Class 9 (Geography) Chapter 3 (Drainage)

 

Class 9 (Geography)

Chapter 3 (Drainage)

 

Notes

 

1. Drainage is the term used to describe the river system within a particular area. It refers to the network of rivers and streams that drain water from the land into larger bodies of water such as lakes, seas, or oceans. A drainage basin, also known as a river basin, encompasses the entire area drained by a single river system. A water divide, typically an elevated landform like a mountain or upland, separates adjacent drainage basins.

2. In India, there are two main river systems based on their origin: the Himalayan rivers and the Peninsular rivers. Himalayan rivers are characterized by their perennial flow, as they are fed by both rainwater and snowmelt throughout the year. These rivers create distinctive features such as meanders and oxbow lakes along their courses. On the other hand, Peninsular rivers are seasonal and primarily rely on rainfall, making them non-navigable for most of the year. They originate in the Western Ghats and flow towards the Bay of Bengal.

3. The Himalayan Rivers:

• The major Himalayan rivers include the Indus, Ganga, and Brahmaputra.
• The Indus River system originates in Tibet and flows through Ladakh into Pakistan before emptying into the Arabian Sea.
• The Ganga River system, with its headwaters in the Gangotri Glacier, is joined by various tributaries like the Yamuna and Ghaghara before flowing into the Bay of Bengal via Bangladesh.
• The Brahmaputra River system, originating in Tibet, enters India through Arunachal Pradesh and flows through Assam, forming riverine islands along its course.

4. The Peninsular Rivers:

• Major Peninsular rivers such as the Godavari, Krishna, and Kaveri flow eastward into the Bay of Bengal, while the Tapi and Narmada flow westward into the Arabian Sea.
• The Godavari, originating in Maharashtra, has a vast basin covering parts of Maharashtra, Madhya Pradesh, Orissa, and Andhra Pradesh.
• The Krishna and Kaveri rivers have their origins in the Western Ghats and drain into the Bay of Bengal, with their basins spanning multiple states.

5. India is also home to various types of lakes, including permanent and non-permanent ones, glacial lakes, oxbow lakes, lagoons, saltwater lakes, freshwater lakes, and man-made lakes. These lakes serve multiple purposes such as regulating river flow, hydroelectric power generation, and supporting aquatic ecosystems.

6. Rivers play a crucial role in India's economy by providing water for agriculture, facilitating transportation and navigation, generating hydroelectric power, and supporting human settlements. However, pollution from untreated sewage, industrial effluents, and agricultural runoff poses significant threats to river ecosystems and water quality, necessitating efforts to mitigate pollution and protect these vital resources.

7. Role of rivers role in the economy of India. They are a vital source of water for agriculture, which is the backbone of the country's economy. The fertile plains along riverbanks support extensive agricultural activities, providing livelihoods for millions of people.

Moreover, settlements and cities have historically developed along the banks of rivers, facilitating trade and commerce. Rivers serve as natural transportation routes, enabling the movement of goods and people, which is essential for economic growth and development.

Additionally, rivers are utilized for hydropower generation, which contributes to India's energy needs. Hydroelectric power plants harness the kinetic energy of flowing water to produce electricity, reducing reliance on fossil fuels and promoting sustainable energy sources.

8. River Pollution : However, despite their economic significance, rivers face numerous challenges, particularly regarding pollution. The quality of river water is adversely affected by various factors, including untreated sewage, industrial effluents, and agricultural runoff containing pesticides and fertilizers. This pollution not only degrades water quality but also harms aquatic ecosystems and human health.

To address these issues, various initiatives and action plans have been implemented to clean and restore rivers across India. For example, the Narmada Bachao Movement advocates for the protection of the Narmada River and its surrounding environment from large-scale development projects that could potentially harm the ecosystem.

9. In conclusion, rivers are indispensable resources that play a crucial role in India's economy. They support agriculture, transportation, energy generation, and human settlements. However, the sustainable management and conservation of rivers are essential to ensure their continued contribution to India's economic prosperity and environmental well-being.

 

Some Important Facts

 

1)    Different Patterns Formed by Streams:

a.    Dendritic,

b.    Trellis,

c.    Radial.

2)    Main Drainage Basins:

a.    The Indus Basin,

b.    The Ganga-Brahmaputra Basin.

3)    Drainage Pattern Where Hard and Soft Rocks Exist Parallel:

a.    Trellis pattern.

4)    Definition of Drainage River Basin:

a.    The area drained by a single river system is called a river basin or a drainage basin.

5)    Main Water Divide in Southern India:

a.    Western Ghats.

6)    Important Tributaries of Indus River:

a.    Zaskar and Nubra.

7)    Three Main Himalayan River Systems:

a.    The Indus River System,

b.    The Ganga River System,

c.    The Brahmaputra River System.

8)    Definition of a Gorge:

a.    A deep narrow opening formed by the river in the upper course, e.g., the gorge formed by the river Indus.

9)    Origin of River Indus:

a.    In Tibet, near the Mansarovar lake.

10) Tributaries of River Indus:

a.    The Zaskar, the Shyok, the Nubra, and the Hunza.

11) Reasons for Perennial Nature of Himalayan Rivers:

a.    Most originate from glaciers,

b.    Receive water from rainfall and glaciers.

12) City Located on Water Divide Between Indus and Ganga River Systems:

a.    Ambala.

13) Indus Water Treaty:

a.    Treaty signed between India and Pakistan allowing India to use only 20% of the total water carried by the Indus river system.

14) Plan Launched to Reduce Pollution in River Ganga:

a.    The Ganga Action Plan.

15) Tributaries of Ganga Rising in Nepal Himalayas:

a.    The Ghaghara and Kosi.

16) Northernmost Point of Ganga Delta:

a.    Farakka in West Bengal.

17) Largest River Basin in India:

a.    The Ganga Basin.

18) Length of River Ganga:

a.    About 2500 km.

19) Headstreams of River Ganga and Their Confluence:

a.    Bhagirathi and Alaknanda meet at Devprayag.

20) City Where Ganga Enters Plains from Himalayas:

a.    Haridwar.

21) Tributaries of River Ganga Entering Northern Plains from Nepal:

a.    Ghaghara, Gandak, and Kosi.

22) Main Right Bank Tributaries of the Ganga:

a.    The Yamuna and the Son.

23) Brahmaputra River in Tibet:

a.    Known as Tsangpo.

24) Origin of River Brahmaputra:

a.    Arises in Tibet east of Mansarover lake.

25) Perennial Rivers:

a.    Rivers that have water throughout the year.

26) Largest Peninsular River and Origin:

a.    Godavari, originates from Nasik district of Maharashtra.

27) Peninsular Rivers Flowing Through Rift Valley:

a.    The Narmada and the Tapti.

28) Main Watershed in Peninsular India:

a.    Formed by the Western Ghats.

29) Major Rivers of Peninsular India:

a.    The Mahanadi, the Godavari, the Krishna, and the Kaveri.

30) Small River Basins of the Peninsular Region:

a.    The Pennar, and

b.    The Mahi.

31) Large Rivers of India Flowing into the Arabian Sea:

a.    The Narmada and the Tapti.

32) Drainage Pattern Made by Narmada River:

a.    Trellis.

33) Primary Reason for Nonperennial Nature of Peninsular Rivers:

a.    Dependence on rainfall as the sole water source.

34) Origin of Narmada River:

a.    Near Amarkantak, in Madhya Pradesh.

35) Hills Where the Tapi River Rises:

a.    Satpura ranges.

36) Origin of the Tapti River:

a.    In the Betul district of Madhya Pradesh.

37) States Through Which the Tapti River Flows:

a.    Madhya Pradesh, Gujarat, and Maharashtra.

38) State With Largest Part of Godavari Basin:

a.    Maharashtra.

39) River Known as Dakshin Ganga:

a.    Godavari.

40) Tributaries of Godavari River:

a.    The Purna, the Wardha, the Pranhita, the Manjra, the Wainganga, and the Pehganga.

41) Reasons for Godavari River's Nickname:

a.    Due to its large size and extensive coverage.

42) Tributaries of Krishna River:

a.    The Tungabhadra, the Koyna, the Ghatprabha, the Musi, and the Bhima.

43) Source of River Yamuna:

a.    Yamunotri glacier in the Himalayas.

44) City at the Confluence of Yamuna and Ganga:

a.    Allahabad.

45) Punjab Rivers Flowing into the Indus:

a.    The Sutlej, the Beas, the Ravi, the Chenab, and the Jhelum.

46) Definition of Canyon:

a.    A deep gorge with steep sides containing many streams.

47) Location of Most Freshwater Lakes:

a.    In the Himalayan region.

48) Largest Natural Freshwater Lake of India:

a.    The Wular lake in Jammu and Kashmir.

49) Lake Formed Due to Tectonic Activities:

a.    The Wular lake.

50) Saltwater Lakes on Eastern Coast of India:

a.    The Chilika Lake,

b.    The Pulicat Lake.

51) Causes of Increase in Demand for Water:

a.    Growing population,

b.    Urbanization.

52) Uses of River Water:

a.    Farming, drinking, domestic, and industrial uses.

53) Causes of Ganga River Water Pollution:

a.    Disposal of raw sewage and industrial wastes,

b.    Reduction in water flow due to irrigation abstraction through canals.

 

 

  Important Question Answers

 

 

Question 1: Define a river system as a river combined with its tributaries. Then, elucidate two key features of the River Indus:
Answer: A river system encompasses a river and its tributaries, forming an interconnected network that drains water from a particular region. One prominent example is the River Indus, which originates near the Mansarovar lake in Tibet. With a remarkable total length of 2,900 kilometers, the River Indus stands as one of the longest rivers globally. Its extensive reach predominantly spans through Pakistan, where it serves as a vital resource for agricultural activities, contributing significantly to the region's economy and sustenance. Noteworthy tributaries such as the Nubra, Hunza, Sulley, Beas, Ravi, Chenab, and Jhelum further enrich the River Indus's flow, augmenting its significance in the landscape and livelihoods of the areas it traverses.

Question 2: Provide a brief overview of the Brahmaputra river system.

Answer: The Brahmaputra River system originates in Tibet, known as the Tsangpo River. It flows eastward parallel to the Himalayas, making a significant U-turn around the Namcha Barwa peak before entering India through Arunachal Pradesh. This river is notorious for causing devastating floods in Assam and Bangladesh. Interestingly, while the Brahmaputra receives less water and sediment in its Tibetan segment, it carries a substantial volume of both when it reaches India. Moreover, the river exhibits a braided channel for most of its length in Assam, featuring several large islands within its course.

Question 3: Detail three characteristics of the Ganga-Brahmaputra delta.

Answer: The Ganga-Brahmaputra delta, also known as the Sundarbans Delta, derives its name from the Sundari tree that thrives in marshland conditions. This expansive delta, formed by the convergence of the Ganga and Brahmaputra rivers, is the largest and fastest-growing delta globally. Notably, the Sundarbans Delta serves as the habitat for the endangered Royal Bengal Tiger, showcasing rich biodiversity within its ecosystem.

Question 4 What factors contribute to the annual flooding of Himalayan rivers, and what benefits do these floods bring?

Answer: Himalayan rivers experience annual flooding due to factors such as snowmelt from the lofty mountain peaks and heavy rainfall during the monsoon season. These floods bring several advantages, such as enriching the soil in the northern plains, making them highly conducive for agriculture. The fertile lands resulting from these floods support the cultivation of various food and cash crops, contributing significantly to agricultural productivity and livelihoods in the region.

Question 5: What advancements have been made under the Ganga Action Plan?

Answer: The Ganga Action Plan has made significant strides in addressing pollution and environmental degradation along the Ganga River. Sixty-nine schemes have been successfully completed, yielding positive outcomes. Efforts include tree plantation in badly eroded areas, repair of check dams in the river's upper reaches, and the interception and diversion of major drains carrying sewage and industrial wastes in cities like Varanasi, Kanpur, and Patna, effectively reducing pollution levels. Additionally, the reappearance of turtles and Gangetic dolphins, once disappeared for several years, in places like Varanasi, signifies the plan's positive impact on river health and biodiversity.

Question 6.
Why are most of the Peninsular rivers draining into the Bay of Bengal? Give reasons. Name the two rivers draining into the Arabian Sea.
Answer:
(i)
(a) The main water divide in Peninsular India is formed by the Western Ghats, which runs from north to south close to the western coast..
(b) The Deccan Plateau is higher in the west and slopes gently eastwards.
Thus, most of the peninsular rivers such as Mahanadi, the Godavari, the Krishna and the Kaveri flow eastwards and drain into the Bay of Bengal.
(ii) The river Narmada and river Tapi drain into the Arabian Sea.

Question 7: Which two rivers of Peninsular India form estuaries, and in which states do these rivers drain the water?

Answer: The rivers Narmada and Tapi create estuaries as they flow into the sea. The Narmada basin spans parts of Madhya Pradesh and Gujarat, while the Tapi basin covers regions of Madhya Pradesh, Gujarat, and Maharashtra.

Question 8: What are the reasons behind the seasonal nature of Peninsular rivers, and provide three factors contributing to this phenomenon?

Answer: Peninsular rivers exhibit a seasonal flow pattern primarily due to their dependence on rainfall. Their shorter and shallower courses, compared to Himalayan rivers, also contribute to this characteristic. Additionally, the Peninsular rivers' limited number of short tributaries, which bring minimal water to the main river, further exacerbate the reduction in water flow during dry seasons.

Question 9: Detail the primary characteristics of the Narmada Basin.

Answer: The Narmada Basin features tributaries that join the mainstream at right angles, with the river originating from the Amarkantak hills. It flows westward through a rift valley formed by faulting, ultimately forming an estuary before meeting the Gulf of Khambhat.

Question 10: Describe the significant features of the Tapi Basin.

Answer: The Tapi Basin is home to the second-largest peninsular river, originating in the Satpura ranges of Madhya Pradesh. Similar to the Narmada, it flows through a rift valley parallel to its counterpart but has a shorter length. The basin encompasses parts of Madhya Pradesh, Gujarat, and Maharashtra.

Question 11: Outline three notable features of the Krishna Basin.

Answer: The Krishna River originates near Mahabaleshwar and spans approximately 1400 kilometers in length. It is joined by tributaries such as the Tungabhadra, Koyana, Ghatprabha, Musi, and Bhima. The river's drainage basin is shared by the states of Maharashtra, Karnataka, and Andhra Pradesh.

Question 12: What attributes earn the Godavari River the nickname 'Dakshin Ganga'?

Answer: The Godavari River, recognized as the largest peninsular river, boasts the largest drainage basin among its counterparts, covering regions of Maharashtra, Madhya Pradesh, Odisha, and Andhra Pradesh. Its extensive length and drainage area have led to its alternate moniker, 'Dakshin Ganga.'

Question 13: Identify three significant features of the Mahanadi Basin.

Answer: The Mahanadi River originates in the highlands of Chhattisgarh and flows through Odisha before emptying into the Bay of Bengal. With a length of about 860 kilometers, it traverses regions of Maharashtra, Chhattisgarh, Jharkhand, and Odisha.

Question 14: Enumerate three essential features of the Kaveri Basin.

Answer: The Kaveri River originates in the Brahmagiri range of the Western Ghats, terminating at the Bay of Bengal near Cuddalore, Tamil Nadu. Its primary tributaries include the Amravati, Bhavani, Hemavati, and Kabini rivers. The basin spans regions of Karnataka, Kerala, and Tamil Nadu.

Question 15: List three similarities shared between Himalayan rivers and Peninsular rivers.

Answer: Both Himalayan and Peninsular rivers exhibit delta formation and possess large drainage basins. Additionally, these river systems are characterized by numerous tributaries contributing to their water volume and silt content.

Question 16: What is the significance of rivers as the lifelines of human civilization?

Answer: Rivers are pivotal to human civilization as they have historically facilitated the development of settlements and civilizations along their valleys. They provide fertile lands for agriculture, support transportation networks for trade and travel, and serve as a vital source of water for various human activities.

Question 17: Predict the consequences for humans in the absence of freshwater scarcity.

Answer: The absence of freshwater scarcity would have profound implications for human beings. Freshwater is essential for bodily functions, constituting a significant portion of our body composition. Without access to freshwater, humans would face challenges in waste removal, nutrient circulation, and overall health maintenance. Additionally, the absence of freshwater would impact ecosystems, affecting plant and animal life dependent on these water sources for survival.

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Question 18: Explain the four drainage patterns.

Answer: There are four main drainage patterns:

• Dendritic: This pattern forms when river channels follow the slope of the terrain, resembling the branching structure of a tree.

 • Trellis: Tributaries join the main river at right angles, often occurring where hard and soft rock layers run parallel.

 • Rectangular: Found in areas with strongly-jointed rocky terrain, this pattern creates a grid-like network.

• Radial: Streams flow outward from a central peak or dome-like structure, forming a radial pattern.

Question 19: Provide five examples supporting the statement "Rivers constitute the most useful natural resources."

Answer: Rivers are vital natural resources because: • They provide water essential for the survival and growth of all organisms. • They facilitated early human settlements, offering ideal conditions for settled life. • River processes created fertile flood plains and deltas, supporting agriculture. • River water is utilized for drinking, irrigation, and hydroelectric power generation. • Rivers provide a food source through fishing and serve as natural waterways, facilitating transportation. Additionally, river valleys have historically been centers of civilization development.

Question 20: Describe the key features of rivers originating from the Himalayas.

Answer: Rivers originating from the Himalayas exhibit several distinctive features: • Most Himalayan rivers are perennial, ensuring a continuous water supply. • They have long courses from their source in the mountains to their endpoints. • These rivers erode the landscape aggressively, carrying substantial sediment loads. • They carve deep gorges through the mountains and often develop well-defined deltas.

Question 21: List the main characteristics of the Ganga river system.

Answer: The Ganga river system is characterized by: • Two main headstreams, Alaknanda and Bhagirathi, merging at Devprayag. • Entry into the plains at Haridwar, followed by the convergence with numerous tributaries like Ghaghara, Gandak, and Kosi. • The Yamuna and Son rivers are significant right bank tributaries. • In Bangladesh, it becomes Padma and further downstream, Jamuna, before merging with the Brahmaputra and Meghna rivers. • With a length exceeding 2500 km, the Ganga has the largest basin among Indian rivers.

Question 22: Explain why the Brahmaputra becomes a major river upon entering India.

Answer: The Brahmaputra expands into a significant river in India due to several factors: • In Tibet, where it originates, the Brahmaputra carries less water and sediment due to the cold and dry climate. • Upon entering India from Arunachal Pradesh, it receives contributions from various tributaries like the Dibang and Lohit, increasing its volume. • The region it traverses in India experiences high rainfall, causing the river to carry a substantial water flow and sediment load. • Seasonal monsoon rains lead to frequent overflow, depositing large amounts of sediment and raising the riverbed.

Question 23: Identify the key features of the Ganga Action Plan.

Answer: The main components of the Ganga Action Plan include: • Diverting sewage from flowing directly into the river for treatment and energy conversion. • Providing safe drinking water by constructing electric crematoriums and separating bathing Ghats. • Diverting major drains carrying waste away from the river in cities like Varanasi, Patna, and Kanpur, reducing pollution levels. • Creating infrastructure capable of diverting and treating significant amounts of domestic sewage daily. • Expanding the scope of the plan, which now covers 152 towns along 27 interstate rivers in 16 states, by integrating it with the National River Conservation Plan.

Question 24: Differentiate between a Delta and an Estuary.

Answer:

Delta	Estuary
Triangular deposits formed by the river at its mouth constitute a delta.	An estuary lacks deposits, featuring a sharp edge at the river mouth.
Deltas are typically found in regions of low tide and coastal plains.	Estuaries occur in areas with high tides and rift valleys.
Deltas create fertile lands conducive to agriculture.	Estuaries do not provide fertile lands.
Examples of rivers forming deltas include the Ganga, Krishna, and Godavari.	Estuaries are formed by rivers like the Narmada and Tapi.

 

Question 25: Describe the differences between perennial and non-perennial rivers.

Answer:

Perennial Rivers	Non-Perennial Rivers
These rivers have water throughout the year.	Non-perennial rivers flow only during the rainy season.
Perennial rivers are sustained by rainfall and melted snow.	Non-perennial rivers solely rely on rainfall for water supply.
Most Himalayan rivers fall under this category.	The majority of Peninsular rivers are non-perennial.

 

Question 26: Explain the 'National River Conservation Plan' (NRCP) briefly.

Answer: The National River Conservation Plan (NRCP) evolved from the Ganga Action Plan (GAP) Phase-I, which concluded in 2000. The NRCP, integrating lessons learned from GAP Phase-I, aims to address pollution in major rivers across India. Under the NRCP, pollution abatement initiatives extend to 152 towns along 27 interstate rivers in 16 states. Notably, 57 towns are currently undergoing pollution abatement efforts, with 215 schemes sanctioned and 69 completed. The plan targets the interception, diversion, and treatment of one million liters of sewage daily.

Question 27: Differentiate between freshwater lakes and saltwater lakes, providing examples of each.

Answer:

Freshwater Lakes	Saltwater Lakes
Typically found in the Himalayan region, often of glacial origin.	Formed by spits and bars in coastal areas or inland drainage regions.
Examples include the Wular Lake in Jammu and Kashmir and the Dal Lake.	Notable examples are the Chilika Lake and the Sambhar Lake in Rajasthan.

 

Question 28: Why are rivers important for the country’s economy?

Answer: Rivers significantly contribute to a country's economy due to several reasons:

• Rivers provide essential water resources for various human, agricultural, and industrial activities, fostering economic development.
• Agriculture, which forms the backbone of many economies, heavily relies on surface water from rivers for irrigation.
• Rivers facilitate tourism, contributing to economic growth through revenue generated from travel and related services.
• Additionally, rivers serve as conduits for cultural exchange and trade, promoting economic interactions between regions and countries.

Question 29: Identify the major factors responsible for river pollution and explain them.

Answer:

• High demand for water: Increasing demand for water for domestic, municipal, industrial, and agricultural purposes affects river quality by reducing its volume.
• Industrialization: Discharge of untreated sewage and industrial effluents into rivers degrades water quality and hampers self-cleansing abilities.
• Agricultural pollution: The use of fertilizers and pesticides contaminates water bodies with heavy metals, posing health risks through food consumption.
• Oil spills: Leakage of oil from tankers pollutes oceans and water bodies, disrupting aquatic ecosystems.

Question 30: What are the causes of water pollution, and how can it be controlled?

Answer: Water pollution is caused by various factors:

• Industrial discharge and urban sewage disposal into rivers.
• Overuse of fertilizers and pesticides in agriculture.
• Oil spills from tankers contaminating water bodies. Controlling water pollution involves:
• Preventing factories from discharging waste into rivers.
• Treating waste before disposal into water bodies.
• Implementing proper sewage management practices.
• Regulating the use of fertilizers and pesticides.
• Enforcing measures to prevent oil spills and leakage into water sources.