{"id":4009,"date":"2019-11-06T16:08:08","date_gmt":"2019-11-06T16:08:08","guid":{"rendered":"https:\/\/onlinefreenotes.com\/?p=4009"},"modified":"2026-01-05T09:41:56","modified_gmt":"2026-01-05T09:41:56","slug":"drainage","status":"publish","type":"post","link":"https:\/\/mockupbw.site\/2025\/onlinefreenotes\/drainage\/","title":{"rendered":"Drainage: NBSE class 9 social science chapter 7 answers"},"content":{"rendered":"\n<p>Get here solutions, questions, answers, and notes of chapter 7:&nbsp;<em>Drainage<\/em>&nbsp;which is a part of social science class 9 syllabus of students studying under the <a href=\"http:\/\/www.nbsenagaland.com\/\" target=\"_blank\" rel=\"noreferrer noopener\">Nagaland Board of School Education<\/a>. However, these notes should be used only for references and additions\/modifications should be made as per the requirements.<\/p>\n\n\n  <style>\r\n    .notice {\r\n      background: yellow;       \/* simple yellow background *\/\r\n      text-align: center;       \/* centre alignment *\/\r\n      padding: 12px 16px;\r\n      margin: 20px auto;\r\n      width: fit-content;       \/* shrink to text and centre via auto margins *\/\r\n      font-family: Arial, sans-serif;\r\n    }\r\n  <\/style>\r\n  <div class=\"notice\">\r\n    If you notice any errors in the notes, please mention them in the comments\r\n  <\/div>\r\n<nav id=\"toc\" class=\"toc-box\"><\/nav>\r\n<style>\r\n.toc-box{\r\n  border:1px solid #e5e7eb;\r\n  border-radius:8px;\r\n  background:#fff;\r\n  margin:20px 0;\r\n  font-family:Arial, Helvetica, sans-serif\r\n}\r\n.toc-header{\r\n  padding:10px 14px;\r\n  font-size:16px;\r\n  font-weight:600;\r\n  border-bottom:1px solid #eef2f7;\r\n  background:#f8fafc\r\n}\r\n.toc-content{\r\n  padding:12px 18px\r\n}\r\n\r\n\/* Base list *\/\r\n.toc-content ul{\r\n  margin:0 25px;\r\n  padding-left:0;\r\n  list-style:none\r\n}\r\n\r\n\/* Level-based bullets *\/\r\n.toc-content li{\r\n  position:relative;\r\n  margin:6px 0;\r\n  margin-left:6px;\r\n  line-height:1.5;\r\n\tlist-style:disc;\r\n}\r\n\r\n\/* H2 bullet \u25cf *\/\r\n.toc-content li.level-2{\r\n  list-style:disc;\r\n\t\r\n}\r\n\r\n\/* H3 bullet \u25cb *\/\r\n.toc-content li.level-3{\r\n  margin-left:26px;\r\n\tlist-style:disc;\r\n}\r\n\r\n\r\n\/* H4+ bullet \u2013 *\/\r\n.toc-content li.level-4{\r\n  margin-left:46px;\r\n\tlist-style:disc;\r\n}\r\n.toc-content li.level-5,\r\n.toc-content li.level-6{\r\n  margin-left:66px;\r\n\tlist-style:disc;\r\n}\r\n\r\n.toc-content a{\r\n  text-decoration:none;\r\n  color:#000\r\n}\r\n.toc-content a:hover{\r\n  text-decoration:underline\r\n}\r\n\r\nhtml{scroll-behavior:smooth}\r\nh1[id],h2[id],h3[id],h4[id],h5[id],h6[id]{\r\n  scroll-margin-top:110px\r\n}\r\n<\/style>\r\n\r\n<script>\r\ndocument.addEventListener('DOMContentLoaded', function () {\r\n\r\n  const toc = document.getElementById('toc');\r\n  if (!toc) return;\r\n\r\n  \/* MAIN CONTENT ONLY *\/\r\n  const content = document.querySelector('#pdf-content');\r\n\r\n  \/* EXCLUDE AREAS *\/\r\n  const excludeSelectors = `\r\n    .author, .byline, .entry-meta, .post-meta,\r\n    #comments, .comments-area, .comment-respond,\r\n    .comment-form, .comment-list,\r\n    .login, .login-required,\r\n    .sidebar, aside, footer, nav,\r\n    .widget, .widgets\r\n  `;\r\n\r\n  \/* TEXT TO IGNORE *\/\r\n  const ignoreText = [\r\n    'leave a comment',\r\n    'cancel reply',\r\n    'login required',\r\n    'get notes',\r\n    'ron\\'e dutta',\r\n    'comments'\r\n  ];\r\n\r\n  \r\nconst headings = [...content.querySelectorAll('h1,h2,h3,h4,h5,h6')]\r\n  .filter(h => !excludeSelectors || !h.closest(excludeSelectors))\r\n  .filter(h => {\r\n    const txt = h.textContent.trim().toLowerCase();\r\n    return txt.length > 0 && !ignoreText.some(t => txt.includes(t));\r\n  });\r\n\r\n\/\/alert(content);\r\n  if (!headings.length) {\r\n    toc.style.display = 'none';\r\n    return;\r\n  }\r\n\r\n  \/* UNIQUE IDs *\/\r\n  const used = {};\r\n  const slug = t => t.toLowerCase().trim()\r\n    .replace(\/[^a-z0-9\\s-]\/g, '')\r\n    .replace(\/\\s+\/g, '-');\r\n\r\n  headings.forEach(h => {\r\n    if (!h.id) {\r\n      let base = slug(h.textContent) || 'section';\r\n      used[base] = (used[base] || 0) + 1;\r\n      h.id = used[base] > 1 ? base + '-' + used[base] : base;\r\n    }\r\n  });\r\n\r\n  \/* BUILD TOC *\/\r\n  const ul = document.createElement('ul');\r\n\r\n  headings.forEach(h => {\r\n    const level = parseInt(h.tagName.substring(1));\r\n    if (level < 2) return; \/\/ skip H1 like your reference site\r\n\r\n    const li = document.createElement('li');\r\n    li.className = 'level-' + level;\r\n\r\n    const a = document.createElement('a');\r\n    a.href = '#' + h.id;\r\n    a.textContent = h.textContent.trim();\r\n\r\n    li.appendChild(a);\r\n    ul.appendChild(li);\r\n  });\r\n\r\n  toc.innerHTML = `\r\n    <div class=\"toc-header\">Table of Contents<\/div>\r\n    <div class=\"toc-content\"><\/div>\r\n  `;\r\n  toc.querySelector('.toc-content').appendChild(ul);\r\n\r\n});\r\n<\/script>\r\n\n\n\n\n<h3 class=\"wp-block-heading\" id=\"Introduction\"><strong>Introduction<\/strong><\/h3>\n\n\n\n<p>The term drainage describes the river system of an area. Small streams flowing from different directions come together to form the main river, which ultimately drains into a large water body such as a lake or a sea or an ocean. The area drained by a single river system is called a drainage basin.<\/p>\n\n\n\n<p>A closer observation on a map will indicate that any elevated area, such as a mountain or an upland, separates two drainage basins. Such an upland is known as water divide.  The drainage systems of India are mainly controlled by the broad relief features of the subcontinent.<\/p>\n\n\n\n\n\n<h3 class=\"wp-block-heading\" id=\"Textual_questions_and_answers\"><strong>Textual questions and answers<\/strong><\/h3>\n\n\n\n<h4 class=\"wp-block-heading\" id=\"I_Choose_the_correct_answer\"><strong>Choose the correct answer<\/strong><\/h4>\n\n\n\n<p><strong>1. In which of the following states is the Wular lake located?<\/strong><\/p>\n\n\n\n<p>(a) Rajasthan (b) Punjab (c) Uttar Pradesh (d) Jammu and Kashmir<\/p>\n\n\n\n<p><strong>Answer<\/strong>: D. Jammu and Kashmir<\/p>\n\n\n\n<p><strong>2. Why is the Godavari River sometimes referred to as the &#8220;Dakshin Ganga&#8221;?<\/strong><\/p>\n\n\n\n<p>(a) Due to its spiritual significance (b) Because it flows northwards (c) It is the longest river in India (d) It flows through the Himalayas<\/p>\n\n\n\n<p><strong>Answer<\/strong>: A. Due to its spiritual significance<\/p>\n\n\n\n<p><strong>3. The river Narmada has its source at<\/strong><\/p>\n\n\n\n<p>(a) Satpura (b) Amarkantak (c) Brahmagiri (d) Slopes of the Western Ghats<\/p>\n\n\n\n<p><strong>Answer<\/strong>: B. Amarkantak<\/p>\n\n\n\n<p><strong>4. Which one of the following lakes is a salt water lake?<\/strong><\/p>\n\n\n\n<p>(a) Sambhar (b) Wular (c) Dal (d) Gobind Sagar<\/p>\n\n\n\n<p><strong>Answer<\/strong>: A. Sambhar<\/p>\n\n\n\n<p><strong>5. Which of the following statements about the above drainage pattern is incorrect?<\/strong><\/p>\n\n\n\n<p>(a) This pattern develops in a region made of rocks having a uniform structure (b) There is a single main stream with tributaries joining like the branches of a tree (c) The direction of the river and its tributaries are determined by the slope (d) The river flows outward forming a pattern like the spokes of a wheel<\/p>\n\n\n\n<p><strong>Answer<\/strong>: B. There is a single main stream with tributaries joining like the branches of a tree<\/p>\n\n\n\n<p><strong>6. Consider the statements given below and choose the correct answer.<\/strong><\/p>\n\n\n\n<p>Statement I: The Indus is about 2900 km long.<br>Statement II: It originates near Mansarovar lake.<\/p>\n\n\n\n<p>(a) Statement (I) is correct and (II) is incorrect (b) Statement (I) is incorrect and (II) is correct (c) Both (I) and (II) are incorrect (d) Both (I) and (II) are correct<\/p>\n\n\n\n<p><strong>Answer<\/strong>: D. Both (I) and (II) are correct<\/p>\n\n\n\n<h4 class=\"wp-block-heading\" id=\"II_Very_Short_Answer_Type_Questions\"><strong>Very short answer type questions<\/strong><\/h4>\n\n\n\n<p><strong>1. What is a drainage basin.<\/strong><\/p>\n\n\n\n<p><strong>Answer<\/strong>: The area drained by a single river system is called a drainage basin.<\/p>\n\n\n\n<p><strong>2. Where do the following rivers originate?<br>(a) Kaveri (b) Brahmaputra (c) Mahanadi (d) Tapi<\/strong><\/p>\n\n\n\n<p><strong>Answer<\/strong>: (a) Brahmagir Hills, ht. 1,341 m.<\/p>\n\n\n\n<p>(b) About 100 km S.W. of Mansarovar ht. 5,150 m.<\/p>\n\n\n\n<p>(c) Raipur district, Chhattisgarh ht. 442 m.<\/p>\n\n\n\n<p>(d) Rises in Betul district.<\/p>\n\n\n\n<p><strong>3. What is a watershed?<\/strong><\/p>\n\n\n\n<p><strong>Answer<\/strong>: Watershed is the boundary between two rivers.<\/p>\n\n\n\n<p><strong>4. What is the radial pattern of rivers?<\/strong><\/p>\n\n\n\n<p><strong>Answer<\/strong>: This has the streams flowing in different directions from a central peak or dome-like structure.<\/p>\n\n\n\n<p><strong>5. Name the different stages of rivers.<\/strong><\/p>\n\n\n\n<p><strong>Answer<\/strong>: The different stages of rivers are:<\/p>\n\n\n\n<p>i. Source of river<br>ii. Upper course<br>iii. Middle course<br>iv. Oxbow lake<br>v. Lower course<br>vi. Delta<\/p>\n\n\n\n<p><strong>6. Where do the river Indus and Ganga have their origin?<\/strong><\/p>\n\n\n\n<p><strong>Answer<\/strong>: Indus has its origins in the Himalayas of western Tibet, near the lake Mansarowar. The Ganga rises in the Himalayas on the Indian side of the Tibet border.<\/p>\n\n\n\n<h4 class=\"wp-block-heading\" id=\"III_Short_Answer_Type_Questions\"><strong>Short answer type questions.<\/strong><\/h4>\n\n\n\n<p><strong>1. Differentiate between dendritic and trellis pattern of rivers.<\/strong><\/p>\n\n\n\n<p><strong>Answer<\/strong>: <em>A dendritic patter<\/em>: This consists of a single mainstream with tributaries joining like the branches of a tree.<\/p>\n\n\n\n<p><em>A trellis pattern<\/em>: This is a rectangular pattern formed when a long river is joined by short flowing streams, approximately at right angles.<\/p>\n\n\n\n<p><strong>2. Give any three characteristics of Himalayan rivers.<\/strong><\/p>\n\n\n\n<p><strong>Answer<\/strong>: Three characteristics of Himalayan rivers are:<\/p>\n\n\n\n<p>i. These rivers have large basins, e.g. Indus Basin.<br>ii. The rivers passing through the Himalayas create spectacular gorges.<br>iii. The steep rock-sided deep valleys were created by the down-cutting of the river during the period of the Himalayan uplift.<\/p>\n\n\n\n<p><strong>3. Why are rivers important for the country&#8217;s economy?<\/strong><\/p>\n\n\n\n<p><strong>Answer<\/strong>: Rivers are important for the country&#8217;s economy because of the following reasons:<\/p>\n\n\n\n<p>i. River valleys provided easy routes and fertile land. This helps in the transportation of goods and agriculture.<br>ii. Rivers are needed for hydroelectric projects which powers the country.<\/p>\n\n\n\n<h4 class=\"wp-block-heading\" id=\"V_Long_Answer_Type_Questions\"><strong>Long answer type questions<\/strong><\/h4>\n\n\n\n<p><strong>1. What is the difference between the peninsular rivers and Himalayan rivers?<\/strong><\/p>\n\n\n\n<p><strong>Answer<\/strong>: The difference between the peninsular and Himalayan rivers are as follows:<\/p>\n\n\n\n<figure class=\"wp-block-table\"><table><tbody><tr><td><strong>Peninsular rivers <\/strong><\/td><td><strong>Himalayan rivers <\/strong><\/td><\/tr><tr><td>Most of these rivers are seasonal and their flow depends on rainfall.<\/td><td>These rivers are perennial as they receive water from rainfall and melting ice all the time.<\/td><\/tr><tr><td>The gentler slopes cause a low intensity of erosional activity as compared to other rivers.<\/td><td>These rivers carry out intensive erosional activities upstream and also carry huge loads of sand and silt.<\/td><\/tr><tr><td>These rivers do not have many meanders as the hard rock bed and lack of silt and sand does not allow them.<\/td><td>When in the plains, these rivers form large meanders and depositional features such as flood plains, river cliffs and levees.<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n<p><strong>2. Write notes on (i) Ganga System (ii) Brahmaputra System (iii) Indus System.<\/strong><\/p>\n\n\n\n<p><strong>Answer<\/strong>: (i) <em>The Ganga System<\/em>: The length of the river Ganga is 2510 km. Rising in the Himalayas on the Indian side of the Tibet border, the Ganga&#8217;s five headstreams Bhagirathi, Alaknanda, Mandakini, Dhauliganga and Pindar have their origins in Uttarakhand. The Alaknanda and Bhagirathi meet at Devaprayag to form the Ganga. In Bangladesh, Brahmaputra joins Ganga to form the combined stream called the Padma.<\/p>\n\n\n\n<p>(ii) <em>The Brahmaputra System<\/em>: The Brahmaputra or Yarlung Zangbo is one of the great rivers of southern Asia. The river&#8217;s source lies in the Chemayungdung Glacier. The river flows for nearly 1,126 km in an easterly direction. Throughout its upper course, the river is generally known as the Tsangpo. Near Sadiya, Assam, the Dihang changes course to the southwest and is known as the Brahmaputra. After flowing 800 km in this direction it turns south again, going through Bangladesh.<\/p>\n\n\n\n<p>(iii) <em>The Indus System<\/em>: The Indus is approximately 2900 kilometres long. Its sources are in western Tibet&#8217;s Himalayas, near Lake Mansarowar. It winds its way through Ladakh. It is joined by various tributaries at Gilgit. Attock is where it emerges from the mountains. The Indian states of Jammu and Kashmir, Himachal Pradesh, and Punjab make up a third of the Indus Basin. The remainder is located in Pakistan. The Indus has a drainage area of around 1,165,500 square kilometres, with 453,250 square kilometres in the Himalayan ranges and foothills and the rest in Pakistan&#8217;s semi-arid plains. It is one of the world&#8217;s longest rivers. The Sutlej, Ravi, Chenab, Jhelum, and Beas are five of its tributaries.<\/p>\n\n\n\n<p><strong>3. Suppose, you are travelling from Haridwar to Siliguri along the foothills of the Himalayas. Name the important rivers you will come across. Describe the characteristics of any one of them.<\/strong><\/p>\n\n\n\n<p><strong>Answer<\/strong>: Travelling from Haridwar to Siliguri along the foothills of the Himalayas, you would encounter several major rivers that are part of the rich and extensive river systems of the region. These include the Ganga, Yamuna, and the Brahmaputra, among others.<\/p>\n\n\n\n<p>The Ganga, also known as the Ganges, is particularly notable among these. Originating from the Gangotri Glacier in the Uttarakashi district of Uttarakhand, the river travels through the plains of North India, flowing southeast through the Gangetic Plain of North India into Bangladesh, where it empties into the Bay of Bengal. The Ganga is sacred to Hindus, and its water is considered purifying. It supports some of the most densely populated areas in the world, with millions depending on it for their daily water needs.<\/p>\n\n\n\n<p>The Ganga is characterised by its extensive basin, which is the largest river basin in India, covering more than a million square kilometres. It is a lifeline to millions of Indians who live along its course and depend on it for their daily needs. The river is known for its strong religious significance as well as its pivotal role in agriculture, particularly through its fertile plains. However, it is also one of the world&#8217;s most polluted rivers, with severe pollution threatening the health of humans and wildlife dependent on it. Efforts to clean and rejuvenate the Ganga have been ongoing for decades, highlighting its environmental and cultural importance.<\/p>\n\n\n\n<h3 class=\"wp-block-heading\" id=\"Extra_MCQs\"><strong>Extra MCQs<\/strong><\/h3>\n\n\n\n<p><strong>1. What is the term for an elevated area, such as a mountain, that separates two drainage basins?<\/strong><\/p>\n\n\n\n<p>A. Drainage divide<br>B. Watershed<br>C. Water divide<br>D. River basin<\/p>\n\n\n\n<p><strong>Answer:<\/strong>&nbsp;C. Water divide<\/p>\n\n\n\n\n\n<p><strong>2. The river Narmada has its source at which of the following locations?<\/strong><\/p>\n\n\n\n<p>A. Satpura<br>B. Brahmagiri<br>C. Betul<br>D. Amarkantak<\/p>\n\n\n\n<p><strong>Answer:<\/strong>&nbsp;D. Amarkantak<\/p>\n\n\n\n<p><strong>3. A curved lake formed from a horseshoe bend in a river, where the main stream has cut a new, shorter course, is known as a:<\/strong><\/p>\n\n\n\n<p>A. Meander<br>B. Oxbow lake<br>C. Delta<br>D. Gorge<\/p>\n\n\n\n<p><strong>Answer:<\/strong>&nbsp;B. Oxbow lake<\/p>\n\n\n\n<p><strong>4. Which of the following is the largest peninsular river in India?<\/strong><\/p>\n\n\n\n<p>A. Krishna<br>B. Godavari<br>C. Mahanadi<br>D. Kaveri<\/p>\n\n\n\n<p><strong>Answer:<\/strong>&nbsp;B. Godavari<\/p>\n\n\n\n<p><strong>5. The confluence of the Alaknanda and Bhagirathi rivers, which marks the beginning of the Ganga river, occurs at:<\/strong><\/p>\n\n\n\n<p>A. Haridwar<br>B. Rishikesh<br>C. Devaprayag<br>D. Gangotri<\/p>\n\n\n\n<p><strong>Answer:<\/strong>&nbsp;C. Devaprayag<\/p>\n\n\n\n<p><strong>6. Which of the following is an example of a salt water lake?<\/strong><\/p>\n\n\n\n<p>A. Dal<br>B. Wular<br>C. Gobind Sagar<br>D. Sambhar<\/p>\n\n\n\n<p><strong>Answer:<\/strong>&nbsp;D. Sambhar<\/p>\n\n\n\n<p><strong>7. The drainage pattern that resembles the branches of a tree is called:<\/strong><\/p>\n\n\n\n<p>A. Dendritic<br>B. Trellis<br>C. Radial<br>D. Centrifugal<\/p>\n\n\n\n<p><strong>Answer:<\/strong>&nbsp;A. Dendritic<\/p>\n\n\n\n<p><strong>8. In Tibet, the Brahmaputra river is known by what name?<\/strong><\/p>\n\n\n\n<p>A. Dihang<br>B. Tsangpo<br>C. Jamuna<br>D. Padma<\/p>\n\n\n\n<p><strong>Answer:<\/strong>&nbsp;B. Tsangpo<\/p>\n\n\n\n<p><strong>9. The river Krishna originates from a spring near:<\/strong><\/p>\n\n\n\n<p>A. Nasik<br>B. Amarkantak<br>C. Brahmagiri<br>D. Mahabaleshwar<\/p>\n\n\n\n<p><strong>Answer:<\/strong>&nbsp;D. Mahabaleshwar<\/p>\n\n\n\n<p><strong>10. Which two major Himalayan rivers originate from the north of the mountain ranges, near Lake Mansarovar?<\/strong><\/p>\n\n\n\n<p>A. Ganga and Yamuna<br>B. Indus and Brahmaputra<br>C. Jhelum and Chenab<br>D. Sutlej and Beas<\/p>\n\n\n\n<p><strong>Answer:<\/strong>&nbsp;B. Indus and Brahmaputra<\/p>\n\n\n\n<p><strong>11. The famous &#8216;Marble Rocks&#8217; are formed by which river near Jabalpur?<\/strong><\/p>\n\n\n\n<p>A. Tapi<br>B. Godavari<br>C. Narmada<br>D. Mahanadi<\/p>\n\n\n\n<p><strong>Answer:<\/strong>&nbsp;C. Narmada<\/p>\n\n\n\n<p><strong>12. According to the International Commission on Large Dams (ICOLD), a &#8216;large dam&#8217; is defined as one measuring how many metres or more from foundation to crest?<\/strong><\/p>\n\n\n\n<p>A. 10 metres<br>B. 15 metres<br>C. 20 metres<br>D. 25 metres<\/p>\n\n\n\n<p><strong>Answer:<\/strong>&nbsp;B. 15 metres<\/p>\n\n\n\n<p><strong>13. Which of the following is a major west-flowing peninsular river that flows in a trough parallel to the Narmada?<\/strong><\/p>\n\n\n\n<p>A. Kaveri<br>B. Krishna<br>C. Mahanadi<br>D. Tapi<\/p>\n\n\n\n<p><strong>Answer:<\/strong>&nbsp;D. Tapi<\/p>\n\n\n\n<p><strong>14. The area drained by a single river system is called a:<\/strong><\/p>\n\n\n\n<p>A. Water divide<br>B. Drainage basin<br>C. Watershed<br>D. Catchment area<\/p>\n\n\n\n<p><strong>Answer:<\/strong>&nbsp;B. Drainage basin<\/p>\n\n\n\n<p><strong>15. The Sunderbans Delta is formed by the combined waters of which two rivers?<\/strong><\/p>\n\n\n\n<p>A. Ganga and Yamuna<br>B. Indus and Jhelum<br>C. Ganga and Brahmaputra<br>D. Godavari and Krishna<\/p>\n\n\n\n<p><strong>Answer:<\/strong>&nbsp;C. Ganga and Brahmaputra<\/p>\n\n\n\n<p><strong>16. (I) Himalayan rivers are described as perennial.<\/strong><br><strong>(II) They receive water from both rainfall and the melting of snow from mountains.<\/strong><\/p>\n\n\n\n<p>A. I is a contradiction of II.<br>B. I is independent of II.<br>C. II is the cause of I.<br>D. I is an example of II.<\/p>\n\n\n\n<p><strong>Answer:<\/strong>&nbsp;C. II is the cause of I.<\/p>\n\n\n\n<p><strong>17. Statement 1: The Narmada and Tapi are major rivers that flow westwards into the Arabian Sea.<\/strong><br><strong>Statement 2: Most of the main peninsular rivers, like the Godavari and Krishna, flow eastwards into the Bay of Bengal.<\/strong><\/p>\n\n\n\n<p>A. Statement 1 is true, and Statement 2 is false.<br>B. Both statements are true.<br>C. Statement 1 is false, and Statement 2 is true.<br>D. Both statements are false.<\/p>\n\n\n\n<p><strong>Answer:<\/strong>&nbsp;B. Both statements are true.<\/p>\n\n\n\n<p><strong>18. (I) In their upper courses, Himalayan rivers engage in intensive erosional activity.<\/strong><br><strong>(II) As a result, they carry huge loads of silt and sand downstream.<\/strong><\/p>\n\n\n\n<p>A. I is independent of II.<br>B. I is a contradiction of II.<br>C. I is an example of II.<br>D. II is the result of I.<\/p>\n\n\n\n<p><strong>Answer:<\/strong>&nbsp;D. II is the result of I.<\/p>\n\n\n\n<p><strong>19. (I) A trellis drainage pattern develops in regions with alternating belts of hard and soft rocks.<\/strong><br><strong>(II) This pattern is characterized by a long main river joined by shorter tributaries at approximately right angles.<\/strong><\/p>\n\n\n\n<p>A. I is the cause for the feature described in II.<br>B. I is a contradiction of II.<br>C. II is the cause of I.<br>D. I is independent of II.<\/p>\n\n\n\n<p><strong>Answer:<\/strong>&nbsp;A. I is the cause for the feature described in II.<\/p>\n\n\n\n<p><strong>20. (I) The Godavari River is often referred to as the &#8216;Dakshin Ganga&#8217;.<\/strong><br><strong>(II) The Kaveri river has its source in the Brahmagiri range of the Western Ghats.<\/strong><\/p>\n\n\n\n<p>A. I is the cause for II.<br>B. I is a contradiction of II.<br>C. I is independent of II.<br>D. II is an example of I.<\/p>\n\n\n\n<p><strong>Answer:<\/strong>&nbsp;C. I is independent of II.<\/p>\n\n\n\n<p><strong>21. Statement 1: A radial drainage pattern is formed when streams flow in different directions from a central peak or dome-like structure.<\/strong><br><strong>Statement 2: A dendritic drainage pattern is formed when streams converge from all sides towards a central depression.<\/strong><\/p>\n\n\n\n<p>A. Both the statements are true.<br>B. Both the statements are false.<br>C. Statement 1 is true, and Statement 2 is false.<br>D. Statement 1 is false, and Statement 2 is true.<\/p>\n\n\n\n<p><strong>Answer:<\/strong>&nbsp;C. Statement 1 is true, and Statement 2 is false.<\/p>\n\n\n\n<p><strong>22. (I) Large dams can create vast reservoirs and generate significant hydroelectric power.<\/strong><br><strong>(II) The creation of these reservoirs can displace thousands of people and upset the local ecological balance.<\/strong><\/p>\n\n\n\n<p>A. I is the cause of II.<br>B. I and II present the positive and negative aspects of the same subject.<br>C. I is a contradiction of II.<br>D. II is an example of I.<\/p>\n\n\n\n<p><strong>Answer:<\/strong>&nbsp;B. I and II present the positive and negative aspects of the same subject.<\/p>\n\n\n\n<p><strong>23. Arrange the typical stages of a river&#8217;s course from its origin to its end.<\/strong><\/p>\n\n\n\n<p>(i) Middle Course<br>(ii) Lower Course<br>(iii) Upper Course<\/p>\n\n\n\n<p>A. (iii) \u2192 (i) \u2192 (ii)<br>B. (i) \u2192 (iii) \u2192 (ii)<br>C. (ii) \u2192 (i) \u2192 (iii)<br>D. (iii) \u2192 (ii) \u2192 (i)<\/p>\n\n\n\n<p><strong>Answer:<\/strong>&nbsp;A. (iii) \u2192 (i) \u2192 (ii)<\/p>\n\n\n\n<p><strong>24. Select the option that correctly lists the sequence of events in the formation of an oxbow lake.<\/strong><\/p>\n\n\n\n<p>(i) The river cuts across the narrow neck of the meander loop.<br>(ii) A river flows in a winding, curvy path called a meander.<br>(iii) Deposition seals off the old meander, forming a separate curved lake.<\/p>\n\n\n\n<p>A. (i) \u2192 (iii) \u2192 (ii)<br>B. (ii) \u2192 (i) \u2192 (iii)<br>C. (iii) \u2192 (ii) \u2192 (i)<br>D. (ii) \u2192 (iii) \u2192 (i)<\/p>\n\n\n\n<p><strong>Answer:<\/strong>&nbsp;B. (ii) \u2192 (i) \u2192 (iii)<\/p>\n\n\n\n<p><strong>25. Arrange the following peninsular rivers in descending order of their approximate length.<\/strong><\/p>\n\n\n\n<p>(i) Krishna<br>(ii) Godavari<br>(iii) Narmada<br>(iv) Kaveri<\/p>\n\n\n\n<p>A. (ii) \u2192 (i) \u2192 (iii) \u2192 (iv)<br>B. (i) \u2192 (ii) \u2192 (iv) \u2192 (iii)<br>C. (ii) \u2192 (iii) \u2192 (i) \u2192 (iv)<br>D. (i) \u2192 (iii) \u2192 (ii) \u2192 (iv)<\/p>\n\n\n\n<p><strong>Answer:<\/strong>&nbsp;A. (ii) \u2192 (i) \u2192 (iii) \u2192 (iv)<\/p>\n\n\n\n\n\n<p><strong>26. Consider the journey of the Brahmaputra river. Choose the correct chronological order of the names it assumes.<\/strong><\/p>\n\n\n\n<p>(i) Dihang (as it enters India)<br>(ii) Jamuna (in Bangladesh)<br>(iii) Tsangpo (in Tibet)<br>(iv) Brahmaputra (in Assam valley)<\/p>\n\n\n\n<p>A. (iii) \u2192 (iv) \u2192 (i) \u2192 (ii)<br>B. (i) \u2192 (iii) \u2192 (iv) \u2192 (ii)<br>C. (iii) \u2192 (i) \u2192 (iv) \u2192 (ii)<br>D. (iv) \u2192 (iii) \u2192 (ii) \u2192 (i)<\/p>\n\n\n\n<p><strong>Answer:<\/strong>&nbsp;C. (iii) \u2192 (i) \u2192 (iv) \u2192 (ii)<\/p>\n\n\n\n<h3 class=\"wp-block-heading\" id=\"Extra_questions_and_answers\"><strong>Extra questions and answers<\/strong><\/h3>\n\n\n\n<p><strong>1. Into which two major groups are the rivers of India divided?<\/strong><\/p>\n\n\n\n<p><strong>Answer<\/strong>: The Indian rivers are divided into two major groups:<br>(i) The Himalayan rivers; and<br>(ii) The Peninsular rivers.<\/p>\n\n\n\n\n\n<p><strong>2. Why are most of the Himalayan rivers considered perennial?<\/strong><\/p>\n\n\n\n<p><strong>Answer<\/strong>: Most of the Himalayan rivers are considered perennial because they have water throughout the year.<\/p>\n\n\n\n<p><strong>3. What are the two main sources of water for the Himalayan rivers?<\/strong><\/p>\n\n\n\n<p><strong>Answer<\/strong>: The Himalayan rivers receive water from rain as well as from melted snow from the lofty mountains.<\/p>\n\n\n\n<p><strong>5. Name the two major Himalayan rivers that originate north of the mountain ranges.<\/strong><\/p>\n\n\n\n<p><strong>Answer<\/strong>: The two major Himalayan rivers that originate from the north of the mountain ranges are the Indus and the Brahmaputra.<\/p>\n\n\n\n<p><strong>6. What landforms do Himalayan rivers create when they cut through mountains?<\/strong><\/p>\n\n\n\n<p><strong>Answer<\/strong>: The Himalayan rivers cut through the mountains making gorges.<\/p>\n\n\n\n<p><strong>7. What features do Himalayan rivers form in their middle and lower courses?<\/strong><\/p>\n\n\n\n<p><strong>Answer<\/strong>: In their middle and lower courses, Himalayan rivers form meanders, oxbow lakes, and many other depositional features in their floodplains. They also have well-developed deltas.<\/p>\n\n\n\n<p><strong>8. What are the small rivers that join larger rivers called?<\/strong><\/p>\n\n\n\n<p><strong>Answer<\/strong>: Small rivers that join bigger rivers are called tributaries.<\/p>\n\n\n\n<p><strong>9. What is the beginning of a river called? What is its end called?<\/strong><\/p>\n\n\n\n<p><strong>Answer<\/strong>: The beginning of a river is called its source. The place where a river ends its flow is the river&#8217;s mouth.<\/p>\n\n\n\n<p><strong>11. What is the part of a river valley that is covered by water called?<\/strong><\/p>\n\n\n\n<p><strong>Answer<\/strong>: The part of a river valley covered by water is called the bed or channel.<\/p>\n\n\n\n<p><strong>12. What is another name for divides that determine the direction of rainwater flow?<\/strong><\/p>\n\n\n\n<p><strong>Answer<\/strong>: Divides that decide in which direction the rainwater will flow are sometimes called watersheds.<\/p>\n\n\n\n<p><strong>13. What is the area of land drained by a single river called?<\/strong><\/p>\n\n\n\n<p><strong>Answer<\/strong>: An area drained by a single river is called its catchment area.<\/p>\n\n\n\n<p><strong>14. What factors determine the drainage patterns formed by streams and rivers?<\/strong><\/p>\n\n\n\n<p><strong>Answer<\/strong>: The drainage patterns formed by streams and rivers are determined based on the relief, geological structure, and climatic conditions of the area.<\/p>\n\n\n\n<p><strong>15. Describe the appearance of a dendritic drainage pattern.<\/strong><\/p>\n\n\n\n<p><strong>Answer<\/strong>: A dendritic drainage pattern consists of a single main stream with tributaries joining like the branches of a tree.<\/p>\n\n\n\n<p><strong>16. In what type of geological region does a trellis pattern typically develop?<\/strong><\/p>\n\n\n\n<p><strong>Answer<\/strong>: A trellis pattern develops in a region which is made up of alternate belts of hard and soft rocks all of which dip in the same direction.<\/p>\n\n\n\n<p><strong>17. What is the characteristic shape of a radial drainage pattern?<\/strong><\/p>\n\n\n\n<p><strong>Answer<\/strong>: In a radial drainage pattern, the rivers flow outward forming a pattern like the spokes of a wheel.<\/p>\n\n\n\n<p><strong>18. In which type of areas is the centrifugal drainage pattern usually found?<\/strong><\/p>\n\n\n\n<p><strong>Answer<\/strong>: The centrifugal drainage pattern is usually found in arid areas.<\/p>\n\n\n\n<p><strong>19. Name the three main river systems that originate in the Himalayas.<\/strong><\/p>\n\n\n\n<p><strong>Answer<\/strong>: The three main river systems that originate in the Himalayas are:<br>(i) The Indus System<br>(ii) The Ganga System<br>(iii) The Brahmaputra System.<\/p>\n\n\n\n<p><strong>20. What is the approximate length of the Indus river?<\/strong><\/p>\n\n\n\n<p><strong>Answer<\/strong>: The Indus river is about 2900 km long.<\/p>\n\n\n\n<p><strong>21. From which Sanskrit word is the name of the river Indus derived?<\/strong><\/p>\n\n\n\n<p><strong>Answer<\/strong>: The name of the river Indus has its origins from the Sanskrit word sindhu, which means &#8216;river&#8217; or &#8216;stream&#8217;.<\/p>\n\n\n\n<p><strong>22. What is the approximate length of the river Ganga?<\/strong><\/p>\n\n\n\n<p><strong>Answer<\/strong>: The length of the river Ganga is 2510 km.<\/p>\n\n\n\n<p><strong>23. Name the five headstreams that form the river Ganga.<\/strong><\/p>\n\n\n\n<p><strong>Answer<\/strong>: The five headstreams that form the river Ganga are Bhagirathi, Alaknanda, Mandakini, Dhauliganga, and Pindar.<\/p>\n\n\n\n<p><strong>24. Where do the Alaknanda and Bhagirathi rivers meet to form the Ganga?<\/strong><\/p>\n\n\n\n<p><strong>Answer<\/strong>: The Alaknanda and Bhagirathi rivers meet at Devaprayag to form the Ganga.<\/p>\n\n\n\n<p><strong>25. What is the main channel of the Brahmaputra river called in Bangladesh?<\/strong><\/p>\n\n\n\n<p><strong>Answer<\/strong>: In Bangladesh, the main channel of the Brahmaputra river becomes known as the Jamuna river.<\/p>\n\n\n\n<p><strong>26. What is the combined stream of the Ganga and Brahmaputra called in Bangladesh?<\/strong><\/p>\n\n\n\n<p><strong>Answer<\/strong>: In Bangladesh, the Brahmaputra joins the Ganga to form the combined stream called Padma.<\/p>\n\n\n\n<p><strong>27. What is the name of the delta formed by the Ganga and Brahmaputra rivers?<\/strong><\/p>\n\n\n\n<p><strong>Answer<\/strong>: The delta formed by the Ganga and Brahmaputra rivers is the Sunderbans Delta.<\/p>\n\n\n\n<p><strong>28. What is the Brahmaputra river known as in Tibet?<\/strong><\/p>\n\n\n\n<p><strong>Answer<\/strong>: Throughout its upper course in Tibet, the Brahmaputra river is generally known as the Tsangpo, which means &#8220;the Purifier&#8221;.<\/p>\n\n\n\n<p><strong>29. What geographical feature forms the main watershed in Peninsular India?<\/strong><\/p>\n\n\n\n<p><strong>Answer<\/strong>: Peninsular India&#8217;s main watershed is formed by the Western Ghats.<\/p>\n\n\n\n<p><strong>30. Name the only two long rivers in Peninsular India that flow towards the west.<\/strong><\/p>\n\n\n\n<p><strong>Answer<\/strong>: The Narmada and the Tapi are the only long rivers in Peninsular India that flow west.<\/p>\n\n\n\n<p><strong>31. Where is the source of the Narmada river located?<\/strong><\/p>\n\n\n\n<p><strong>Answer<\/strong>: The Narmada river has its source near Amarkantak in Madhya Pradesh.<\/p>\n\n\n\n<p><strong>32. Name a famous waterfall formed by the Narmada river.<\/strong><\/p>\n\n\n\n<p><strong>Answer<\/strong>: A famous waterfall formed by the Narmada river is the Dhuadhar Falls.<\/p>\n\n\n\n<p><strong>33. Where does the river Kaveri have its source?<\/strong><\/p>\n\n\n\n<p><strong>Answer<\/strong>: The river Kaveri has its source in the Brahmagir range of the Western Ghats.<\/p>\n\n\n\n<p><strong>34. From where does the river Krishna rise?<\/strong><\/p>\n\n\n\n<p><strong>Answer<\/strong>: The river Krishna rises from a spring near Mahabaleshwar.<\/p>\n\n\n\n<p><strong>35. Which is the largest peninsular river in India?<\/strong><\/p>\n\n\n\n<p><strong>Answer<\/strong>: The Godavari is the largest peninsular river.<\/p>\n\n\n\n<p><strong>36. Where does the Mahanadi river rise?<\/strong><\/p>\n\n\n\n<p><strong>Answer<\/strong>: The Mahanadi river rises in Chhattisgarh.<\/p>\n\n\n\n<p><strong>37. Name three other small river basins found in the peninsular region.<\/strong><\/p>\n\n\n\n<p><strong>Answer<\/strong>: Three other small river basins found in the peninsular region include Mahi, Pennar, and Subarnarekha.<\/p>\n\n\n\n<p><strong>38. How is a &#8216;large dam&#8217; defined by the International Commission on Large Dams?<\/strong><\/p>\n\n\n\n<p><strong>Answer<\/strong>: A &#8216;large dam&#8217; is defined by the International Commission on Large Dams (ICOLD) as one measuring 15 metres or more from foundation to crest, taller than a four-storey building.<\/p>\n\n\n\n<p><strong>39. How does a hydroelectric power station generate electricity?<\/strong><\/p>\n\n\n\n<p><strong>Answer<\/strong>: In a hydroelectric power station, water from a huge lake behind a dam flows down pipes. The moving water spins turbines which drive generators and produce electricity.<\/p>\n\n\n\n<p><strong>40. Define a braided channel or stream.<\/strong><\/p>\n\n\n\n<p><strong>Answer<\/strong>: A braided channel or stream is defined as streams having diverging and converging channels separated by bars and islands.<\/p>\n\n\n\n<p><strong>41. What is meant by the term inland drainage?<\/strong><\/p>\n\n\n\n<p><strong>Answer<\/strong>: Inland drainage is a drainage pattern restricted to an island basin, having no outflow to the sea.<\/p>\n\n\n\n<p><strong>42. Explain the term &#8216;drainage basin&#8217;. What is a &#8216;water divide&#8217;?<\/strong><\/p>\n\n\n\n<p><strong>Answer<\/strong>: The area drained by a single river system is called a drainage basin. It is the area of land from which a river collects water and describes an area drained collectively by the network of a river along with its tributaries and sub-tributaries of various dimensions.<\/p>\n\n\n\n<p>Any elevated area, such as a mountain or an upland, that separates two drainage basins is known as a water divide.<\/p>\n\n\n\n<p><strong>43. How are the Himalayan and the Peninsular rivers different from each other?<\/strong><\/p>\n\n\n\n<p><strong>Answer<\/strong>: The Himalayan and the Peninsular rivers are different from each other in many ways.<\/p>\n\n\n\n<p>Most of the Himalayan rivers are perennial, meaning they have water throughout the year as they receive water from rain as well as from melted snow. In contrast, most of the Peninsular rivers are seasonal, and their flow depends on rainfall, with even large rivers having a highly reduced flow of water in their channels during the summer season.<\/p>\n\n\n\n<p>Himalayan rivers have long courses from their source to the sea and have large basins. They perform intensive erosional activity in their upper courses, carry huge loads of silt and sand, and form meanders, oxbow lakes, and well-developed deltas. Peninsular rivers, on the other hand, flow through shallow valleys, have comparatively small drainage basins, and their gentler slopes cause a low intensity of erosional activity. They do not have many meanders due to the hard rock bed and lack of silt, resulting in a straight and linear course.<\/p>\n\n\n\n<p><strong>44. Describe the journey of a typical Himalayan river from its source to the sea.<\/strong><\/p>\n\n\n\n<p><strong>Answer<\/strong>: Himalayan rivers have long courses from their source to the sea. In their upper courses, they pass through the Himalayas, creating spectacular gorges and steep rock-sided deep valleys. In this stage, they perform intensive erosional activity and carry huge loads of silt and sand.<\/p>\n\n\n\n<p>In the middle and the lower courses, as the rivers enter the plains, they form large meanders, which are curvy paths like a snake. They also form oxbow lakes and many other depositional features in their floodplains, such as river cliffs and levees. Finally, they have well-developed deltas before they drain into the sea.<\/p>\n\n\n\n<p><strong>45. What is a dendritic pattern? How is this drainage pattern formed?<\/strong><\/p>\n\n\n\n<p><strong>Answer<\/strong>: A dendritic pattern consists of a single main stream with tributaries joining like the branches of a tree.<\/p>\n\n\n\n<p>This pattern develops in a region which is made of rocks having uniform structure. The direction of the river and its tributaries are determined by the slope.<\/p>\n\n\n\n<p><strong>46. Explain the formation and characteristics of a trellis drainage pattern.<\/strong><\/p>\n\n\n\n<p><strong>Answer<\/strong>: A trellis pattern is a rectangular pattern formed when a long river is joined by short flowing streams, approximately at right angles.<\/p>\n\n\n\n<p>It develops in a region which is made up of alternate belts of hard and soft rocks, all of which dip in the same direction. These belts lie at right angles to the general slope, below which the main river flows.<\/p>\n\n\n\n<p><strong>47. What is a radial drainage pattern? Where does it typically develop?<\/strong><\/p>\n\n\n\n<p><strong>Answer<\/strong>: A radial pattern has streams flowing in different directions from a central peak or a dome-like structure, forming a pattern like the spokes of a wheel.<\/p>\n\n\n\n<p>This pattern typically develops on a dome or a volcanic cone.<\/p>\n\n\n\n<p><strong>48. List the key characteristics of the Himalayan Rivers.<\/strong><\/p>\n\n\n\n<p><strong>Answer<\/strong>: The key characteristics of the Himalayan Rivers are:<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>These rivers have large basins, e.g. Indus Basin.<\/li>\n\n\n\n<li>The rivers passing through the Himalayas create spectacular gorges.<\/li>\n\n\n\n<li>The steep rock-sided deep valleys were created by the down cutting of the river during the period of the Himalayan uplift.<\/li>\n\n\n\n<li>These rivers are perennial as they receive water from rainfall and melting ice all the time.<\/li>\n\n\n\n<li>These rivers carry out intensive erosional activities upstream and also carry huge loads of sand and silt.<\/li>\n\n\n\n<li>When in the plains, these rivers form large meanders and depositional features such as flood plains, river cliffs and levees. They also have well-developed deltas.<\/li>\n<\/ul>\n\n\n\n<p><strong>49. What are the main characteristics of the Peninsular Rivers?<\/strong><\/p>\n\n\n\n<p><strong>Answer<\/strong>: The main characteristics of the Peninsular Rivers are:<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>These rivers flow through shallow valleys.<\/li>\n\n\n\n<li>Most of these rivers are seasonal and their flow depends on rainfall.<\/li>\n\n\n\n<li>When summer season arrives, even the large rivers have highly reduced flow of water in their channels.<\/li>\n\n\n\n<li>The gentler slopes cause a low intensity of erosional activity as compared to other rivers.<\/li>\n\n\n\n<li>These rivers do not have many meanders as the hard rock bed and lack of silt and sand does not allow them.<\/li>\n\n\n\n<li>Most of the peninsular rivers have a straight and linear course.<\/li>\n\n\n\n<li>They have comparatively small drainage basins.<\/li>\n<\/ul>\n\n\n\n<p><strong>50. Describe the course of the Indus river from its origin to where it enters the plains.<\/strong><\/p>\n\n\n\n<p><strong>Answer<\/strong>: The Indus river has its origins in the Himalayas of western Tibet, near lake Mansarowar. It flows through Ladakh and through a very beautiful gorge at Gilgit. At this junction, it is joined by several tributaries. After passing through Baltistan and Gilgit, it comes out of the mountains at Attock.<\/p>\n\n\n\n<p><strong>51. Trace the origin of the river Ganga. How is the main river formed?<\/strong><\/p>\n\n\n\n<p><strong>Answer<\/strong>: The river Ganga rises in the Himalayas on the Indian side of the Tibet border. Its five headstreams\u2014Bhagirathi, Alaknanda, Mandakini, Dhauliganga and Pindar\u2014have their origins in Uttarakhand. Of these, the Alaknanda rises about 48 km north of the Himalayan peak of Nanda Devi, and the Bhagirathi finds its origins in an ice cave at the foot of the Himalayan glacier called the Gangotri.<\/p>\n\n\n\n<p>The main river is formed when the Alaknanda and Bhagirathi meet at Devaprayag to form the Ganga.<\/p>\n\n\n\n<p><strong>52. Describe the journey of the Brahmaputra river through Tibet and India.<\/strong><\/p>\n\n\n\n<p><strong>Answer<\/strong>: The Brahmaputra river&#8217;s source lies in the Chemayungdung Glacier in southwestern Tibet. From its source, the river flows for nearly 1,126 km in an easterly direction. Throughout its upper course in Tibet, the river is generally known as the Tsangpo, which means &#8220;the Purifier,&#8221; and it receives a number of tributaries.<\/p>\n\n\n\n<p>Near Sadiya in Assam, the river, known as Dihang, changes its course to the southwest and is then known as the Brahmaputra. In Assam, the river is mighty, and its braided course through the valley receives several rapidly rushing streams. After flowing for 800 km in this direction, it turns south again, going through Bangladesh.<\/p>\n\n\n\n<p><strong>53. How is the Sunderbans Delta formed?<\/strong><\/p>\n\n\n\n<p><strong>Answer<\/strong>: In Bangladesh, the Brahmaputra joins the Ganga to form the combined stream called Padma. This stream then meets the river Meghna. The waters then flow into the Bay of Bengal through numerous channels, the largest one of which is called the Meghna estuary. This process forms the Sunderbans Delta.<\/p>\n\n\n\n<p><strong>54. Why do most peninsular rivers flow eastwards? Which major rivers flow westwards?<\/strong><\/p>\n\n\n\n<p><strong>Answer<\/strong>: Peninsular India&#8217;s main watershed is formed by the Western Ghats, which lie very close to the western coast. This geography causes most of the main peninsular rivers like the Kaveri, Krishna, Godavari, and Mahanadi to flow eastwards and drain into the Bay of Bengal.<\/p>\n\n\n\n<p>The Narmada and the Tapi are the only long rivers that flow west.<\/p>\n\n\n\n<p><strong>55. Write a short note on the Narmada Basin, including its source and course.<\/strong><\/p>\n\n\n\n<p><strong>Answer<\/strong>: The Narmada has its source near Amarkantak in Madhya Pradesh. It flows south-westward in a trough for about 1300 km and meets the Arabian Sea through an estuary. Its basin is restricted to Madhya Pradesh and Gujarat, and it does not have a developed tributary system. The famous &#8216;Marble Rocks&#8217; near Jabalpur are formed where the Narmada flows through a deep gorge. Another famous spot is the Dhuadhar Falls, where the Narmada flows over deep wells.<\/p>\n\n\n\n<p><strong>56. Describe the Godavari Basin and name its major tributaries.<\/strong><\/p>\n\n\n\n<p><strong>Answer<\/strong>: The Godavari is the largest peninsular river, often known as Vridha Ganga or Dakshin Ganga. It rises in Nasik, Maharashtra, and after flowing for 1500 km, it drains into the Bay of Bengal. It has the largest drainage basin among the peninsular rivers; half of this basin is in Maharashtra, and the rest is shared by Madhya Pradesh, Odisha, Andhra Pradesh, and Telangana.<\/p>\n\n\n\n<p>The tributaries of the Godavari are Purna, Wardha, Pranhita, Manjra, Wainganga, and Penganga. The last three of these are very large tributaries.<\/p>\n\n\n\n<p><strong>57. What have been the main uses of rivers for human civilisation?<\/strong><\/p>\n\n\n\n<p><strong>Answer<\/strong>: Rivers have always been of great use to man. They provided early man with water to drink, and the fish they provided were valuable as food. When man learnt to build and manage boats, rivers supplied a cheap and easy way of travel. River valleys provided easy routes and fertile land. In many places, rivers have been set to work to produce electric power. Rivers also often form the boundaries of countries, as their crossings can be easily controlled. River valley civilisations could thrive as rivers were the lifelines that sustained them.<\/p>\n\n\n\n<p><strong>58. What are some negative environmental impacts of building large dams in the tropics?<\/strong><\/p>\n\n\n\n<p><strong>Answer<\/strong>: Large dams in the tropics seriously affect the environment. The creation of a reservoir and the resulting change in the downstream flow of a large river can upset the delicate ecological balance in the river. Whole species of fish and other aquatic life may vanish within a short span of time.<\/p>\n\n\n\n<p><strong>59. How can large reservoirs and irrigation canals affect human health and settlements?<\/strong><\/p>\n\n\n\n<p><strong>Answer<\/strong>: In the area around a large tropical reservoir and related irrigation canals, water-borne diseases\u2014such as schistosomiasis, malaria, and dysentery\u2014can become widespread.<\/p>\n\n\n\n<p>Regarding settlements, in almost all cases, thousands of people are displaced from their villages.<\/p>\n\n\n\n<p><strong>60. Define meander and oxbow lake. How is an oxbow lake formed?<\/strong><\/p>\n\n\n\n<p><strong>Answer<\/strong>: A meander forms when water flows in a curvy, bandy path, like a snake.<\/p>\n\n\n\n<p>An oxbow lake is a curved lake. It is formed from a horseshoe bend in a river where the main stream has cut across the narrow end and no longer flows around the loop.<\/p>\n\n\n\n<p><strong>61. What is a river system? What are its main components?<\/strong><\/p>\n\n\n\n<p><strong>Answer<\/strong>: A river system is the network of rivers in an area. Its main components are a large river and its tributaries.<\/p>\n\n\n\n<p><strong>62. Describe the different stages in the life of a river.<\/strong><\/p>\n\n\n\n<p><strong>Answer<\/strong>: The different stages in the life of a river begin from its source. In the upper course, the river performs intensive erosional activity. In the middle course and the lower course, the river forms features like meanders and oxbow lakes. Finally, the river may form a delta before it drains into a large water body like a sea or an ocean.<\/p>\n\n\n\n<p><strong>63. Explain the different types of drainage patterns discussed. Provide details on their formation.<\/strong><\/p>\n\n\n\n<p><strong>Answer<\/strong>: The different types of drainage patterns are:<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>A dendritic pattern consists of a single main stream with tributaries joining like the branches of a tree. This pattern develops in a region which is made of rocks having uniform structure. The direction of the river and its tributaries are determined by the slope.<\/li>\n\n\n\n<li>A trellis pattern is a rectangular pattern formed when a long river is joined by short flowing streams, approximately at right angles. It develops in a region which is made up of alternate belts of hard and soft rocks all of which dip in the same direction. These lie at right angles to the general slope, below which the main river flows.<\/li>\n\n\n\n<li>A radial pattern has streams flowing in different directions from a central peak or dome-like structure. This develops on a dome or volcanic cone. The rivers flow outward, forming a pattern like the spokes of a wheel.<\/li>\n\n\n\n<li>The centrifugal drainage pattern is usually found in arid areas, where streams converge from all sides towards a central depression where there is a lake.<\/li>\n<\/ul>\n\n\n\n<p><strong>64. Compare the erosional and depositional activities of Himalayan rivers in their different courses.<\/strong><\/p>\n\n\n\n<p><strong>Answer<\/strong>: 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 floodplains. They also have well-developed deltas.<\/p>\n\n\n\n<p><strong>65. Write a detailed note on the Indus River System.<\/strong><\/p>\n\n\n\n<p><strong>Answer<\/strong>: The Indus River is about 2900 km long. It has its origins in the Himalayas of western Tibet, near lake Mansarowar. It flows through Ladakh and through a very beautiful gorge at Gilgit. At this junction, it is joined by several tributaries. It comes out of the mountains at Attock after passing through Baltistan and Gilgit.<\/p>\n\n\n\n<p>The Indus has a total drainage area of about 1,165,500 sq km, of which 453,250 sq km lies in the Himalayan mountains and foothills. A third of the Indus Basin is in Jammu &amp; Kashmir, Himachal Pradesh and the Punjab. The rest is in Pakistan.<\/p>\n\n\n\n<p><strong>66. Describe the Ganga River System.<\/strong><\/p>\n\n\n\n<p><strong>Answer<\/strong>: The length of the river Ganga is 2510 km. For most of its course, it is a wide and sluggish stream which flows through one of the most fertile and densely populated regions of India, which shows its importance.<\/p>\n\n\n\n<p>Rising in the Himalayas on the Indian side of the Tibet border, the Ganga&#8217;s five headstreams\u2014Bhagirathi, Alaknanda, Mandakini, Dhauliganga and Pindar\u2014have their origins in Uttarakhand. The Alaknanda rises about 48 km north of the Himalayan peak of Nanda Devi, and the Bhagirathi finds its origins in an ice cave at the foot of the Himalayan glacier called the Gangotri. The Alaknanda and Bhagirathi meet at Devaprayag to form the Ganga. This river cuts through the southern Himalayas and comes from the mountains at Rishikesh. Then the river flows into the Haridwar plain.<\/p>\n\n\n\n<p><strong>67. Explain the course of the Brahmaputra River System from its source to the Bay of Bengal.<\/strong><\/p>\n\n\n\n<p><strong>Answer<\/strong>: The Brahmaputra river&#8217;s source lies in the Chemayungdung Glacier, about 97 km southeast of Mapang Yangeno (Mapam) Lake in southwestern Tibet. From the source, the river flows for nearly 1,126 km in an easterly direction. Throughout its upper course, the river is generally known as the Tsangpo (&#8220;the Purifier&#8221;).<\/p>\n\n\n\n<p>Near Sadiya, Assam, the Dihang changes course to the southwest and is known as the Brahmaputra. After flowing 800 km in this direction, it turns south again, going through Bangladesh. At the Ganga delta, the river divides into two channels, and the main channel becomes known as the Jamuna river. In Bangladesh, the Brahmaputra joins the Ganga to form the combined stream called Padma, which then meets the river Meghna. The waters then flow into the Bay of Bengal through numerous channels.<\/p>\n\n\n\n<p><strong>68. Discuss the key features of the Peninsular river system. Why are these rivers mostly seasonal?<\/strong><\/p>\n\n\n\n<p><strong>Answer<\/strong>: The key features of the Peninsular river system are that these rivers flow through shallow valleys and have small drainage basins. Peninsular India&#8217;s main watershed is formed by the Western Ghats. Most of the main peninsular rivers like the Kaveri, Krishna, Godavari, and Mahanadi flow eastwards, drain into the Bay of Bengal, and make deltas at their mouths. The Narmada and the Tapi are the only long rivers that flow west.<\/p>\n\n\n\n<p>Most of these rivers are seasonal, and their flow depends on rainfall. When the summer season arrives, even the large rivers have a highly reduced flow of water in their channels.<\/p>\n\n\n\n<p><strong>69. Explain the role of rivers as lifelines of human civilisation. How are they being misused today?<\/strong><\/p>\n\n\n\n<p><strong>Answer<\/strong>: Rivers have always been of great use to man. They provided early man with water to drink, and the fish they provided were valuable as food. When man learnt to build and manage boats, rivers supplied a cheap and easy way of travel. River valleys provided easy routes and fertile land. In many places, rivers have been set to work to produce electric power. River valley civilisations could thrive as the rivers were the lifelines that sustained them.<\/p>\n\n\n\n<p>Even today, rural and urban people misuse water in various ways. They use river waters as a means of throwing away wastes.<\/p>\n\n\n\n<p><strong>70. What is hydroelectric power? Discuss its generation process and its benefits.<\/strong><\/p>\n\n\n\n<p><strong>Answer<\/strong>: Hydroelectric power is electricity produced from water in hydroelectric (water-driven) power stations.<\/p>\n\n\n\n<p>Hydroelectric power stations are often built inside dams. Water from a huge lake behind the dam flows down pipes. The moving water spins turbines which drive generators and produce electricity. The benefit of this process is that hydroelectric power produces electricity without causing pollution, using scarce resources.<\/p>\n\n\n\n<p><strong>71. Describe the Narmada and Tapi river basins. How are they different from other major peninsular rivers?<\/strong><\/p>\n\n\n\n<p><strong>Answer<\/strong>: <strong>The Narmada basin:<\/strong> The Narmada has its source near Amarkantak in Madhya Pradesh. It meets the Arabian Sea through an estuary after flowing south-westward in a trough for a distance of about 1300 km. Its basin is restricted to Madhya Pradesh and Gujarat. The Narmada does not have a developed tributary system.<\/p>\n\n\n\n<p><strong>The Tapi basin:<\/strong> With its source in Betul, Madhya Pradesh, the Tapi flows in a trough, parallel to the Narmada. The Tapi basin includes parts of Madhya Pradesh, Gujarat, and Maharashtra but is still smaller in size than the Narmada basin.<\/p>\n\n\n\n<p>These two rivers are different from other major peninsular rivers because most of the main peninsular rivers, like the Kaveri, Krishna, Godavari, and Mahanadi, flow eastwards and drain into the Bay of Bengal. The Narmada and the Tapi are the only long rivers that flow west.<\/p>\n\n\n\n<p><strong>72. Provide a detailed comparison between the Himalayan and Peninsular river systems of India.<\/strong><\/p>\n\n\n\n<p><strong>Answer<\/strong>: The Himalayan and the Peninsular rivers are different from each other in many ways.<\/p>\n\n\n\n<p><strong>The Himalayan rivers have the following characteristics:<\/strong><\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Most of the Himalayan rivers are perennial, meaning they have water throughout the year. They receive water from rain as well as from melted snow from the lofty mountains.<\/li>\n\n\n\n<li>These rivers have large basins, for example, the Indus Basin.<\/li>\n\n\n\n<li>The rivers passing through the Himalayas create spectacular gorges. The steep rock-sided deep valleys were created by the down-cutting of the river during the period of the Himalayan uplift.<\/li>\n\n\n\n<li>They have long courses from their source to the sea.<\/li>\n\n\n\n<li>They perform intensive erosional activity in their upper courses and carry huge loads of silt and sand.<\/li>\n\n\n\n<li>In the middle and lower courses, these rivers form large meanders, oxbow lakes, flood plains, river cliffs, levees, and other depositional features. They also have well-developed deltas.<\/li>\n<\/ul>\n\n\n\n<p><strong>The Peninsular rivers have the following characteristics:<\/strong><\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Most of these rivers are seasonal, and their flow depends on rainfall. When the summer season arrives, even the large rivers have a highly reduced flow of water in their channels.<\/li>\n\n\n\n<li>These rivers flow through shallow valleys.<\/li>\n\n\n\n<li>The peninsular rivers have comparatively small drainage basins.<\/li>\n\n\n\n<li>The gentler slopes cause a low intensity of erosional activity.<\/li>\n\n\n\n<li>These rivers do not have many meanders as the hard rock bed and lack of silt and sand does not allow them. Most of these rivers have a straight and linear course.<\/li>\n<\/ul>\n\n\n\n<p><strong>73. Discuss the major Peninsular river systems that drain into the Bay of Bengal.<\/strong><\/p>\n\n\n\n<p><strong>Answer<\/strong>: Most of the main peninsular rivers, like the Kaveri, Krishna, Godavari, and Mahanadi, flow eastwards and drain into the Bay of Bengal. These rivers make deltas at their mouths.<\/p>\n\n\n\n<p><strong>The Godavari Basin:<\/strong> The Godavari is the largest peninsular river. It rises in Nasik, Maharashtra. After flowing for 1500 km, the river drains into the Bay of Bengal. It has the largest drainage basin among the peninsular rivers; half of this basin is located in Maharashtra, while the rest is shared by Madhya Pradesh, Odisha, Andhra Pradesh, and Telangana. The Godavari is also known as Vridha Ganga or Dakshin Ganga. Its tributaries include Purna, Wardha, Pranhita, Manjra, Wainganga, and Penganga.<\/p>\n\n\n\n<p><strong>The Krishna Basin:<\/strong> The river Krishna rises from a spring near Mahabaleshwar. It reaches the Bay of Bengal after flowing for about 1400 km. It is the second-longest river of Peninsular India. Its basin drains parts of Maharashtra, Karnataka, Andhra Pradesh, and Telangana. Its tributaries include the Bhima, Musi, Ghatprabha, Koyna, and the Tungabhadra.<\/p>\n\n\n\n<p><strong>The Mahanadi Basin:<\/strong> Rising in Chhattisgarh, the Mahanadi flows through Odisha to reach the Bay of Bengal. The 885 km long river has its drainage basin lying in Chhattisgarh, Jharkhand, Odisha, and Maharashtra.<\/p>\n\n\n\n<p><strong>The Kaveri Basin:<\/strong> The Kaveri has its source in the Brahmagir range of the Western Ghats. The river reaches the Bay of Bengal after flowing over 800 km. It ends at Kaveripatnam, and its basin is shared by Karnataka, Tamil Nadu, and Kerala.<\/p>\n\n\n\n<p><strong>74. &#8220;Rivers are the lifelines of human civilisation, but the construction of large dams can cause problems.&#8221; Elaborate on this statement.<\/strong><\/p>\n\n\n\n<p><strong>Answer<\/strong>: Rivers have always been of great use to man and are considered the lifelines of human civilisation. They provided early man with water to drink, and the fish they provided were valuable as food. When man learnt to build and manage boats, rivers supplied a cheap and easy way of travel. River valleys provided easy routes and fertile land. In many places, rivers have been set to work to produce electric power. River valley civilisations could thrive as the rivers were the lifelines that sustained them. Even today, rural and urban people need and utilise water in various ways.<\/p>\n\n\n\n<p>As the need for electric power and water continued to grow, more dams were built. However, the construction of large dams can cause problems. A &#8216;large dam&#8217; is defined as one measuring 15 metres or more from foundation to crest. Large dams in the tropics seem to cause almost as many problems as they solve. They seriously affect the environment. The creation of a reservoir and the resulting change in the downstream flow of a large river can upset the delicate ecological balance in the river. Whole species of fish and other aquatic life may vanish within a short span of time. In the area around a large tropical reservoir and related irrigation canals, water-borne diseases\u2014such as schistosomiasis, malaria, and dysentery\u2014can become widespread. Almost in all cases, thousands of people are displaced from their villages.<\/p>\n\n\n\n<p><strong>75. Explain the various drainage patterns formed by rivers. How do geological structures and relief features influence these patterns?<\/strong><\/p>\n\n\n\n<p><strong>Answer<\/strong>: When water drains into streams and rivers, it forms different patterns, depending on the shape of the land and the type of rocks it is made of. Based on the relief, geological structure, and climatic conditions of the area, streams form different patterns. The streams may form the following patterns:<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li><strong>A dendritic pattern:<\/strong> This consists of a single main stream with tributaries joining like the branches of a tree. The dendritic pattern develops in a region which is made of rocks having a uniform structure. The direction of the river and its tributaries are determined by the slope.<\/li>\n\n\n\n<li><strong>A trellis pattern:<\/strong> This is a rectangular pattern formed when a long river is joined by short flowing streams, approximately at right angles. It develops in a region which is made up of alternate belts of hard and soft rocks, all of which dip in the same direction. These lie at right angles to the general slope, below which the main river flows.<\/li>\n\n\n\n<li><strong>A radial pattern:<\/strong> This has streams flowing in different directions from a central peak or dome-like structure. This develops on a dome or volcanic cone. The rivers flow outward, forming a pattern like the spokes of a wheel.<\/li>\n\n\n\n<li><strong>The centrifugal drainage pattern:<\/strong> This is usually found in arid areas, where streams converge from all sides towards a central depression where there is a lake.<\/li>\n<\/ul>\n\n\n\n<p><strong>76. Trace the complete journey of the river Ganga from its source in the Himalayas to its mouth in the Bay of Bengal.<\/strong><\/p>\n\n\n\n<p><strong>Answer<\/strong>: The journey of the river Ganga begins in the Himalayas on the Indian side of the Tibet border. The Ganga&#8217;s five headstreams\u2014Bhagirathi, Alaknanda, Mandakini, Dhauliganga, and Pindar\u2014have their origins in Uttarakhand. The Bhagirathi finds its origins in an ice cave at the foot of the Himalayan glacier called the Gangotri. The Alaknanda and Bhagirathi meet at Devaprayag to form the Ganga.<\/p>\n\n\n\n<p>From Devaprayag, the river cuts through the southern Himalayas and comes from the mountains at Rishikesh. Then, the river flows into the Haridwar plain. For most of its course from here, it is a wide and sluggish stream that flows through one of the most fertile and densely populated regions of India.<\/p>\n\n\n\n<p>Finally, in Bangladesh, the Brahmaputra joins the Ganga to form the combined stream called Padma. This stream meets the river Meghna. The waters then flow into the Bay of Bengal through numerous channels, the largest of which is called the Meghna estuary. Here, it forms the Sunderbans Delta.<\/p>\n\n\n\n\n\n<p><strong>77. Trace the journey of the Brahmaputra river from its source to its mouth, highlighting its different names and characteristics along its course.<\/strong><\/p>\n\n\n\n<p><strong>Answer<\/strong>: The Brahmaputra, also known as Yarlung Zangbo, is one of the great rivers of southern Asia. Its journey begins at its source in the Chemayungdung Glacier, which covers the slopes of the Himalaya in southwestern Tibet.<\/p>\n\n\n\n<p>From the source, the river flows for nearly 1,126 km in an easterly direction. Throughout its upper course in Tibet, the river is generally known as the Tsangpo, which means &#8220;the Purifier&#8221;. It receives a number of tributaries in Tibet.<\/p>\n\n\n\n<p>Near Sadiya in Assam, the river, known as Dihang, changes its course to the southwest and is then known as the Brahmaputra. In Assam, the river is mighty, even in the dry season, and during the rains, its banks are more than 8 km apart. As the river follows its braided 724 km course through the valley, it receives several rapidly rushing streams.<\/p>\n\n\n\n<p>After flowing for 800 km in this direction, it turns south again, going through Bangladesh. At the Ganga delta, the river divides into two channels, and the main channel becomes known as the Jamuna river. Both channels empty into the Bay of Bengal. In Bangladesh, the Brahmaputra joins the Ganga to form the combined stream called Padma. It then meets the river Meghna, and the waters flow into the Bay of Bengal, forming the Sunderbans Delta.<\/p>\n\n\n\n<p><\/p>\n","protected":false},"excerpt":{"rendered":"<p>Get here solutions, questions, answers, and notes of chapter 7:&nbsp;Drainage&nbsp;which is a part of social science class 9 syllabus of students studying under the Nagaland Board of School Education. However, these notes should be used only for references and additions\/modifications should be made as per the requirements. Introduction The term drainage describes the river system&hellip; <a class=\"more-link\" href=\"https:\/\/mockupbw.site\/2025\/onlinefreenotes\/drainage\/\">Continue reading <span class=\"screen-reader-text\">Drainage: NBSE class 9 social science chapter 7 answers<\/span><\/a><\/p>\n","protected":false},"author":1044,"featured_media":5712,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[11,34],"tags":[],"class_list":["post-4009","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-nagaland","category-notes","entry"],"acf":[],"_links":{"self":[{"href":"https:\/\/mockupbw.site\/2025\/onlinefreenotes\/wp-json\/wp\/v2\/posts\/4009","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/mockupbw.site\/2025\/onlinefreenotes\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/mockupbw.site\/2025\/onlinefreenotes\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/mockupbw.site\/2025\/onlinefreenotes\/wp-json\/wp\/v2\/users\/1044"}],"replies":[{"embeddable":true,"href":"https:\/\/mockupbw.site\/2025\/onlinefreenotes\/wp-json\/wp\/v2\/comments?post=4009"}],"version-history":[{"count":1,"href":"https:\/\/mockupbw.site\/2025\/onlinefreenotes\/wp-json\/wp\/v2\/posts\/4009\/revisions"}],"predecessor-version":[{"id":33314,"href":"https:\/\/mockupbw.site\/2025\/onlinefreenotes\/wp-json\/wp\/v2\/posts\/4009\/revisions\/33314"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/mockupbw.site\/2025\/onlinefreenotes\/wp-json\/wp\/v2\/media\/5712"}],"wp:attachment":[{"href":"https:\/\/mockupbw.site\/2025\/onlinefreenotes\/wp-json\/wp\/v2\/media?parent=4009"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/mockupbw.site\/2025\/onlinefreenotes\/wp-json\/wp\/v2\/categories?post=4009"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/mockupbw.site\/2025\/onlinefreenotes\/wp-json\/wp\/v2\/tags?post=4009"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}