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.

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…

Q.16: Write in brief about the spatial distribution of rainfall in Assam ?

Ans: The spatial distribution of rainfall in Assam is as follows:

(i) Heavy rainfall : In the hills and foothill areas.

(ii) Moderate rainfall : Annual rainfall above 250cm occurs in the districts of Tinsukia,Dibrugarh,Dhemaj,. Lakhimpur and Sivsagar (Upper Assam ); Kokrajhar and Dhubri(lower Assam ); Cachar,Karimganj and Hailakandi(Southern Assam).

(iii) Low rainfall: In the districts of Nagaon and Karbi Anglong(Central Assam ).

Q.17: Give a short account of different types of soil found in Assam.

Ans: The different types of soil found in Assam are :

(i) Alluvial soil : Alluvial soils are found in the Brahmaputra plains and Barak Valley. These have formed due to deposition of sit and  clay transported by the rivers and their tributaries. These soils are fertile and are suitable for agriculture.

There are two types of alluvial soil:

(a) New alluvial soil: Found in active floodplains of the Brahmaputra and Barak rivers and their tributaries and in the river side plains.

Characteristics :

 ● Moderately deep

 ● Grey in colour

 ● Composed of sandy to silty loams.

 ● Slightly

 ● Sometimes neutral or slightly alkaline on river banks.

 ● Deficient in phosphoric acid,nitrogen and humus.

(b) Old alluvial soil : Found in the following regions :

(i) Between regions of the northern Piedmont zone of the Kokrajhar,Barpeta,Nalbari,Kamrup,Darrang,Sonitpur, Lakhimpur,Dhemaji districts and the new alluvial soil region of the south bank of the Brahmaputra.

(ii) In the south bank districts lying between the southern hill soil zone and the new alluvial soil zone along the Brahmaputra river.

(iii) In the plains of the Kopili river in Nowgang district.

(iv) In a narrow zone of the Barak plain between the active floodplain of Barak and the hill soils of the Assam-Mizoram border.

Characteristics :

● Layers are deep 

● Brown in colour

● Composed of fine to coarse loams.

● More or less acidic.

(iii) Piedmont soils : Piedmont soils are found in the northern narrow zone along the Piedmont zone comprising Bhabar and Tarai belts of the Himalayan foothills.

(a) Bhabar belt : The Bhabar belt spans in east-west direction along the Assam-Arunachal Pradesh border and is composed of a series of alluvial cones. These are composed of unassorted materials of Boulders,pebbles,sands and silts. These soils have deep to very deep.

(b) Tarai belt : Tarai belt is found to the south of the Bhabar belt. These soils are saturated with water and support tall grasses.

(iii) Hill soils : Hill soils are confined to the southern hill areas of Assam . These soils contain nitrogen and organic materials in abundant quantity. On the basis of physical structure and chemical properties. These soils are of two types :

(a) Red sandy soils : Found in the Assam-Meghalaya border region,Karbi Plateau,southern part of the Barail range in the North Cachar Hills district,some parts of the foothills along the eastern boundary of the Cachar district. These soils are formed as a result of erosion of rocks and have deep layers. These soils are highly organic,moderately to strongly acidic in nature.

(b) Red loamy soils : Found to the narrow belt to the south of Assam-Arunachal border,Karbi Plateau,southern parts of the Barail range in the North Cachar Hills district and along the Assam-Mizoram border. These soils are deep and made of fine to coarse sand,silt and clay. These soils are slightly to moderately acidic in nature and contain nitrogen,phosphoric acid,humus and little amount of lime.

(iv) Laterite soils : Laterite soils are seen almost over the entire North Cachar Hills and south Karbi Plateau. They are also seen in the eastern border of the Hamren sub- division of Karbi Anglong district,southern border of Golaghat district and the Barail range foothills in the northern Barak plain. These soils are sandy-black and contain less  amount of nitrogen,potash,phosphoric acid and lime.

Q.18: What are the reasons behind soil erosion in Assam ?

Ans: The main reasons behind soil erosion in Assam are: 

[I] Physical factors :

(i) Natural factors : Soil erosion occurs in the hill slopes mainly due to natural causes like heavy rain leading to landslides.

(ii) Water logging : Water logging on the plains and low-lying areas causes soil erosion.

[II] Human factors :Soil degradation caused by human beings contributes greatly to soil erosion through :

(a) Surface soil erosion caused by increase surface waterflow due to cutting of trees.

(b)Land cultivation on hill slopes in an unscientific manner.

(c) Jhum (shifting) cultivation in the hill areas.

(d) Water logging caused by human settlements and other activities.

(e) Increased use of chemical production to enhance crop production.

Q.19: What are the different types of forests in Assam ?

Ans: The different types of forests in assam are :

(i) Tropical evergreen forest : Tropical evergreen forests or rainforest are found in the areas of yearly rainfall of 300cm or more. These forests are found in the foothills near Arunachal Pradesh,southern part of Tinsukia and Dibrugarh and hilly areas of the Barak valley. These forests are  found in three layers,viz.

(a) Tall trees : Includes Holong and Mekai.

(b) Shorter trees : Includes Nahar,ChiyaNahar,Amari,etc.

(c) Short trees and grasses This forest also includes climbers,bamboos,canes and orchids.

(ii) Tropical semi-evergreen forest : The tropical semi-evergreen forests are found in the northern Bhabar zone of Brahmaputra valley,parts of hilly Karbi Anglong,Dima Hasao district and southern Barak valley. These forests include Nahar,Bonchom,Cham,Sirish,Ou,Gandhsoroi,Agaru,Poma,bamboos,canes,ferms,etc. These forests has been reduced in size due to expansion of settlements and roads to the foothill zones.

(iii) Tropical moist deciduous forest : Deciduous forest comprises of trees that shed their leaves in the winter season. These forests are found in the areas having an annual rainfall  of 200-250cm such as in parts of lower Brahmaputra valley,Karbi Anglong,Dima Hasao districts and the Barak valley. The species found here include Sal,Makori Sal,Gomari, Amlokhi,Bhomaro,Gohara,    Khokun,Simul,etc.

(iv) Riverine forest : Forests found in the wet peripheries of the rivers and wetlands are called riverine forests. These forests include :

(a) Tall trees :  Chom,Showalu,Uriam,Moz,Ou, Ajar,etc.

(b) Grasses and bushes :Nal,Khagori,Tora,Koupat,cane, Jao,Kohua,etc.Dibru-Saikhowa and Orang national parks and Pabitora wildlife sanctuary are located in the riverine tracts. These forests have been rapidly reduced in size due to increase in human settlements in the riverine areas.

(v) Tropical dry deciduous forest : Tropical dry deciduous forests are found in dry floodplains and sandy areas close to the wet riverine forest areas. These forests include :

(a) Tall trees : Sisoo,Bhelkor,Simul,Khair,Bogori,etc.

(b) Grasses : Birina,Khagori,Ulu,Khush,etc.These forests are getting degraded due to expansion of settlements in the riverine tracts. Apart from the forests mentioned above,pine forests are found in the high hills of Karbi Anglong and Dima Hasao districts. Besides short bushy vegetations known as degraded forest are commonly seen in most of the districts of Assam.

Q.20: What is rain forest ? Describe the characteristics of rain forest in Assam .

Ans: Do Your Self.

Q.21: Write in brief about the importance and characteristics of riverine vegetation.

Ans: Do Your Self.

Q.22: State the location and land area of Kaziranga national park.

Ans: Kaziranga national park is located in the districts of Golaghat,Nagaon and Sonitpur having a land area of around 858.98 sq.km.

Q.23 : Write the names and location of the national parks of Assam .

Ans: The names and location of the national parks of Assam are :

Q.24: Write how the wildlife sanctuaries maintain the ecological balance.

Ans: The contribution of wildlife sanctuaries in maintaining ecological balance are :

(i) Provide homes to wild elephants,tigers, rhinoceros,buffaloes,deer, monkeys,etc.

(ii) Protect the animals from the destructive impact of human beings.

(iii) Attract tourists through variety of grasslands,trees and wetlands.

(iv) Conserve biodiversity through protecting these areas.

Q.25: Write about the changes in administrative boundaries in Assam during the post-independance period.

Ans: The changes in administrative boundaries in Assam during the post-independence period are :

(i) In 1947,Sylhet was separated from Assam and joined East Pakistan (present Bangladesh).

(ii) Three independence states,i.e Nagaland (1963), Meghalaya (1970) and Mizoram(1971) were separated from Assam .

(iii) In 1947,Shillong was the capital of Assam which was changed to Dispur (Guwahati) in 1973.

(iv) There were 11 districts in Assam at the time of independence which has now increased to 27 districts.

(v) Since 1971,there has been no significant change in the area of Assam including its geographical boundary and spatial extent.

Q.26: Write the names of the present districts of Assam and their headquarters.

Ans: The names of the present districts of Assam and their headquarters are :

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.

Ans: The land area of Assam is 78,438 sq km. Assam’s capital is located at Dispur(Guwahati).

In terms of land area, the largest district of Assam is Karbi Anglong with an area of 10,434 sq km and smallest is Kamrup Metro with an area of 627 sq km.

Q.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.

Ans: According to 2011 census,the population of Assam is 31.16 million. In terms of population size,the largest district of Assam is Nagaon with a total population of 2,826,006(2.8million) and smallest is the Dima-Hasao with a total population of 213,529(2.1 lakh).

Q.29: Write short notes :

(a) Assam and monsoon climate

Ans: Do Your Self.

(b) South-West monsoon wind

Ans: The south-west monsoon wind blows from the south-west in summer and come to Assam as moisture-laden winds. They are obstructed by the Himalayan mountain range and its branches that spread to the north and east of the Brahmaputra and Barak valleys and are forced to shed their moisture bringing heavy rainfall to the North-eastern part of the Brahmaputra valley and the Barak plains. The amount of rainfall caused by the south-west monsoons varies across the state.Besides the above mentioned,the Himalayan foothills also receive high rainfall,while the leeward side of the hills such as east of Karbi Anglong,North and east of Dima Hasao and southern part of Nagaon district.

(c) North-east monsoon wind.

Ans: During winter a high pressure system is formed over the Brahmaputra valley and a low pressure system is formed over the Bay of Bengal. Due to such change in the pressure condition between summer and winter,the direction of wind now is opposite to that of the south-west monsoon wind. The wind that blows from the upper Brahmaputra valley to the Bay of Bengal is known as north-east monsoon wind or retreating monsoon. This wind brings a little rain to south-west Assam due after absorbing some moisture from the Brahmaputra river.

(d) Summer season of Assam .

Ans: Do Your Self.

(e) Pre-monsoon season of Assam .

Ans: Do Your Self.

(f) Spatial distribution of rainfall in Assam .

Ans:Do Your Self.

(g) Administrative divisions of Assam .

Ans: Assam’s land area of 78,438 sq km is divided into 27 administrative districts. Before the separation of the states of Nagaland, Meghalaya and Mizoram,there were only 11 districts in Assam. However for better administration and to fulfil the hopes and aspirations of the different ethnic groups of Assam,new districts were created from time to time. The largest district in terms of area is the hill districts of Karbi Anglong with over 10,000 sq km,followed by Sonitpur district (just over 5000 sq km and Dima Hasao (almost 5000 sq km),districts in second and third places. There are 8 districts measuring between 3000-4000 sq km,and 1 district,i.e. Kamrup Metropolitan district (covering the capital Dispur and Guwahati)measuring 627 sq km.

(h) District level population of Assam.

Ans: As per 2011 census the population of Assam is 31.16 million. Due to the varied physiography,the population of Assam is not evenly distributed over the state. Obviously the plain areas with better agriculture, transport and other facilities are better developed and more densely populated. At the district level Nagaon is the most populous district with a population of 2.83 million,followed by Dhubri (1.95million) and Sonitpur (1.92million). Among the least populated districts are Dima Hasao (2.1 lakh),Hailakandi (6.6 lakh) and Dhemaji (6.9lakh). It may be noted that though Kamrup Metro is the smallest district with only 627 sq km area it has a population of 1.26 million.

(i) BTAD

Ans: BTAD stands  for Bodoland Territorial Area Districts. Four major districts,viz. Kokrajhar, Chirang, Baksa and Udalguri comes under the BTAD. It was formed in 2003 with the intention of fulfilling the hopes and expectations of Bodo tribal groups. The total land area of BTAD is 8821 sq km and it has a population of 3.5 million. Kokrajhar is the largest district in terms of area with 3165 sq km while Baksa has the most population with 9.5 lakhs.