NCERT Solutions for Class 9 Geography Chapter 3 Drainage
NCERT Solutions for Class 9 Geography Chapter 3 covers Drainage Systems in India, Himalayan Rivers, Peninsular Rivers, Lakes, and the Economic Importance of Rivers.
Overview of Topics & Subtopics (Click to Jump)
1. Drainage Systems & Drainage Patterns
Short Note:
• Drainage Basin: The area drained by a single river system is called its drainage basin.
• Water Divide: An elevated area, such as a mountain or upland, that separates two drainage basins (e.g., Ambala separates the Indus and Ganga river systems).
• Drainage Patterns: Based on topography and slope, rivers form patterns like Dendritic (tree-like), Trellis (hard & soft rock alternating), Rectangular (jointed rocks), and Radial (flowing outwards from a central peak).
2. The Himalayan Rivers (Indus, Ganga & Brahmaputra)
Short Note:
• Himalayan Rivers Characteristics: Perennial (flow year-round fed by rain and snow melt), long courses, cause high erosion and form deep gorges, meanders, and oxbow lakes.
• Indus System: Rises in Tibet near Lake Mansarovar, enters India in Ladakh, and drains into the Arabian Sea near Karachi.
• Ganga System: Originates as Bhagirathi from Gangotri Glacier, joins Alaknanda at Devprayag, and along with Brahmaputra forms the world's largest delta (Sundarbans Delta) before entering the Bay of Bengal.
• Brahmaputra System: Originates in Tibet (where it is called Tsangpo), enters Arunachal Pradesh as Dihang, and flows through Assam forming riverine islands like Majuli.
3. The Peninsular Rivers, Lakes & River Pollution
Short Note:
• Peninsular Rivers Characteristics: Seasonal (dependent on monsoon rain), shorter and shallower courses. Main water divide is formed by the Western Ghats.
• East-Flowing Rivers: Mahanadi, Godavari (Dakshin Ganga), Krishna, and Kaveri drain into the Bay of Bengal and form rich deltas.
• West-Flowing Rivers: Narmada and Tapi flow through rift valleys and drain into the Arabian Sea forming estuaries.
• Lakes: Freshwater lakes (Wular Lake created by tectonic activity, Dal, Bhimtal) and saltwater lagoons (Chilika, Pulicat, Sambhar).
Intext & Conceptual Questions
| Feature | Himalayan Rivers | Peninsular Rivers |
|---|---|---|
| Origin | Originate from snow-capped Himalayan mountains. | Originate in Peninsular plateaus and central highlands. |
| Nature of Flow | Perennial (flow throughout the year). | Seasonal (dependent entirely on monsoon rainfall). |
| Course & Features | Long course, deep gorges, meanders, and large deltas. | Shorter, fixed courses, shallower valleys, estuaries/deltas. |
1. Length & Extent: The Godavari is the longest Peninsular river, spanning about 1,500 km.
2. Large Drainage Basin: It covers the largest basin area among all southern rivers, spanning Maharashtra, Madhya Pradesh, Odisha, and Andhra Pradesh.
3. Because of its large length and vast basin area comparable to the Ganga in Northern India, it is referred to as 'Dakshin Ganga'.
Textbook Chapter End Exercise Questions
(a) Rajasthan (b) Punjab (c) Uttar Pradesh (d) Jammu and Kashmir
Answer: (d) Jammu and Kashmir
(ii) The river Narmada has its source at:
(a) Satpura (b) Amarkantak (c) Brahmagiri (d) Slopes of Western Ghats
Answer: (b) Amarkantak
(iii) Which one of the following lakes is a salt water lake?
(a) Sambhar (b) Wular (c) Dal (d) Gobind Sagar
Answer: (a) Sambhar
(iv) Which one of the following is the longest river of Peninsular India?
(a) Narmada (b) Krishna (c) Godavari (d) Mahanadi
Answer: (c) Godavari
1. Agriculture: Rivers provide natural irrigation, essential for sustaining agricultural production across India.
2. Hydroelectric Power Generation: Flowing water is harnessed to generate clean hydroelectricity for industry and homes.
3. Inland Water Transport: Rivers act as cost-effective channels for inland navigation and trade.
4. Urban & Industrial Development: Rivers supply water required for domestic human consumption and industrial processing.
1. Untreated Sewage Discharge: Heavy dumping of untreated domestic municipal waste directly into river waters.
2. Industrial Effluents: Direct release of toxic chemical waste and heavy metals from factories.
3. Agricultural Runoff: Chemical fertilizers and pesticides washed off farmlands into river basins.
4. Over-extraction: Continuous water withdrawal reduces self-purifying capacity of rivers.
Read More & Chapter Resources
These short notes are designed for quick revision. Read the main points once, then use the related material below to practise the same chapter. Revising a concept and checking it with questions can make your preparation more focused.