What is a Drainage System? 

Drainage is the movement of water via well-defined channels, and the system of such channels is referred to as a ‘drainage system.’ The drainage pattern of a region is determined by the geological time frame, the kind and structure of the rocks, the terrain, the slope, the volume of water moving, and the flow’s periodicity. 

Division of Indian Drainage System:

• The following is based on the discharge of water (seaward orientations):

• It may be broken down into two categories: the drainage of the Arabian Sea and the drainage of the Bay of Bengal. 
• They are separated from one another by the Delhi Ridge, the Aravallis, and the Sahyadris ranges of mountains. 

• Based on the magnitude of the Watershed, the following division is made: 

• Major River Basins: It has a catchment area of more than 20,000 square kilometres. In all, 14 drainage basins are included in this area, including rivers like the Ganga, Brahmaputra, Krishna, Tapi, Narmada, the Mahi, Pennar, Sabarmati, and the Barak, among others.

• Medium River Basins: It has a catchment area ranging from 2,000 to 20,000 square kilometres and includes 44 river basins, including the Kalindi, the Periyar, and the Meghna, among others.

• Minor River Basins: These basins have a catchment area of less than 2,000 square kilometres and include a significant number of rivers that run in a region with minimal rainfall. 

Drainage Systems of India:

• The Himalayan drainage system and the Peninsular drainage system are the two most widely recognized classifications.
• The Indian drainage system is comprised of a huge number of minor and major rivers.
• It is the result of the evolutionary process of the three primary physiographic units, as well as the type and properties of precipitation, among other factors.

Himalayan Drainage System:

• The Himalayan drainage system has developed through millions of years of geological evolution.
• It mostly comprises the river systems of the Ganga, the Indus, and the Brahmaputra, with a small portion of the Indus River basin. These rivers originate in enormous gorges that have been cut out by erosional action that has occurred concurrently with the ascent of the Himalayas.
• Large gorges, V-shaped valleys, cascades, and waterfalls are carved into the landscape by these rivers as they go upward on their steep trek.
• As they make their way onto the plains, they deposit depositional features such as flat valleys, ox-bow lakes, flood plains, braided channels, and deltas at the river’s mouth, among other things.
• The route of these rivers is exceedingly tortuous in the Himalayan ranges, but across the plains, they exhibit a strong meandering propensity and vary their courses on a regular basis.
• In Bihar, the River Kosi, often known as the ‘sorrow of Bihar,’ has a reputation for altering its course on a regular basis. As a result of the large amount of silt and deposit that this river deposits on its plains, its channel becomes obstructed. 

Evolution of Himalayan Drainage System: 

• For a brief period during the Miocene epoch (approximately 5-24 million years ago), the river Shiwalik, also known as the Indo-Brahma, flowed through an area spanning the entire longitudinal variety of the Himalaya from Assam to Punjab and on to Sind, prior to actually ultimately releasing into the Gulf of Sind in lower Punjab, where it became.
• Strong support for this opinion may be found in the extraordinary continuity of the Shiwalik, as well as its lacustrine origin and alluvial deposits consisting mostly of sands, silts, clay, boulders, and conglomerates.
• There are three main Indian drainage systems that flow from the Indo-Brahma river: 

• the Indus and its five rivers in the western portion, 
• the Ganga and its Himalayan tributaries in the central area of the nation, and the Yamuna and its tributaries in the eastern section.
• The Brahmaputra River in Assam and its Himalayan sources in the eastern region of the nation are included in this category. 

• The elevation of the Potwar plateau (also known as the Delhi ridge), as well as major disruptions caused in the western region of the Himalayas in the Pleistocene epoch, are two major reasons why the region stands disjointed today.
• Additionally, during the mid-Pleistocene era, the down pushing of the Malda gap forced the Ganga and Brahmaputra rivers to flow towards the Bay of Bengal rather than the Indus River.

CONCLUSION

Conclusively, we have looked into the drainage system of India.The Indian drainage system is made up of a huge number of minor and major rivers, for example  the Ganga, Indus, and Brahmaputra river basins are part of the Himalayan drainage system. The peninsular plateau is drained by the Narmada, Tapi, Mahanadi, Godavari, Krishna, and Kaveri rivers.