Chapter 3 - Physiography and Drainage
Q 1. Complete the sentences by choosing the right option :
(a) Brazil is covered mainly by ……………
(i) Highlands.
(ii) Plains.
(iii) Mountainous region.
(iv) Dissected hills.
Ans: Option (i) – Highlands
(b) Like Brazil, India too has …………..
(i) high mountains.
(ii) ancient plateau.
(iii) west-flowing rivers.
(iv) snow-capped mountains.
Ans: Option (ii) – ancient plateau
(c) The Amazon Basin is mainly …………
(i) characterized by droughts.
(ii) filled by swamps.
(iii) covered by dense forests.
(iv) fertile.
Ans: Option (iii) – covered by dense forests
(d) Amazon is a large river in the world. Near its mouth …………..
(i) deltaic regions are found.
(ii) no deltas are found.
(iii) deposition of sediments occurs.
(iv) fishing is done.
Ans: Option (ii) – no deltas are found
(e) The Lakshadweep Islands of Arabian Sea are …………….
(i) made from the part separated from the mainland.
(ii) coral islands.
(iii) volcanic islands.
(iv) continental islands.
Ans: Option (ii) – coral islands
(f) To the foot hills of the Aravalis ……….
(i) lies the Bundelkhand Plateau.
(ii) lies the Mewad Plateau.
(iii) lies the Malwa Plateau.
(iv) lies the Deccan Plateau.
Ans: Option (ii) – lies the Mewad Plateau
Q 2. Answer the following questions
(a) Differentiate between the physiography of Brazil and India.
Ans:
| Physiography of Brazil | Physiography of India |
|---|---|
(i) The physiographic divisions of Brazil are: The Highlands, The Great Escarpment, The Coastal region, The Plains and The Islands. | (i) The physiographic divisions of India are the Himalayas, the North Indian Plains and the Peninsula, Coastal Plains Island Groups. |
(ii) In Brazil there are no high and continuous mountain ranges. The easterside of the Highlands is demarcated because of the Escarpment. The Great Escarpment located in the south-eastern part of the Highlands has an altitude of 790 m in this region with the height gradually decreasing. | (ii) There are long and high mountain ranges in northern and north eastern part of India in the form of Himalayan ranges. The Western Ghats and Eastern Ghats lie to the west and east of the Peninsular region. The average altitude of Greater Himalayas is around 6000 m. |
(iii) In Brazil we have the Amazon Basin in the North and the Parana-Paraguay Basin to the South West which constitutes the Plain. Also a narrow coastal plain is confined to the North and the East. | (iii) In India the Plains occupy a wide area in the north. The Plains be between Himalayas in the North and the Peninsula in the South. It extends from Rajasthan in the West to Assam in the East. The Coastal Plains lie to the west and east of the Peninsula. |
(iv) In Brazil the Highlands occupy an extensive area in the South and is described as the Brazilian Highlands or the Brazilian Shield. Also to the North is the Guyana Highland. | (iv) The Peninsular Plateau region of India lies to the South of the North Indian Plains and is divided into 2 groups. The Central Highlands and the Deccan Plateau |
(v) The islands in Brazil are mainly depositional and some of them are corral in nature. | (v) The islands in India are either volcanic or coral in origin. |
(b) What measures are being taken to control pollution in the rivers of India?
Ans: Rivers in India are getting polluted due to the sewage and effluents being added to it and thus affecting its quality. Following measures are being taken to control pollution in the rivers in India:
(i) Treating the sewage before draining it into the rivers.
(ii) Reducing the use of pesticides and insecticides as they drain into the water sources and pollute it.
(iii) Discharge of industrial effluents into rivers without proper treatment is now controlled.
(iv) Reusing the water for different purposes which reduces the overuse and pollution of water.
(v) Carrying out the cleaning and purification of the river’s water under the National River Conservation Plan (NRCP).
(vi) Creating awareness in the people about the importance of rivers and harmful effects of pollution.
(vii) Setting up of Pollution Control Boards (PCB) at the state and national level to curb pollution.
(c) Explain the characteristics of the North Indian Plains.
Ans:
(i) This division lies between Himalayan Mountains in the north and the Peninsula in the south.
(ii) Similarly, it extends from Rajasthan and Punjab in the west to Assam in the east.
(iii) It is mostly a flat low lying area.
(iv) The North Indian Plains are divided into two parts. The part lying to the east of the Aravalis is the basin of the river Ganga and is therefore known as the Ganga Plains. It slopes eastward.
(v) Most of the West Bengal state of India and Bangladesh together constitute the delta of the Ganga-Brahmaputra system. It is known as Sunderbans. It is considered to be the world’s largest delta.
(vi) The western part of the North Indian Plains is occupied by desert. It is also known as Thar Desert or Marusthali. Most of Rajasthan is occupied by this desert.
(vii) To the north of the desert lie the plains of Punjab. This region is spread to the west of Aravalis and Delhi ranges. These plains have formed as a result of the depositional work by river Satluj and its tributaries. The slope of the plains is towards the west.
(viii) Because the soil here is very fertile, agriculture is largely practiced in this region.
(d) What could be the reasons behind the formation of swamps in the extensive continental location of Pantanal ?
Ans:
(i) Pantanal is one of the largest wetlands in the world, lying in the south west part of the highland areas.
(ii) It is a region of swamps and marshes in northwestern Mato Grosso do Sul in Brazil and it extends into Argentina too.
(iii) This region is drained by the river Paraguay and its tributaries.
(iv) They collect the water from the highland areas and deposit the sediments in the low lying Pantanal region.
(v) Pantanal is a gently sloped basin which is submerged throughout the year due to the filling of the sediments and water in the depression area of the Pantanal.
(e) Which are the major water divides of India? Explain by giving examples.
Ans: A mountain or an upland which separates two drainage basins is known as Water Divide. The major Water Divides of India are:
(i) Western Ghats: The Western Ghats acts as a water divide and separates the west flowing rivers like Zuari, Mandvi, Vaitarna draining into the Arabian Sea, from the east flowing rivers the Godavari, Krishna and Kaveri draining into the Bay of Bengal.
(ii) Vindhya ranges: It divides the drainage basin of the River Ganga and the River Narmada.
(iii) Aravali ranges: The Aravalis separates the west flowing river Luni from the east flowing River Banas.
(iv) Satpuda ranges: The Satpudas separate the Narmada drainage basin and the Tapi drainage basin.
Q 3. Write notes on
(a) Amazon River basin
Ans:
(i) Amazon collects its headwaters from the eastern slopes of the Andes Mountains in Peru.
(ii) Amazon River receives a huge discharge. This is about 2 lakh m/s.
(iii) As a result, Amazon washes off the load supplied to it from the catchment.
(iv) Consequently, sediments are not deposited even at the mouth.
(v) A dense network of distributaries, which is a characteristic feature of river mouth areas, is by and large absent in the mouth region of Amazon.
(vi) Instead, we find a series of islands developed along the mouth of Amazon, beyond the coastline into the Atlantic Ocean.
(vii) At the mouth, the width of the Amazon channel is 150 km.
(viii) Most of the course of the Amazon river is suitable for navigation.
(b) Himalayas
Ans:
(i) The Himalayas is one of the young fold mountains in the world.
(ii) The Himalayas extend from Pamir Knot in Tajikistan to the east. It is a major mountain system of the Asian continent.
(iii) In India, it extends from Jammu and Kashmir to Arunachal Pradesh.
(iv) The Himalayas is not a single mountain range. There are many parallel ranges in the system.
(v) The southernmost is known as Shiwaliks. It is also the youngest range.
(vi) Next to Shiwaliks are Lesser Himalayas, Greater Himalayas (Himadri) and Trans Himalayan ranges from south to north.
(vii) These ranges are young to old respectively.
(viii) These mountain ranges are also divided into Western Himalayas (or Kashmir Himalayas), Central Himalayas (or Kumaun Himalayas) and Eastern Himalayas (or Assam Himalayas).
(c) The coasts of Brazil
Ans:
(i) Brazil has a coastline of about 7400 km. They are divided into two parts namely northern and the eastern coast.
(ii) The northern coast extends from Amapa province in the north to Rio Grande De Norte in the east. This can be called the North Atlantic Coast. From there, the eastern coast extends towards the south.
(iii) The northern coast is characterized by mouths of many rivers including the Amazon. Therefore, this region is a low-lying region.
(iv) On this coast lie the Marajo island, Marajo and Sao Marcos Bays.
(v) Marajo, a large coastal island located between River Amazon and River Tocantins, lies on the northern coast.
(vi) The eastern coast receives large number of smaller rivers. The only major river which meets the Atlantic Ocean here is Sao Francisco.
(vii) The Brazilian Coast is characterized by a large number of beaches and sand dune complexes.
(viii) The Brazilian Coast is protected in some areas by coral reefs and atoll islands.
(d) The Indian peninsula
Ans:
(i) The area lying to the south of North Indian Plains and tapering towards the Indian Ocean is called Indian Peninsula.
(ii) It consists of many plateaus and hill ranges.
(iii) The Aravalis in the north are the oldest folded mountains here.
(iv) It includes a series of plateaus bordering the Plains, Vindhyas and Satpuda ranges in the central part and the hilly regions of Western and Eastern Ghats.
(e) The Great Escarpment
Ans:
(i) Though it occupies a very small area, the nature of its slope and the effect it has on the climate makes it a separate physiographic region.
(ii) The eastern side of the Highland is demarcated because of the escarpment.
(iii) In this region, the altitude of the escarpment is 790 m.
(iv) In some regions, the height decreases gradually.
(v) The escarpment is very steep particularly from Sao Paulo to Porto Alegre.
(vi) The escarpment acts as a barrier to the Southeast Trade winds giving rise to the rainshadow area in the northeast part of the highlands. The region to the north of this area is called ‘Drought Quadrilateral’.
Q 4. Write geographical reasons.
(a) There are no west-flowing rivers in Brazil.
Ans:
(i) Many rivers originating from the terminal portion of the Brazilian highlands flow northwards to meet the Amazon river and finally terminate in the Atlantic Ocean.
(ii) Also, the Sao Francisco River flows 1000 kms towards the north and then turns east to join the Atlantic Ocean.
(iii) The rivers Parana, Paraguay and Uruguay originating from the southern part of Brazilian highlands flow southwest and enter Argentina.
(iv) The Amazon river, originating from the Andes mountain in the west flows eastwards to meet the Atlantic Ocean.
(v) Thus, there are no west flowing rivers in Brazil.
(b) There are dissimilarities between the eastern and western coasts of India.
Ans:
(i) The western coast borders the Arabian Sea and the eastern coast borders the Bay of Bengal.
(ii) The western coast is by and large a rocky coast. At places, spurs taking off from the Western Ghats have extended right up to the coast. The eastern coast has formed as a result of depositional work of rivers.
(iii) The width of western coast is narrow, whereas that of the eastern coast is wide.
(iv) Short and swift rivers originating from Western Ghats form estuaries, whereas because of the gentle slope the east flowing rivers flowing at low speed deposit sediments and form deltas.
(v) Thus there are dissimilarities between the eastern and the western coasts of India.
(c) There are fewer natural ports on the eastern coast of India.
Ans:
(i) The Western coast is a coast of submergence whereas the eastern coasts are emergent or shallow, so the bigger ships cannot enter close to the land.
(ii) The Eastern rivers form the delta and so due to the deposition of the sediments by the river the ships find it difficult to reach the east coast.
(iii) The continental shelf on the east extends upto 500 km into the sea and water here is comparatively not very deep. As a result the ships can enter and leave only during tides.
(iv) As the eastern coastline is not indent, there are fewer natural ports on the eastern coast of India.
(d) As compared to the Amazon, pollution in river Ganga will affect human life greatly.
Ans:
(i) The Amazon Basin is a sparsely populated region of Brazil. Unfavourable climate, heavy rainfall, inaccessibility and dense forest are the barriers for development of human settlements and industrialisation here.
(ii) On the other hand, Ganga Plain region is one of the most densely populated regions of India.
(iii) Due to flat fertile plains, availability of water, suitable climate, dense human settlements have been established in this region.
(iv) Mining activities in the Amazon basin causes pollution in the Amazon River, whereas industrial and domestic sewage adds to pollution of River Ganga.
(v) But as compared to Amazon, the pollution in the River Ganga affects human life greatly as the Ganga Plain is densely populated as compared to the Amazon Plains.
Q 5. Identify the correct group
(a) The order of physiographic units in Brazil while going from North-West to South-East.
(i) Parana River basin – Guyana Highlands – Brazilian Highlands
(ii) Guyana Highlands – Amazon river basin – Brazilian Highlands
(iii) Coastal Plains – Amazon river basin – Brazilian Highlands
Ans: Guyana Highlands – Amazon River basin – Brazilian Highlands
(b) These rivers of Brazil are north-flowing
(i) Juruika – Xingu – Aragua
(ii) Negro – Branco – Paru
(iii) Japura – Jarua – Purus
Ans: Juruika – Xingu – Aragua
(c) The order of plateaus of India from south to north
(i) Karnataka – Maharashtra – Bundelkhand
(ii) Chhota Nagpur – Malwa – Marwad
(iii) Telangana – Maharashtra – Marwad
Ans: Karnataka – Maharashtra – Bundelkhand