Topic

Ch-3 | Drainage System of India | NCERT Class 9

Topic Progress:

←Back to Course

Subscribe

Download PDF Notes for this Topic

Download PDF

SUMMARY

  • The term drainage describes the river system of an area.
  • The area drained by a single river system is called a drainage basin.
  • Any elevated area, such as a mountain or an upland that separates two drainage basins is known as a water divide.

DRAINAGE SYSTEMS IN INDIA

  • The drainage systems of India are mainly controlled by the broad relief features of the subcontinent. Accordingly, the Indian rivers are divided into two major groups:
    1. The Himalayan Rivers
    2. The Peninsular Rivers
  • Most of the Himalayan rivers are perennial. It means that they have water throughout the year. These rivers receive water from rain as well as from melted snow from the lofty mountains.
  • A large number of the Peninsular rivers are seasonal, as their flow is dependent on rainfall. The Peninsular rivers have shorter and shallower courses as compared to their Himalayan counterparts.

Rivers of India

DRAINAGE PATTERNS

  • The streams within a drainage basin form certain patterns, depending on the slope of land, underlying rock structure as well
    as the climatic conditions of the area.
  • These patterns are:
    • Dendritic Pattern
    • Trellis Pattern
    • Rectangular Pattern
    • Radial Pattern
  • Dendritic Pattern: The dendritic pattern develops where the river channel follows the slope of the terrain. The stream with its tributaries resembles the branches of a tree, thus the name dendritic.
  • Trellis Pattern: A river joined by its tributaries, at approximately
    right angles, develops a trellis pattern. A trellis drainage pattern develops where hard and soft rocks exist parallel to each
    other.
  • Rectangular Pattern: A rectangular drainage pattern develops on a strongly jointed rocky terrain.
  • Radial Pattern: The radial pattern develops when streams flow in different directions from a central peak or dome-like structure.

SOME IMPORTANT TERMS

1. MEANDERING

Rivers flowing over gently sloping ground begin to curve back and forth across the landscape. These are called meandering rivers.

Meandering and Ox-Bow Lakes

2. OX-BOW LAKES

Oxbow lakes form when a meander grows so big and loopy that two bends of the river join together. Once the meander bends join, the flow of water reduces and sediment begins to build up. Over time oxbow lakes will fill with sediment and can even disappear. The point where the two bends intersect is called a meander cut-off.

3. DELTA

A river delta is a landform where the mouth of a river flows into an ocean, sea, desert, estuary, lake or another river. It is formed by sediment carried by the river being deposited in the wider mouth. The flow of water is often slower-moving there.

HIMALAYAN RIVERS

We made this Video for Himalayan Rivers:

1. INDUS RIVER SYSTEM

  • Indus originates near Lake Mansarovar, Tibet.
    • Jhelum originates at Verinag (J&K).
    • Chenab originates near Kelong (H.P).
    • Ravi originates near Rohtang Pass (H.P),
    • Beas originates near Rohtang Pass (Beas Kund, H.P),
    • Satluj originates near Mansarovar Lake, Tibet. 
  • Indus flows through J&K in India & then through Pakistan into the Arabian Sea.
  • Important Tributaries of Indus: Jhelum, Chenab, Beas, Ravi, Sutlej, Zanskar, Nubra, Shyok etc.
  • Indus Water Treaty: According to the regulations of the Indus Water Treaty (1960), India can use only 20 percent of the total water carried by Indus river system. The usage rights of the 3 Northern Rivers (Indus, Jhelum & Chenab) have majorly been given to Pakistan whereas the usage rights of the 3 Southern Rivers (Beas, Ravi & Satluj have been given to India.

2. GANGA RIVER SYSTEM

  • The headwaters of the Ganga called the ‘Bhagirathi’ is originates at the Gangotri Glacier and joined by the Alaknanda at Devaprayag in Uttarakhand.
  • Important Tributaries of Ganga: Yamuna, Ghaggara, Gandak, Kosi, Chambal, Betwa, Son etc.
  • Enlarged with the waters from its right and left bank tributaries, the Ganga flows eastwards till Farakka in West Bengal.
  • The Ganga bifurcates at Farakka Barrage; the Bhagirathi-Hooghly (a distributary) flows southwards through the deltaic plains to the Bay of Bengal. The mainstream flows southwards into Bangladesh and is joined by the Brahmaputra leading to the Sunderbans Delta.

3. BRAHMAPUTRA RIVER SYSTEM

  • The Brahmaputra rises in Tibet east of Mansarowar lake very close to the sources of the Indus and the Satluj.
  • It is slightly longer than the Indus, and most of its course lies outside India.
  • It flows eastwards parallel to the Himalayas.
  • On reaching the Namcha Barwa, it takes a ‘U’ turn and enters India in Arunachal Pradesh through a gorge.
  • Tributaries: Dihang, Dibang, Kameng, Subansiri, Lohit, Manas, Teesta etc.

PENINSULAR RIVERS

  • The main water divide for the Peninsular Rivers is the Western Ghats.
  • East flowing Rivers (Bay of Bengal): Mahanadi, Krishna, Godavari & Kaveri.
  • West flowing Rivers (Arabian Sea): Narmada, Tapi, Sabarmati, Mahi etc.
  • NARMADA BASIN: The Narmada rises in the Amarkantak hills in Madhya Pradesh. It flows towards the west in a rift valley formed due to faulting.
  • TAPI BASIN: The Tapi rises in the Satpura ranges, in the Betul district of Madhya Pradesh. It also flows in a rift valley parallel to the Narmada but it is much shorter in length.
  • GODAVARI BASIN: The Godavari is the largest Peninsular river. It rises from the slopes of the Western Ghats in the Nasik district of Maharashtra. Its drainage basin is also the largest among the peninsular rivers. That is why it is also known as the ‘Dakshin Ganga’.
  • MAHANADI BASIN: The Mahanadi rises in the highlands of Chhattisgarh and drains into the Bay of Bengal.
  • KRISHNA BASIN: It rises near Mahabaleshwar and flows into the Bay of Bengal.
  • KAVERI BASIN: The Kaveri rises in the Brahmagri range of the Western Ghats and it reaches the Bay of Bengal in south of Cuddalore, in Tamil Nadu.

Course Discussion