Looking for complete, textbook-verified solutions for SEBA Class 9 Social Science Geography Chapter 4 (Geography of Assam / অসমৰ ভূগোল) for the 2026–27 academic session? Access step-by-step solutions to all official textbook exercises—including Very Short Answer (VSA), Short Answer (SA), and Long Answer (LA) questions. Master high-scoring answers covering Assam’s exact geographical position, international boundaries (Bhutan and Bangladesh), interstate frontiers, and total area (78,438 sq. km); the physical layout and morphological characteristics of its three main physiographic divisions—the Brahmaputra Valley, the Barak Valley, and the Southern Hill Region (Karbi Plateaus and Barail Range); drainage networks of the Brahmaputra River with its major north-bank and south-bank tributaries, braiding patterns, and char-chaporis; the Barak River and its tributaries; seasonal climate variations, monsoon influence, and rainfall patterns; major soil types (newer and older alluvium, red, and laterite soils); forest resources and protected wildlife areas (Kaziranga, Manas, Orang, Nameri, Dibru-Saikhowa, Raimona, Dehing Patkai); and textbook questions on annual floods and severe riverbank erosion problems along with remediation measures, structured strictly according to the Assam Board (SEBA) examination pattern.
Q.1. What are the physiographic divisions of Assam?
Answer: Physiographically, the state of Assam is divided into four main natural divisions:
- The Brahmaputra Valley
- The Barak Valley
- The Karbi Plateau
- The Barail Range and Southern Hills
Q.2. What are the physiographic regions of the Brahmaputra Valley?
Answer: The Brahmaputra Valley is divided into four main physiographic sub-regions:
- The Northern Foothills (Bhabar and Terai belts)
- The North and South Bank Plains
- The Floodplain and Charlands (active sandbars and riverbed islands)
- The Southern Foothills
Q.3. Write four names each of the north-bank and south-bank tributaries of the Brahmaputra River.
Answer: 1. North-Bank Tributaries: Subansiri, Ranganadi, Jia Bharali, and Manas.
2. South-Bank Tributaries: Burhi Dihing, Disang, Dikhow, and Dhansiri (or Kopili).
Q.4. Give a brief description of the Brahmaputra plain region.
Answer: The Brahmaputra plain has been built up by massive alluvial deposits brought down by the Brahmaputra and its numerous tributaries from surrounding hills. It consists of:
- North Bank Plain: Stretches from the northern Himalayan foothills to the Brahmaputra River. It is wider in the lower reaches (about 30 km) and narrower in the upper reaches (about 10 km).
- South Bank Plain: Stretches from the southern hills and plateaus to the river bank. It is exceptionally fertile, supports intensive agriculture, is densely populated, and features an extensive road and rail network.
Q.5. Give a brief description of the floodplain region of the Brahmaputra.
Answer: The floodplain region lies directly along both margins of the river channel and includes riverine sandbars and islands. Its key features are:
- It is composed of active silt deposits, sandbars, and temporary islands called chars or charlands.
- It suffers from severe annual flooding and intense riverbank erosion during the monsoon season.
- The width of the floodplain varies; it narrows where hard rocky hillocks touch the river bank (such as at Guwahati and Tezpur) and widens near river confluence zones.
SEBA Class 9 Geography Chapter 4 Solutions
Q.6. Write about the geographic location and origin of Majuli (misspelled as Sijuli).
Answer: 1. Location: Majuli is a world-famous river island located in the upper course of the Brahmaputra River in Assam (presently recognized as an administrative district). Ferries connect it to Jorhat.
2. Origin: It was formed due to major tectonic shifts and heavy catastrophic flooding in the Brahmaputra River, particularly following the great flood of 1750. The Brahmaputra breached into an older southern channel (Burhi Dihing), while its northern branch (Kherkutia Xuti) was fed by the Subansiri River, isolating this massive landmass into a river island.
Q.7. Write briefly about the boundaries and characteristics of the Barak Valley.
Answer: 1. Boundaries: The Barak Valley (or Cachar Plain) is bounded by the Meghalaya Plateau and North Cachar (Barail) hills on the north, the Manipur hills on the east, the Mizo (Lushai) hills on the south, and opens to the Surma plain of Bangladesh on the west.
2. Characteristics:
1. It is a horseshoe-shaped plain drained by the westward-flowing Barak River and its tributaries.
2. The valley has very gentle gradients with low-lying swampy wetlands locally called beels and haors.
3. It features isolated low residual hillocks called tillas, which are extensively used for tea plantations.
Q.8. Write briefly about the boundaries and characteristics of the Karbi Plateau.
Answer: 1. Boundaries: It is bounded by the Brahmaputra plain to the north, the Barak plain to the south, the Naga Hills to the east, and the Meghalaya Plateau to the west.
2. Characteristics:
1. Geologically, it is a dissected eastern fragment of the ancient Shillong (Meghalaya) Plateau.
2. The Kopili river valley divides it into two parts: the Eastern Karbi Plateau and the Western Karbi Plateau.
3. The plateau is characterized by undulating hilly terrain, steep escarpments, and radial drainage patterns.
Q.9. Write briefly the characteristics of the Barail Range and Southern Hills.
Answer: 1. The Barail Range is the highest mountain relief in Assam, connecting the Meghalaya Plateau in the west to the Naga Hills in the east.
2. It divides the Dima Hasao (North Cachar Hills) district into two slopes: a northern slope falling into the Brahmaputra drainage basin and a steeper southern slope falling into the Barak basin.
3. The southern hills feature rugged topography, steep sandstone ridges, and deep river gorges.
Q.10. What is the type of Assam’s climate? Write briefly about its characteristics.
Answer: Assam enjoys a Sub-Tropical Monsoon Rainforest Climate.
- Characteristics:
- Heavy rainfall occurs during the hot summer season.
- Winters are generally cool, clear, and dry.
- The atmosphere remains excessively humid almost throughout the year.
- Extremes of temperature are rare due to the dense forest canopy, river networks, and surrounding mountains.
Q.11. What is the main reason behind the occurrence of rainfall in Assam during summer season?
Answer: The main reason is the influx of the moisture-laden South-West Monsoon Winds blowing from the Bay of Bengal, which are trapped and forced upward by the surrounding mountain walls of the Himalayas and northeastern ranges, causing intense orographic and cyclonic rainfall.
Q.12. Discuss briefly the geographical factors influencing the climate of Assam.
Answer: 1. Geographical Location: Situated between the Tropic of Cancer and the sub-tropical belt, giving it warm temperate summers and mild winters.
2. Topography and Relief: Surrounded by towering mountain ranges on three sides (north, east, and south), forcing incoming monsoon winds to condense and precipitate.
3. Proximity to Water Bodies: The Bay of Bengal lies nearby, and the presence of huge river systems (Brahmaputra and Barak) and thousands of wetlands maintains high atmospheric moisture.
4. Local Winds: Mountain breezes, valley winds, and pre-monsoon squalls (Bordoisila) modify daily weather patterns.
Q.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: Assam experiences four distinct seasons:
- Pre-Monsoon (March–May): Temperatures rise steadily; frequent afternoon thunderstorms and showers occur, making it humid.
- Monsoon (June–September): Characterized by high temperatures (average 30°C–35°C), high humidity, and maximum rainfall (about 70% of total annual rain).
- Retreating Monsoon (October–November): Monsoon winds withdraw; rainfall declines sharply, skies clear up, and temperatures gradually decrease.
- Dry Winter (December–February): Coolest period of the year (temperatures fall to 7°C–10°C), with clear mornings, heavy night fogs, and very little rainfall.
Q.14. Write the names of places in Assam receiving the highest and lowest rainfall along with their amount of rainfall.
Answer: 1. Highest Rainfall Place: North Lakhimpur, receiving an annual average of about 335 cm.
2. Lowest Rainfall Place: Lumding (in the rain-shadow area of Central Assam), receiving an annual average of about 129 cm.
Q.15. Why does the amount of rainfall vary in all places of Assam?
Answer: Rainfall is not uniform because of:
- Varying Topography and Elevation: Foothill areas receive heavy relief rainfall when winds hit the mountains, whereas valley interiors receive less.
- Rain-Shadow Effect: Areas like Lumding and parts of Karbi Anglong lie on the leeward (rain-shadow) side of the Meghalaya and Barail hills, resulting in low precipitation.
- Distance from Monsoon Tracks: Regions closer to wind pathways receive earlier and heavier rainfall.
Geography of Assam Textual Questions SEBA 2026-27
Q.16. Write a brief about the spatial distribution of rainfall in Assam.
Answer: 1. Heavy Rainfall Zones (>250–300 cm): Foothill districts of Upper Assam (Lakhimpur, Dhemaji, Tinsukia), Lower Assam foothills (Kokrajhar), and the southern Barak Valley.
2. Moderate Rainfall Zones (200–250 cm): Central plains of the Brahmaputra Valley, including Kamrup, Darrang, and Sonitpur districts.
3. Low Rainfall Zones (<150 cm): Central Assam rain-shadow belt, notably parts of Nagaon and Karbi Anglong districts.
Q.17. Give a short account of different types of soil found in Assam.
Answer: Assam’s soils are grouped into four main categories:
- Alluvial Soil: Widely distributed in the Brahmaputra and Barak plains. Subdivided into New Alluvium (Khadar along active floodplains) and Old Alluvium (Bhangar on older high grounds); very fertile and suitable for rice and jute.
- Piedmont Soil: Confined to the narrow Bhabar and Terai belt along the Himalayan foothills; composed of unassorted sands, pebbles, and coarse silt.
- Hill Soil: Found on slopes of Karbi Anglong, Dima Hasao, and southern hills; acidic and rich in nitrogen, formed under heavy forest cover.
- Laterite Soil: Occurs in parts of Dima Hasao, the Karbi Hills, and southern Barak borders where heavy rainfall leaches silica and leaves iron and aluminum oxides.
Q.18. What are the sources behind soil erosion in Assam?
Answer: 1. Physical/Natural Sources: Steep terrain slopes, heavy monsoon downpours, and intense surface runoff; high erosive velocity of rivers causing riverbank slicing.
2. Human/Anthropogenic Sources:
1. Large-scale deforestation and felling of trees.
2. Shifting (Jhum) cultivation on unprotected hill slopes.
3. Unscientific farming and earth-cutting for roads and settlements.
4. Wetland filling and poor urban drainage causing severe gully erosion.
Q.19. What are the different types of forests in Assam?
Answer: The natural forests of Assam are classified into five major types:
- Tropical Evergreen Forest
- Tropical Semi-Evergreen Forest
- Tropical Moist Deciduous Forest
- Riverine Grassland and Swamp Forest
- Tropical Dry Deciduous Forest (and Hill Pine Forests at high altitudes)
Q.20. What is rain forest? Describe the characteristics of rain forests in Assam.
Answer: A rainforest is a dense, multi-layered forest that grows in warm regions with heavy annual rainfall (usually exceeding 250–300 cm).
- Characteristics of Assam’s Rainforests:
- Found in Upper Assam foothill districts (Tinsukia, Dibrugarh) and parts of the Barak Valley.
- Trees grow in distinct vertical tiers: the top layer comprises giant trees (over 30–45 m) like Hollong and Mekai; the middle layer consists of trees like Nahar and Amari; and the forest floor has thick shrubs, canes, and grasses.
- They remain green throughout the year and are heavily loaded with epiphytes, climbers, and wild orchids.
Q.21. Write in brief about the importance and characteristics of riverine vegetation.
Answer: 1. Characteristics: Found along active floodplains, sandbars (chars), and riverbanks. Dominated by tall wetland grasses (birina, khagori, nal, kohua) and moisture-loving trees (simul, sissoo, uriam, khair).
2. Importance:
1. It acts as a primary buffer that binds loose sandy soil and curtails riverbank erosion.
2. It provides critical habitat and feeding grounds for endangered megafauna like the one-horned rhinoceros, 3. wild water buffalo, and deer.
Q.22. State the location and land area of Kaziranga National Park.
Answer: 1. Location: Situated along the southern bank of the Brahmaputra River, spread across parts of
2. Golaghat, Nagaon, and Sonitpur districts.
3. Land Area: Its core area covers approximately 858.98 sq km (historically around 430 sq km prior to its peripheral additions).
Q.23. Write the names and locations of the national parks of Assam.
Answer: As per the standard textbook syllabus, the national parks and their district locations are:
- Kaziranga National Park: Golaghat, Nagaon, and Sonitpur districts.
- Manas National Park: Chirang and Baksa districts.
- Orang National Park: Udalguri and Sonitpur districts.
- Nameri National Park: Sonitpur district.
- Dibru-Saikhowa National Park: Dibrugarh and Tinsukia districts.
(Note: Newer protected parks include Raimona in Kokrajhar and Dihing Patkai in Dibrugarh/Tinsukia).
Q.24. Write how the wildlife sanctuaries maintain the ecological balance.
Answer: 1. Habitat Protection: They offer safe, undisturbed natural breeding grounds and sanctuaries for endangered wildlife (rhinos, tigers, elephants, birds).
2. Biodiversity Preservation: They protect floral diversity and genetic seed stock from human poaching, logging, and encroachment.
3. Environmental Stability: The dense tree cover within sanctuaries regulates local hydrology, cleans air, prevents soil erosion, and curbs flash flooding.
Q.25. Write about the changes in administrative boundaries in Assam during the post-independence period.
Answer: 1. Partition (1947): Sylhet district (except three and a half thanas of Karimganj) was detached from Assam and awarded to East Pakistan. Assam had 11 districts with its capital at Shillong.
2. Reorganization of States: Several separate tribal states were carved out of greater Assam:
Nagaland was carved out in 1963.
Meghalaya was formed as an autonomous state in 1970 and a full state in 1972.
Mizoram was carved out as a Union Territory in 1972 (gained statehood in 1987).
3. Shifting of Capital: The capital was relocated from Shillong to Dispur (Guwahati) in 1973.
4. Subdivision of Districts: Existing large districts were repeatedly reorganized into smaller districts (growing to 23, then 27, and later 33/35 districts) to decentralize administration and satisfy local ethnic demands.
Class 9 Social Science Geography Chapter 4 Question Answer Assam Board
Q.26. Write the names of the present districts of Assam and their headquarters.
Answer:
- Dhubri — Dhubri
- Kokrajhar — Kokrajhar
- Goalpara — Goalpara
- Bongaigaon — Bongaigaon
- Chirang — Kajalgaon
- Barpeta — Barpeta
- Baksa — Mushalpur
- Nalbari — Nalbari
- Kamrup — Amingaon
- Kamrup Metropolitan — Guwahati
- Darrang — Mangaldai
- Udalguri — Udalguri
- Sonitpur — Tezpur
- Lakhimpur — North Lakhimpur
- Dhemaji — Dhemaji
- Morigaon — Morigaon
- Nagaon — Nagaon
- Golaghat — Golaghat
- Jorhat — Jorhat
- Sivasagar — Sivasagar
- Dibrugarh — Dibrugarh
- Tinsukia — Tinsukia
- Karbi Anglong — Diphu
- Dima Hasao — Haflong
- Cachar — Silchar
- Karimganj — Karimganj
- Hailakandi — Hailakandi
Q.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:
- Total Land Area: 78,438 sq km.
- Capital City: Located at Dispur (Guwahati).
- Largest District by Area: Karbi Anglong (approx. 10,434 sq km).
- Smallest District by Area: Kamrup Metropolitan (approx. 627 sq km / 955 sq km depending on pre-bifurcation survey records).
Q.28. What is the population of Assam according to the 2011 Census? Write the names of the largest and smallest districts of Assam in terms of population size.
Answer:
- Total Population (2011 Census): 31,205,576 (approx. 3.12 crore).
- Largest District by Population: Nagaon (approx. 28.24 lakh people).
- Smallest District by Population: Dima Hasao (approx. 2.14 lakh people).
Assam Board Class 9 Geography Chapter 4 Solved Textbook Solutions PDF
Q.29. Write short notes on the following:
(a) Assam and Monsoon Climate:
Assam falls directly under a humid sub-tropical monsoon climate. The cycle of seasons, high summer precipitation, and overall agrarian life are guided by the monsoon winds. It provides the water required for paddy, jute, and tea, though it frequently triggers severe river floods during mid-summer.
(b) South-West Monsoon Wind:
Active from June to September, these moisture-laden winds blow across the Bay of Bengal into the funnel-like topography of Assam. Blocked by the Himalayas and southern hills, they cause widespread orographic rainfall, accounting for over 70% of the state’s total annual precipitation.
(c) North-East Monsoon Wind:
During winter (December to February), high pressure develops over continental Asia and Northern India, reversing wind direction from northeast to southwest. Blowing over land, these winds are dry and cold, resulting in pleasant, rain-free winter days with low morning temperatures and dense fog.
(d) Summer Season of Assam:
Lasting from June to August/September, the summer season is hot, humid, and wet. Average temperatures range between 30°C and 35°C. Continuous downpours cause rivers like the Brahmaputra and Barak to overflow their banks, leading to annual flood hazards.
(e) Pre-Monsoon Season of Assam:
Prevailing from March to May, this season marks a transition from winter to the rainy monsoon. It is characterized by increasing warmth, gusty evening squalls, thunderstorms, and hailstorms locally called Bordoisila. Pre-monsoon showers are vital for early sowing of summer rice and sprouting tea leaves.
(f) Spatial Distribution of Rainfall in Assam:
Rainfall distribution in Assam is uneven. The southern slopes of the Himalayas (Lakhimpur, Dhemaji) and the Barak border hills receive heavy downpours exceeding 250–300 cm. In contrast, the central part (Lumding and southern Nagaon) lies in the rain-shadow of the Barail and Karbi hills, receiving the lowest rainfall in the state (around 129 cm).
(g) Administrative Divisions of Assam:
To streamline regional governance, the districts of Assam are grouped into broader administrative divisions overseen by Divisional Commissioners (such as Lower Assam, Upper Assam, Central Assam, North Assam, and Hills & Barak Valley Divisions), coordinating administration, law enforcement, and development across districts.
(h) District Level Population of Assam:
According to the 2011 Census, Assam’s population distribution is highly uneven across districts. Nagaon, Dhubri, and Sonitpur are heavily populated plain districts, while the rugged hill district of Dima Hasao has the lowest population count. Kamrup Metropolitan has the highest population density due to Guwahati’s urban concentration.
(i) BTAD (referred to in prompt as ITAD):
BTAD stands for Bodoland Territorial Area Districts. It was created in 2003 under the amended Sixth Schedule of the Indian Constitution to fulfill the political, cultural, and developmental aspirations of the Bodo people. It originally comprised four contiguous districts: Kokrajhar, Chirang, Baksa, and Udalguri.
🌿 Class 9 Social Science Solutions Notice: This page features the complete SEBA Class 9 Social Science (Geography Section) Chapter 4: Geography of Assam Official Textual Questions and Answers updated for the 2026–27 academic session. Formatted according to the official Assam Board evaluation marking scheme, every core topic—from Assam’s geographical coordinates and administrative boundaries, structural differences between the Brahmaputra and Barak Valleys, the drainage network of major tributaries, to forest types, national parks, and flood/erosion issues—is presented with point-wise clarity, accurate geographical data, and structured subheadings to help you secure full marks in your school assessments, half-yearly, and final annual examinations.
💡 Master SEBA Class 9 Geography Textual Solutions:
- Having difficulty framing a comprehensive 5-mark answer explaining the geographical causes and remedial strategies for the annual flood hazards in the Brahmaputra Valley, detailing the physical divisions of the Karbi and Dima Hasao hill ranges, or listing the key north-bank and south-bank tributaries of the Brahmaputra River? Leave your query in the comments section below!
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