erosion: The tidal waters of the sea cause considerable damage to the soil along the coast. The powerful waves dash against the coast and break hanging cliff rocks. The broken material is then removed by the retreating sea waves. (vi) Stream Bank Erosion: Streams and rivers change their courses by cutting one bank and depositing the silt loads on the other. During flash floods, the damage is accelerated. Click here to buy Latest ICSE Class 10 Books-https://amzn.to/3xib8Bu 2. SOIL EROSION DUE TO HUMAN ACTION (i) The loss of vegetation cover leads to Sheet Erosion on hilly slopes because water instead of sinking into the ground washes the soil down. In the second stage, in the absence of vegetation cover and washing off of the absorbent top soil, rills begin to appear on the landscape. In the third stage, the water run off during heavy rains may develop deep grooves causing Gully Erosion. (ii) Local population practise shifting cultivation. The heavy rains then wash away the bare soil from the slopes to the valleys below. (iii) Another important cause of Sheet, Rill and Gully Erosion is uncontrolled grazing of domestic animals in the valleys and the upper slopes. 3. EROSION BY WIND Wind Erosion refers to the movement and deposition of soil particles by wind. It occurs when soil devoid of vegetation is exposed to high-velocity wind. Wind moves soil particles 0.1- 0.5mm in size in bouncing or hopping fashion and those greater than 0.5 mm by rolling. The former is known as saltation and the latter as soil creep. The particles less than 0.1 mm or the finest particles detach into suspension. Causes of Soil Erosion: (i) Heavy Population Pressure on Land: India's forest cover continues to be very low, just *21.54 per cent of the total area. On the other hand, the population continues to rise at a rapid rate and has already crossed the one billion mark in the year 2000. More forests are being destroyed to house and feed the Click here to buy Latest ICSE Class 10 Books-https://amzn.to/3xib8Bu increasing population. The heavy pressure on land is the main cause of soil erosion. (ii) Nature of Rainfall: India receives 80 to 90 per cent of rainfall in the monsoon season. Heavy downpour during monsoon months causes floods. In the remaining months droughts are frequent. This affects the soils. (iii) Overgrazing: The number of domestic animals particularly the cattle in India is the highest in the world. The cattle freely graze in open lands making them bare of vegetation. Winds carry away dry soil particles from the bare landscape. Thus, soil erosion takes place. In many parts of Rajasthan, excessive grazing by cattle has resulted in the exposure of the top soil to elements of denudation. (iv) Bad Farming Techniques: The poor farmers plough fields in traditional ways. The farming techniques and small size of holdings lead to soil erosion on a large scale. The absence of terracing, contour cultivation, crop rotation and the improper use of manure etc., have caused serious problems of soil erosion. (v) Topography: Northeastern parts of India, Shiwaliks and hilly regions in South India are affected by soil erosion because of steep slopes and heavy rainfall. During heavy rainfall, soils are washed away by running water down the slope. (vi) Deforestation: Forests are destroyed so that more land can be used for cultivation. Cutting of trees exposes the soil to water and wind, which leads to soil erosion. REGIONS OF SOIL EROSION: According to an estimate every year rainwater alone washes out 1/8 cm thick fertile topsoil. Among the States, Rajasthan comes on the top of the soil eroded regions, followed by Madhya Pradesh, Maharashtra, Uttar Pradesh, Gujarat, Andhra Pradesh and Karnataka. The worst affected areas include: (i) the badlands of the Chambal and Yamuna rivers; Click here to buy Latest ICSE Class 10 Books-https://amzn.to/3xib8Bu (ii) the piedmont zone of the western Himalayas, (iii) the Chotanagpur plateau region; (iv) the Tapi-Sabarmati valley region in Gujarat; soil area of Maharashtra; and (v) the dry areas of Rajasthan, Gujarat and Haryana.. PREVENTION 1. Terrace Farming: On hilly slopes, terraces act as bunds and prevent the soil from being washed away by running water. Terrace farming is with successful results in Japan South- East Asia and the USA. 2. Shelter Belts: Farmers plant trees in several rows to check wind erosion. They are known as wind breaks. 3. Contour Ploughing: Ploughing along contours on a slope prevents soil being washed away by rainwater or by surface run off. Contours act like bunds. Terraces are levelled into step-like small fields with even slope. Contour ploughing is common in Japan, China and some South-East Asian countries. 4. Strip Cropping: Crops are grown in alternate strips of land to check the impact of the winds. 5. Construction of Dams: Rivers cause soil erosion. Dams are built in the upper course of rivers to control erosion of soil. Click here to buy Latest ICSE Class 10 Books-https://amzn.to/3xib8Bu 6. Plugging Gullies: The gullies made in the soil are plugged with deposition of silt during heavy rains. 7. Planting Trees: The trees, like in the case of Shelter Belts, are planted along the edges of the fields the waste land and on steep slopes to prevent soil erosion as well as to enhance the capacity of the soil to retain water. SOIL CONSERVATION Soil conservation means prevention of soil loss from erosion or prevention of reduced fertility of soil caused by over usage, acidification, salinisation or other types of soil contamination. There is an acute need to prevent soil erosion, because of its adverse effects which include the following: (i) Loss of fertile top soil together with its mineral nutrients, from the upper surface lead to gradual loss of soil fertility and agricultural productivity. (ii) Lowering of the underground water table and decreasing soil moisture. (iii) Drying of vegetation and extension of arid lands; Increase in the frequency of droughts and floods. (iv) Silting of river and canal beds; Recurrence of landslides; Adverse effect on economic prosperity and cultural development. SOIL CONSERVATION SCHEMES In India, from the very first Five Year Plan, soil conservation measures were launched. The programmes under the State Plan aim at conservation of soil mainly on agricultural lands with some components of land reclamation, soil and land use survey, raising of utility trees on private and common lands. Click here to buy Latest ICSE Class 10 Books-https://amzn.to/3xib8Bu (i) The centrally sponsored scheme of Integrated Watershed Management in the catchments of flood-prone rivers aims at n enhancing the ability of the catchment, reducing erosion and consequent silt load. (ii) A scheme for reclamation and development of ravine areas was launched in Madhya Pradesh, Uttar Pradesh and Rajasthan. The components of this scheme included peripheral bunding to halt further ingress of ravines, afforestation of ravines for fuel, fodder and reclamation of shallow ravines. (iii) The scheme for control of shifting cultivation is being implemented in the north eastern States. It encourages farmers to practise terraced cultivation and afforestation to support fuel and fodder requirements. (iv) National Project on Development and Use of Bio-Fertilizers and National Project on Quality Control encourage the use of bio- fertilizers as well as balanced and integrated use of fertilizers. (v) In urban areas, rainwater harvesting is a means of checking soil erosion, besides recharging ground water. Click here to buy Latest ICSE Class 10 Books-https://amzn.to/3xib8Bu Click here to buy Latest ICSE Class 10 Books-https://amzn.to/3xib8Bu