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DRAINAGE 3 T he term drainage describes the river subcontinent. Accordingly, the Indian rivers system of an area. Look...

DRAINAGE 3 T he term drainage describes the river subcontinent. Accordingly, the Indian rivers system of an area. Look at the physical are divided into two major groups: map. You will notice that small streams the Himalayan rivers; and flowing from different directions come together the Peninsular rivers. to form the main river, which ultimately drains Apart from originating from the two major into a large water body such as a lake or a sea physiographic regions of India, the Himalayan or an ocean. The area drained by a single river and the Peninsular rivers are different from system is called a drainage basin. A closer each other in many ways. Most of the observation on a map will indicate that any Himalayan rivers are perennial. It means elevated area, such as a mountain or an upland, that they have water throughout the year. separates two drainage basins. Such an upland These rivers receive water from rain as well is known as a water divide (Figure 3.1). as from melted snow from the lofty mountains. The two major Himalayan rivers, BB eaam m the Indus and the Brahmaputra originate SStrre A W from the north of the mountain ranges. They am at Strreea er have cut through the mountains making S Di vi de gorges. The Himalayan rivers have long courses from their source to the sea. They perform intensive erosional activity in their upper courses and carry huge loads of silt and sand. In the middle and the lower courses, these rivers form meanders, oxbow lakes, and many other depositional features in their Figure 3.1 : Water Divide The world’s largest drainage basin is of the Amazon river Which river has the largest basin in India? DRAINAGE SYSTEMS IN INDIA The drainage systems of India are mainly controlled by the broad relief features of the Figure 3.2 : A Gorge Drainage Patterns 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 are dendritic, trellis, rectangular, and radial patterns. The dendritic pattern develops where the river channel follows the slope of the terrain. The stream with its tributaries resembles the branches of a tree, thus the name dendritic. A river joined by its tributaries, at approximately right angles, develops a trellis pattern. A trellis drainage pattern develops where hard and soft rocks exist parallel to each other. A rectangular drainage pattern develops on a strongly jointed rocky terrain. The radial pattern develops when streams flow in different directions from a central peak or dome like structure. A combination of several patterns may be found in the same drainage basin. floodplains. They also have well-developed shallower courses as compared to their deltas (Figure 3.3). Himalayan counterparts. However, some of them originate in the central highlands and flow Source of River towards the west. Can you identify two such large rivers? Most of the rivers of peninsular Upper Course India originate in the Western Ghats and flow towards the Bay of Bengal. The Himalayan Rivers Middle Course The major Himalayan rivers are the Indus, the Ganga and the Brahmaputra. These rivers are long, and are joined by many large and important tributaries. A river alongwith its tributaries may be called a river system. Meander Ox-Bow Lake The Indus River System The river Indus rises in Tibet, near Lake Lower Mansarowar. Flowing west, it enters India in the Course Ladakh district of Jammu and Kashmir. It forms a picturesque gorge in this part. Several tributaries, the Zaskar, the Nubra, the Shyok Delta and the Hunza, join it in the Kashmir region. The Indus flows through Baltistan and Gilgit and emerges from the mountains at Attock. The Figure 3.3 : Some Features Made by Rivers Satluj, the Beas, the Ravi, the Chenab and the Jhelum join together to enter the Indus near A large number of the Peninsular rivers are Mithankot in Pakistan. Beyond this, the Indus seasonal, as their flow is dependent on rainfall. flows southwards eventually reaching the During the dry season, even the large rivers Arabian Sea, east of Karachi. The Indus plain have reduced flow of water in their channels. has a very gentle slope. With a total length of The Peninsular rivers have shorter and 2900 km, the Indus is one of the longest rivers 18 CONTEMPORARY INDIA  Figure 3.4 : Major Rivers and Lakes DRAINAGE 19 of the world. A little over a third of the Indus The main tributaries, which come from the basin is located in India in the states of Jammu peninsular uplands, are the Chambal, the and Kashmir, Himachal Pradesh and the Punjab Betwa and the Son. These rise from semi arid and the rest is in Pakistan. areas, have shorter courses and do not carry much water in them. Find out where and how According to the regulations they ultimately join the Ganga. of the Indus Water Treaty (1960), India can use Enlarged with the waters from its right and only 20 per cent of the total water carried by Indus river system. This water is used for irrigation in left bank tributaries, the Ganga flows the Punjab, Haryana and the southern and eastwards till Farakka in West Bengal. This is western parts of Rajasthan. the northernmost point of the Ganga delta. The river bifurcates here; the Bhagirathi-Hooghly The Ganga River System (a distributary) flows southwards through the The headwaters of the Ganga, called the deltaic plains to the Bay of Bengal. The ‘Bhagirathi’ is fed by the Gangotri Glacier and mainstream, flows southwards into joined by the Alaknanda at Devaprayag in Bangladesh and is joined by the Brahmaputra. Uttarakhand. At Haridwar the Ganga emerges Further down stream, it is known as the from the mountains on to the plains. 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 Sunderban delta. The Sundarban Delta 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 Royal Bengal tiger. The length of the Ganga is over 2500 km. Look at figure 3.4; can you identify the type of drainage pattern formed by the Ganga river system? Ambala is located on the water divide between the Indus and the Ganga river systems. The plains from Ambala to the Sunderban stretch over nearly 1800 km, but the fall in its Figure 3.5 : Confluence of Bhagirathi and Alaknanda at slope is hardly 300 metres. In other words, there Devaprayag is a fall of just one metre for every 6 km. Therefore, the river develops large meanders. The Ganga is joined by many tributaries from the Himalayas, a few of them being major The Brahmaputra River System rivers such as the Yamuna, the Ghaghara, the Gandak and the Kosi. The river Yamuna rises The Brahmaputra rises in Tibet east of from the Yamunotri Glacier in the Himalayas. Mansarowar lake very close to the sources of It flows parallel to the Ganga and as a right the Indus and the Satluj. It is slightly longer bank tributary, meets the Ganga at Allahabad. than the Indus, and most of its course lies The Ghaghara, the Gandak and the Kosi rise outside India. It flows eastwards parallel to in the Nepal Himalaya. They are the rivers, the Himalayas. On reaching the Namcha which flood parts of the northern plains every Barwa (7757 m), it takes a ‘U’ turn and enters year, causing widespread damage to life and India in Arunachal Pradesh through a gorge. property but enriching the soil for the extensive Here, it is called the Dihang and it is joined agricultural lands. by the Dibang, the Lohit, and many other 20 CONTEMPORARY INDIA tributaries to form the Brahmaputra in All the tributaries of the Narmada are very Assam. short and most of these join the main stream at right angles. The Narmada basin covers parts Brahmaputra is known as of Madhya Pradesh and Gujarat. the Tsang Po in Tibet and Jamuna in Bangladesh. The Tapi Basin In Tibet the river carries a smaller volume of The Tapi rises in the Satpura ranges, in the water and less silt as it is a cold and a dry area. Betul district of Madhya Pradesh. It also flows In India it passes through a region of high rainfall. in a rift valley parallel to the Narmada but it is Here the river carries a large volume of water and much shorter in length. Its basin covers parts considerable amount of silt. The Brahmaputra of Madhya Pradesh, Gujarat and Maharashtra. has a braided channel in its entire length in The coastal plains between Western Ghats Assam and forms many riverine islands. Do you and the Arabian sea are very narrow. Hence, remember the name of the world’s largest riverine the coastal rivers are short. The main west island formed by the Brahmaputra? flowing rivers are Sabarmati, Mahi, Every year during the rainy season, the Bharathpuzha and Periyar. Find out the states river overflows its banks, causing widespread in which these rivers drain the water. devastation due to floods in Assam and The Godavari Basin Bangladesh. Unlike other north Indian rivers the Brahmaputra is marked by huge deposits The Godavari is the largest Peninsular river. It rises from the slopes of the Western Ghats of silt on its bed causing the river bed to rise. in the Nasik district of Maharashtra. Its The river also shifts its channel frequently. length is about 1500 km. It drains into the Bay of Bengal. Its drainage basin is also the The Peninsular Rivers largest among the peninsular rivers. The The main water divide in Peninsular India is basin covers parts of Maharashtra (about 50 formed by the Western Ghats, which runs from per cent of the basin area lies in Maharashtra), north to south close to the western coast. Most Madhya Pradesh, Odisha and Andhra of the major rivers of the Peninsula such as Pradesh. The Godavari is joined by a number the Mahanadi, the Godavari, the Krishna and of tributaries such as the Purna, the Wardha, the Kaveri flow eastwards and drain into the the Pranhita, the Manjra, the Wainganga and Bay of Bengal. These rivers make deltas at the Penganga. The last three tributaries are their mouths. There are numerous small very large. Because of its length and the streams flowing west of the Western Ghats. area it covers, it is also known as the The Narmada and the Tapi are the only long ‘Dakshin Ganga’. rivers, which flow west and make esturies. The The Mahanadi Basin drainage basins of the peninsular rivers are The Mahanadi rises in the highlands of comparatively small in size. Chhattisgarh. It flows through Odisha to reach The Narmada Basin the Bay of Bengal. The length of the river is about 860 km. Its drainage basin is shared by The Narmada rises in the Amarkantak hills Maharashtra, Chhattisgarh, Jharkhand, in Madhya Pradesh. It flows towards the west and Odisha. in a rift valley formed due to faulting. On its way to the sea, the Narmada creates many The Krishna Basin picturesque locations. The ‘Marble rocks’, Rising from a spring near Mahabaleshwar, the near Jabalpur where the Narmada flows Krishna flows for about 1400 km and reaches through a deep gorge, and the ‘Dhuadhar the Bay of Bengal. The Tungabhadra, the falls’ where the river plunges over steep rocks, Koyana, the Ghatprabha, the Musi and the are some of the notable ones. Bhima are some of its tributaries. Its drainage DRAINAGE 21 basin is shared by Maharasthra, Karnataka India has many lakes. These differ from and Andhra Pradesh. each other in the size, and other characteristics. Most lakes are permanent; The Kaveri Basin some contain water only during the rainy The Kaveri rises in the Brahmagri range of the season, like the lakes in the basins of inland Western Ghats and it reaches the Bay of Bengal drainage of semi-arid regions. There are some in south of Cuddalore, in Tamil Nadu. Total of the lakes which are the result of the action length of the river is about 760 km. Its main of glaciers and ice sheets, while the others tributaries are Amravati, Bhavani, Hemavati have been formed by wind, river action, and and Kabini. Its basin drains parts of human activities. Karnataka, Kerala and Tamil Nadu. A meandering river across a flood plain forms cut-offs that later develop into ox-bow The river Kaveri makes the lakes. Spits and bars form lagoons in the second biggest waterfall in India, known as coastal areas, eg the Chilika lake, the Pulicat Sivasamudram. The hydroelectric power generated from the falls is supplied to Mysore, lake, the Kolleru lake. Lakes in the region of Bangalore and the Kolar Gold Field. inland drainage are sometimes seasonal; for example, the Sambhar lake in Rajasthan, which is a salt water lake. Its water is used for The name of the biggest waterfall in India. producing salt. Most of the fresh water lakes are in the Beside these major rivers, there are some Himalayan region. They are of glacial origin. smaller rivers flowing towards the east. The In other words, they formed when glaciers Damoder, the Brahmani, the Baitarni and the dug out a basin, which was later filled with Subarnrekha are some notable examples. snowmelt. The Wular lake in Jammu and Locate them in your atlas. Kashmir, in contrast, is the result of the tectonic activity. It is the largest freshwater 71 per cent of the world’s lake in India. The Dal lake, Bhimtal, Nainital, surface is covered with water, but 97 per cent of that is salt water. Loktak and Barapani are some other Of the 3 per cent that is available as freshwater, important fresh water lakes. three quarters of it is trapped as ice. Apart from natural lakes, the damming of the rivers for the generation of hydel power has LAKES also led to the formation of Lakes such as Guru Gobind Sagar (Bhakra Nangal Project). You may be familiar with the valley of Kashmir and the famous Dal Lake, the house boats and shikaras, which attract thousands of tourists every year. Similarly, you may have visited some other tourist spot near a lake and enjoyed boating, swimming and other water games. Imagine that if Srinagar, Nainital and other tourists 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? Apart from attraction for tourists lakes are also useful to human beings in many ways. Lakes of large extent are called the seas, like the Caspian, the Dead and the Aral seas. Figure 3.6 : Loktak Lake 22 CONTEMPORARY INDIA  Activity Make a list of natural and artifcial National River Conservation Plan (NRCP) lakes with the help of the atlas. The activities of Ganga Action Plan (GAP) phase-I, initiated in 1985, were declared closed on 31st March 2000. The Steering Lakes are of great value to human beings. Committee of the National River A lake helps to regulate the flow of a river. Conservation Authority reviewed the During heavy rainfall, it prevents flooding and progress of the GAP and necessary correction during the dry season, it helps to maintain on the basis of lessons learnt and experiences gained from GAP Phase-I. These an even flow of water. Lakes can also be used have been applied to the major polluted for developing hydel power. They moderate the rivers of the country under the NRCP. climate of the surroundings; maintain the The Ganga Action Plan (GAP) Phase-II, aquatic ecosystem, enhance natural beauty, has been merged with the NRCP. The expanded NRCP now covers 152 towns located help develop tourism and provide recreation. along 27 interstate rivers in 16 states. Under this action plan, pollution abatement works are being taken up in 57 towns. A total of ROLE OF RIVERS IN THE ECONOMY 215 schemes of pollution abatement have been sanctioned. So far, 69 schemes have Rivers have been of fundamental importance been completed under this action plan. A throughout the human history. Water from the million litres of sewage is targeted to be rivers is a basic natural resource, essential for intercepted, diverted and treated. various human activities. Therefore, the river banks have attracted settlers from ancient times. These settlements have now become big sewage and industrial effluents are emptied cities. Make a list of cities in your state which into the rivers. This affects not only the quality are located on the bank of a river. of water but also the self-cleansing capacity Using rivers for irrigation, navigation, of the river. For example, given the adequate hydro-power generation is of special streamflow, the Ganga water is able to dilute significance – particularly to a country like and assimilate pollution loads within 20 km India, where agriculture is the major source of large cities. But the increasing of livelihood of the majority of its population. urbanisation and industrialisation do not allow it to happen and the pollution level of many rivers has been rising. Concern over RIVER P OLLUTION rising pollution in our rivers led to the The growing domestic, municipal, industrial launching of various action plans to clean the and agricultural demand for water from rivers rivers. Have you heard about such action naturally affects the quality of water. As a plans? How does our health get affected by result, more and more water is being drained polluted river water? Think about “life of out of the rivers reducing their volume. On human beings without fresh water”. Arrange the other hand, a heavy load of untreated a debate on this topic in the class. EXERCISE 1. Choose the right answer from the four alternatives given below. (i) Which one of the following describes the drainage patterns resembling the branches of a tree? (a) Radial (c) Centrifugal (b) Dendritic (d) Trellis DRAINAGE 23  (ii) In which of the following states is the Wular lake located? (a) Rajasthan (c) Punjab (b) Uttar Pradesh (d) Jammu and Kashmir (iii) The river Narmada has its source at (a) Satpura (c) Amarkantak (b) Brahmagiri (d) Slopes of the Western Ghats (iv) Which one of the following lakes is a salt water lake? (a) Sambhar (c) Wular (b) Dal (d) Gobind Sagar (v) Which one of the following is the longest river of the Peninsular India? (a) Narmada (c) Godavari (b) Krishna (d) Mahanadi (vi) Which one amongst the following rivers flows through a rift valley? (a) Mahanadi (c) Krishna (b) Tungabhadra (d) Tapi 2. Answer the following questions briefly. (i) What is meant by a water divide? Give an example. (ii) Which is the largest river basin in India? (iii) Where do the rivers Indus and Ganga have their origin? (iv) Name the two headstreams of the Ganga. Where do they meet to form the Ganga? (v) Why does the Brahmaputra in its Tibetan part have less silt, despite a longer course? (vi) Which two Peninsular rivers flow through trough? (vii) State some economic benefits of rivers and lakes. 3. Below are given names of a few lakes of India. Group them under two categories – natural and created by human beings. (a) Wular (b) Dal (c) Nainital (d) Bhimtal (e) Gobind Sagar (f) Loktak (g) Barapani (h) Chilika (i) Sambhar (j) Rana Pratap Sagar (k) Nizam Sagar (l) Pulicat (m) Nagarjuna Sagar (n) Hirakund 4. Discuss the significant difference between the Himalayan and the Peninsular rivers. 5. Compare the east flowing and the west flowing rivers of the Peninsular plateau. 6. Why are rivers important for the country’s economy? Map Skills (i) On an outline map of India mark and label the following rivers: Ganga, Satluj, Damodar, Krishna, Narmada, Tapi, Mahanadi, and Brahmaputra. (ii) On an outline map of India mark and label the following lakes: Chilika, Sambhar, Wular, Pulicat, Kolleru. 24 CONTEMPORARY INDIA  Project/Activity Solve this crossword puzzle with the help of given clues. Across 1. Nagarjuna Sagar is a river valley project. Name the river? 2. The longest river of India. 3. The river which originates from a place known as Beas Kund. 4. The river which rises in the Betul district of MP and flows westwards. 5. The river which was known as the “Sorrow” of West Bengal. 6. The river on which the reservoir for India Gandhi canal has been built. 7. The river whose source lies near Rohtang Pass. 8. The longest river of Peninsular India? Down 9. A tributary of Indus originating from Himachal Pradesh. 10. The river flowing through fault, drains into the Arabian Sea. 11. A river of south India, which receives rain water both in summer and winter. 12. A river which flows through Ladakh, Gilgit and Pakistan. 13. An important river of the Indian desert. 14. The river which joins Chenab in Pakistan. 15. A river which rises at Yamunotri glacier. DRAINAGE 25