Drainage Systems in India

Antecedent rivers keep cutting their old course after uplift. Exam tip: connect gorges with antecedent rivers.

Jhelum Chenab Ravi Beas and Sutlej are major Indus system rivers. Exam tip: remember them with the Punjab region.

Brahmaputra spreads in plains with heavy water and sediment. Exam tip: connect Assam with floods and river islands.

Brahmaputra is called Tsangpo in Tibet and Jamuna in Bangladesh. Exam tip: connect names with route.

Devprayag is an important confluence in the upper Ganga river system. At this place, the Bhagirathi and Alaknanda rivers meet. Downstream from their meeting, the combined river is known as the Ganga. This makes Devprayag important for understanding how the Ganga is identified in the Himalayan drainage system. It should not be confused with other famous confluences in northern India.

Option A states the relevant geographical relationship exactly. The Yamuna and Chambal do not meet at Devprayag, the Brahmaputra does not enter India there, and the Narmada flows westward toward the Arabian Sea in a different river system. Prayagraj is a separate confluence associated with the Ganga, Yamuna, and the traditional Saraswati. Therefore, option A is the correct choice.

Prayagraj in Uttar Pradesh is known for the confluence of the Ganga and the Yamuna; traditionally, Saraswati is also associated with this Triveni Sangam. Devprayag in Uttarakhand is where the Bhagirathi and Alaknanda meet, and their combined flow is called the Ganga. Option B reverses these two confluences. Exam tip: remember Devprayag as the point where the river is named Ganga, and Prayagraj as the Ganga–Yamuna confluence.

The Kosi carries a large sediment load from the Himalayas. When the slope decreases in the plains, sediment is deposited on the riverbed, making it shallow and the channel unstable. The river may then shift its course or spread water near embankments, flooding large parts of Bihar. Option B is incorrect because the Kosi carries abundant sediment. Exam tip: remember the Kosi as the ‘Sorrow of Bihar’ and link it with sediment deposition and course shifting.

These rivers bring water and sediment from the Himalayas to the Ganga plain. Exam tip: keep them among northern tributaries.

Son is counted among southern tributaries of Ganga. Exam tip: separate northern and southern tributaries.

The direct answer is A: Hooghly is a distributary connected with the delta region of the Ganga system. A river system may divide into branches in its lower course when it approaches a flat coast and the sea. These branches carry water and sediment toward different parts of the delta. Hooghly is an important branch of the Ganga in West Bengal. Thus option A is correct. Option B is wrong because Hooghly does not belong to the Indus system and is not a Himalayan tributary of the Indus. Option C is wrong because a rift valley is a landform, not a river identity, and Hooghly is not the Narmada’s rift valley. Option D is wrong because Hooghly has no connection with the upper course of the Kaveri, which is a separate peninsular river. Remember the direction: a tributary enters a main river, whereas a distributary leaves it. Since Hooghly branches from the Ganga in the deltaic lower course, the correct description is option A. Exam cue: Ganga delta branch in West Bengal means Hooghly.

A tributary and a distributary are identified by the direction in which water moves relative to the main river. A tributary is a smaller stream that flows into and adds water to a larger main river. A distributary leaves the main channel and carries part of its water away, often across a delta or a branching channel system. Thus, one joins the main river and the other branches from it.

The correct choice is A. The phrase “joins the main river” describes a tributary, while “branches away from it” describes a distributary. Option B reverses the essential distinction because both do not branch away. Water divides are high areas separating drainage basins, not rivers, and tributaries or distributaries are not restricted to rift valleys. Direction of flow is the simplest test.

In a delta deposition divides the river into many distributaries. Exam tip: connect delta with distributaries.

Sundarbans is linked with the Ganga Brahmaputra delta and distributaries. Exam tip: remember both delta and mangrove.

Direct answer: Option A is correct. Most major Peninsular rivers flow generally eastward because the Peninsular Plateau has an overall eastward slope toward the Bay of Bengal. Narmada and Tapi are important exceptions. They flow westward and enter the Arabian Sea. Their courses are associated with rift valleys and a westward regional slope, which helps explain their unusual direction. Option A states the relevant comparison accurately. Option B is wrong because neither river is a northern tributary of the Ganga; both belong to the west-flowing Peninsular river group. Option C is wrong because the Sundarbans are formed mainly by the Ganga-Brahmaputra-Meghna system, not by Narmada and Tapi. Option D is wrong because Tsangpo is the Tibetan name of the Brahmaputra, not of these rivers. Exam cue: pair Narmada and Tapi as west-flowing exceptions, while Godavari, Krishna and Kaveri are commonly remembered as east-flowing rivers.

The direct answer is A: the Narmada flows westward through a valley controlled by crustal faults, so it is called a rift valley river. A rift valley forms when movements and fractures in the Earth’s crust create a depressed zone between faults. The Narmada follows such a structurally controlled valley between the Vindhya and Satpura regions and finally reaches the Arabian Sea. Therefore option A gives the correct geological basis. Option B is wrong because Narmada is not a northern tributary of the Ganga; it is a major west-flowing peninsular river. Option C is wrong because it is not located in the Ganga-Brahmaputra delta. Option D is wrong because Narmada is not a distributary of the Luni; Luni is a separate river of Rajasthan. The important reasoning chain is: crustal faults create a depressed linear valley; the river follows that valley; hence Narmada is associated with a rift valley. Memory cue: Narmada and Tapi are famous west-flowing rivers; Narmada is especially linked with a rift valley.

The Deccan Plateau generally slopes from west to east. Therefore, most Peninsular rivers, such as the Godavari, Krishna, Kaveri and Mahanadi, flow eastward and drain into the Bay of Bengal. The Narmada and Tapi are important west-flowing exceptions, so option C is not true for most rivers. Exam tip: learn a river’s direction together with the plateau slope and the sea or bay into which it drains.

Godavari is one of the largest river systems of Peninsular India. Exam tip: connect Dakshin Ganga with Godavari.

The Luni is an example of inland drainage. It flows through the arid region of western Rajasthan and ends in the marshy region of the Rann of Kachchh rather than reaching the sea. Therefore, option A is correct. Option C is incorrect because the Luni is mainly a seasonal, rain-fed river, not a perennial one. Exam tip: Remember the Luni of Rajasthan as an inland-drainage river.

In arid regions low water and high evaporation may stop rivers from reaching sea. Exam tip: remember Thar with Luni.

Bhangar is older alluvium and Khadar is newer alluvium. Exam tip: connect both with flood plains and deposition.

Khadar is the newer alluvial soil found mainly on river flood plains. Rivers carry fine particles such as silt, sand and clay from higher areas. During floods, the river spreads over nearby land and leaves a fresh layer of these materials when the water level falls. This repeated addition keeps Khadar comparatively young and often replenishes nutrients, making it generally fertile.

Option A is correct because repeated flooding brings new alluvial deposits and renews the soil. Coral grows in marine environments and does not create the alluvium of northern flood plains. Glaciers do not form in deserts as the normal cause of Khadar renewal, and volcanic lava is unrelated to ordinary river deposition. The key chain is flood, transport of sediment, deposition on the flood plain and renewal of Khadar. This also distinguishes Khadar from older alluvium, which is called Bhangar.

Northern plains are formed by alluvial deposits of Himalayan river systems. Exam tip: connect plain formation with deposition.

Erosion may dominate upstream and deposition downstream. Exam tip: connect river sections with processes.

In plains rivers slow down and form winding courses. Exam tip: connect meanders with lateral erosion.

Delta is linked with deposition and estuary with tidal open mouth. Exam tip: remember eastern and western coast difference.