Chapter 3: Drainage
1. Introduction
Definition: Drainage refers to the river systems of an area, where streams combine to form larger rivers, draining into seas or lakes.
Drainage Basin: The area drained by a single river system.
Water Divide: An elevated area separating two drainage basins.
2. Types of Drainage Systems
2.1 Himalayan Rivers
Characteristics: Perennial rivers originating in the Himalayas, receiving water from both rain and melting snow.
Key Rivers:
Indus River System: Originates in Tibet, joined by rivers like Jhelum and Chenab; flows into the Arabian Sea.
Ganga River System: Begins with the Bhagirathi in Uttarakhand, joined by tributaries like Yamuna and Kosi, forming the Sundarban Delta.
Brahmaputra River System: Originates in Tibet, enters India in Arunachal Pradesh, known for causing floods in Assam.
2.2 Peninsular Rivers
Characteristics: Seasonal rivers, mainly rain-fed, with shorter and shallower courses.
Key Rivers:
Narmada and Tapi: Flow westwards through rift valleys into the Arabian Sea.
Godavari: Known as Dakshin Ganga, flows eastwards, largest basin in the peninsula.
Krishna and Kaveri: Flow eastwards into the Bay of Bengal with large deltas.
3. Lakes
Types: Freshwater (e.g., Wular Lake) and saltwater (e.g., Sambhar Lake).
Formation: Lakes can form through tectonic activity, glacial action, river deposition, or human activities.
Importance: Regulate river flow, support tourism, maintain aquatic ecosystems, and help in hydel power generation.
4. Role of Rivers in the Economy
Uses: Provide water for irrigation, hydroelectric power, transportation, and urban water supply. Rivers contribute to agriculture and industrial growth.
5. River Pollution
Causes: Industrial waste, sewage, and agricultural runoff degrade river water quality.
Conservation Efforts: Initiatives like the National River Conservation Plan (NRCP) aim to reduce river pollution and improve water quality.
6. Exercises and Map Skills
Questions: Topics include identifying water divides, differences between river types, and benefits of rivers.
Map Skills: Identify major rivers and lakes on an Indian map.
