Drainage basin
Also called: River basin · Topic: Drainage System of India: Rivers, Basins and Patterns · NCERT: Class 11, Ch 3 "Drainage System"
Meaning
A drainage basin is all the land drained by one river and its tributaries (smaller rivers that join it). Every drop of rain that falls inside it ends up in the same river. A higher line of land called the watershed marks its edge. The basin works as one unit: cutting forests, building dams or dumping waste upstream affects everyone downstream. That is why basins are the best units for planning at small (micro), middle (meso) and large (macro) scales.
Example
The Ganga basin covers about 8.6 lakh sq km in India. That is about 26 per cent of the country, spread across 11 states, and more than 500 million people live in it. Namami Gange treats the whole basin as one unit for cleaning the river.
Don't confuse with
- Watershed: the boundary line between two basins, or the small catchment of a stream. A drainage basin is the whole area of a large river.
Related concepts
- Catchment area
- Watershed
- Arabian Sea and Bay of Bengal drainage
- Classification of river basins by size