Drainage

Hello students, welcome to today's geography lesson. I'm so happy to see you all here, ready to learn about one of the most fascinating chapters in your Class 9 Geography textbook - Chapter 3, which is all about Drainage. Now, before we begin, let me tell you why this chapter is so important. Understanding drainage systems helps us know how water flows across our beautiful country, how rivers shape the land, and how they support the lives of millions of people. So let's begin our journey, shall we?

Let us start with the most basic question - what do we mean by the term 'drainage'? Now, students, I want you to imagine a small stream near your village or town. You must have seen how smaller streams or nallahs come together to form a bigger river. This entire system of rivers, from the smallest stream to the biggest river, is what we call drainage. In simple words, drainage describes the river system of an area. Now, if you look at a physical map of India, you will notice something very interesting. You will see small streams flowing from different directions, and they all come together to form the main river, which ultimately drains into a large water body such as a lake, a sea, or an ocean. This is the essence of drainage.

Now, students, there is an important term you need to remember - the drainage basin. The area drained by a single river system is called a drainage basin. Think of it like this - when it rains on a hill, the water flows down in many directions, but eventually all the water that flows down from that hill goes into one main river. That entire area from which water collects to form one river is the drainage basin. Now, let me ask you something - have you ever noticed that between two river basins, there is always some high land, like a mountain or an upland? This elevated area separates two drainage basins. This elevated land is what we call a water divide. Let me give you a simple example. Imagine two slopes facing opposite directions - water from one slope goes to one river, and water from the other slope goes to a different river. The high land between these two slopes is the water divide. In India, students, you should know that Ambala is located on the water divide between the Indus and the Ganga river systems. This is an important point to remember.

Now, let us move forward and understand how drainage systems work in our country. The drainage systems of India are mainly controlled by the broad relief features of the subcontinent. What does this mean? It means that the shape of the land - whether it is mountainous or flat - determines how rivers flow. Accordingly, Indian rivers are divided into two major groups - the Himalayan rivers and the Peninsular rivers. Now, students, these two groups are very different from each other, and it is important to understand how they differ.

Let us first talk about the Himalayan rivers. These rivers originate from the great Himalayan mountain ranges. One very important characteristic of these rivers is that they are perennial. Now, what does perennial mean? It means that these rivers have water throughout the year. They receive water from two sources - from rain during the monsoon season, and from melted snow from the lofty mountains. This is why they never dry up. The two major Himalayan rivers, the Indus and the Brahmaputra, originate from the north of the mountain ranges. These rivers have cut through the mountains, making deep gorges. Because they come from high mountains and have to travel all the way to the sea, they have long courses. Now, students, let me tell you about the Peninsular rivers. Most of the Peninsular rivers are seasonal, which means their flow is dependent on rainfall. During the dry season, even large rivers have reduced flow of water in their channels. This is because the Peninsular rivers do not have permanent snow glaciers to feed them. The Peninsular rivers have shorter and shallower courses as compared to their Himalayan counterparts. Some of them originate in the central highlands and flow towards the west. Now, I want you to remember this important difference - Himalayan rivers are perennial, while most Peninsular rivers are seasonal.

Now, let us discuss the major Himalayan rivers in detail. The three major Himalayan rivers are the Indus, the Ganga, and the Brahmaputra. These rivers are very long and are joined by many large and important tributaries. A river along with its tributaries may be called a river system. So when we talk about the Ganga river system, we mean the Ganga plus all its tributaries.

Let us start with the Indus River System. Students, the river Indus rises in Tibet, near Lake Mansarowar. Now, this is interesting - it originates in Tibet, which is outside India, and then flows west and enters India in Ladakh. It forms a picturesque gorge in this part. Several tributaries join the Indus in the Kashmir region - these are the Zaskar, the Nubra, the Shyok, and the Hunza. The Indus flows through Baltistan and Gilgit and emerges from the mountains at Attock. Now, students, here comes an important point - the Satluj, the Beas, the Ravi, the Chenab, and the Jhelum all join together and enter the Indus near Mithankot in Pakistan. Beyond this, the Indus flows southwards and finally reaches the Arabian Sea, east of Karachi. The Indus plain has a very gentle slope. With a total length of 2900 kilometers, the Indus is one of the longest rivers of the world. Now, here is an important fact for you - a little over a third of the Indus basin is located in India, in Ladakh, Jammu and Kashmir, Himachal Pradesh, and Punjab. The rest is in Pakistan. Now, students, there is something very important called the Indus Water Treaty of 1960. According to this treaty, India can use only 20 percent of the total water carried by the Indus river system. This water is used for irrigation in Punjab, Haryana, and the southern and western parts of Rajasthan. This is a very significant treaty, and you should remember it.

Now, let us talk about the Ganga River System. The headwaters of the Ganga, called the Bhagirathi, is fed by the Gangotri Glacier. This is where the Ganga begins its journey. The Bhagirathi is joined by the Alaknanda at Devaprayag in Uttarakhand. This confluence is very famous - at Devaprayag, you can see two rivers coming together to form one. At Haridwar, the Ganga emerges from the mountains onto the plains. Now, the Ganga is joined by many tributaries from the Himalayas. Some of these are major rivers - the Yamuna, the Ghaghara, the Gandak, and the Kosi. The river Yamuna rises from the Yamunotri Glacier in the Himalayas. It flows parallel to the Ganga and as a right bank tributary meets the Ganga at Allahabad. The Ghaghara, the Gandak, and the Kosi rise in the Nepal Himalaya. These are the rivers that flood parts of the northern plains every year, causing widespread damage to life and property. But interestingly, while they cause destruction, they also enrich the soil for agricultural use by depositing silt. Now, the main tributaries that come from the peninsular uplands are the Chambal, the Betwa, and the Son. These rise from semi-arid areas, have shorter courses, and do not carry much water in them.

Now, students, let me tell you about the Ganga's journey after it receives all these tributaries. Enlarged with the waters from its right and left bank tributaries, the Ganga flows eastwards till Farakka in West Bengal. This is the northernmost point of the Ganga delta. The river bifurcates here - it splits into two branches. The Bhagirathi-Hooghly, which is a distributary, flows southwards through the deltaic plains to the Bay of Bengal. The mainstream flows southwards into Bangladesh and is joined by the Brahmaputra. Further downstream, it is known as the Meghna. This mighty river, with waters from the Ganga and the Brahmaputra, flows into the Bay of Bengal. The delta formed by these rivers is known as the Sundarban Delta. Now, students, the Sundarban Delta is very special - it derived its name from the Sundari tree, which grows well in marshland. It is the world's largest and fastest growing delta. It is also the home of the Royal Bengal tiger. The length of the Ganga is over 2500 kilometers. Now, there is an interesting fact about the Ganga plains - the plains from Ambala to the Sunderban stretch over nearly 1800 kilometers, but the fall in its slope is hardly 300 meters. In other words, there is a fall of just one meter for every 6 kilometers. This is why the river develops large meanders - it flows very slowly and winds back and forth across the plain.

Now, students, I want to tell you about an important initiative of the Government of India. It is called the Namami Gange Programme. This is an Integrated Conservation Mission approved as a 'flagship programme' by the Union Government in June 2014. Its twin objectives are effective abatement of pollution, and conservation and rejuvenation of the national river, Ganga. This shows how important the Ganga is for our country.

Now, let us move on to the Brahmaputra River System. The Brahmaputra rises in Tibet, east of Mansarowar lake, very close to the sources of the Indus and the Satluj. It is slightly longer than the Indus, and most of its course lies outside India. It flows eastwards parallel to the Himalayas. On reaching the Namcha Barwa, which is 7757 meters high, it takes a 'U' turn and enters India in Arunachal Pradesh through a gorge. Here, it is called the Dihang, and it is joined by the Dibang, the Lohit, and many other tributaries to form the Brahmaputra in Assam. Now, students, here is an interesting fact - in Tibet, the Brahmaputra is known as the Tsang Po, and in Bangladesh, it is known as the Jamuna. In Tibet, the river carries a smaller volume of water and less silt because it is a cold and dry area. But in India, it passes through a region of high rainfall, so it carries a large volume of water and a considerable amount of silt. The Brahmaputra has a braided channel in its entire length in Assam and forms many riverine islands. In fact, students, do you know the name of the world's largest riverine island? It is Majuli island in Assam, formed by the Brahmaputra. Every year during the rainy season, the river overflows its banks, causing widespread devastation due to floods in Assam and Bangladesh. Unlike other north Indian rivers, the Brahmaputra is marked by huge deposits of silt on its bed, causing the riverbed to rise. The river also shifts its channel frequently. This is why flooding is such a common problem in Assam.

Now, students, let me ask you a question that was in your textbook - which river has the largest basin in India? The answer is the Ganga, followed by the Godavari. The Ganga has the largest drainage basin in India.

Now, let us move on to the Peninsular rivers. The main water divide in Peninsular India is formed by the Western Ghats, which runs from north to south close to the western coast. Most of the major rivers of the Peninsula, such as the Mahanadi, the Godavari, the Krishna, and the Kaveri, flow eastwards and drain into the Bay of Bengal. These rivers make deltas at their mouths. There are numerous small streams flowing west of the Western Ghats. The Narmada and the Tapi are the only long rivers that flow west and make estuaries. The drainage basins of the peninsular rivers are comparatively smaller in size than the Himalayan rivers.

Let us start with the Narmada Basin. The Narmada rises in the Amarkantak hills in Madhya Pradesh. It flows towards the west in a rift valley formed due to faulting. Now, students, what is a rift valley? A rift valley is a valley formed when the land between two parallel faults sinks down. The Narmada flows through such a valley. On its way to the sea, the Narmada creates many picturesque locations. The 'Marble rocks' near Jabalpur, where the Narmada flows through a deep gorge, and the 'Dhuadhar falls', where the river plunges over steep rocks, are some of the notable ones. All tributaries of the Narmada are very short, and most of these join the main stream at right angles. The Narmada basin covers parts of Madhya Pradesh and Gujarat. Now, students, there is a government mission for the conservation of the Narmada called Namami Devi Narmade, undertaken by the government of Madhya Pradesh.

Now, the Tapi Basin - the Tapi rises in the Satpura ranges, in the Betul district of Madhya Pradesh. It also flows in a rift valley parallel to the Narmada, but it is much shorter in length. Its basin covers parts of Madhya Pradesh, Gujarat, and Maharashtra. The coastal plains between Western Ghats and the Arabian Sea are very narrow, so the coastal rivers are short. The main west flowing rivers are Sabarmati, Mahi, Bharathpuzha, and Periyar.

Now, let us talk about the Godavari Basin. The Godavari is the largest Peninsular river. It rises from the slopes of the Western Ghats in the Nasik district of Maharashtra. Its length is about 1500 kilometers. It drains into the Bay of Bengal. Its drainage basin is also the largest among the peninsular rivers. The basin covers parts of Maharashtra - about 50 percent of the basin area lies in Maharashtra - as well as Madhya Pradesh, Odisha, and Andhra Pradesh. The Godavari is joined by a number of tributaries, such as the Purna, the Wardha, the Pranhita, the Manjra, the Wainganga, and the Penganga. The last three tributaries are very large. Because of its length and the area it covers, it is also known as the Dakshin Ganga, which means the Ganga of the South.

Now, the Mahanadi Basin - the Mahanadi rises in the highlands of Chhattisgarh. It flows through Odisha to reach the Bay of Bengal. The length of the river is about 860 kilometers. Its drainage basin is shared by Maharashtra, Chhattisgarh, Jharkhand, and Odisha.

The Krishna Basin - the Krishna rises from a spring near Mahabaleshwar and flows for about 1400 kilometers to reach the Bay of Bengal. The Tungabhadra, the Koyana, the Ghatprabha, the Musi, and the Bhima are some of its tributaries. Its drainage basin is shared by Maharashtra, Karnataka, and Andhra Pradesh.

Now, students, here is an interesting fact - the river Kaveri makes the second biggest waterfall in India, known as Shivasamudram Falls. The hydroelectric power generated from the falls is supplied to Mysuru, Bengaluru, and the Kolar Gold Field. You should find out the name of the biggest waterfall in India.

Now, besides these major rivers, there are some smaller rivers flowing towards the east - the Damodar, the Brahmani, the Baitarni, and the Subarnrekha are some notable examples. You should locate them in your atlas.

Now, students, let me tell you some amazing facts about water. Did you know that 71 percent of the world's surface is covered with water, but 97 percent of that is salt water? And of the 3 percent that is available as freshwater, three quarters of it is trapped as ice. This is why freshwater is such a precious resource, and why we must take care of our rivers and lakes.

Now, let us move on to the next section - Lakes. You may be familiar with the valley of Kashmir and the famous Dal Lake, with its house boats and shikaras, which attract thousands of tourists every year. Similarly, you may have visited some other tourist spots near a lake and enjoyed boating, swimming, and other water games. Imagine that if Srinagar, Nainital, and other tourist places did not have a lake - would they have been as attractive as they are today? Lakes are not just important for tourism; they are also useful to human beings in many ways.

India has many lakes, and these differ from each other in size and other characteristics. Most lakes are permanent, but some contain water only during the rainy season, like the lakes in the basins of inland drainage of semi-arid regions. There are some lakes which are the result of the action of glaciers and ice sheets, while others have been formed by wind, river action, and human activities.

Now, let me explain how different types of lakes are formed. A meandering river across a floodplain forms cut-offs that later develop into ox-bow lakes. Spits and bars form lagoons in the coastal areas - for example, the Chilika lake, the Pulicat lake, and the Kolleru lake are all coastal lagoons. Lakes in the region of inland drainage are sometimes seasonal - for example, the Sambhar lake in Rajasthan, which is a salt water lake. Its water is used for producing salt. Now, students, here is an interesting point - lakes of large extent are called seas, like the Caspian, the Dead, and the Aral seas.

Most of the freshwater lakes are in the Himalayan region. They are of glacial origin, which means they formed when glaciers dug out a basin, which was later filled with snowmelt. The Wular lake in Jammu and Kashmir, in contrast, is the result of tectonic activity - it was formed due to earth movements. It is the largest freshwater lake in India. The Dal lake, Bhimtal, Nainital, Loktak, and Barapani are some other important freshwater lakes.

Now, apart from natural lakes, the damming of the rivers for the generation of hydel power has also led to the formation of lakes. For example, Guru Gobind Sagar is formed by the Bhakra Nangal Project.

Now, let me tell you about the value of lakes. Lakes are of great value to human beings. A lake helps to regulate the flow of a river. During heavy rains, it prevents flooding, and during the dry season, it helps to maintain an even flow of water. 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.

Now, students, let us discuss the role of rivers in the economy. Rivers have been of fundamental importance throughout human history. Water from rivers is a basic natural resource, essential for various human activities. Therefore, riverbanks have attracted settlers from ancient times. These settlements have now become big cities. For example, look at cities like Varanasi, Allahabad, Kolkata, and many others - they all developed on riverbanks. Using rivers for irrigation, navigation, and hydro-power generation is of special significance, particularly to a country like India, where agriculture is the major source of livelihood for the majority of its population.

Now, let us talk about a very important and concerning topic - river pollution. The growing domestic, municipal, industrial, and agricultural demand for water from rivers naturally affects the quality of water. As a result, more and more water is being drained out of the rivers, reducing their volume. On the other hand, a heavy load of untreated sewage and industrial effluents are emptied into the rivers. This affects not only the quality of water but also the self-cleansing capacity of the river. For example, given the adequate streamflow, the Ganga water is able to dilute and assimilate pollution loads within 20 kilometers of large cities. But the increasing urbanisation and industrialisation do not allow it to happen, and the pollution level of many rivers has been rising. Concern over rising pollution in our rivers led to the launching of various action plans to clean the rivers. Now, students, I want you to think about how our health gets affected by polluted river water. Think about "life of human beings without fresh water". You can arrange a debate on this topic in your class.

Now, let me tell you about the National River Conservation Plan, or NRCP. The river cleaning programme in the country was initiated with the launching of the Ganga Action Plan in 1985. The Ganga Action Plan was expanded to cover other rivers under the National River Conservation Plan in the year 1995. The objective of the NRCP is to improve the water quality of the rivers, which are major water sources in the country, through the implementation of pollution abatement work.

Now, students, we have covered all the concepts in the chapter. Now it is time to solve the exercises. Let me guide you through each question.

Let us start with Exercise 1, Question 1. We need to choose the right answer from the four alternatives given.

Question (i) asks: In which of the following states is the Wular lake located? The options are Rajasthan, Uttar Pradesh, Punjab, and Jammu and Kashmir. Now, students, we learned that Wular lake is the largest freshwater lake in India, and it is in Jammu and Kashmir. So the correct answer is (d) Jammu and Kashmir.

Question (ii) asks: The river Narmada has its source at. The options are Satpura, Brahmagiri, Amarkantak, and Slopes of the Western Ghats. We learned that the Narmada rises in the Amarkantak hills in Madhya Pradesh. So the correct answer is (c) Amarkantak.

Question (iii) asks: Which one of the following lakes is a salt water lake? The options are Sambhar, Dal, Wular, and Gobind Sagar. We learned that Sambhar lake in Rajasthan is a salt water lake, and its water is used for producing salt. So the correct answer is (a) Sambhar.

Question (iv) asks: Which one of the following is the longest river of Peninsular India? The options are Narmada, Krishna, Godavari, and Mahanadi. We learned that the Godavari is the largest Peninsular river, with a length of about 1500 kilometers. So the correct answer is (c) Godavari.

Question (v) asks: Which one amongst the following rivers flows through a rift valley? The options are Mahanadi, Tungabhadra, Krishna, and Tapi. We learned that both Narmada and Tapi flow through rift valleys. But among the options, Tapi is the one that flows through a rift valley. So the correct answer is (d) Tapi.

Now, let us move to Exercise 1, Question 2, where we need to answer the following questions briefly.

Question (i) asks: What is meant by a water divide? Give an example. Students, we learned that a water divide is an elevated area, such as a mountain or an upland, that separates two drainage basins. The example we gave was Ambala, which is located on the water divide between the Indus and the Ganga river systems.

Question (ii) asks: Which is the largest river basin in India? The answer is the Ganga basin. It is the largest drainage basin in India.

Question (iii) asks: Where do the rivers Indus and Ganga have their origin? The Indus rises in Tibet, near Lake Mansarowar. The Ganga's headwaters, called the Bhagirathi, is fed by the Gangotri Glacier in Uttarakhand.

Question (iv) asks: Name the two headstreams of the Ganga. Where do they meet to form the Ganga? The two headstreams are the Bhagirathi and the Alaknanda. They meet at Devaprayag in Uttarakhand to form the Ganga.

Question (v) asks: Why does the Brahmaputra in its Tibetan part have less silt, despite a longer course? This is because Tibet is a cold and dry area. The river carries a smaller volume of water and less silt in Tibet. When it enters India, it passes through a region of high rainfall, where it carries a large volume of water and considerable amount of silt.

Question (vi) asks: Which two Peninsular rivers flow through trough? The two Peninsular rivers that flow through troughs (rift valleys) are the Narmada and the Tapi.

Question (vii) asks: State some economic benefits of rivers and lakes. Let me list the benefits for you. Rivers are used for irrigation, which is crucial for agriculture. They are used for navigation and transport. They help in generating hydroelectric power. Rivers provide water for domestic and industrial use. Lakes help in regulating river flow, preventing floods during heavy rains and maintaining water during dry seasons. Lakes can be used for developing hydel power. They moderate the climate, maintain aquatic ecosystems, enhance natural beauty, help develop tourism, and provide recreation. Both rivers and lakes are important for fishing and for the livelihood of people who depend on them.

Now, let us move to Exercise 3. We need to group the given names of lakes under two categories - natural and created by human beings.

Let me go through each lake one by one.

(a) Wular - This is a natural lake, formed by tectonic activity. It is in Jammu and Kashmir.

(b) Dal - This is a natural lake, a glacial lake in Jammu and Kashmir.

(c) Nainital - This is a natural lake, a glacial lake in Uttarakhand.

(d) Bhimtal - This is a natural lake, a glacial lake in Uttarakhand.

(e) Gobind Sagar - This is an artificial lake, created by damming the river for the Bhakra Nangal Project.

(f) Loktak - This is a natural lake, a large lake in Manipur.

(g) Barapani - This is a natural lake, also known as Umiam Lake, in Meghalaya.

(h) Chilika - This is a natural lake, a lagoon in Odisha.

(i) Sambhar - This is a natural lake, a salt water lake in Rajasthan.

(j) Rana Pratap Sagar - This is an artificial lake, created by the Rana Pratap Sagar dam in Rajasthan.

(k) Nizam Sagar - This is an artificial lake, created by the Nizam Sagar dam in Telangana.

(l) Pulicat - This is a natural lake, a lagoon in Andhra Pradesh and Tamil Nadu.

(m) Nagarjuna Sagar - This is an artificial lake, created by the Nagarjuna Sagar dam on the Krishna river.

(n) Hirakund - This is an artificial lake, created by the Hirakud dam in Odisha.

So, the natural lakes are: Wular, Dal, Nainital, Bhimtal, Loktak, Barapani, Chilika, Sambhar, and Pulicat.

The artificial lakes created by human beings are: Gobind Sagar, Rana Pratap Sagar, Nizam Sagar, Nagarjuna Sagar, and Hirakund.

Now, let us move to Exercise 4. We need to discuss the significant difference between the Himalayan and the Peninsular rivers.

Students, here are the main differences:

First, the origin - Himalayan rivers originate from the Himalayan mountains, while Peninsular rivers originate from the Peninsular plateau.

Second, the nature of flow - Himalayan rivers are perennial, meaning they have water throughout the year from both rain and melted snow. Most Peninsular rivers are seasonal, dependent on rainfall.

Third, the course - Himalayan rivers have long courses from the mountains to the sea. They have cut through the mountains making gorges. Peninsular rivers have shorter and shallower courses.

Fourth, the tributaries - Himalayan rivers have many large tributaries. Peninsular rivers have fewer tributaries.

Fifth, the drainage pattern - Himalayan rivers form dendritic drainage patterns. Peninsular rivers form rectangular drainage patterns.

Sixth, the valleys - Himalayan rivers have V-shaped valleys in the mountains and broad, flat valleys in the plains. Peninsular rivers flow in relatively shallow valleys.

Now, let us move to Exercise 5. We need to compare the east flowing and the west flowing rivers of the Peninsular plateau.

The east flowing rivers of the Peninsular plateau are the Mahanadi, Godavari, Krishna, and Kaveri. They flow eastwards and drain into the Bay of Bengal. They form deltas at their mouths. Their basins are larger.

The west flowing rivers of the Peninsular plateau are the Narmada and the Tapi. They flow westwards and drain into the Arabian Sea. They form estuaries at their mouths. Their basins are smaller. There are also smaller west flowing rivers like the Sabarmati, Mahi, Bharathpuzha, and Periyar.

The main difference is the direction of flow and the type of mouth they form - east flowing rivers form deltas, while west flowing rivers form estuaries.

Now, let us move to Exercise 6. We need to answer why rivers are important for the country's economy.

Rivers are important for the country's economy in many ways. First, they provide water for irrigation, which is essential for agriculture. Agriculture is the main source of livelihood for most Indians. Second, rivers are used for navigation and transportation of goods and people. Third, rivers help in generating hydroelectric power, which is a clean and renewable source of energy. Fourth, rivers provide water for domestic and industrial purposes. Fifth, rivers support fisheries and provide livelihood to fishermen. Sixth, riverbanks have been sites for settlements since ancient times, and many major cities are located on riverbanks. Seventh, rivers have religious significance and attract pilgrims and tourists. Overall, rivers are the lifeline of India's economy.

Now, let us move to the Map Skills section. For question (i), we need to mark and label the following rivers on an outline map of India: Ganga, Satluj, Damodar, Krishna, Narmada, Tapi, Mahanadi, and Brahmaputra. Let me tell you where each river flows so you can mark them correctly.

The Ganga flows from Uttarakhand through Uttar Pradesh, Bihar, and West Bengal to the Bay of Bengal. The Satluj flows from Tibet through Himachal Pradesh and Punjab into Pakistan. The Damodar flows through Jharkhand and West Bengal. The Krishna flows from Maharashtra through Karnataka and Andhra Pradesh to the Bay of Bengal. The Narmada flows from Madhya Pradesh through Gujarat to the Arabian Sea. The Tapi flows from Madhya Pradesh through Gujarat to the Arabian Sea. The Mahanadi flows from Chhattisgarh through Odisha to the Bay of Bengal. The Brahmaputra flows from Tibet through Arunachal Pradesh and Assam into Bangladesh.

For question (ii), we need to mark and label the following lakes: Chilika, Sambhar, Wular, Pulicat, and Kolleru.

Chilika is in Odisha, near the coast. Sambhar is in Rajasthan. Wular is in Jammu and Kashmir. Pulicat is in Andhra Pradesh and Tamil Nadu, near the coast. Kolleru is in Andhra Pradesh.

Now, let us move to the Project/Activity - the crossword puzzle. Let me solve it with the help of the given clues.

Across:

1. Nagarjuna Sagar is a river valley project. Name the river? The answer is Krishna.

2. The longest river of India. The answer is Indus. (The Indus is 2900 km long, while the Ganga is over 2500 km. However, the Ganga is the longest river wholly within India.)

3. The river which originates from a place known as Beas Kund. The answer is Beas.

4. The river which rises in the Betul district of MP and flows westwards. The answer is Tapi.

5. The river which was known as the "Sorrow" of West Bengal. The answer is Damodar.

6. The river on which the reservoir for Indira Gandhi Canal has been built. The answer is Sutlej or Satluj.

7. The river whose source lies near Rohtang Pass. The answer is Beas.

8. The longest river of Peninsular India? The answer is Godavari.

Down:

9. A tributary of Indus originating from Himachal Pradesh. The answer is Beas or Sutlej.

10. The river flowing through fault, drains into the Arabian Sea. The answer is Narmada.

11. A river of south India, which receives rainwater both in summer and winter. The answer is Kaveri.

12. A river which flows through Ladakh, Gilgit and Pakistan. The answer is Indus.

13. An important river of the Indian desert. The answer is Luni.

14. The river which joins Chenab in Pakistan. The answer is Jhelum or Ravi.

15. A river which rises at Yamunotri glacier. The answer is Yamuna.

Now, students, we have covered the entire chapter. Let me give you a brief summary of what we have learned today.

In this chapter, we learned about drainage - the river system of an area. We learned about drainage basins and water divides. We understood that Indian rivers are divided into two major groups - Himalayan rivers and Peninsular rivers. Himalayan rivers are perennial, originate from mountains, have long courses and many tributaries. Peninsular rivers are mostly seasonal, originate from the Peninsular plateau, and have shorter courses.

We studied the Indus River System - its origin in Tibet, its tributaries, and the Indus Water Treaty. We studied the Ganga River System - its headstreams Bhagirathi and Alaknanda, its tributaries like Yamuna, Ghaghara, Gandak, and Kosi, and its journey to the Bay of Bengal forming the Sundarban Delta. We studied the Brahmaputra River System - its origin in Tibet, its journey through Assam, and its flooding problems.

We studied the Peninsular rivers - the Narmada and Tapi which flow through rift valleys, the Godavari known as the Dakshin Ganga, the Mahanadi, the Krishna, and the Kaveri. We learned about lakes - their types, how they are formed, and their importance. We learned about the economic importance of rivers and the problem of river pollution. We also learned about the Namami Gange Programme and the National River Conservation Plan.

We solved all the exercises, including multiple choice questions, short answer questions, grouping of lakes, comparison between Himalayan and Peninsular rivers, comparison between east flowing and west flowing rivers, and the importance of rivers for the economy. We also learned about the map skills and solved the crossword puzzle.

Students, I hope this lesson has helped you understand the chapter thoroughly. Remember, rivers and lakes are precious resources, and it is our responsibility to protect them from pollution. Thank you for listening so patiently. Keep studying and keep exploring the wonderful world of geography. Good luck!