Introduction to Drainage System
* A drainage basin is an area drained by a single river system.
* The drainage basin works as a funnel, by collecting all the water within the area and channelling it into a waterway.
* Himalayan rivers are perennial, whereas Peninsular Rivers are seasonal.
* This upland area is known as a water divide.
* Drainage systems in India can broadly be categorised as Himalayan rivers and Peninsular rivers.
The four main patterns are:
* Dendritic Drainage
* Rectangular Drainage
* Trellis Drainage
* Radial Drainage
Himalayan Rivers
* The three important Himalayan Rivers are the Ganga, the Brahmaputra and the Indus.
* The main tributaries of the Indus are the Sutlej, the Beas, the Ravi, the Chenab and the Jhelum.
* The Ganga starts off as the Bhagirathi and is joined by the Alaknanda at Devaprayag.
* The major tributaries of the Ganga are the Yamuna, the Ghaghara, the Gandak and the Kosi.
* The Brahmaputra is slightly longer than the Indus, and flows its course eastwards, parallel to the Himalayas and mostly outside of India.
* The Brahmaputra gathers strength through its tributaries, the Dihang, the Dibang and the Lohit.
Peninsular Rivers
* The Western Ghats make up an important water divide in peninsular India.
* The major rivers are the Mahanadi, the Godavari, the Krishna and the Kaveri, which flow eastwards and drain into the Bay of Bengal.
* The two major rivers that flow westward and drain in the Arabian Sea are the Narmada and the Tapi.
* The Godavari is the longest and the largest peninsular river.
* The Krishna river is the second longest peninsular river.
Importance of Lakes and Rivers
* Lakes are important of several reasons, like regulating the flow of river water, storage of water during the dry seasons, maintaining the eco-system and also for the generation of hydroelectric power.
* The Wular Lake in Jammu and Kashmir is the largest freshwater lake in India.
* Other fresh water lakes include the Dal in Jammu and Kashmir, and the Bhimatal and Nainital lakes in Uttarakhand.
* The Sambhar Lake in Rajasthan is the largest salt water late in India.
* The Chilika Lake in Orissa is the largest back water lagoon in India.
* Rivers are considered the most basic natural resources required for human settlement.
* The government has launched activities such as the NRCP and GAP to save our lakes and rivers.
