Landforms by River

1. Match List-I with List-II and select the correct answer using the code

Match List-I with List-II and select the correct answer using the code given below the Lists :

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List-I
(Type of plain)		List-II
(Characteristic feature)
A. Bhabar1. Marsh
B. Bhangar2. Silt
C. Khadar3. Gravels
D. Delta4. Kankar

Code :

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A-3, B-2, C-4, D-1
A-3, B-4, C-2, D-1
A-1, B-4, C-2, D-3
A-1, B-2, C-4, D-3
This question was previously asked in
UPSC CAPF – 2022
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The correct option is B. The characteristics are correctly matched as A-3, B-4, C-2, D-1.
– A. Bhabar: This is a narrow belt (8-10 km wide) running parallel to the Shiwalik range. It consists of pebbles and boulders deposited by rivers coming down from the mountains. Rivers often disappear into this porous belt. Matches with Characteristic 3 (Gravels).
– B. Bhangar: This is the older alluvial plain, located away from the floodplains. It is slightly elevated and contains calcareous concretions known as ‘Kankar’. Matches with Characteristic 4 (Kankar).
– C. Khadar: This is the newer alluvial plain, located along the river banks. It is formed by fresh alluvial deposits during annual floods. It is fertile and consists of fine silt and clay. Matches with Characteristic 2 (Silt).
– D. Delta: This is a landform created by deposition of sediment that is carried by a river as the flow leaves its mouth and enters slower-moving or standing water. Deltas are typically low-lying, flat, and often contain marshy areas, especially near the coast. Matches with Characteristic 1 (Marsh).
– The plains of Northern India are primarily formed by alluvial deposits from the Indus, Ganga, and Brahmaputra river systems.
– These plains are geographically divided into different belts based on sediment characteristics and elevation relative to flood levels (Bhabar, Terai, Bhangar, Khadar).
– The Terai belt is located south of the Bhabar, it is a wet, swampy, and marshy region with dense forest cover. (Not included in this question, but relevant context).

2. The heaviest rocks, which are rolled along the river bed in river tran

The heaviest rocks, which are rolled along the river bed in river transport, come under which type of load?

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Solution load
Suspension load
Saltation load
Traction load
This question was previously asked in
UPSC CAPF – 2021
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The heaviest rocks rolled along the river bed come under traction load.
Traction load refers to the largest and heaviest sediment particles transported by a river, which are moved by being rolled or dragged along the river bed.
River load transport mechanisms include:
– **Solution load:** Dissolved material carried within the water.
– **Suspension load:** Fine particles like clay and silt held up and carried within the main flow of water.
– **Saltation load:** Medium-sized particles like sand and gravel that move by bouncing or hopping along the bed.
– **Traction load:** Coarsest and heaviest material like pebbles, cobbles, and boulders that are rolled or slid along the river bed by the force of the water.
The description “heaviest rocks, which are rolled along the river bed” directly matches the definition of traction load.

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3. In the course of a river, in time, which one of the following features

In the course of a river, in time, which one of the following features is formed when the old meander is closed off by deposition?

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Pothole
Levee
Oxbow lake
Flood plain
This question was previously asked in
UPSC CAPF – 2021
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An oxbow lake is a U-shaped lake that forms when a wide meander from the main stem of a river is cut off, creating a free-standing body of water. This occurs as erosion and deposition processes narrow the neck of a meander loop. Eventually, during high flow, the river cuts across the neck, and deposition seals off the old meander channel, leaving a crescent-shaped lake.
– Meanders are bends or curves in a river channel.
– Erosion occurs on the outer bend, and deposition occurs on the inner bend.
– This process leads to the migration and accentuation of meanders.
– An oxbow lake is a relict feature of a former meander.
Other river features mentioned:
– Potholes are cylindrical or bowl-shaped depressions drilled into the rocky bed of a river by abrasive action of pebbles and sediment swirled by turbulent water.
– Levees are natural or artificial embankments along the sides of a river channel, especially in its lower course, formed by deposition of sediment during floods.
– A flood plain is a flat or nearly flat land adjacent to a stream or river that stretches from the bank of its channel to the base of the enclosing valley walls, and experiences flooding during periods of high discharge.

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4. The gently sloping accumulation of coarse alluvium deposits by a braid

The gently sloping accumulation of coarse alluvium deposits by a braided stream is known as

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sand bar
alluvial fan
bajada
diaras
This question was previously asked in
UPSC CAPF – 2019
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The correct answer is B) alluvial fan. A gently sloping accumulation of coarse alluvium deposited by a stream, especially where it exits a confined area (like a mountain valley) onto a flatter plain, is known as an alluvial fan. Braided streams, due to their high sediment load and variable discharge, are commonly associated with the formation of alluvial fans, particularly in arid or semi-arid environments or areas with high sediment supply.
– Alluvial fans are triangular or cone-shaped depositional landforms created by streams.
– They form where a stream undergoes a decrease in gradient and/or velocity, leading to the deposition of its sediment load.
– Braided streams are often the type of channel found on the surface of alluvial fans, as they are effective transporters and depositors of coarse sediment.
– The deposits typically consist of sand, gravel, and larger clasts (coarse alluvium).
While a braided stream can deposit material in other forms (like sandbars within channels or extensive alluvial plains), the description “gently sloping accumulation” points towards a large, widespread landform, and among the given options, ‘alluvial fan’ best fits the description of a significant depositional feature composed of coarse alluvium deposited by a stream, often braided, losing energy.

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5. Match List-I with List-II and select the correct answer using the code

Match List-I with List-II and select the correct answer using the code given below the Lists :

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List-I
(Landform feature)		List-II
(Location)
A. Alluvial fans1. Mountainous Areas
B. ‘V’-shaped valleys2. Coasts
C. Deltas3. Lower Reaches of the river
D. Ox-bow lakes4. Mountain Foothills

Code :

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ABCD
(a)4123
(b)4213
(c)3214
(d)3124
A-4, B-1, C-2, D-3
A-4, B-2, C-1, D-3
A-3, B-2, C-1, D-4
A-3, B-1, C-2, D-4
This question was previously asked in
UPSC CAPF – 2015
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The correct matching is A-4, B-1, C-2, D-3.
– Alluvial fans are fan-shaped deposits of sediment formed at the base of a mountain or at the mouth of a narrow valley where a stream flows onto a flatter surface, characteristic of mountain foothills.
– ‘V’-shaped valleys are formed by the erosional action of rivers in their upper course, typically found in mountainous areas where downcutting is dominant.
– Deltas are landforms created by deposition of sediment that is carried by a river as the flow leaves its mouth and enters slower-moving or standing water, usually the sea or a lake. They are characteristic features of the lower reaches of rivers, often found at coasts.
– Ox-bow lakes are crescent-shaped lakes formed in abandoned meander loops of a river, typically found in the flat, alluvial plains of the river’s lower course.
The lower reaches of a river are often characterized by meandering, the formation of ox-bow lakes, and ultimately the development of a delta at its mouth on the coast. V-shaped valleys are associated with the youthful stage and mountainous terrain, while alluvial fans form where mountain streams transition to flatter land.

6. Which one of the following features is the result of erosion and depos

Which one of the following features is the result of erosion and deposition work of a river?

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Pothole
Oxbow lake
Levee
Rapid
This question was previously asked in
UPSC NDA-2 – 2021
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An oxbow lake is a crescent-shaped lake formed when a river meander is cut off from the main channel. This process involves erosion (cutting through the neck of the meander) and deposition (sealing off the ends of the abandoned channel).
Oxbow lakes are landforms typically found in the mature stage of a river valley, resulting from lateral erosion and deposition.
Potholes are cylindrical depressions drilled in the river bed by abrasion (erosion). Levees are natural or artificial embankments formed along the river banks by deposition of sediment. Rapids are turbulent sections of a river where the water flows rapidly over a steep gradient, primarily an erosional environment or flow characteristic rather than a depositional landform.

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7. A deep valley characterized by steep step-like slope is known as

A deep valley characterized by steep step-like slope is known as

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U-shaped valley.
Blind valley.
Gorge.
Canyon.
This question was previously asked in
UPSC NDA-2 – 2019
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A deep valley characterized by steep step-like slopes is known as a canyon.
Canyons are deep gorges, often with steep to sheer walls, frequently carved by rivers, especially in arid or semi-arid regions where differential erosion of layered sedimentary rock creates a stair-step appearance on the slopes.
While a gorge is also a deep, narrow valley with steep sides, the description “step-like slope” is particularly characteristic of canyons formed in horizontally layered rock where resistant layers form cliffs and weaker layers erode into slopes or benches, creating a stepped profile. A U-shaped valley is glacial in origin, and a blind valley ends abruptly at a sinkhole.

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8. Where is Mekong Delta located ?

Where is Mekong Delta located ?

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Thailand
Cambodia
Myanmar
Vietnam
This question was previously asked in
UPSC NDA-2 – 2017
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The Mekong Delta is located in Vietnam.
The Mekong River is a transnational river flowing through six countries: China, Myanmar, Laos, Thailand, Cambodia, and Vietnam. The Mekong Delta is the vast delta region in southwestern Vietnam where the Mekong River splits into numerous distributaries and empties into the South China Sea.
The Mekong Delta is a major rice-growing region in Vietnam and is known for its complex network of rivers, swamps, and islands. It is also a popular tourist destination. While the Mekong River flows through several countries, the delta formation occurs primarily within Vietnam.

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9. Consider the following diagram : In which one among the following lett

Consider the following diagram :
In which one among the following lettered areas of the diagram would erosion most likely change the shapes of the riverbed ?

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A
B
C
D
This question was previously asked in
UPSC NDA-1 – 2015
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The diagram shows a meandering river. In a meandering river bend, water flows faster on the outer bank (due to centrifugal force and deeper water) and slower on the inner bank (where sediment is deposited, forming a point bar). Erosion is most active on the outer bank of the bend due to the faster current. Area C is located on the outer bank of the river bend where erosion is dominant, leading to the cutting away of the bank and changing the shape of the riverbed and bend over time. Areas A and D are on the inner bank where deposition occurs. Area B is likely in a straighter section or near the transition, but erosion is most pronounced at the apex of the outer bend, which is represented by C.
Erosion in a meandering river is concentrated on the outer bends where water flows fastest, while deposition occurs on the inner bends where water is slower.
Over time, continuous erosion on the outer bends and deposition on the inner bends cause the meanders to migrate laterally across the floodplain and can eventually lead to the formation of oxbow lakes when a meander neck is cut off.

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10. Match List I with List II and select the correct answer using the code

Match List I with List II and select the correct answer using the code given below the Lists :

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List I
(Drainage Pattern of River)		List II
(Feature)
A. Insequent1. Whose direction of flow is controlled by the rock structure
B. Consequent2. No apparent reason why it follows the path it takes
C. Subsequent3. Flow in the same direction as the consequent stream but at a lower level
D. Resequent4. Whose course is determined by the original slope of the land
A-2, B-1, C-4, D-3
A-2, B-4, C-1, D-3
A-3, B-4, C-1, D-2
A-3, B-1, C-4, D-2
This question was previously asked in
UPSC CDS-2 – 2022
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The correct answer is B) A-2, B-4, C-1, D-3.
The match is as follows:
A. Insequent: 2. Whose direction of flow is controlled by the rock structure – This is incorrect. Insequent streams follow no discernible pattern and are not controlled by underlying rock structure; they often develop on newly exposed, uniform surfaces or areas of thick regolith. Their path has “no apparent reason.”
B. Consequent: 4. Whose course is determined by the original slope of the land – Correct. Consequent streams flow directly down the steepest slope of the land.
C. Subsequent: 1. Whose direction of flow is controlled by the rock structure – Correct. Subsequent streams develop along belts of weaker rock resistance, often parallel to the strike of folded rock layers or along fault lines. They adjust their course to the underlying geological structure.
D. Resequent: 3. Flow in the same direction as the consequent stream but at a lower level – Correct. Resequent streams are tributaries that flow in the same general direction as the original consequent streams but form later, often on a lower erosion level.
Let’s re-evaluate the match for Insequent based on the options provided. Option 2 “No apparent reason why it follows the path it takes” fits Insequent better than any other pattern. Option 1 “Whose direction of flow is controlled by the rock structure” fits Subsequent. Option 3 “Flow in the same direction as the consequent stream but at a lower level” fits Resequent. Option 4 “Whose course is determined by the original slope of the land” fits Consequent.
Thus, A-2, B-4, C-1, D-3 is the correct matching.
Drainage patterns are determined by the relationship between the stream course and the underlying bedrock structure. Other common patterns include Dendritic (tree-like, on uniform resistance rocks), Trellis (rectangular pattern in areas of folded rock), Radial (flowing outwards from a central point, like a volcano), Centripetal (flowing inwards towards a central depression), and Annular (circular pattern in dome or basin structures). Understanding these patterns helps geomorphologists interpret the underlying geology and landscape history.

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