Introduction to Drainage
Drainage refers to the river systems of an area. India has a well-developed drainage system with numerous rivers, lakes, and tributaries.
Question: What is a drainage basin? Answer: A drainage basin is the area drained by a single river system, also called a watershed or catchment area.
River Systems of India
Classification of Rivers
| Type | Origin | Flow | Examples |
|---|---|---|---|
| Himalayan Rivers | Glaciers | Perennial | Ganga, Brahmaputra, Indus |
| Peninsular Rivers | Western Ghats | Seasonal | Godavari, Krishna, Kaveri |
Drainage Patterns
- Dendritic: Tree-like pattern (most common)
- Radial: Rivers flow in all directions from a central point
- Centripetal: Rivers converge towards a central point
- Trellis: Rectangular pattern along fault lines
Himalayan Rivers
Characteristics
- Originate from glaciers and snow fields
- Flow throughout the year (perennial)
- Large volume of water
- Form meanders and ox-bow lakes
- Carry large amounts of silt
Major Himalayan Rivers
| River | Length (km) | Origin | Mouth |
|---|---|---|---|
| Indus | 2,880 | Mansarovar Lake | Arabian Sea |
| Ganga | 2,525 | Gangotri Glacier | Bay of Bengal |
| Brahmaputra | 2,900 | Mansarovar Lake | Bay of Bengal |
Ganga River System
- Main tributaries: Yamuna, Ghaghra, Gandak, Kosi
- Right bank tributaries: Yamuna, Son, Damodar
- Left bank tributaries: Ghaghra, Gandak, Kosi
- Delta: Sundarbans (largest delta in the world)
Peninsular Rivers
Characteristics
- Originate from Western Ghats
- Seasonal flow (depend on monsoon)
- Shorter and have less water
- Flow in well-defined channels
- Do not form meanders
East Flowing Rivers
| River | Length (km) | States | Mouth |
|---|---|---|---|
| Godavari | 1,465 | Maharashtra, Telangana, AP | Bay of Bengal |
| Krishna | 1,400 | Maharashtra, Karnataka, AP | Bay of Bengal |
| Kaveri | 760 | Karnataka, Tamil Nadu | Bay of Bengal |
| Mahanadi | 858 | Chhattisgarh, Odisha | Bay of Bengal |
West Flowing Rivers
- Narmada: Flows westward, drains into Arabian Sea
- Tapti: Parallel to Narmada, also flows west
- Characteristics: Flow through rift valleys, form estuaries
Lakes in India
Types of Lakes
| Type | Formation | Examples |
|---|---|---|
| Freshwater | Natural/Artificial | Dal, Wular |
| Saltwater | Inland drainage | Sambhar, Chilika |
| Glacial | Glacial action | Lakes in Himalayas |
| Lagoons | Coastal processes | Chilika, Pulicat |
Important Lakes
- Wular Lake: Largest freshwater lake (J&K)
- Dal Lake: Famous tourist destination (J&K)
- Chilika Lake: Largest saltwater lagoon (Odisha)
- Sambhar Lake: Largest inland salt lake (Rajasthan)
- Vembanad Lake: Longest lake in India (Kerala)
Water Conservation
Need for Conservation
- Increasing population and demand
- Pollution of water bodies
- Depletion of groundwater
- Climate change affecting rainfall
Conservation Methods
- Rainwater Harvesting: Collecting and storing rainwater
- Watershed Management: Protecting catchment areas
- Check dams: Small dams to store water
- Afforestation: Planting trees to increase rainfall
- River linking: Connecting surplus and deficit basins
Government Initiatives
- National River Conservation Plan
- Ganga Action Plan
- Jal Jeevan Mission
- Pradhan Mantri Krishi Sinchayee Yojana