Class 9 Social Science Geography Chapter 4 Geography of Assam

Class 9 Social Science Geography Chapter 4 Geography of Assam The answer to each chapter is provided in the list so that you can easily browse throughout different chapters Assam Board Class 9 Social Science Geography Chapter 4 Geography of Assam and select needs one.

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Class 9 Social Science Geography Chapter 4 Geography of Assam

Also, you can read the SCERT book online in these sections Solutions by Expert Teachers as per SCERT (CBSE) Book guidelines. These solutions are part of SCERT All Subject Solutions. Here we have given Assam Board SEBA Class 9 Social Science Geography Chapter 4 Geography of Assam Solutions for All Subject, You can practice these here…

Geography of Assam

Chapter: 4



Q.1: What are the physiographic divisions of Assam  ?

Ans: The four main physiographic divisions of Assam are :

(i) The Brahmaputra Valley

(ii) The Barak Valley

(iii) The Karbi Plateau

(iv) The Barail and Southern hills.

Q.2: What are the physiographic regions of the Brahmaputra Valley ?

Ans: The Brahmaputra Valley extends over 72 % of the total area of Assam . It is 720 km long and 80 km wide. It is surrounded by the Eastern Himalayas on its north,the Naga hills in the east and Karbi and Meghalaya plateaus in the south. In the West,it is open and merges with the plains of west Bengal and Bangladesh. The valley is drained by the 64 km long Brahmaputra river and its tributaries. The valley slopes from north-east to the south-west with an average gradient of 13 cm per km. The main physiographic units of the Brahmaputra valley are :

(i) Northern foothills : The northern foothills is confined to the sub-Himalayan ranges and are composed of tertiary sandstones. The average height of the foothills is 150 m to 600 m. On the western side it is broad,where as on the eastern side it is narrower in Sonitpur,Lakhimpur and Dhemaji districts. The foothills slope southward and consist of a series of cone – like alluvial land features,composed of a mixture of sand and  stones. The area has water flow in the stream beds flowing down to the plains. It has damp soils suitable for tall grasses like reeds,etc.and provide a suitable ecological condition for reserved forests and wildlife sanctuaries.

(ii) North and South bank plains: Refer to answer of question no. 4 [Textual question and answer]

(iii) Floodplain and charlands : Refer to answer of question no.5 [Textual question and answer]

(iv) Southern foothills : The southern foothills of the Brahmaputra Valley include :

(a) Foothills of Meghalaya plateau: Lies along the low ranges of the Garo,Khasi and Jaintia hills.

(b) Foothills of Karbi Plateau : Lies along the lower ranges of the northern,eastern and western boundary of the Karbi Plateau.

(c) Foothills of Barail Range: Lies along the northern part boundary of the North Cachar Hill district.

(d) Foothills of Patkai-Naga Hills : Lies along the borders.

Q.3: Write four names each of the north-bank and south-bank tributaries of the Brahmaputra river.

Ans: (i) North-bank tributaries :

Subansiri,Ranganadi,Buroi and Borgong.

(ii) South-bank tributaries : Burhi Dihing,Dikhow and Jhanzi.

Q.4: Give a brief description of the Brahmaputra plain region.

Ans: The Brahmaputra plain region was formed due to the deposition of alluvial sediments carried by the Brahmaputra and its tributaries from the northern and southern hills and highlands. The region is composed of alluvial soil which are suitable for agriculture. The region is highly populated  and has a well-developed transport system. The Brahmaputra plain region is divided into two parts,viz.

(i) North bank plain:

(a) Extends from the northern foothills to the Brahmaputra river in the south.

(b) Major tributaries of the Brahmaputra flowing here are Subansiri,Ranganadi,Buroi, Borgong,Jia Bharali,Gabharu,Belsiri,Dhansiri, Noa Nodi,Nanoi,Barnadi,Puthimari,Pagladia,Manas-Aie-Beki, Champamati,Gaurang,Tipkai and Godadhar,

(c) Average width is 30 km in the lower part and 10 km its upper part.

(ii) South bank plain: 

(a) Extends from the southern foothills to the Brahmaputra river in the north.

(b) Major tributaries of the Brahmaputra flowing here are Burhi Dihing,Disang,Dikhow,Jhanzi, Bhogdoi,Dhansiri,Kopili,Kulsi, Krishnai and Jinari.

(c) Has a narrow width of 5 km in Kamrup, Goalpara and Dhubri due to the extension of Meghalaya Plateau. However, intermittently becomes wider and narrower as it extends to Dibrugarh because of presence of river valleys and plateaus respectively.

Q.5: Give a brief description of the floodplain region of the Brahmaputra.

Ans: The flood plain region of the Brahmaputra is characterised by the following features :

(i) Location : Lies between the north bank and south bank plains.

(ii) Composed of : Charlands developed on the bed of the Brahmaputra.

(iii) Characterised by : Bank erosion and frequent floods.

(iv) Uneven at all places. The width of the flood plain reduces due to the presence of hillocks and formation of levees on the banks of the river Brahmaputra.

(v) The North bank floodplain consists of wetlands and swamps especially in Dhemaji and Barpeta.

(vi) The south bank floodplain is wide in the confluence areas of Burhi Dihing,Disang,Dhansiri, Kolang-Kopili and Kulshi rivers,but is comparatively narrower than the north bank floodplain.

(vii) There are over 600 sandbars of various sizes on the bed of the Brahmaputra. They can be permanent,semi-permanent or temporary.

Q.6: Write about the geographic location and origin of Majuli.

Ans: Majuli is one the biggest river islands of the world. The island extends over a land area of 422 sq. Km.(approximately) and has a population of 1.68 lakh(2011 census). It is formed within the Brahmaputra river under Jorhat district of Assam .

Majuli is shaped by the continuous erosional, transportation and depositional work of the Brahmaputra. Bank erosion and floods have affected the people adversely and also reduced the land area of the island . Majuli is a permanent sandbar accumulated over a long period of time.

Q.7: Write briefly about the boundaries and characteristics of the Barak valley.

Ans: Barak valley is one of the major physiographic regions situated at the southern end of Assam.

Boundaries: On the north,it is surrounded by the Meghalaya Plateau and the Barail ranges of the North Cachar hills,on the east lie the Manipur hills,on the south lie the Mizo hills and on the west lies the Kushiyara-Surma plain of the Sylhet district of Bangladesh.Characteristics:

(i) Extension : Barak valley consists of the Barak plain and its adjacent northern and southern foothills.

(ii)Formation: Barak plain is also known as Cachar plain. It has been formed due to the deposition of alluvial sediments carried by the river Barak and its tributaries from the hills in the north and the south.

(iii) Barak river : Barak river flows over a distance of 225 km from east to west through Cachar district towards the northern boundary districts of Hailakandi and Karimganj. Its major tributaries are :

(a) North bank tributaries: Chiri,Diksa,Digli,Jiri,Madhura, Jutinga,Larang,etc.

(b) South bank tributaries: Sonai,Dhakeshwari-Katakhal, Singla,Langai,etc.

Q.8: Write briefly about the boundaries and characteristics of the Karbi plateau.

Ans: The northern part of the hill tracts of Assam is known as the Karbi plateau.The boundaries and characteristics of the Karbi plateau are :

(i) Karbi plateau is considered to be a part of Meghalaya plateau on the basis of its origin and geological formation.

(ii) Two divisions : Kopili valley divides the Karbi plateau into two parts,viz.

(a) Eastern part : The eastern part extends over the Diphu and Bokajan sub-divisions of Karbi Anglong district and is covered by the Rengma hills. Its size is double than that of the western part.

(b) Western part : The western part spans over the Hamren sub-division of the district. It has an average height of 900 m and slopes from south-west to north-east. The physiography of this part has developed due to the works of the river Kopili and Barapani and their tributaries.

Q.9: Write briefly about the characteristics of the Barail range and southern hills.

Ans: The characteristics of the Barail range and southern hills are : 

(i) Extension : The Barail range spans westward from Thensang stretching over the North Cachar Hills district of Assam .

(ii) Connection: The Barail range links the Naga hills in the east and the Meghalaya plateau in the West.

(iii) Two divisions : The Barail range divisions the North Cachar Hills into two parts,viz.

(a) North-sloping part : The north-sloping part comes under the Brahmaputra valley and is  comparatively lower than the south-sloping part.

(b) South-sloping part: The south-sloping part comes under the Barak  valley.

Q.10: What is the type of Assam’s climate ? Write briefly about its characteristics.

Ans: Assam has a sub-tropical monsoon climate.

(i) Heavy rainfall in summer.

(ii) Dry condition in winter.

(iii) Extreme humidity and relatively low temperature throughout the year.

Q.11: What is the main reason behind the occurrence of rainfall in Assam during summer season ?

Ans: The main reason behind the occurrence of rainfall in Assam during summer season  is the orographic and cyclonic processes of the moist south-west monsoon wind.

Q.12: Discuss briefly about the geographical factors influencing the climate of Assam .

Ans: The geographical factors influencing the climate of Assam are :

(i) Variations in geographic location.

(ii) Topography.

(iii) Water surface area of Arabian sea, Bay of Bengal and Indian Ocean.

(iv) South-west monsoon wind.

(v) Variations in changing air pressure of north-west India due to change in seasons.

(vi) Impact of local winds like mountain wind,valley wind and rivers including wetlands.

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.

Ans: The main seasons of Assam along with the variation in temperature and rainfall are :

(i) Pre- monsoon season : The pre-monsoon season starts in early March and ends by the month of May. The season is characterised by pleasant mornings,scorching mid-day,tiring afternoons,sudden rainfall with lightning and thunder. In this season, atmospheric condition remains unstable and dust stroms occur. Spring season is experienced during this season.

Temperature : Atmospheric temperature increase slowly as this season occurs immediately after winter.

Rainfall : High and frequent rainfall occurs that helps in the cultivation of paddy,tea and  jute in Assam .

(ii) Monsoon season : The monsoon season starts in early June and ends in September. In this season,Sali paddy is transplanted.Temperature :  Temperature remains calm but humid.Rainfall: Moderate to heavy rainfall occurs during June,July and August due to the influence of south-west monsoon. The average total annual rainfall is 200 cm which is 70 % of the total rainfall that occurs in Assam throughout the year. Due to heavy rainfall,flood often occurs in the rivers Brahmaputra and Barak and their tributaries.

(iii) Retreating monsoon season : Retreating monsoon season prevails during October and November.

Temperature : Temperature decreases which leads to formation of fog at night and in the morning and the air pressure increases. The high air pressure deflects the south-west monsoon wind and starts blowing from north-east to south-west. This wind is called north-east monsoon or retreating monsoon.Rainfall: Rainfall decrease in this season.

(iv) Dry winter season : Dry winter season starts in the end of November or beginning of December and ends in February.In this season,Sali paddy is harvested.

Temperature: Low temperature prevails,i.e. below 10℃ which leads to thick clouds in the morning and makes the weather cold.

Rainfall : Lack of rainfall leads to dry condition in the season.

Q.14 : Write the names of places in Assam witnessing the highest and lowest rainfall along with the amount of rainfall.

Ans: The place in Assam that witnesses the highest and lowest  annual rainfall are :

Q.15: Why is the amount of rainfall not uniform in all places of Assam ?

Ans: The amount of rainfall is not uniform in all places of Assam due to : 

(i) Topographic condition.

(ii) Location .

(iii) Presence of hills in the neighbouring areas.

See Next Page No Below…

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