SEBA Board Solution Class 9 Geography Chapter 4 Geography of Assam
SEBA Board Solution Class 9 Geography Chapter 4 Geography of Assam full exercise Solution by Computer Sir. Here in this page we have provided SEBA – The Board Of Secondary Education, Assam Class 9 Geography Chapter 4 all Question Answer Solution.
Board |
SEBA / Assam State Board |
Class |
9 |
Subject |
Geography |
Chapter Number |
4 |
Chapter Name |
Geography of Assam |
Topic |
Solution |
1.) What are the physiographic divisions of Assam?
Assam is a north -eastern state. The state extends from 24°09’N latitude to 27°58’N latitude and from 89°42’E longitude to 96°01’E longitude. The physiographic divisions of Assam are described in terms of plains, floodplains, hills and mountains, foothills, plateaus, river valleys etc. Assam can be divided into Brahmaputra Valley, Barak Valley, Karbi Plateau Barail and Southern Hills
2.) What are the physiographic regions of the Brahmaputra Valley?
The Brahmaputra Valley is the major physiographic division of Assam. The valley is long, narrow with 720 km length and 80 km width in average. The valley is surrounded by hills and plateaus on its three sides north, east and south. The north and east side has the Eastern Himalayas, the southern side is bounded by the Naga hills, Karbi and Meghalaya plateaus. The plains of West Bengal and Bangladesh are in the west. The Brahmaputra valley can be divided into four distinct physiographic units from north to south- the northern foothills, the North and South bank plains, the floodplains and char lands and the Southern foothills.
3.) Write four names each of the north-bank and south-bank tributaries of the Brahmaputra river.
The Brahmaputra River has an average length of 640 km and consists of large number tributaries. The four north bank tributaries of Brahmaputra are Subansiri, Ranganadi, Buroi and Jia Bharali. The four south bank tributaries are Burhi Dihing, Disang, Dikhow and Jhanzi.
4.) Give a brief description of the Brahmaputra plain region.
The plains of Brahmaputra include both north bank plain and south bank plain. The extension of the North bank from northern foothills to the Brahmaputra River in the south and the south bank lies from the northern foothills to the Brahmaputra River in the north. The entire plain is the result of alluvial deposition in large amount carried by the Brahmaputra River and its tributaries from the northern and southern hills and highlands. The north bank is wider with an average width of 30km in the lower part and upper part with an average width of 10km.The south bank is about 5 km. Both the sides of the plains are covered with alluvial soil suitable for agriculture. The area is thickly populated and developed in transportation.
5.) Give a brief description of the floodplain region of the Brahmaputra.
The area which is in between the North Bank and South Bank plains are drained by frequent floods caused by the Brahmaputra River is known as the floodplain of the Brahmaputra. The floodplain includes the charlands developed on the bed of the Brahmaputra. The floodplain is wide in all places, its width decreases because of the hillocks at some places and the levees along the banks of the Brahmaputra River. Most of the wetlands and swamps are found in the districts of Dhemaji and Barpeta. The confluence areas of Burhi Dihing, Dihang, Dhansiri, Kolang-Kopili and Kulshi rivers.
6.) Write about the geographic location and origin of Majuli.
Majuli river island is one of the biggest islands of the word and covers a land area of approx. 422 square kilometers and is located within the Brahmaputra River. It has a population of about 1.68 lakh and has been declared as a district of Assam in 2016. The area faces continuous problems of flood and bank erosion and the land area of the island is decreasing continuously due to bank erosion.
7.) Write briefly about the boundaries and characteristics of the Barak Valley.
The Barak Valley is an important physiographic region of Assam. The region consists of Barak plain, its adjacent northern and southern foothills. The Barak River flows for 225 km in Assam from east to west through Cachar district and along the northern boundary Hailakandi and Karimgang districts. The plain is full of alluvial sediments created due to the depositional activity of the Barak River and its tributaries. The plain area is known as Cachar plain and is enclosed by hills on its northern, southern and eastern sides.
8.) Write briefly about the boundaries and characteristics of the Karbi Plateau.
Karbi plateau was originally a part of the Meghalaya Plateau. The Kopili Valley has divided the Karbi Plateau in two parts: the eastern part and the western part. The eastern part covered by the Rengma hills covers the whole Diphu and Bokjan sub-divisions of Karbi Anglong district and is twice the size of the western part. The western part covers the Hamren sub-division of the district and has the average height of 900 mand it slopes from south-west to north -east. The rivers like Kopili and Barapani and their tributaries have formed the western part of the Karbi plateau.
9.) Write briefly the characteristics of the Barail Range and Southern Hills..
The ranges of Barail extends towards west direction from Thensang across Nagaland and moves towards North Cachar Hills district of Assam. This hill range connects the Naga hills in the east with the Meghalaya Plateau in the west. The range also divides the North Cachar Hills region into two parts- the north part falls within the Brahmaputra valley which is lower and the south part slopes falls within the Barak Valley which is higher.
10.) What is the type of Assam’s climate? Write briefly about its characteristics.
Assam lies under the sub-tropical monsoon climate and experiences heavy rainfall during summer. In winter the climate is dry, the temperature always humid and low. The state has different climate in different areas due to the differences in geographical location, topography, water areas of the Arabian Sea, Bay of Bengal and Indian ocean and prevalence of south-west monsoon. The climate of Assam is influenced by the monsoon winds also. Seasonal variations, changing air pressure of the north-west Indian landmass. The local winds like mountain wind, valley winds, rivers, wetlands influence the climate of the state.
11.) What is the main reason behind occurrence of rainfall in Assam during summer season.
The summer rainfall of Assam occurs due to the orographic and cyclonic processes of the moist south-west monsoon wind.
12.) Discuss briefly about the geographical factors influencing the climate of Assam.
The geographical factors that influence the climate of Assam are as follows: –
Assam lies under the sub-tropical monsoon climate and experiences heavy rainfall during summer. In winter the climate is dry, the temperature always humid and low.The state has different climate in different areas due to the differences in geographical location, topography, water areas of the Arabian Sea, Bay of Bengal and Indian ocean and prevalence of south-west monsoon. The climate of Assam is influenced by the monsoon winds also. Seasonal variations, changing air pressure of the north-west Indian landmass. The local winds like mountain wind, valley winds, rivers, wetlands influence the climate of the state. The temperature of the Brahmaputra and Barak valley stays little higher than the hilly region. The variation in energy of the monsoon wind and water vapour also affects the amount the annual rainfall across the state.
13.) What are the main seasons of Assam? Write in brief about the seasonal variation in the distribution of temperature and rainfall in Assam.
The different climatic elements of different times in a year result in mainly four climatic seasons are found in the state of Assam. The four seasons are Pre-Monsoon, Monsoon, Retreating Monsoon and Dry Winter. In Assam the temperature difference between winter and summer in a year is very significant. The average temperature in winter is 7°C and in summer is 35°C. The state experiences average rainfall of about 200 cm. The temperature differences in different places in the state is due to the variation in the rainfall. The topographic condition, location of the state, presence of hills result in the varied distribution of rainfall. The upper Assam like districts of Tinsukia, Dibrugarh, Lakhimpur and Sivasagar, Kokrajhar etc in lower Assam, Cachar, Karimgang etc in southern Assam experiences annual rainfall of about 250cm. Rainfall is quite less in the districts of central Assam like Nagaon and Karbi Anglong.
14.) Write the names of place in Assam witnessing the highest and lowest rainfall along with their amount of rainfall.
North Lahimpur witnesses highest annual rainfall of about 335 cm and Lumding witnesses lowest annual rainfall of about 129 cm.
15.) Why does the amount of rainfall not uniform in all places of Assam?
The state has varied topographic features, location and presence of neighboring hills surrounding the state affects the distribution of rainfall in the state. All these factors affect the distribution of rainfall in the state of Assam.
16.) Write in brief about the spatial distribution of rainfall in Assam.
The study of the pattern of occurrence of rainfall in different places of Assam show that there are spatial variations in rainfall across the state. Variations in geographic location, presence of neighboring hills, the distribution of rainfall in the state is quite uneven. The hills, mountains and foothills record more rainfall. The annual rainfall takes place in the districts of Tinsukia, Dibrugarh, Lakhimpur and Sivasagar in upper Assam. Kokrajhar and Dhubri districts of lower Assam and Cachar, Karimganj and Hailakandi districts of southern Assam. Again, it is studied that in places like Nagaon, Karbi Anglong districts of Central Assam there is very little rainfall. In places like Lumding region of Nagaon district receives annual of 129 cm only.
17.) Give a short account of different types of soil found in Assam.
Soil is one of the most valuable natural resources. Soils are of different types which are found in the different parts of the earth. Soils are formed by various factors which are parent materials, climate, organic processes, physiography and time. All these factors are also responsible in the formation of the soil of Assam. The state of Assam has four distinctive types of soils: i. Alluvial Soil, ii. Piedmont Soil, iii. Hill Soil and iv. Laterite soil.
i). Alluvial Soil- This type of soil is found in the plains of the Brahmaputra and Barak Valleys formed from the deposition of silt and clays carried by the rivers and their tributaries. This soil is also of two types- New Alluvial Soil and Old Alluvial Soil. The alluvial soil is very fertile.
ii.)Piedmont Soil- This type of soil is found in the northern narrow zone along the piedmont zone of the Himalayan foothills. This zone consists of the Bhabar and Terai belts. The soil consists of boulders, pebbles, sand and silts and form very deep layers. Tall grasses are found in this type of soil.
iii.) Hill Soil- The Hill Soils are found in the southern hills of areas of Assam like Assam- Meghalaya border, Karbi plateau North Cachar Hills districts etc. The fertility of this soil differs from one place to another. The soil has abundant nitrogenic and organic materials. This soil has two types also- Red sandy soil and Red loamy soil.
iv.) Laterite Soil-This soil is predominant in the areas like North Cachar Hill districts, some southern parts of Karbi Plateau, foothills of Barail range. The laterite soil contains less amount of nitrogen, potash, phosphoric acid and lime.
18.) What are the reasons behind soil erosion in Assam?
The problems of soil erosion is a very serious issue in the state of Assam. The physical factors which cause soil erosion are hilly slopes due to the natural causes, water logging problems created on the plains and low-lying areas. Apart from these reasons the human factors like deforestation leading to increased surface water flow, cultivation of land on hill slopes in unscientific manner, jhum cultivation, water logging due to human settlements and other activities and excessive use of chemical fertilizers in the soil in order to increase crop production.
19.) What are the different types of forest in Assam?
Assam is a one of the botanically rich states of India. The natural environment varies from one place to another. The presence of riverine plains, hills and plateau of different altitudes, wetlands etc various types of forests are seen in the state. The forests can be divided into five types:
a.) Tropical Evergreen forests-This type of forest is found in the areas which have very heavy rainfall like 300 cm, these forests are called rain forest. These forests are found to occur in the foothills near to Arunachal Pradesh, Dibrugarh districts, some hilly areas of the Barak valley. These forests have very tall trees, in Assam Holong, Mekai, Nahar, Chiya Nahar, Amari etc. Climbers, bamboos, canes and orchids are found in the evergreen forests.
b.) Tropical Semi-Evergreen forest- This type of forest is found in the northern Bhabar zone of the Brahmaputra valley, parts of the hilly Karbi Anglong and Dima Hasao districts and the southern part of the Barak Valley. These forests have trees like Nahar, Bonchom, Cham, Sirish, Ou, agaru, Bamboos and canes, ferns etc in abundance.
c) Tropical Moist Deciduous forest- These forests are found in parts of lower Brahmaputra valley, Karbi Anglong and Dima Hasao districts and the Barak Valley. These areas have rainfall of 200-250 cm. Most of the trees shed their leaves during winter. Trees like Gomari, Amlokhi, Bhomora, Gohara Simul are found here.
d.) Riverine Forest – A large part of Assam is covered by riverine forests and these forests are dominated by tall trees and grasses. Trees like Chom, Showalu, Uriam, Moz, Ou Ajar is found. Grasses and bushy vegetations like Nal, Khagori, Tora, Koupat, cane, Jao Kohua etc are found. Kaziranga, Saikhoa, Orang National parks, Pabitora wildlife sanctuary are located mainly in the riverine tracts.
e.) Tropical Dry Deciduous forest- These types of forests are found in the dry floodplains away from the rivers. Two different groups of plant are found here – tall grasses and grasses. Trees like Sisoo, Bhelkor, Simul, Khair and Bogori are found. Birina, Khagori, Ulu, Khush etc are the grasses found here.
20.) What is rain forest? Describe the characteristics of rain forest in Assam.
Tropical Evergreen forests- This type of forest is found in the areas which have very heavy rainfall like 300 cm and are called rain forest. These forests are found to occur in the foothills near to Arunachal Pradesh, Dibrugarh districts, some hilly areas of the Barak valley. These forests have very tall trees, in Assam Holong, Mekai, Nahar, Chiya Nahar, Amari etc. Climbers, bamboos, canes and orchids are found in the evergreen forests. The main characteristics are that these evergreen forests occur in three layers. The first layer is composed of very tall trees like Holong, Mekai. The second layer is formed by some shorter trees like Nahar, ChiyaNahar, Amari etc. The third layer is composed of short trees and grasses.
21.) Write in brief about the importance and characteristics of riverine vegetation.
Riverine Forest – A large part of Assam is covered by riverine forests and these forests are dominated by tall trees and grasses. Trees like Chom, Showalu, Uriam, Moz, Ou Ajar is found. Grasses and bushy vegetations like Nal, Khagori, Tora, Koupat, cane, Jao Kohua etc are found in the riverine tracts. Kaziranga, Saikhoa, Orang National parks, Pabitora wildlife sanctuary are located mainly in the riverine tracts.
22.) State the location and land area of Kaziranga National Park.
In Assam, there are 5 national parks and 18 wildlife sanctuaries covering a total are of 3592.94 sq.km. Animals like deer, monkeys, buffaloes, wild elephants, tigers, rhinoceros etc are found in these national parks.Kaziranga National Park is located in Golaghat, Nagaon and Sonitpur district and covers an area of 858.98 sq.km.
23.) Write the names and location of the national parks of Assam.
National Parks of Assam are as follows: –
i.) Kaziranga National Park located in Golaghat, Nagaon and Sonitpur.
ii.) Manas National Park located in Chirang and Baksa
iii. Orang National Park located in Odalgiri and Sonitpur
iv. Nameri National Park located in Sonitpur iv.) Dibru -Saikhowa National Park located in Dibrugarh and Tinsukia.
24.) Write how the wildlife sanctuaries maintain the ecological balance.
The wildlife sanctuaries and national parks play a great role in conserving and maintaining the ecological balances.In Assam, there are 5 national parks and 18 wildlife sanctuaries covering a total are of 3592.94 sq.km. Animals like deer, monkeys, buffaloes, wild elephants, tigers, rhinoceros etc are found in these national parks. The presence of grasslands, trees, and wetlands attract large number of domestic and foreign tourists. The sanctuaries protect the animals from poachers by prohibiting the killing and capturing and providing the animals safe environment to live. The natural vegetation of the region also gets saved and nurtured in these national parks and sanctuaries and the balance is maintained.
25.) Write about the changes in administrative boundaries in Assam during the post- independence period.
The spatial extent of the Assam has witnessed many changes with time. Assam was a large state during the British rule. Meghalaya, Nagaland and Sylhet (now in Bangladesh) were part of Assam. During 1947 after the partition of the country, Sylhet was joined in east Pakistan(now Bangladesh) and 11 districts in Assam and Shillong became its capital. After some time three new states were formed. Meghalaya in 1970, Nagaland in 1963 and Mizoram in 1971 getting separated from Assam. Dispur became the capital of Assam. Since 1973 till date the geographical extent and spatial extent has been same.
26.) Write the names of the present districts of Assam and their headquarters.
The state of Assam is divided into 33 districts. The names are as follows: –
1.)Dhubri 2. Kokrajhar 3. Goalpara 4. Bongaigaon 5. Chirang 6. Barpeta 7. Nalbari8. Baksa9. Kamrup10. Kamrup Metro 11. Darrang 12. Udalgiri 13. Sonitpur 14. Lakhimpur 15. Dhemaji 16. Nagaon 17. Morigaon 18. Golaghat 19. Jorhat 20. Sivasagar 21. Tinsukia22.Dibrugarh23. Karbi Anglong 24. DimaHasao 25. Karimganj 26. Cachar 27. Hailakandi 28. Biswanath 29. Charideo 30. Hojai 31. Majuli 32. South Salmara Mankachar 33. West Karbi Anglong.
27.) What is the land area of Assam? Where is the state’s capital located? Write the names of the largest and smallest districts of Assam in respect of land area.
The land area of Assam is 78,438 sq.km. The capital city of Assam is Dispur (Guwahati) in Kamrup Metrodistrict. The smallest district is Kamrup Metro with total land areaof 955 sq.km. The largest district is Karbi Anglong with land area of 10,434 sq.km.
28.) What is the population of Assam according to 2011 Census? Write the names of the largest and smallest districts of Assam in terms of population size.
The population of Assam is around 31.16 million according to the 2011 Census. The largest district in terms of population is Nagaon with 28,23,768 and Dima-Hasao with 2,14,102 population is the smallest district.
29.) Write Short Notes:
(a) Assam and Monsoon Climate
(b) South-West Monsoon Wind
(c) North-East Monsoon Wind
(d) Summer Season of Assam
(e) Pre-Monsoon Season of Assam
(f) Spatial Distribution of Rainfall in Assam
(g) Administrative Divisions of Assam
(h) District Level Population of Assam
(i) BTAD
Answer:
a.) Assam and Monsoon Climate-The state of Assam falls under the sub-tropical monsoon climate and the state receives heavy rainfall in the summer season and dry winters. It is always excessive humid and low temperature. The climate of the state is influenced by the monsoon winds, the geographical variations also affect the climate diversely.
b.) South -West Monsoon Wind-Monsoon Season prevails during early June to end of September in Assam and it is rainy season in the state. During this period moderate to heavy rainfall takes place under the influence of south -west monsoon wind almost continuously in different places of the state. June, July and August are the months of maximum rainfall in Assam, about 200 cm rainfall takes place. During this period, the main crop Sali paddy is transplanted. Due to the occurrence of the heavy rainfall in most parts of the state including the surrounding hilly areas, the water level of the Brahmaputra and Barak and their tributaries rise and often create floods.
c.) North-East Monsoon Wind- The wind that is formed in the upper Brahmaputra valley in winter blows towards the Bay of Bengal is known as North-East Monsoon Wind or Retreating Monsoon. This prevails in thestate in Assam during October and November for two months. Fogs occur during this time at night and morning due to temperature decrease.
d.) Summer Season of Assam- The summer season in Assam witnesses heavy rainfall. This rainfall occurs mainly due to the orographic and cyclonic processes of the moist south-west monsoon wind and the temperature remains around 35°C.
e.) Pre-Monsoon Season of Assam-The pre-monsoon season in Assam prevails during early March to the end of the May. This season starts immediately after winter, and the atmospheric pressure starts increasing slowly. The pre-monsoon mornings become pleasant, days are very hot and sudden rainfall takes place with thunder and lightning during evening or night. Slowly, amount of rainfall with lightning increases and becomes more regular which helps in the cultivation of paddy, tea and jute in the state.
f.) Spatial Distribution of Rainfall in Assam-The study of the pattern of rainfall in different places of Assam points that there is existence of marked spatial variation in rainfall across the state. The topographic condition, location and presence of the nearby hills make the rainfall uneven in the state. The rainfall exceeds 250 cm in the districts of Tinsukia, Dibrugarh, Dhemaji, Lakhimpur and Sivasagar in upper Assam, districts of Kokrajhar, Dhubri in lower Assam, Cachar, Karimganj and Hailakandi in lower assam. The amount of rainfall is very less in Nagaon, Karbi Anglong in Central Assam around 129 cm only.
g.) Administrative Divisions of Assam-The spatial extent of the Assam has witnessed many changes with time. Assam was a large state during the British rule. Meghalaya, Nagaland and Sylhet (now in Bangladesh) were part of Assam. During 1947 after the partition of the country, Sylhet was joined in east Pakistan (now Bangladesh) and 11 districts in Assam and Shillong became its capital. After some time three new states were formed. Meghalaya in 1970, Nagaland in 1963 and Mizoram in 1971 getting separated from Assam. Dispur became the capital of Assam. Since 1973 till date the geographical extent and spatial extent has been same.
h.) District Level Population of Assam-The state of Assam is divided into 33 districts with different number of populations. The most populated district is Nagaon with 28,23,768 and Dima-Hasao with 2,14,102 population is the smallest district.
i.) BTAD- The BTAD is the short form of Bodoland Territorial Area Districts. The four districts Kokrajhar, Chirang Baksa and Udalgiri fall under the BTAD. The BTAD was formed in 2003 for fulfilment of aspirations of hopes and requirements of the Bodo Tribal Groups.
Also See: Atmosphere: Structure, Air Pressure and Wind System Class 9 Solution