Drainage Systems in India
The drainage system refers to the system of flow of surface water mainly through rivers. An area drained by a river and its tributaries is called a drainage basin. The drainage system is related to a number of factors like slope of land, geological structure, amount and velocity of water.
A river through its drainage system performs several tasks. These are excess water removal from a particular area, transportation of sediments from one place to other, providing natural source for irrigation and maintaining the water table of a region. Traditionally, rivers were useful as a source of abundant fresh water and navigation. In today’s world rivers importance has risen to include hydro power generation and setting up water-based industries.
These are also important tourist attraction for activities such as boating, river rafting and cliff jumping. Because of their utility, rivers are important for life and hence regarded as lifeline. Many cities are located along the rivers and are densely populated. Delhi on the banks of Yamuna, Patna along Ganga, Guwahati along Brahmaputra, Nasik along Godavari and Cuttack along Mahanadi are some examples.
On the basis of the origin the drainage can be divided in to two parts:
- Himalayan drainage system
- Peninsular drainage system
Tributary: A stream or river that flows into a larger river. For example, Yamuna
Delta: A triangular shaped land at the mouth of a river formed from the deposition of silt, sand and small rocks that flow downstream in the river. For example, Ganga delta.
Estuary: A partially enclosed coastal body of water where the salty tidal water mixes with the fresh water of the river. For example, Narmada river makes an estuary.
Himalayan River System
- They are Perennial rivers originating from glaciers.
- Rivers form valleys by the process of erosion.
- The rivers are ideal for irrigation purposes as they pass through plain fertile tracts.
- These rivers have meandering courses which shift over time.
Most of the Himalayan Rivers are perennial. This means they have water throughout the year. This is because most of these rivers originate from the glaciers and snowy peaks. They also receive water from the rainfall. The main river system in this category are:
- The Indus River System - Jhelum, Ravi, Beas and Satluj
- The Ganga Rivers System - Yamuna, Ramganga, Ghaghara, Gomti, Gandak and Kosi
- The Brahmaputra River System - Dibang, Lohit, Tista and Meghna
Peninsular Drainage System
Most of the Peninsular rivers flow eastwards and enters into Bay of Bengal. Only Narmada and Tapi rivers flow westwards of the Western Ghats. They are good for generating hydro power because these rivers form rapids and water falls. The major peninsular rivers are Mahanadi, Godavari, Krishna and Kaveri.