Fluvial geomorphology studies the running water of rivers and streams as primary exogenic agents shaping the Earth’s surface through erosion, transportation, and deposition. As water flows from high-altitude headwaters through varying gradients to base levels, it carves V-shaped valleys, deposits alluvial fans, meanders across broad floodplains, and builds complex deltas at river mouths. Mastering these fluvial processes and landforms is essential for physical geography, earth sciences, and competitive examinations. These multiple-choice questions are designed to test academic recall, spatial reasoning, and critical knowledge regarding river dynamics.
1. What is the primary definition of fluvial geomorphology?
Correct Answer: c) The study of landforms and processes associated with flowing surface water
Explanation:
Fluvial geomorphology focuses on how rivers and streams shape the Earth's surface through erosion, transportation, and deposition of sediment.
2. Which term refers to the lowest elevation to which a stream can erode its channel?
Correct Answer: b) Base level
Explanation:
Base level is the lowest point to which a river can flow and erode. A stream cannot erode below its base level.
3. What is considered the ultimate base level for most global river systems?
Correct Answer: c) Sea level
Explanation:
Sea level is the ultimate base level because the vast majority of rivers eventually discharge into the ocean.
4. Which of the following acts as a temporary or local base level for a river?
Correct Answer: c) A lake or a dam
Explanation:
Lakes, dams, and resistant rock outcrops act as temporary or local base levels, preventing the stream from eroding deeper upstream of that point.
5. What is the topographic boundary that separates adjacent drainage basins called?
Correct Answer: a) Drainage divide
Explanation:
A drainage divide is a ridge or area of higher ground that separates one watershed or drainage basin from another.
6. The total area of land that contributes water to a specific river is known as its:
Correct Answer: b) Drainage basin
Explanation:
A drainage basin, also known as a watershed or catchment area, is the entire geographic area drained by a river and its tributaries.
7. In the Strahler stream classification system, what happens when two first-order streams merge?
Correct Answer: c) They form a second-order stream
Explanation:
According to the Strahler ordering system, when two streams of the same order merge (e.g., two 1st-order streams), they form a stream of the next higher order (2nd-order).
8. Which drainage pattern resembles the branching of a tree and typically forms on uniform, flat-lying rock?
Correct Answer: c) Dendritic
Explanation:
The dendritic drainage pattern is the most common and looks like tree branches. It develops where the underlying rock offers uniform resistance to erosion.
9. A trellis drainage pattern is most likely to develop in an area characterized by:
Correct Answer: b) Alternating bands of hard and soft rock
Explanation:
Trellis patterns form in areas with parallel ridges and valleys consisting of alternating resistant and non-resistant rock, such as the Appalachian Mountains.
10. Which drainage pattern is characterized by streams flowing outward in all directions from a central high point, like a volcano?
Correct Answer: b) Radial
Explanation:
A radial drainage pattern develops on isolated peaks, domes, or volcanoes, where water flows outward from the center.
11. A rectangular drainage pattern is primarily controlled by:
Correct Answer: c) Faults and joints in the bedrock
Explanation:
Rectangular drainage patterns form in areas where bedrock is highly faulted or jointed, causing streams to make sharp, right-angle turns.
12. A drainage pattern where streams converge into a central basin or depression is called:
Correct Answer: a) Centripetal
Explanation:
Centripetal drainage is the opposite of radial; streams flow inward toward a central depression, such as a sinkhole or an endorheic basin.
13. Which drainage pattern is chaotic, with no clear geometry, often featuring many lakes and swamps, typically found in recently glaciated areas?
Correct Answer: b) Deranged
Explanation:
Deranged drainage patterns have no coherent pattern and are typical of landscapes recently disrupted by glaciation, where the original drainage was destroyed.
14. An annular drainage pattern is typically associated with:
Correct Answer: b) Eroded structural domes or basins
Explanation:
Annular patterns consist of circular or ring-like stream courses that follow bands of softer rock around an eroded dome or basin.
15. The erosive force of moving water wedging into cracks and pulling away loose rock is known as:
Correct Answer: b) Hydraulic action
Explanation:
Hydraulic action is the mechanical weathering and erosion caused by the sheer force of moving water forcing air into cracks and dislodging rock.
16. Which fluvial erosion process involves rocks and sediments scraping against the river bed and banks, much like sandpaper?
Correct Answer: c) Abrasion
Explanation:
Abrasion (or corrasion) occurs when a river uses its sediment load to scrape and grind away at the riverbed and banks.
17. The process by which rocks carried by a river smash into each other and break into smaller, rounder pieces is called:
Correct Answer: b) Attrition
Explanation:
Attrition is the collision of rock fragments in the river load against one another, causing them to become smaller and more rounded over time.
18. Corrosion in a river system refers to:
Correct Answer: c) The chemical dissolution of soluble rocks like limestone
Explanation:
Corrosion (or solution) is a chemical erosion process where slightly acidic river water dissolves soluble minerals in rocks, such as calcium carbonate in limestone.
19. Which type of erosion deepens a river channel and is most dominant in the youthful, upper course of a river?
Correct Answer: b) Vertical erosion
Explanation:
Vertical erosion (downcutting) deepens the river channel and is the dominant erosional process in steep, youthful streams, creating V-shaped valleys.
20. Lateral erosion is responsible for:
Correct Answer: c) Widening a river valley and creating meanders
Explanation:
Lateral erosion cuts into the banks of a river, widening the valley and promoting the development of meanders in the middle and lower courses.
21. The process by which a river lengthens its course at its source by cutting back upstream is known as:
Correct Answer: a) Headward erosion
Explanation:
Headward erosion occurs at the origin of a stream, cutting back into the landscape and lengthening the stream channel.
22. River capture, or stream piracy, occurs primarily as a result of aggressive:
Correct Answer: b) Headward erosion
Explanation:
River capture happens when a stream with a steeper gradient aggressively erodes headward until it intercepts and diverts the water of an adjacent stream.
23. An abandoned river valley through a ridge, left dry after a river capture event, is known as a:
Correct Answer: b) Wind gap
Explanation:
A wind gap is a former water gap that is now dry because the stream that created it was captured or diverted.
24. A gorge or valley cut through a ridge by a stream that currently flows through it is called a:
Correct Answer: b) Water gap
Explanation:
A water gap is a pass through a mountain or ridge that is actively occupied by a flowing river.
25. A stream that maintains its original course and pattern despite subsequent uplift or folding of the land is an:
Correct Answer: a) Antecedent stream
Explanation:
An antecedent stream existed before the current topography formed and eroded downward at a rate equal to the tectonic uplift, maintaining its course.
26. A stream that eroded through a covering of sedimentary rock to cut into buried geologic structures below, regardless of their shape, is called a:
Correct Answer: b) Superimposed stream
Explanation:
A superimposed stream's course was established on a younger cover of rock and then eroded down into older, buried structures, 'superimposing' its pattern on them.
27. The portion of a stream's sediment load that rolls, slides, or bounces along the riverbed is the:
Correct Answer: c) Bedload
Explanation:
The bedload consists of heavier particles, like gravel and large sand grains, that move along the bottom of the river channel.
28. Which term describes the fine particles (silt and clay) carried within the main body of the water column?
Correct Answer: b) Suspended load
Explanation:
The suspended load is made up of fine-grained particles that are kept aloft in the water by turbulence, often giving rivers a muddy appearance.
29. The invisible portion of a river's load, derived primarily from chemical weathering, is the:
Correct Answer: a) Dissolved load
Explanation:
The dissolved load consists of chemical ions (like calcium and sodium) dissolved in the water, which are invisible and move at the same velocity as the water.
30. The transportation process where medium-sized particles, like sand, bounce or hop along the riverbed is called:
Correct Answer: c) Saltation
Explanation:
Saltation is the bouncing or hopping movement of particles too heavy to be suspended continuously but light enough to be lifted briefly by turbulent flow.
31. The transportation process where large boulders are rolled or dragged along the bottom of the river channel is:
Correct Answer: b) Traction
Explanation:
Traction involves the rolling or dragging of large, heavy materials along the riverbed by the force of the water.
32. What does a stream's 'competence' measure?
Correct Answer: c) The maximum particle size a stream is capable of transporting
Explanation:
Competence refers to the maximum size (diameter) of a rock particle that a stream is able to transport, which is highly dependent on water velocity.
33. What does a stream's 'capacity' refer to?
Correct Answer: b) The maximum total sediment load it can transport
Explanation:
Stream capacity is the maximum total volume or mass of sediment that a river can carry, which depends on both velocity and discharge.
34. According to the sixth-power law, if a stream's velocity doubles, its competence (maximum particle weight it can move) increases by a factor of:
Correct Answer: d) 64
Explanation:
The sixth-power law states that stream competence increases with the sixth power of its velocity. Therefore, 2^6 = 64 times the carrying power.
35. The Hjulström curve illustrates the relationship between:
Correct Answer: a) Water velocity and the erosion, transport, and deposition of sediment sizes
Explanation:
The Hjulström curve graphs water velocity against particle size to show the thresholds at which particles are eroded, transported, or deposited.
36. According to the Hjulström curve, which sediment type requires the highest velocity to be eroded despite its small particle size?
Correct Answer: c) Clay
Explanation:
Clay requires a very high velocity to initially erode because the microscopic particles possess strong cohesive forces binding them together.
37. General term for any sediment deposited by flowing water is:
Correct Answer: c) Alluvium
Explanation:
Alluvium is loose, unconsolidated sediment (clay, silt, sand, gravel) that has been eroded, reshaped by water, and deposited in a non-marine setting.
38. The line connecting the deepest points of a river channel is called the:
Correct Answer: b) Thalweg
Explanation:
The thalweg is a line drawn to join the lowest points along the entire length of a stream bed or valley in its downward slope, defining its deepest channel.
39. The corkscrew-like, secondary flow of water in a meandering river that contributes to bank erosion and point bar deposition is known as:
Correct Answer: b) Helicoidal flow
Explanation:
Helicoidal flow is a secondary, three-dimensional, corkscrew-like water movement in a meander that sweeps eroded material from the outer bank to the inner bank.
40. Shallow, fast-flowing sections of a river with a rocky bed, often alternating with deeper, slower sections, are known as:
Correct Answer: b) Riffles
Explanation:
Riffles are shallow, turbulent sections of a stream, which commonly alternate with deeper, calmer pools in a 'riffle-pool sequence'.
41. In a meandering river, deposition occurs predominantly on the inner curve of the bend, forming a:
Correct Answer: b) Point bar
Explanation:
A point bar is an accumulation of alluvium found on the inside bend of streams and rivers below the slip-off slope, caused by lower water velocity.
42. The steep, eroding outer bank of a meandering river is called the:
Correct Answer: c) Cut bank
Explanation:
The cut bank (or river cliff) is located on the outside of a meander where water velocity is highest, causing active lateral erosion.
43. What triggers the formation of a meandering river pattern rather than a straight channel?
Correct Answer: c) Gentle gradients and cohesive banks
Explanation:
Meanders typically form in the middle and lower courses of rivers where gradients are gentle, banks are cohesive, and flow becomes laterally unstable.
44. The sinuosity index of a river is a ratio between:
Correct Answer: a) Channel length and valley length
Explanation:
Sinuosity is measured by dividing the actual channel length by the straight-line distance (valley length). A value >1.5 is generally considered a meandering stream.
45. A U-shaped body of water that forms when a wide meander from the main stem of a river is cut off is called an:
Correct Answer: c) Oxbow lake
Explanation:
An oxbow lake is created when a river cuts through the neck of a meander loop, abandoning the old curve to form a crescent-shaped lake.
46. When an oxbow lake completely dries up or fills with sediment, it becomes a:
Correct Answer: b) Meander scar
Explanation:
A meander scar (or meander scroll) is the geological remnant of an oxbow lake that has filled with sediment and vegetation.
47. A shortcut across a meander loop formed during high flood stages is known as a:
Correct Answer: a) Chute cutoff
Explanation:
A chute cutoff occurs during floods when water bypasses the meander loop by flowing directly over the point bar, carving a new, straighter channel.
48. A river channel that divides into a network of small, interlaced channels separated by islands or bars is a:
Correct Answer: b) Braided stream
Explanation:
Braided streams form when a river has a high sediment load (often gravel/sand) and fluctuating discharge, causing it to split into multiple interconnected channels.
49. Anastomosing rivers differ from braided rivers primarily because:
Correct Answer: b) They have multiple interconnected channels separated by stable, vegetated islands rather than shifting sandbars
Explanation:
Anastomosing rivers have a multi-channel pattern like braided rivers, but their channels are separated by highly stable, cohesive, vegetated floodplains.
50. In the youthful, upper stage of a river's course, the dominant landscape feature is typically a:
Correct Answer: c) V-shaped valley
Explanation:
Rapid vertical downcutting by a young stream creates steep-sided V-shaped valleys, typical of mountainous upper courses.
51. Projections of high land that alternate from opposite sides of a V-shaped valley, forcing the river to weave around them, are called:
Correct Answer: b) Interlocking spurs
Explanation:
As a youthful river avoids areas of hard rock, it weaves back and forth, leaving ridges (spurs) that interlock like the teeth of a zipper.
52. A geological feature formed where a river flows over a layer of hard rock that overlays a layer of softer rock, causing vertical erosion, is a:
Correct Answer: b) Waterfall
Explanation:
Waterfalls typically form when a river crosses a band of resistant hard rock situated over softer rock, which is easily eroded to create a vertical drop.
53. The deep depression carved out at the base of a waterfall by the abrasive force of falling water is a:
Correct Answer: a) Plunge pool
Explanation:
A plunge pool is a deep basin excavated at the foot of a waterfall by the sheer hydraulic action and abrasive rock debris swirling in the falling water.
54. Sections of a river characterized by steep gradients, turbulent flow, and exposed rocks are known as:
Correct Answer: b) Rapids
Explanation:
Rapids form where the river gradient is steep and the channel bed is highly irregular, often indicating differential erosion of bedrock.
55. Cylindrical holes drilled into the bedrock of a river channel by swirling stones caught in eddies are called:
Correct Answer: c) Potholes
Explanation:
Potholes are smooth, bowl-shaped or cylindrical hollows carved into the rocky bed of a stream by the grinding action of stones whirled around by turbulent eddies.
56. A deep, narrow valley with exceptionally steep walls, typically carved by a river in arid regions, is a:
Correct Answer: b) Canyon or Gorge
Explanation:
Canyons and gorges are deep ravines between pairs of cliffs, mostly formed by the aggressive vertical downcutting of a river in regions where lateral weathering is slow.
57. A sharp change in the channel slope of a river, often indicating a drop in base level or a waterfall, is called a:
Correct Answer: c) Knickpoint
Explanation:
A knickpoint is a sharp irregularity in a stream's longitudinal profile, such as a waterfall or rapids, often retreating upstream over time.
58. When a river gains new erosional power due to a fall in sea level or tectonic uplift, it is said to undergo:
Correct Answer: c) Rejuvenation
Explanation:
Rejuvenation occurs when a river's base level drops, giving it renewed potential energy to begin aggressively downcutting into its valley again.
59. Rejuvenation caused by a global drop in sea level (e.g., during an ice age) is known as:
Correct Answer: b) Eustatic rejuvenation
Explanation:
Eustatic changes are global variations in sea level. When sea level drops, the ultimate base level falls, causing eustatic rejuvenation.
60. Rejuvenation caused by localized tectonic uplift of the landmass is known as:
Correct Answer: a) Isostatic or dynamic rejuvenation
Explanation:
Dynamic or isostatic rejuvenation occurs when the land itself is uplifted by tectonic forces, increasing the river's gradient.
61. A deeply cut meander with steep, symmetrical valley walls, resulting from rapid vertical downcutting, is called an:
Correct Answer: b) Entrenched (incised) meander
Explanation:
Entrenched meanders form during rapid rejuvenation when a river downcuts so quickly that it preserves its meandering pattern deep in a steep-walled gorge.
62. An incised meander with asymmetrical slopes, indicating that lateral erosion occurred alongside vertical downcutting, is an:
Correct Answer: b) Ingrown meander
Explanation:
Ingrown meanders occur when rejuvenation is slower, allowing the river to erode laterally and undercut the outer bank while depositing on the inner bank, creating asymmetrical valley sides.
63. A step-like landform situated above the modern floodplain, representing an older, higher floodplain level, is a:
Correct Answer: c) River terrace
Explanation:
River terraces are remnants of a former floodplain left stranded at a higher elevation after a river has rejuvenated and downcut into its valley.
64. When river terraces on opposite sides of a valley are at the same elevation, they are called:
Correct Answer: b) Paired terraces
Explanation:
Paired terraces occur when a river downcuts rapidly and evenly across the entire valley floor, leaving remnants at matching heights on both sides.
65. The relatively flat land adjacent to a river that experiences periodic flooding and sediment deposition is the:
Correct Answer: c) Floodplain
Explanation:
The floodplain is a flat area of land next to a river, built up from centuries of alluvium deposited during flood events.
66. Elongated ridges of sediment deposited parallel to the riverbanks during flood events are known as:
Correct Answer: b) Natural levees
Explanation:
Natural levees form when floodwaters overflow the riverbanks and rapidly lose velocity, immediately dropping the coarsest sediment parallel to the channel.
67. A tributary stream that runs parallel to the main river for a long distance because natural levees prevent it from joining is a:
Correct Answer: c) Yazoo stream
Explanation:
A Yazoo stream is forced to flow parallel to the main river across the floodplain because it is blocked by the main river's elevated natural levees.
68. A marshy, poorly drained area on a floodplain located behind the natural levees is called a:
Correct Answer: c) Backswamp
Explanation:
Backswamps are low-lying, poorly drained sections of a floodplain located behind natural levees, often containing fine clays and abundant vegetation.
69. A fan-shaped deposit of sediment formed where a natural levee breaches during a flood, spilling into the floodplain, is a:
Correct Answer: a) Crevasse splay
Explanation:
A crevasse splay is a sedimentary fluvial deposit which forms when a stream breaks its natural or artificial levees and deposits sediment on a floodplain.
70. A conical, fan-shaped accumulation of sediment deposited where a steep mountain stream emerges onto a flat plain is an:
Correct Answer: b) Alluvial fan
Explanation:
Alluvial fans form at the base of mountain fronts in arid or semi-arid environments where stream velocity suddenly decreases, depositing coarse sediment.
71. A broad, continuous slope of alluvium formed by the merging of several adjacent alluvial fans is called a:
Correct Answer: b) Bajada
Explanation:
A bajada is a continuous apron of sediment formed when multiple alluvial fans along a mountain front grow large enough to coalesce.
72. A landform created by the deposition of sediment that is carried by a river as the flow leaves its mouth and enters slower-moving water is a:
Correct Answer: a) Delta
Explanation:
A delta forms when a river loses its competence and capacity upon entering a standing body of water (ocean or lake), depositing sediment.
73. In a classical delta cross-section, the nearly horizontal layers of coarse sediment deposited on the delta plain are:
Correct Answer: c) Topset beds
Explanation:
Topset beds are the horizontal upper layers of a delta consisting of coarse sediment deposited by the river as it flows across the delta plain.
74. In a delta, the steeply dipping layers of sediment deposited just over the edge of the delta front are the:
Correct Answer: b) Foreset beds
Explanation:
Foreset beds are the inclined layers of a delta deposited as sediment avalanches down the front slope into deeper water.
75. The finest sediments (clays) that settle far out in the deep water in front of a delta form the:
Correct Answer: c) Bottomset beds
Explanation:
Bottomset beds are the horizontal layers of fine mud and clay deposited in the deep, calm water beyond the active delta front.
76. A fan-shaped or triangular delta with a rounded outer edge, like the Nile Delta, is classified as an:
Correct Answer: a) Arcuate delta
Explanation:
An arcuate delta is convex-shaped and resembles a fan or a bow. It is characterized by many distributaries and strong wave action, typical of the Nile.
77. A delta featuring long, projecting fingers of sediment built outward into the sea by a single dominant river channel is a:
Correct Answer: b) Bird's-foot delta
Explanation:
A bird's-foot delta, like the Mississippi Delta, has a few dominant, highly active distributary channels that build elongated deposits far into the ocean.
78. A V-shaped delta formed by strong wave action shaping sediment into a pointed tooth-like shape, such as the Tiber Delta, is a:
Correct Answer: c) Cuspate delta
Explanation:
A cuspate delta is formed where coastal wave action pushes sediment back toward the shore, creating a sharp, pointed 'V' shape extending outward.
79. A delta that forms entirely within the submerged mouth of a river valley, filling it with sediment, is called an:
Correct Answer: b) Estuarine delta
Explanation:
An estuarine delta (e.g., the Seine) is formed when a river deposits its sediment inside a flooded river mouth (estuary) before it reaches the open coastline.
80. The small, branching channels that split off from the main river near a delta and carry water to the sea are:
Correct Answer: c) Distributaries
Explanation:
Distributaries are channels that branch off and flow away from a main stream channel, the opposite of tributaries, and are a key feature of deltas.
81. The process of a river abandoning its current channel and delta lobe to seek a steeper, shorter path to the sea is called:
Correct Answer: a) Avulsion
Explanation:
Avulsion is the rapid, abrupt abandonment of a river channel and the formation of a new one, commonly driving the shifting of delta lobes over centuries.
82. An ideal stream profile in which a state of dynamic equilibrium is reached between erosion and deposition is known as a:
Correct Answer: b) Graded stream
Explanation:
A graded stream has reached a balance over time, adjusting its slope and channel size so its velocity is just enough to transport its sediment load without net erosion or deposition.
83. The building up of a river's bed by the continuous deposition of sediment is known as:
Correct Answer: b) Aggradation
Explanation:
Aggradation is the progressive accumulation of sediment along a riverbed, causing the channel elevation to rise, often when sediment supply exceeds transport capacity.
84. The lowering of a riverbed over time through active downward erosion is called:
Correct Answer: b) Degradation
Explanation:
Degradation is the geological process of channel downcutting and lowering of a fluvial surface by erosional processes.
85. The concept that rivers adjust their variables (width, depth, velocity, slope) to accommodate changes in discharge and sediment load is called:
Correct Answer: b) Dynamic equilibrium
Explanation:
Dynamic equilibrium describes a fluvial system in a steady state, constantly self-adjusting its geometry and flow characteristics to handle the inputs of water and sediment.
86. The specific stream discharge that completely fills the river channel without spilling over the banks is the:
Correct Answer: b) Bankfull discharge
Explanation:
Bankfull discharge is the flow that just fills the channel to the top of its banks. It is often considered the primary geomorphic driver determining channel shape.
87. Stream power, a measure of a river's potential to do geomorphic work, is mathematically calculated using:
Correct Answer: b) Water density, gravity, discharge, and channel slope
Explanation:
Total stream power is the product of the specific weight of water, the discharge (Q), and the channel slope (S).
88. Water flow in which streamlines are parallel and there is no mixing between layers is called:
Correct Answer: c) Laminar flow
Explanation:
Laminar flow occurs when water particles move in straight, parallel paths. It is extremely rare in natural rivers, which are almost entirely turbulent.
89. The chaotic, eddying flow typical of most natural rivers, which is highly effective at eroding and suspending sediment, is:
Correct Answer: b) Turbulent flow
Explanation:
Turbulent flow is characterized by chaotic, mixing motions (eddies) that provide the upward velocity necessary to suspend particles and erode channels.
90. The dimensionless number used in fluid mechanics to distinguish between laminar and turbulent flow is the:
Correct Answer: c) Reynolds number
Explanation:
The Reynolds number calculates the ratio of inertial forces to viscous forces; high values indicate turbulent flow, while low values indicate laminar flow.
91. The dimensionless number used to define subcritical, critical, or supercritical flow based on the ratio of water velocity to wave speed is the:
Correct Answer: b) Froude number
Explanation:
The Froude number indicates whether flow is tranquil (subcritical, 1), influencing features like hydraulic jumps.
92. On a storm hydrograph, the highest point of river discharge after a rainfall event is called the:
Correct Answer: b) Peak discharge
Explanation:
Peak discharge represents the maximum volume of water flowing in the river channel during a specific flood event.
93. The delay between the peak rainfall in a drainage basin and the peak discharge in the river is the:
Correct Answer: c) Lag time
Explanation:
Lag time represents how quickly a watershed converts precipitation into river flow. A short lag time often indicates a high risk of flash flooding.
94. The steady, year-round flow of a river, supplied primarily by groundwater seepage rather than immediate rainfall runoff, is called:
Correct Answer: b) Baseflow
Explanation:
Baseflow is the portion of streamflow that comes from deep subsurface flow and delayed shallow subsurface flow, sustaining rivers between rain events.
95. How does intense urbanization typically alter a river's storm hydrograph?
Correct Answer: b) It decreases lag time and increases peak discharge
Explanation:
Urbanization replaces permeable soil with impermeable concrete and asphalt. Runoff reaches rivers much faster, causing a shorter lag time and a higher, 'flashier' peak discharge.
96. What is a common geomorphic consequence downstream of a large dam construction?
Correct Answer: c) Clear-water erosion (degradation)
Explanation:
Dams trap sediment in reservoirs. The water released downstream is 'sediment-starved' and highly erosive, leading to severe channel downcutting (clear-water erosion).
97. The total volume of sediment leaving a drainage basin over a given period is known as its:
Correct Answer: a) Sediment yield
Explanation:
Sediment yield is the amount of sediment per unit area removed from a watershed by flowing water during a specified time, usually measured in tons/km²/year.
98. Which of the following rivers has the largest average discharge in the world?
Correct Answer: d) The Amazon River
Explanation:
The Amazon River has the greatest discharge by far, carrying more water than the next seven largest independent rivers combined.
99. Which river is widely recognized as the longest in the world, flowing northward through Africa into the Mediterranean Sea?
Correct Answer: b) The Nile River
Explanation:
The Nile is generally considered the longest river globally, though recent geographical debates have argued the Amazon might be comparable in length.
100. The Grand Canyon in the United States is a massive gorge primarily carved by which river?
Correct Answer: c) The Colorado River
Explanation:
The aggressive vertical erosion of the Colorado River, combined with the tectonic uplift of the Colorado Plateau, carved out the Grand Canyon over millions of years.
101. In fluvial geomorphology, distinguishing between a delta and an alluvial fan depends primarily on:
Correct Answer: b) Whether the sediment was deposited in a standing body of water or on dry land
Explanation:
Deltas are formed by deposition into standing water (oceans, lakes), while alluvial fans are formed by deposition onto a terrestrial, subaerial surface (usually a flat plain).
