Get summaries, questions, answers, solutions, extra MCQs, PDF for Geography of Assam: SEBA Class 9 Geography, which is part of the syllabus for students studying under Assam Board. These solutions, however, should only be treated as references and can be modified/changed.
Summary
Assam is a state located in the north-eastern part of India. It shares its borders with seven other Indian states and two countries, Bhutan and Bangladesh. The state’s geographical position is between 24°09′ North and 27°58′ North latitude and from 89°42′ East to 96°01′ East longitude. Because of its location, Assam is often called the “gateway to the North-East.” A gateway is like a main door, which means Assam serves as the primary entry point to the other states in the region. This has also resulted in a diverse population, as people from different places have settled here throughout history.
The physical features of Assam can be broadly divided into four parts: the Brahmaputra Valley, the Barak Valley, the Karbi Plateau, and the Barail and Southern Hills. The Brahmaputra Valley is the largest and most important region, covering about 72 percent of the state. It is a long and narrow valley created by the Brahmaputra river and its many tributaries. The river deposits fertile alluvial soil, making the plains suitable for agriculture. The Barak Valley is another plain formed by the Barak river. The Karbi Plateau and the southern hills make up the state’s hilly areas. The famous Majuli island, one of the largest river islands in the world, is located in the Brahmaputra river and faces problems from soil erosion.
Assam has a sub-tropical monsoon climate, which brings heavy rainfall in the summer and dry conditions in the winter. The state experiences four distinct seasons: Pre-Monsoon, Monsoon, Retreating Monsoon, and Dry Winter. About 70 percent of the total annual rainfall occurs during the monsoon months from June to September. The average temperature in winter is around 7°C, while in summer it can reach 35°C.
The state has various types of soils, with the alluvial soil in the river valleys being particularly fertile for crops. Assam is also rich in forests, which are classified into five main types, including tropical evergreen and moist deciduous forests. These forests are home to a wide range of wildlife. To protect its animals and plants, Assam has established 5 national parks and 18 wildlife sanctuaries. These areas provide a safe home for animals such as the one-horned rhinoceros, tigers, and elephants. For administration, the state is divided into 33 districts.
Exercise
1. What are the physiographic divisions of Assam?
Answer: Physiographically, Assam can be divided into four divisions:
(a) Brahmaputra Valley
(b) Barak Valley
(c) Karbi Plateau
(d) Barail and Southern Hills.
2. What are the physiographic regions of the Brahmaputra Valley?
Answer: The entire Brahmaputra valley may be divided into four distinct physiographic units from north to south: the northern foothills, the north and south bank plains, the floodplain and charlands, and the Southern foothills.
3. Write four names each of the north-bank and south-bank tributaries of the Brahmaputra river.
Answer: Four north-bank tributaries of the Brahmaputra river are Subansiri, Jia Bharali, Pagladiya, and Manas.
Four south-bank tributaries of the Brahmaputra are Burhi Dihing, Disang, Dikhow, and Kopili.
4. Give a brief description of the Brahmaputra plain region.
Answer: The Brahmaputra plain includes both the north bank plain and the south bank plain. The north bank plain extends from the northern foothills to the Brahmaputra river in the south, while the south bank plain extends from the southern foothills to the Brahmaputra river in the north. The entire Brahmaputra plain zone has formed as a result of the deposition of alluvial sediments carried by the Brahmaputra and its large number of tributaries. The plains are composed of alluvial soils suitable for agriculture, and the region is thickly populated and developed in transportation.
5. Give a brief description of the floodplain region of the Brahmaputra.
Answer: The region situated between the north bank and south bank plains, where frequent floods are caused by the Brahmaputra river, is known as the floodplain of the Brahmaputra. This floodplain also includes the charlands developed on the river bed. The width of the floodplain is not the same everywhere. The floodplain on the north bank is characterised by a number of wetlands and swamps, while the south bank floodplain is comparatively narrow. All the branching channels within the Brahmaputra river, along with the chars (sandbars) and charlands, are known as the active floodplain.
6. Write about the geographic location and origin of Majuli.
Answer: Majuli river island is located within the Brahmaputra river. It is known as one of the biggest river islands in the world. The shape, size, and location of sandbars like Majuli change due to ongoing erosional, transportation, and depositional activities of the river, as well as the impact of floods.
7. Write briefly about the boundaries and characteristics of the Barak Valley.
Answer: The Barak Valley is an important physiographic region of Assam, consisting of the Barak plain and its adjacent northern and southern foothills. It is enclosed by hill ranges on its northern, southern, and eastern sides. The Meghalaya Plateau and the Barail ranges are on the north, the Manipur hills are on the east, and the Mizo hills are on the south. The plain is open on the west, merging with the Kushiyara-Surma plain of Bangladesh.
The Barak plain, also known as the Cachar plain, was created by the deposition of alluvial sediments carried by the river Barak and its tributaries. The river Barak flows for 225 km in Assam from east to west through the Cachar district and along the northern boundary of the Hailakandi and Karimganj districts.
8. Write briefly about the boundaries and characteristics of the Karbi Plateau.
Answer: Based on its origin and geological formation, the Karbi Plateau is a part of the Meghalaya Plateau. The Kopili valley divides the Karbi Plateau into two parts: the eastern part and the western part. The eastern part is covered by the Rengma hills and spans the Diphu and Bokajan sub-divisions of the Karbi Anglong district. The western part covers the Hamren sub-division of the district, has an average height of 900 m, and slopes from south-west to north-east. The physiography of this part has developed as a result of the works of the rivers Kopili and Barapani and their tributaries.
9. Write briefly the characteristics of the Barail Range and Southern Hills.
Answer: The part of the Barail range extending westward from Nagaland spans over the North Cachar Hills district of Assam. The Barail range connects the Naga hills in the east with the Meghalaya Plateau in the west. This range divides the North Cachar Hills region into two parts: a north-sloping part that falls within the Brahmaputra valley and a south-sloping part that falls within the Barak valley. The north-sloping part is relatively lower than the south-sloping part.
10. What is the type of Assam’s climate? Write briefly about its characteristics.
Answer: Geographically, Assam falls under the sub-tropical monsoon climate. Its characteristics include heavy rainfall in the summer, dry conditions in the winter, almost always excessive humidity, and a relatively low temperature.
11. What is the main reason behind occurrence of rainfall in Assam during summer season.
Answer: The summer rainfall of Assam occurs mainly due to the orographic and cyclonic processes of the moist south-west monsoon wind. The Himalayan mountain range and its branches obstruct the warm and moist monsoon wind blowing from the south-west. Additionally, clouds carried by this wind, after crossing the Meghalaya plateau and other southern hills, result in heavy rainfall, particularly in the north-eastern part of the Brahmaputra valley.
12. Discuss briefly about the geographical factors influencing the climate of Assam.
Answer: The climate of Assam is influenced by several geographical factors. These include variations in geographic location, topography, and the presence of the south-west monsoon wind. The Himalayan mountain range and its branches obstruct winds in both summer and winter. The impact of seasonal variations in air pressure of the north-west Indian landmass also affects the climate. Furthermore, the presence of local winds like mountain and valley winds, along with rivers and other wetlands, greatly influences the local climatic characteristics of 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.
Answer: The four main climatic seasons in Assam are Pre-Monsoon, Monsoon, Retreating Monsoon, and Dry Winter.
There is a remarkable temperature difference between winter and summer. On average, the temperature in winter is 7°C, and in summer, it becomes 35°C.
During the Pre-Monsoon season (March to May), the temperature starts increasing slowly, and there is sudden rainfall with lightning and thunder.
The Monsoon season (June to September) is the rainy season with moderate to heavy rainfall, with June, July, and August being the months of maximum rainfall. About 70 percent of the total annual rainfall occurs during these three months.
In the Retreating Monsoon season (October and November), there is a decrease in temperature and rainfall.
The Dry Winter season (November to February) is characterized by low temperature (below 10°C) and very dry conditions due to a lack of rainfall.
14. Write the names of place in Assam witnessing the highest and lowest rainfall along with their amount of rainfall.
Answer: According to the data provided, the place witnessing the highest rainfall is North Lakhimpur, with an average annual rainfall of 335 cm. The place with the lowest rainfall is Lumding, with an average annual rainfall of 129 cm.
15. Why does the amount of rainfall not uniform in all places of Assam?
Answer: The amount of rainfall is not uniform in all places of Assam because the distribution of rainfall is quite uneven. This is due to the overall impact of the state’s topographic condition, location, and the presence of neighbouring hills. For instance, the amount of rainfall significantly decreases on the leeward side of the hills, such as in areas east of Karbi Anglong and north and east of Dima Hasao.
16. Write in brief about the spatial distribution of rainfall in Assam.
Answer: The distribution of rainfall in Assam is quite uneven. Generally, rainfall is higher in the hills and foothill areas. Annual rainfall exceeds 250 cm in the districts of Tinsukia, Dibrugarh, Dhemaji, Lakhimpur, and Sivasagar in upper Assam; Kokrajhar and Dhubri districts in lower Assam; and Cachar, Karimganj, and Hailakandi districts in southern Assam. In contrast, the amount of rainfall is quite low in the Nagaon and Karbi Anglong districts of central Assam, with the Lanka-Lumding region receiving only about 129 cm annually.
17. Give a short account of different types of soil found in Assam.
Answer: The soils of Assam can be classified into four types:
- Alluvial soil: These soils are extensively found in the plains of the Brahmaputra and Barak Valleys and are generally fertile. They are of two types: new alluvial soils found in active floodplains and old alluvial soils found in other parts of the plains.
- Piedmont soil: These are confined to the northern narrow zone along the Himalayan foothills, in the Bhabar and Tarai belts.
- Hill soil: These are generally found in the southern hill areas of Assam and are divided into two types: red sandy soils and red loamy soils.
- Laterite soils: These soils are found in almost the entire North Cachar Hills district and in some southern parts of the Karbi Plateau.
18. What are the reasons behind soil erosion in Assam?
Answer: The reasons behind soil degradation, including erosion, in Assam are due to both physical and human factors. The physical factors include soil erosion on hill slopes due to natural causes.
The major human factors are:
(a) surface soil erosion caused by increased surface water flow due to tree felling,
(b) cultivation of land on hill slopes in an unscientific manner,
(c) jhum cultivation (shifting cultivation) done in the hill areas.
19. What are the different types of forest in Assam?
Answer: The forests of Assam may be divided into five main types:
(A) Tropical evergreen forest
(B) Tropical semi-evergreen forest
(C) Tropical moist deciduous forest
(D) Riverine forest
(E) Tropical dry deciduous forest.
20. What is rain forest? Describe the characteristics of rain forest in Assam.
Answer: A rain forest is a type of forest seen in areas of high rainfall. Such forests are called rain forests as they occur in areas having a yearly rainfall of 300 cm or more.
In Assam, these forests, also known as Tropical Evergreen Forests, generally occur with three layers. The first layer is composed of very tall trees like Holong and Mekai. The second layer is formed by shorter trees like Nahar, Chiya Nahar, and Amari. The third layer is composed of short trees and grasses. Besides trees, a variety of climbers, bamboos, canes, and orchids are also found in these forests.
21. Write in brief about the importance and characteristics of riverine vegetation.
Answer: Riverine forest is a special type of forest generally seen in the wet peripheries of rivers and wetlands. This type of forest is dominated by some tall trees and grasses. Important trees include Chom, Showalu, Uriam, Moz, Ou, and Ajar. The riverine tracts are also very favourable for grasses and bushy vegetations like Nal, Khagori, Tora, Koupat, cane, Jao, and Kohua.
The importance of this vegetation is highlighted by the fact that Kaziranga, Dibru-Saikhoa, and Orang national parks, as well as Pabitora wildlife sanctuary, are located mainly in the riverine tracts.
22. State the location and land area of Kaziranga National Park.
Answer: Kaziranga National Park is located in the districts of Golaghat, Nagaon, and Sonitpur. Its land area is 858.98 sq. km.
23. Write the names and location of the national parks of Assam.
Answer: The names and locations of the national parks of Assam are:
- Kaziranga National Park: Golaghat, Nagaon and Sonitpur
- Manas National Park: Chirang and Baksa
- Orang National Park: Odalguri and Sonitpur
- Nameri National Park: Sonitpur
- Dibru-Saikhowa National Park: Dibrugarh and Tinsukia
24. Write how the wildlife sanctuaries maintain the ecological balance.
Answer: Wildlife sanctuaries play a far-reaching role in nature conservation. They are protected from the destructive impact of human beings. By providing a home to wild elephants, tigers, rhinoceroses, buffalos, and a variety of other wild animals, and by preserving grasslands, trees, and wetlands, these protected areas help maintain the biodiversity of the state. The ability to protect these areas is directly linked to the future of biodiversity, which is a key component of ecological balance.
25. Write about the changes in administrative boundaries in Assam during the post-independence period.
Answer: Geographically, the spatial extent of Assam has witnessed marked change with time. Assam was quite large during the British rule, and during that period, besides Meghalaya and Nagaland, Sylhet (now in Bangladesh) was a part of Assam.
In 1947, following India’s partition, the Sylhet part was separated from Assam and joined East Pakistan (presently Bangladesh). Accordingly, there were 11 districts in Assam, and Shillong was its capital. In the latter period, three states, Nagaland in 1963, Meghalaya in 1970, and Mizoram in 1971, were separated from Assam. The capital city of Assam was established in Dispur (Guwahati) in 1973. Since 1971, the area of Assam, including its geographical boundary and spatial extent, has remained the same up to 2014.
In view of certain administrative advantages and constraints and fulfilling the hopes and aspirations of different ethnic groups, some new districts have been constituted within the same spatial limit of the state. At present, there are altogether 33 districts in Assam. Out of these, 6 are new districts formed during 2015-16. Among the 33 districts, four districts, viz. Kokrajhar, Chirang, Baksa, and Udalguri, fall under the BTAD (Bodoland Territorial Area Districts), which was formed in 2003 to fulfill the hopes and aspirations of especially Bodo tribal groups.
26. Write the names of the present districts of Assam and their headquarters.
Answer: The names of the present districts of Assam and their headquarters are:
| Name of District | District Headquarters |
| 1. Dhubri | Dhubru |
| 2. Kokrajhar | Kokrajhar |
| 3. Goalpara | Goalpara |
| 4. Bongaigaon | Bongaigaon |
| 5. Chirang | Kajalgaon |
| 6. Barpeta | Barpeta |
| 7. Nalbari | Nalbari |
| 8. Baksa | Masalpur |
| 9. Kamrup | Amingaon |
| 10. Kamrup Metro | Guwahati |
| 11. Darrang | Mangaldoi |
| 12. Udalguri | Udalguri |
| 13. Sonitpur | Tezpur |
| 14. Lakhimpur | North Lakhimpur |
| 15. Dhemaji | Dhemaji |
| 16. Nagaon | Nagaon |
| 17. Morigaon | Morigaon |
| 18. Golaghat | Golaghat |
| 19. Jorhat | Jorhat |
| 20. Sivasagar | Sivasagar |
| 21. Dibrugarh | Dibrugarh |
| 22. Tinsukia | Tinsukia |
| 23. Karbi Anglong | Diphu |
| 24. Dima-Hasao | Haflong |
| 25. Karimganj | Karimganj |
| 26. Cachar | Silchar |
| 27. Hailakandi | Hailakandi |
| 28. Biswanath | Biswanath Chariali |
| 29. Charaideo | Sonari |
| 30. Hojai | Sankardev Nagar |
| 31. Majuli | Garamur |
| 32. South Salmara-Mankachar* | Hatsingimari |
| 33. West Karbi Anglong* | Hamren |
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.
Answer: At present, the state of Assam has a land area of 78,438 km².
The capital city of Assam was established in Dispur (Guwahati) in 1973.
In respect of land area, Karbi Anglong district is the largest (10,434 km²) and Kamrup Metropolitan district is the smallest (955 km²) prior to 2015.
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.
Answer: According to the 2011 Census, the population of Assam is 31.16 million.
In terms of population size, Nagaon district is the most populous with 2.82 million people, and Dima-Hasao district is the least populous with 2.14 lakh people, as per the 2011 census based on the 27 districts that existed prior to 2015.
29. Write Short Notes:
(a) Assam and Monsoon Climate
Answer: Geographically, Assam falls under the sub-tropical monsoon climate. The state witnesses heavy rainfall in the summer season and a dry condition in winter. The Himalayan mountain range and its branches obstruct the warm and moist monsoon wind blowing from the south-west in summer, resulting in heavy rainfall. The clouds carried by the south-west monsoon wind, after crossing the Meghalaya plateau and other southern hills, cause heavy rainfall, particularly in the north-eastern part of the Brahmaputra valley. Similarly, this wind also gives heavy rainfall in the Barak plains after being obstructed by the surrounding hills. During winter, a high-pressure system forms in the Brahmaputra valley, and the wind direction reverses, blowing from north-east to south-west. This is known as the North-East Monsoon or Retreating Monsoon.
(b) South-West Monsoon Wind
Answer: The south-west monsoon is a warm and moist wind that blows in summer. In Assam, it is obstructed by the Himalayan mountain range and its branches, as well as the hills surrounding the Barak valley, which causes heavy rainfall across the state. A branch of this wind enters the Brahmaputra valley from the west after crossing the Meghalaya plateau, bringing a considerable amount of rainfall to the lower Brahmaputra region. The summer rainfall in Assam is mainly due to the orographic and cyclonic processes of the moist south-west monsoon wind. This wind starts withdrawing from the end of September.
(c) North-East Monsoon Wind
Answer: The North-East Monsoon, also known as the Retreating Monsoon, is the wind that forms in the upper Brahmaputra valley during winter. Due to a marked fall in temperature, a high-pressure system develops in the valley, while a low-pressure condition prevails in the Bay of Bengal. This change in pressure conditions causes the wind direction to become the opposite of the summer south-west monsoon. The dry north-east monsoon wind sometimes absorbs moisture from the Brahmaputra river and its tributaries, giving some amount of rainfall in the south-western part of Assam during winter.
(d) Summer Season of Assam
Answer: The summer season in Assam is characterized by heavy rainfall and the formation of a local low-pressure system in the plains. The average temperature in summer becomes 35°C. The monsoon season, which is the rainy season in Assam, prevails from early June to the end of September. During this period, moderate to heavy rainfall occurs continuously under the influence of the south-west monsoon wind. The months of June, July, and August experience the maximum rainfall.
(e) Pre-Monsoon Season of Assam
Answer: The pre-monsoon season in Assam prevails from early March to the end of May. As this season starts immediately after winter, the atmospheric temperature begins to increase slowly. During this period, the morning is pleasant, the mid-day is scorching, the afternoon is tiring, and there can be sudden rainfall with lightning and thunder in the evening or night. Unstable atmospheric conditions prevail, sometimes causing dust storms. The rainfall before the monsoon helps in the cultivation of paddy, tea, and jute. During this season, the spring festival of Bohag Bihu or Rongali Bihu is celebrated in the middle of April.
(f) Spatial Distribution of Rainfall in Assam
Answer: There is a marked spatial variation in rainfall across Assam due to the state’s topography, location, and the presence of neighbouring hills. Generally, rainfall is higher in the hills and foothill areas. Annual rainfall exceeds 250 cm in the districts of Tinsukia, Dibrugarh, Dhemaji, Lakhimpur, and Sivasagar in upper Assam; Kokrajhar and Dhubri districts in lower Assam; and Cachar, Karimganj, and Hailakandi districts in southern Assam. The amount of rainfall is quite low in Nagaon and Karbi Anglong districts of central Assam. Specifically, the Lanka-Lumding region of the Nagaon district receives an annual rainfall of only 129 cm. Rainfall also decreases on the leeward side of the hills, particularly east of Karbi Anglong and north and east of Dima Hasao.
(g) Administrative Divisions of Assam
Answer: The spatial extent of Assam has changed over time. In 1947, after India’s partition, the Sylhet region was separated from Assam. At that time, there were 11 districts, and Shillong was the capital. Later, three states were separated from Assam: Nagaland in 1963, Meghalaya in 1970, and Mizoram in 1971. The capital city was established in Dispur (Guwahati) in 1973. To meet the aspirations of different ethnic groups, new districts have been constituted. At present, there are 33 districts in Assam. Among these, four districts—Kokrajhar, Chirang, Baksa, and Udalguri—fall under the BTAD (Bodoland Territorial Area Districts).
(h) District Level Population of Assam
Answer: Based on the 2011 census for the 27 districts that existed prior to 2015, the Nagaon district is the most populous, with a population of 2.82 million. The Dima-Hasao district is the least populous, with a population of 2.14 lakh. The population for each district is detailed in Table 4.3 of the chapter.
(i) BTAD
Answer: BTAD stands for Bodoland Territorial Area Districts. It was formed in 2003 to fulfill the hopes and aspirations of Bodo tribal groups. Four districts of Assam fall under the BTAD: Kokrajhar, Chirang, Baksa, and Udalguri.
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