Extra Question & Answers (Part - 2) - Drainage Class 9 Notes | EduRev

Social Studies (SST) Class 9

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Class 9 : Extra Question & Answers (Part - 2) - Drainage Class 9 Notes | EduRev

The document Extra Question & Answers (Part - 2) - Drainage Class 9 Notes | EduRev is a part of the Class 9 Course Social Studies (SST) Class 9.
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46) A recent newspaper report from Nagpur states: "The pollution in Nag river and the city's lakes has been increasing with every passing year. The Nagpur Municipal Corporation (NMC) and Nagpur Improvement Trust (NIT) reportedly turned the Nag, Pilli and Pilli rivers flowing through the city into sewage drains. Even though the condition of the lakes has become even more serious, the NMC, with an annual budget of ? 1200 crore, did nothing for the conservation of water bodies as it was depending on the government." 'What should the NMC and NIT have done to prevent this pollution and why?

Answer:The NMC and NIT should have treated the sewage in sewage plants with interceptors for harmful substances, before discharging the sewage in the rivers. As usually the rivers are used to provide drinking water to the city's residents, the drinking water has become polluted, which can cause many diseases in the residents drinking this water and using it for domestic purposes. They should also install suitable purifiers in  the drinking water supply lines to purify the water suitably, so that no water borne diseases occur. 

47) What is a river pattern? Name any four patterns formed by the rivers?

Answer:The streams within a drainage basin form certain patterns depending on the slope of land, underlying rock structure as well as the climatic conditions of the area. These patterns are known as drainage patterns.
The four patterns are
(i) Dendritic Pattern The river and its tributaries follow the slope of the terrain just like the branches of a tree.
(ii) Rectangular Pattern This occurs on a strongly jointed rocky terrain.
(iii) Trellis Pattern This develops where hard and soft rocks exist parallel to each other, so that the tributaries join the river at almost right angles.
(iv) Radial Pattern This pattern develops when streams flow in different directions from a central peak or dome like structure. 

48) Explain any three features of peninsular rivers.

Answer:The three features of peninsular rivers are
(i) A large number of peninsular rivers are seasonal, as their flow depends on rainfall.
(ii) These rivers have shorter and shallower courses.
(iii) Most of the peninsular rivers originate in the Western Ghats and flow towards the Bay of Bengal.  

49) Describe any three features of the Himalayan rivers. Or Explain main features of rivers originating from the Himalayas.

Answer:The three features of the Himalayan rivers are
(i) Most of the Himalayan rivers are perennial. It means that they have water throughout the year.
(ii) The Himalayan rivers have long courses from their source to the sea.
(iii) They perform intensive emotional activity in their upper courses and carry huge loads of silt and sand.  

50)   Name the peninsular river that create many picturesque locations. Write any two features of it Or Where does river Narmada originate? Name any two picturesque location formed by it. Or Identify the drainage pattern of river Narmada. Describe the features of this drainage pattern. Or Describe the largest peninsular West flowing river with regard to its sources, flow and drainage basin.

Answer: (i) The peninsular river that creates many picturesque location is river Narmada. It rises in the Amarkantak hills in Madhya Pradesh.
(ii) The 'Marble rocks' near Jabalpur where Narmada flows through a deep gorge and the 'Dhuandhar falls' where the river plunges over steep rocks, are some of the notable picturesque locations. 

51) Describe the Indus river system on the following heads (i) Source (ii) Any two tributaries (iii) Indus Water Treaty.

Answer:  (i) Source The river Indus rises in Tibet, near lake Mansarowar.
(ii)Tributaries Tributaries of Indus river system are the Zaskar, the Nubra, the Shyok, the Hunza, the Satluj, the Beas, the Ravi, the Chenab and the Jhelum.
(iii) Indus Water Treaty According to the regulations of the Indus Water Treaty, India can use only 20 per cent of the total water carried by the Indus river system. This water is use for irrigation in the Punjab, the Haryana, the Southern and the Western parts of Rajasthan.  

52) Why are the rivers of the Western coastal plains short?

Answer:The Western Ghats run North-South very near to the Arabian sea coast and provides a prominent watershed in the peninsular India. So, the coastal plains between the Western Ghats and the Arabian sea coast are very narrow. Hence, the coastal rivers flowing Westward from Western Ghats are very narrow. Sabarmati, Periyar rivers are example of such rivers. 

53) Describe the three main features of the Ganga river system.

Answer:The three main features of the Ganga river system are
(i) The length of the Ganga is 2500 km. It is India's longest river.
(ii) It has many tributaries which join it from both sides and form the Ganga river basin. It has dendritic drainage pattern.
(iii) The Ganga originates from the Gangotri glacier. The headwater of the Ganga is called 'Bhagirathi'. It joins Alaknanda at Devaprayag in Uttarakhand. At Haridwar the Ganga emerges from the mountains on to the plains.  

54) (i) How are the most of the freshwater lakes in the Himalayan region formed? Give two examples of freshwater lakes of this region.
(ii) How is Sambhar lake useful? 

Answer:(i) Most of the freshwater lakes are in the Himalayan region. They are of the glacial origin. They are formed when glaciers dug out a basin, which was later filled with snowmelt. Examples of such lakes are Bhimtal, Nainital, Dal lake. etc. India's largest freshwater lake is the Wular lake.
(ii) Sambhar lake is India's largest inland salt water lake. It is located in Rajasthan in an inland drainage. It is important source of salt in India. It is famous for  production of edible salt here.  

55) Give four characteristics of the Ganga Brahmaputra delta.

Answer:The four characteristics of the Ganga Brahmaputra delta are
(i) The Ganga Brahmaputra delta, also named Ganga delta, Sunderban delta or Bengal delta is situated in Bangladesh and Paschim Banga state of India, where the Ganga and Brahmaputra rivers discharge into the Bay of Bengal. The total catchment area of the rivers is 1.72 million sq km.
(ii) It is the world s largest delta, with a surface area of 1 lakh sq km.
(iii) It is among the most fertile regions in the world. With more than 130 million inhabitants, this belongs to the most densely populated areas in the world (1300 inhabitants/sq km).
(iv) Downstream of the confluence, the river is named Padma. About halfway to the ocean the Meghna joins the Padma.  

56) Explain the use of salt water lakes in India with particular reference to Chilika and Sambhar lakes.

Answer:The Sambhar lake is India's largest saline lake and has made Rajasthan the third largest salt producing state in India. It produces about 2 lakh tonnes of clean salt every year. Salt is produced by evaporation of brine. This lake is also recognised as a wetland of international importance because it is a key wintering area for flamingos and other birds that migrate from Northern Asia. Chilika lake in Odisha is the largest brackish water lake in India. It is the wintering ground for migratory birds on the Indian sub continent. The lake is home to a number of threatened species of plants and animals. It is an ecosystem with large fishery resources sustaining 150000 fishermen living nearby.  

57) Discuss the significant difference between the Himalayan and the Peninsular rivers. Or Give any three differences between peninsular and Himalayan rivers.

Answer: The three differences between peninsular and Himalayan rivers are

Himalayan Rivers
Peninsular Rivers
They rise  from glaciers or springs in high mountains.
They rise from plateaus and highlands.
Perennial in nature due to originating from glaciers.
Seasonal as they get water from rainfall.
Only suitable for generation of hydroelectricity in hilly regions, as they are slow flowing in the plaints. Dams need to be built to create waterfalls.
They flow at high speed due to form waterfalls, thus being suitable for hydroelectricity. Generation.

58) Explain how pollution is caused to river water and what action the government is taking to minimise it.

Answer: Due to the requirements of the increasing population, large amounts of industrial effluents and untreated sewage are released into drains which ultimately flow into rivers. Further, due to requirements in agriculture and industry, larger amounts of water are being drained out from rivers. All this has led to increased pollution of the water remaining in the rivers. The government has launched various action plans to clean rivers. The major offensive in this regard is the National River Conservation Plan (NRCP), which envisages pollution abatement in 38 major rivers covering 172 towns in 20 states currently. Under this plan, 4400 million litres of sewage is targeted to be intercepted, diverted and treated every day.  

59) Describe the various drainage patterns of rivers giving some examples of Indian rivers.

Answer: There are basically four drainage patterns of rivers
(i) Dendritic Pattern This is the most common pattern followed by rivers like the Ganga. This develops where the river channel follows the slope of the terrain. The stream with its tributaries resembles the branches of a tree.
(ii) Trellis Pattern Short tributaries meet long trunk streams at near right angles. They are formed on sedimentary rocks of different resistance to erosion. An example is the Narmada river.
(iii) Rectangular Pattern Straight tributaries meet straight trunk streams with bends at almost right angles. These are formed on faulted or fractured bedrock.
(iv) Radial Pattern The streams flow outward from a well defined central point like a volcano or other round uplift of land.  

60) Explain the differences between the Indus basin and the Ganga basin in tabular form.


  • Indus Basin
    Ganga Basin
    Formed by the Indus river and its tributaries like the Ravi, Chenab, Satluj, Jhelum, Beas, etc.
    Formed by the Ganga river and its tributaries like the Yamuna, Son, Ghaghara, Gomati, Kosi, Gandak, etc.
    Located in Jammu and Kashmir, Punjab, Haryana, Himachal Pradesh and Rajasthan (besides Pakistan).
    Located in Uttarakhand, Haryana, Uttar Pradesh, Bihar, Madhya Pradesh. Jharkhand and Paschim Banga (besides Bangladesh).
    Indus river flows for 3180 km (including China and Pakistan).Most of its tributaries flow from North-West to South-West.
    Ganga river flows for 2506 km (including Bangladesh).
    It has fertile land and a dense network of canals for irrigation.
    Irrigation facilites required are less as it has high rainfall.
    Separated from the Ganga basin by the Ambala Saharanpur water divide.
    Spreads from Ambala in the North-West to Sunderban in the South-East.

61)  What are the causes of water pollution in rivers and lakes?

Answer:Water in rivers and lakes is being reduced as the requirements of rapid urbanisation, population growth and industrialization cause more water to be drained out from them. In place of this, huge amounts of untreated sewage and industrial effluents are being emptied into the rivers and lakes. This has caused the water bodies to become highly polluted. Human ashes (due to cremation near water bodies), dead animals and leaching out of nitrogen compounds from fertilised agricultural lands also increase the pollution. Nutrient run-off in storm water from "sheet flow" over an agricultural field or a forest is also another cause.  

62) State some economic benefits of rivers and lakes.

Answer:Lake (i) Lakes help to regulate the flow of rivers.
(ii) Lakes help to prevent flooding during rainy season.
(iii) During the dry season, lakes help to maintain an even flow of water.
(iv) Lakes can also be used for developing hydelpower.
(v) Lakes provide opportunities for fishery development.
(vi) They moderate the climate of the surroundings and maintain the acquaric ecosystem. (viii) They enhance natural beauty and help to develop tourism and provide recreation, e.g., Dal lake and Naini lake at Nainital. Rivers
(i) They help to develop hydel power.
(ii)They provide water for irrigation for drinking and other requirements.
(iii) They help to develop fisheries.  

63) The textbook states: "Imagine that if Srinagar, Nainital and other tourist places did not have a lake, would they have been as attractive as they are today? Have you ever tried to know the importance of lakes in making a place attractive to tourists?" Can you answer these questions?

Answer:Definitely, Srinagar without die Dal lake will not attract so many tourists. Similarly, Nainital without the Naini lake will be bereft of tourists. Avast expanse of bright blue water in the midst of dense forests, lofty mountains or barren landscape is marvellous and looks picturesque at dawn, sunset or during full moon nights. The view of a lake shimmering in the spring sunshine is marvellous. The lakes declared as water bird sanctuaries are like fairylands for birds. Shorelines or banks of lakes attract both humans and a diverse community of plants and animals. The biodiversity of lakes make them important as natural resources for tourism. Further, the usage of lakes for sports, entertainment, swimming, fishing, etc is of great importance to the public. Use of lake shores for residential, commercial development and recreation has increased the world over. However, through years of neglect, the lake water has been allowed to deteriorate. This should be looked into by the concerned authorities before lake tourism comes to a stop due to the pollution in the lakes.  

64) Rivers are very important for development in India? Explain. Or Explain any three reasons for the significance of rivers for economy of a country. Or Rivers have been of fundamental importance throughout human history? How do rivers affect economy of a country? Explain Or Highlight the role of rivers in agricultural economy like India. Write any three points.

Answer: Rivers are known as the lifeline of human civilisation. Rivers have been of fundamental importance throughout the human history. Water from the river is a basic natural resource, essential for various human activities. The river banks have attracted the settlers' from ancient times. These settlement have also become big cities. The three points are
(i) The rivers for irrigation, navigation, hydropower generation is of special significance particularly to a country like India, where agriculture is the major source of livelihood for majority of its population.
(ii) River water is used for providing irrigation facilities through various canals. Multi-purpose dams have been constructed on the Indian rivers which provides hydroelectricity,   irrigation   facilities,   navigation, afforestation, etc.
(iii) Rivers are considered of great cultural significance in Indian culture. Many cultural activities like Kumbh melas are organised on river banks in every part of India. Indian rivers like the Ganga form vast basins that are considered as one of the most agriculturally productive part of the world. Indian rivers host many religious, cultural and picturesque tourist spots that are of great significance to tourism industry which is a great source of income to a country's economy. 

65)   How lakes are of great value to human beings? State any six importance's, Or What is lake? Explain the importance of lakes. Or Describe any three benefits of lakes?

Answer: Lake is a large body of water that is entirely surrounded by land. Lake water can be fresh or more rarely salty or saline.
Importance of lakes are
(i) Lake are of great value to human beings. It helps to regulate the flow of a river.
(ii) During heavy rainfall, it prevents flooding and during the dry season, it help to maintain an even flow of water.
(iii) Lakes can also be used for developing hydel power. They moderate the climate of the surroundings  maintain the aquatic ecosystem, enhance natural beauty, help develop tourism and provide recreation.

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