River Physical Processes

Weathering Processes

Water is one of the only substances that expands when it freezes, taking up exactly 10% more space as solid ice than as a liquid. This incredible internal pressure is powerful enough to shatter solid rock over time.
Weathering is the disintegration and decomposition of rocks at the Earth's surface. Crucially, this happens in situ, meaning the rock is NOT moved by an external flowing force like water or ice.
On river valley sides, weathering weakens the rock above the water level. These are known specifically as sub-aerial processes.

There are three main categories of weathering:

Mechanical weathering: Breakdown of rock without any chemical change.
Chemical weathering: Breakdown involving a chemical change in the rock's minerals.
Biological weathering: Breakdown caused by the physical or chemical activities of living organisms, such as tree roots expanding in cracks.

Step-by-Step Describe: Freeze-Thaw (Mechanical Weathering)

First, rainwater enters cracks or joints in the rock on the river valley side.
Then, when temperatures drop below 0°C at night, the water freezes and expands by 10%, exerting massive outward pressure (up to 2,100 kg/cm²) on the crack.
As a result, the crack is forced wider.
When temperatures rise, the ice thaws, allowing water to seep deeper into the newly widened crack.
Finally, repeated cycles of freezing and thawing shatter the rock into angular fragments called scree, which collect at the base of the slope.

Step-by-Step Describe: Carbonation (Chemical Weathering)

First, rainwater absorbs CO₂ from the atmosphere to form a weak carbonic acid.
Then, this mildly acidic water reacts with alkaline rocks like limestone or chalk.
Finally, minerals like calcium carbonate are dissolved and washed away.

Mass Movement Processes

A dry slide down a grassy hill might just give you grass stains, but a saturated, muddy slope can pull down entire trees. Water drastically changes how gravity affects a valley side.
Mass movement is the downhill movement of weathered material under the force of gravity. Any slope with a gradient steeper than 5° is susceptible.
Mass movement supplies sediment to the river, providing the abrasive tools it needs for future erosion.

There are two main types of mass movement relevant to river landscapes:

Sliding: The rapid downhill movement of a large block of rock or soil en masse along a flat slip plane (like a bedding plane). The material remains largely intact and does NOT rotate.
Slumping: The downward movement of saturated material along a curved or concave slip plane.

Step-by-Step Describe: Slumping / Rotational Slip

First, heavy or prolonged rainfall infiltrates a permeable rock layer or soil.
Then, the water hits an underlying impermeable layer (like clay), causing the upper layer to become completely saturated.
Because of this saturation, the material's weight drastically increases, and the water acts as a lubricant, reducing internal friction.
Meanwhile, the river erodes and undercuts the base of the valley side, removing support for the slope above.
Finally, the heavy, unsupported material collapses and moves rotationally backwards down the concave slip plane, leaving a crescent-shaped scar.

River Erosion Processes

Understanding how a river spends its energy explains why most of its power is actually wasted. Approximately 95% of a river's energy is used purely to overcome friction against its bed and banks, leaving just 5% available to erode and transport material.
Vertical erosion acts downwards, deepening the channel (dominant in the upper course).
Lateral erosion acts sideways, widening the channel (dominant in the middle and lower courses).

Rivers erode their channels and load using four specific mechanisms:

Hydraulic action: The sheer force of fast-flowing water hits the river banks and bed. It forces air into cracks, compressing the air and creating intense pressure that eventually fractures the rock.
Abrasion: The sandpapering effect where the river's load scrapes, rubs, and bangs against the bed and banks, wearing them away.
Attrition: Stones and rocks being carried by the river collide with each other, knocking off jagged edges to become smaller and rounder. Crucially, attrition does NOT erode the river channel itself.
Corrosion: The chemical process where slightly acidic river water reacts with and dissolves soluble minerals in rocks.

Step-by-Step Describe: Waterfall Formation

First, a river flows over a band of resistant (hard) rock overlying less resistant (soft) rock.
Then, hydraulic action and abrasion erode the soft rock faster, creating a step in the riverbed.
Over time, continued erosion undercuts the hard rock, creating a plunge pool and a protruding overhang.
As a result of gravity, the unsupported overhang eventually collapses, providing abrasive rock tools that fall into the plunge pool.
Finally, this continuous process causes the waterfall to retreat upstream, leaving a steep-sided gorge behind it.

River Transportation Processes

Why do some rivers look perfectly clear while others look thick and muddy? It all comes down to the size of the load and how the water moves it.
A river's transport ability is directly proportional to its velocity (speed) and discharge (volume of water).
Sediment becomes progressively smaller and rounder downstream due to attrition.

Rivers transport their load in four distinct ways:

Traction: Large boulders and heavy rocks are rolled or pushed along the riverbed by the force of the water.
Saltation: Small pebbles and stones are bounced or hopped along the riverbed. The water momentarily lifts them before dropping them back down.
Suspension: Fine, light particles are carried within the flow of the water, held up by turbulence.
Solution: Dissolved minerals are carried invisibly in the water.

The material transported by traction and saltation is called the bedload. Material transported via suspension is the suspended load, and dissolved minerals form the dissolved load.

River Deposition Processes

Every time you ride a bike up a steep hill and then reach a flat path, your speed drops instantly. Rivers behave the exactly same way when they reach flatter land or enter a lake—they lose speed and drop what they are carrying.
Deposition occurs specifically when a river loses energy due to a decrease in velocity or discharge.
Rivers deposit material strictly in order of weight and size. The heaviest bedload is dropped first, while finer sediment (collectively called alluvium) is carried the furthest.

Conditions that trigger a loss of energy and subsequent deposition include:

Decreased gradient (flattening slopes).
Flowing on the inside bends of meanders, which are furthest from the thalweg (the line of fastest flow).
Entering standing water like a lake or the sea. Here, flocculation can occur, where saltwater causes fine clay particles to clump together into heavier masses that quickly settle.
Flooding across a floodplain, which massively increases the wetted perimeter (the area of land contacting the water), causing a sudden spike in friction.

Step-by-Step Describe: Levee Formation

First, during a period of high discharge, a river overflows its banks and spreads water across the flat floodplain.
Then, the water immediately loses velocity due to massively increased friction with the land.
Finally, this sudden loss of energy causes the heaviest load to be deposited first, directly at the river's edge, building up a natural raised embankment called a levee.

Sign up to continue reading

Get full access to revision notes, key terms, and exam tips for every subtopic.

Exam Tips

Common Mistake
Students often mistakenly claim velocity is lowest in the lower course. In fact, velocity is generally highest in the lower course due to a smoother channel, but extensive deposition still happens here because the river enters the sea and completely loses its energy.
Common Mistake
Students frequently write that attrition deepens or widens the river channel. Remember, attrition does NOT erode the channel itself; it solely affects the rocks within the river, making them smaller and rounder.
3
To secure full marks for hydraulic action definitions, always explicitly mention the 'compression of air in cracks'—examiners look closely for this phrase.
4
For any 4-mark question on depositional landforms like levees or floodplains, explicitly stating 'loss of energy' and 'reduced velocity' is mandatory for top band marks.
5
When explaining the formation of a V-shaped valley, you must mention that weathering weakens the valley sides before mass movement transports the material into the river.

Key Terms(34)

Weathering: The disintegration and decomposition of rocks in situ by the action of the weather, plants, and animals.
In situ: In its original position; without being moved by an external flowing force like water or ice.
Sub-aerial processes: Weathering and mass movement processes occurring on the valley sides above the river's water level.
Mechanical weathering: The breakdown of rock into smaller angular fragments without any change in its chemical composition.
Chemical weathering: The breakdown of rock involving a chemical change in the minerals that make up the rock.
Biological weathering: The breakdown of rocks caused by the physical or chemical activities of living organisms.
Scree: Angular rock fragments produced by repeated freeze-thaw cycles that collect at the base of valley slopes.
Mass movement: The downhill movement of weathered material under the force of gravity.
Sliding: The rapid downhill movement of a large block of rock or soil en masse along a flat slip plane.
Slip plane: The line of weakness, either flat or curved, along which mass movement occurs.
Slumping: The downward movement of saturated material along a curved or concave slip plane, often rotating backwards as it falls.
Vertical erosion: Downward erosion that deepens the river channel or valley.
Lateral erosion: Sideways erosion that widens the river channel.
Hydraulic action: The sheer force of water forcing air into cracks, compressing it, and creating pressure that eventually fractures the rock.
Abrasion: The sandpapering effect where the river's load scrapes and rubs against the bed and banks, wearing them away.
Attrition: The process where stones carried by the river collide with each other, becoming smaller and rounder.
Corrosion: The chemical process where slightly acidic river water reacts with and dissolves soluble minerals in rocks.
Gorge: A narrow, steep-sided valley formed as a waterfall retreats upstream.
Velocity: The speed at which the river water is flowing.
Discharge: The volume of water flowing through a river channel at a given point, measured in cubic metres per second.
Traction: A transportation process where large boulders and heavy rocks are rolled or pushed along the riverbed.
Saltation: A transportation process where small pebbles and stones are bounced or hopped along the riverbed.
Suspension: A transportation process where fine, light particles are carried within the flow of the water, held up by turbulence.
Solution: A transportation process where dissolved minerals are carried invisibly within the water.
Bedload: The heavier material transported along the bottom of the river channel via traction and saltation.
Suspended load: The fine material transported within the water column via suspension.
Dissolved load: The invisible minerals transported chemically within the water via solution.
Deposition: The process where a river's velocity decreases, causing it to lose energy and drop the material it was transporting.
Alluvium: Fine-grained, highly fertile soil deposited by a river on its floodplain or delta.
Thalweg: The invisible line of fastest flow and highest energy within a river channel.
Flocculation: A chemical process at river mouths where salt causes fine clay particles to clump together and settle rapidly.
Floodplain: The flat area of land adjacent to a river that is prone to flooding.
Wetted perimeter: The total length of the riverbed and banks that is in direct contact with the water.
Levee: A natural, raised embankment of coarse sediment deposited directly along the banks of a river during flooding.

Previous Subtopic: Case Study: Coastal LandscapeHuman Intervention in Coastal Landscapes Next NoteRiver Profiles and Downstream Changes

Back to River Physical Processes

Put your knowledge into practice — try past paper questions for Geography A

Key Terms(34)

Weathering: The disintegration and decomposition of rocks in situ by the action of the weather, plants, and animals.
In situ: In its original position; without being moved by an external flowing force like water or ice.
Sub-aerial processes: Weathering and mass movement processes occurring on the valley sides above the river's water level.
Mechanical weathering: The breakdown of rock into smaller angular fragments without any change in its chemical composition.
Chemical weathering: The breakdown of rock involving a chemical change in the minerals that make up the rock.
Biological weathering: The breakdown of rocks caused by the physical or chemical activities of living organisms.
Scree: Angular rock fragments produced by repeated freeze-thaw cycles that collect at the base of valley slopes.
Mass movement: The downhill movement of weathered material under the force of gravity.
Sliding: The rapid downhill movement of a large block of rock or soil en masse along a flat slip plane.
Slip plane: The line of weakness, either flat or curved, along which mass movement occurs.
Slumping: The downward movement of saturated material along a curved or concave slip plane, often rotating backwards as it falls.
Vertical erosion: Downward erosion that deepens the river channel or valley.
Lateral erosion: Sideways erosion that widens the river channel.
Hydraulic action: The sheer force of water forcing air into cracks, compressing it, and creating pressure that eventually fractures the rock.
Abrasion: The sandpapering effect where the river's load scrapes and rubs against the bed and banks, wearing them away.
Attrition: The process where stones carried by the river collide with each other, becoming smaller and rounder.
Corrosion: The chemical process where slightly acidic river water reacts with and dissolves soluble minerals in rocks.
Gorge: A narrow, steep-sided valley formed as a waterfall retreats upstream.
Velocity: The speed at which the river water is flowing.
Discharge: The volume of water flowing through a river channel at a given point, measured in cubic metres per second.
Traction: A transportation process where large boulders and heavy rocks are rolled or pushed along the riverbed.
Saltation: A transportation process where small pebbles and stones are bounced or hopped along the riverbed.
Suspension: A transportation process where fine, light particles are carried within the flow of the water, held up by turbulence.
Solution: A transportation process where dissolved minerals are carried invisibly within the water.
Bedload: The heavier material transported along the bottom of the river channel via traction and saltation.
Suspended load: The fine material transported within the water column via suspension.
Dissolved load: The invisible minerals transported chemically within the water via solution.
Deposition: The process where a river's velocity decreases, causing it to lose energy and drop the material it was transporting.
Alluvium: Fine-grained, highly fertile soil deposited by a river on its floodplain or delta.
Thalweg: The invisible line of fastest flow and highest energy within a river channel.
Flocculation: A chemical process at river mouths where salt causes fine clay particles to clump together and settle rapidly.
Floodplain: The flat area of land adjacent to a river that is prone to flooding.
Wetted perimeter: The total length of the riverbed and banks that is in direct contact with the water.
Levee: A natural, raised embankment of coarse sediment deposited directly along the banks of a river during flooding.

River Physical Processes

Weathering Processes

Water is one of the only substances that expands when it freezes, taking up exactly 10% more space as solid ice than as a liquid. This incredible internal pressure is powerful enough to shatter solid rock over time.
Weathering is the disintegration and decomposition of rocks at the Earth's surface. Crucially, this happens in situ, meaning the rock is NOT moved by an external flowing force like water or ice.
On river valley sides, weathering weakens the rock above the water level. These are known specifically as sub-aerial processes.

There are three main categories of weathering:

Mechanical weathering: Breakdown of rock without any chemical change.
Chemical weathering: Breakdown involving a chemical change in the rock's minerals.
Biological weathering: Breakdown caused by the physical or chemical activities of living organisms, such as tree roots expanding in cracks.

Step-by-Step Describe: Freeze-Thaw (Mechanical Weathering)

First, rainwater enters cracks or joints in the rock on the river valley side.
Then, when temperatures drop below 0°C at night, the water freezes and expands by 10%, exerting massive outward pressure (up to 2,100 kg/cm²) on the crack.
As a result, the crack is forced wider.
When temperatures rise, the ice thaws, allowing water to seep deeper into the newly widened crack.
Finally, repeated cycles of freezing and thawing shatter the rock into angular fragments called scree, which collect at the base of the slope.

Step-by-Step Describe: Carbonation (Chemical Weathering)

First, rainwater absorbs CO₂ from the atmosphere to form a weak carbonic acid.
Then, this mildly acidic water reacts with alkaline rocks like limestone or chalk.
Finally, minerals like calcium carbonate are dissolved and washed away.

Mass Movement Processes

A dry slide down a grassy hill might just give you grass stains, but a saturated, muddy slope can pull down entire trees. Water drastically changes how gravity affects a valley side.
Mass movement is the downhill movement of weathered material under the force of gravity. Any slope with a gradient steeper than 5° is susceptible.
Mass movement supplies sediment to the river, providing the abrasive tools it needs for future erosion.

There are two main types of mass movement relevant to river landscapes:

Sliding: The rapid downhill movement of a large block of rock or soil en masse along a flat slip plane (like a bedding plane). The material remains largely intact and does NOT rotate.
Slumping: The downward movement of saturated material along a curved or concave slip plane.

Step-by-Step Describe: Slumping / Rotational Slip

First, heavy or prolonged rainfall infiltrates a permeable rock layer or soil.
Then, the water hits an underlying impermeable layer (like clay), causing the upper layer to become completely saturated.
Because of this saturation, the material's weight drastically increases, and the water acts as a lubricant, reducing internal friction.
Meanwhile, the river erodes and undercuts the base of the valley side, removing support for the slope above.
Finally, the heavy, unsupported material collapses and moves rotationally backwards down the concave slip plane, leaving a crescent-shaped scar.

River Erosion Processes

Understanding how a river spends its energy explains why most of its power is actually wasted. Approximately 95% of a river's energy is used purely to overcome friction against its bed and banks, leaving just 5% available to erode and transport material.
Vertical erosion acts downwards, deepening the channel (dominant in the upper course).
Lateral erosion acts sideways, widening the channel (dominant in the middle and lower courses).

Rivers erode their channels and load using four specific mechanisms:

Hydraulic action: The sheer force of fast-flowing water hits the river banks and bed. It forces air into cracks, compressing the air and creating intense pressure that eventually fractures the rock.
Abrasion: The sandpapering effect where the river's load scrapes, rubs, and bangs against the bed and banks, wearing them away.
Attrition: Stones and rocks being carried by the river collide with each other, knocking off jagged edges to become smaller and rounder. Crucially, attrition does NOT erode the river channel itself.
Corrosion: The chemical process where slightly acidic river water reacts with and dissolves soluble minerals in rocks.

Step-by-Step Describe: Waterfall Formation

First, a river flows over a band of resistant (hard) rock overlying less resistant (soft) rock.
Then, hydraulic action and abrasion erode the soft rock faster, creating a step in the riverbed.
Over time, continued erosion undercuts the hard rock, creating a plunge pool and a protruding overhang.
As a result of gravity, the unsupported overhang eventually collapses, providing abrasive rock tools that fall into the plunge pool.
Finally, this continuous process causes the waterfall to retreat upstream, leaving a steep-sided gorge behind it.

River Transportation Processes

Why do some rivers look perfectly clear while others look thick and muddy? It all comes down to the size of the load and how the water moves it.
A river's transport ability is directly proportional to its velocity (speed) and discharge (volume of water).
Sediment becomes progressively smaller and rounder downstream due to attrition.

Rivers transport their load in four distinct ways:

Traction: Large boulders and heavy rocks are rolled or pushed along the riverbed by the force of the water.
Saltation: Small pebbles and stones are bounced or hopped along the riverbed. The water momentarily lifts them before dropping them back down.
Suspension: Fine, light particles are carried within the flow of the water, held up by turbulence.
Solution: Dissolved minerals are carried invisibly in the water.

The material transported by traction and saltation is called the bedload. Material transported via suspension is the suspended load, and dissolved minerals form the dissolved load.

River Deposition Processes

Every time you ride a bike up a steep hill and then reach a flat path, your speed drops instantly. Rivers behave the exactly same way when they reach flatter land or enter a lake—they lose speed and drop what they are carrying.
Deposition occurs specifically when a river loses energy due to a decrease in velocity or discharge.
Rivers deposit material strictly in order of weight and size. The heaviest bedload is dropped first, while finer sediment (collectively called alluvium) is carried the furthest.

Conditions that trigger a loss of energy and subsequent deposition include:

Decreased gradient (flattening slopes).
Flowing on the inside bends of meanders, which are furthest from the thalweg (the line of fastest flow).
Entering standing water like a lake or the sea. Here, flocculation can occur, where saltwater causes fine clay particles to clump together into heavier masses that quickly settle.
Flooding across a floodplain, which massively increases the wetted perimeter (the area of land contacting the water), causing a sudden spike in friction.

Step-by-Step Describe: Levee Formation

First, during a period of high discharge, a river overflows its banks and spreads water across the flat floodplain.
Then, the water immediately loses velocity due to massively increased friction with the land.
Finally, this sudden loss of energy causes the heaviest load to be deposited first, directly at the river's edge, building up a natural raised embankment called a levee.

Sign up to continue reading

Get full access to revision notes, key terms, and exam tips for every subtopic.

Exam Tips

Common Mistake
Students often mistakenly claim velocity is lowest in the lower course. In fact, velocity is generally highest in the lower course due to a smoother channel, but extensive deposition still happens here because the river enters the sea and completely loses its energy.
Common Mistake
Students frequently write that attrition deepens or widens the river channel. Remember, attrition does NOT erode the channel itself; it solely affects the rocks within the river, making them smaller and rounder.
3
To secure full marks for hydraulic action definitions, always explicitly mention the 'compression of air in cracks'—examiners look closely for this phrase.
4
For any 4-mark question on depositional landforms like levees or floodplains, explicitly stating 'loss of energy' and 'reduced velocity' is mandatory for top band marks.
5
When explaining the formation of a V-shaped valley, you must mention that weathering weakens the valley sides before mass movement transports the material into the river.

Key Terms(34)

Weathering: The disintegration and decomposition of rocks in situ by the action of the weather, plants, and animals.
In situ: In its original position; without being moved by an external flowing force like water or ice.
Sub-aerial processes: Weathering and mass movement processes occurring on the valley sides above the river's water level.
Mechanical weathering: The breakdown of rock into smaller angular fragments without any change in its chemical composition.
Chemical weathering: The breakdown of rock involving a chemical change in the minerals that make up the rock.
Biological weathering: The breakdown of rocks caused by the physical or chemical activities of living organisms.
Scree: Angular rock fragments produced by repeated freeze-thaw cycles that collect at the base of valley slopes.
Mass movement: The downhill movement of weathered material under the force of gravity.
Sliding: The rapid downhill movement of a large block of rock or soil en masse along a flat slip plane.
Slip plane: The line of weakness, either flat or curved, along which mass movement occurs.
Slumping: The downward movement of saturated material along a curved or concave slip plane, often rotating backwards as it falls.
Vertical erosion: Downward erosion that deepens the river channel or valley.
Lateral erosion: Sideways erosion that widens the river channel.
Hydraulic action: The sheer force of water forcing air into cracks, compressing it, and creating pressure that eventually fractures the rock.
Abrasion: The sandpapering effect where the river's load scrapes and rubs against the bed and banks, wearing them away.
Attrition: The process where stones carried by the river collide with each other, becoming smaller and rounder.
Corrosion: The chemical process where slightly acidic river water reacts with and dissolves soluble minerals in rocks.
Gorge: A narrow, steep-sided valley formed as a waterfall retreats upstream.
Velocity: The speed at which the river water is flowing.
Discharge: The volume of water flowing through a river channel at a given point, measured in cubic metres per second.
Traction: A transportation process where large boulders and heavy rocks are rolled or pushed along the riverbed.
Saltation: A transportation process where small pebbles and stones are bounced or hopped along the riverbed.
Suspension: A transportation process where fine, light particles are carried within the flow of the water, held up by turbulence.
Solution: A transportation process where dissolved minerals are carried invisibly within the water.
Bedload: The heavier material transported along the bottom of the river channel via traction and saltation.
Suspended load: The fine material transported within the water column via suspension.
Dissolved load: The invisible minerals transported chemically within the water via solution.
Deposition: The process where a river's velocity decreases, causing it to lose energy and drop the material it was transporting.
Alluvium: Fine-grained, highly fertile soil deposited by a river on its floodplain or delta.
Thalweg: The invisible line of fastest flow and highest energy within a river channel.
Flocculation: A chemical process at river mouths where salt causes fine clay particles to clump together and settle rapidly.
Floodplain: The flat area of land adjacent to a river that is prone to flooding.
Wetted perimeter: The total length of the riverbed and banks that is in direct contact with the water.
Levee: A natural, raised embankment of coarse sediment deposited directly along the banks of a river during flooding.

Previous Subtopic: Case Study: Coastal LandscapeHuman Intervention in Coastal Landscapes Next NoteRiver Profiles and Downstream Changes

Back to River Physical Processes

Put your knowledge into practice — try past paper questions for Geography A

Key Terms(34)

Weathering: The disintegration and decomposition of rocks in situ by the action of the weather, plants, and animals.
In situ: In its original position; without being moved by an external flowing force like water or ice.
Sub-aerial processes: Weathering and mass movement processes occurring on the valley sides above the river's water level.
Mechanical weathering: The breakdown of rock into smaller angular fragments without any change in its chemical composition.
Chemical weathering: The breakdown of rock involving a chemical change in the minerals that make up the rock.
Biological weathering: The breakdown of rocks caused by the physical or chemical activities of living organisms.
Scree: Angular rock fragments produced by repeated freeze-thaw cycles that collect at the base of valley slopes.
Mass movement: The downhill movement of weathered material under the force of gravity.
Sliding: The rapid downhill movement of a large block of rock or soil en masse along a flat slip plane.
Slip plane: The line of weakness, either flat or curved, along which mass movement occurs.
Slumping: The downward movement of saturated material along a curved or concave slip plane, often rotating backwards as it falls.
Vertical erosion: Downward erosion that deepens the river channel or valley.
Lateral erosion: Sideways erosion that widens the river channel.
Hydraulic action: The sheer force of water forcing air into cracks, compressing it, and creating pressure that eventually fractures the rock.
Abrasion: The sandpapering effect where the river's load scrapes and rubs against the bed and banks, wearing them away.
Attrition: The process where stones carried by the river collide with each other, becoming smaller and rounder.
Corrosion: The chemical process where slightly acidic river water reacts with and dissolves soluble minerals in rocks.
Gorge: A narrow, steep-sided valley formed as a waterfall retreats upstream.
Velocity: The speed at which the river water is flowing.
Discharge: The volume of water flowing through a river channel at a given point, measured in cubic metres per second.
Traction: A transportation process where large boulders and heavy rocks are rolled or pushed along the riverbed.
Saltation: A transportation process where small pebbles and stones are bounced or hopped along the riverbed.
Suspension: A transportation process where fine, light particles are carried within the flow of the water, held up by turbulence.
Solution: A transportation process where dissolved minerals are carried invisibly within the water.
Bedload: The heavier material transported along the bottom of the river channel via traction and saltation.
Suspended load: The fine material transported within the water column via suspension.
Dissolved load: The invisible minerals transported chemically within the water via solution.
Deposition: The process where a river's velocity decreases, causing it to lose energy and drop the material it was transporting.
Alluvium: Fine-grained, highly fertile soil deposited by a river on its floodplain or delta.
Thalweg: The invisible line of fastest flow and highest energy within a river channel.
Flocculation: A chemical process at river mouths where salt causes fine clay particles to clump together and settle rapidly.
Floodplain: The flat area of land adjacent to a river that is prone to flooding.
Wetted perimeter: The total length of the riverbed and banks that is in direct contact with the water.
Levee: A natural, raised embankment of coarse sediment deposited directly along the banks of a river during flooding.