Rivers Flashcards
Source?
The place where a river begins.
Course?
The route the river takes to the sea
Tributary
A small river that joins a larger river.
Confluence
The point where the tributary joins the river.
Mouth
The point where the river enters the sea.
Estuary
The part of the mouth that is tidal.
Basin
The area of land drained by a river.
Watershed
The high ground separating one river basin from another.
Hydraulic action
The force of the moving water wears away the banks and bed of the river.
Abrasion
Small stones carried by the river wear away at the the banks and bed of the river.
Attrition
The small stones in the river are worn down and broken up as they hit off each other.
Solution
Rocks and soil are dissolved by acids in the water.
Discharge
The volume of water in the river, more
water means more erosion
Gradient
The steeper the gradient, the faster it erodes
Roughness
Uneven banks and bed causes friction resulting in a loss of energy.
Shape of river channel
Bigger ‘Wetted Perimeter’ creates more friction and loss of energy.
V shaped valleys
This occurs because of Vertical Erosion. The river cuts down into the river bed, making it deeper. It creates a narrow deep valley.
Mechanical weathering and mass movement create the V shape.
Interlocking spurs
As the rivers flows it meets areas of hard rock. It cannot erode these so it flows around them.
• This creates a zigzag course.
Waterfalls
Waterfalls are formed when rivers flow over areas of hard and soft rock.
4 ways of transportation
• 1. Rolling
• 2. Bouncing
• 3. Suspension
• 4. Solution
Rolling
The large stones are rolled along the bed of the river.
Bouncing
The smaller pebbles are bounced along the bed of the river.
Solution
Dissolved materials are carried along by the river.
Suspension
Light material like sand and silt are carried along (floating) in the water.
Wide river valley
In the mature stage the river moves from side to side and the valley becomes wide and flat. Weathering and Mass Movement continue to wear away at the sides of the valley.
Meanders
Meanders are bends or curves along the river. They are formed by erosion and deposition. Erosion occurs on one side of the river while deposition occurs on the opposite side. This continues, making the bends sharper.
Flood plain
A flood plain is the flat area of land on either side of the river. After heavy rain the river sometimes floods. The water spreads out over the land on either side of the river. When the river retreats it leaves behind a thin layer of alluvium. After many floods a thick layer of alluvium is created. This is very fertile soil.
Ox bow lake
An ox-bow lake is a horseshoe shaped lake found beside a river. Ox-bow lakes are formed when continued erosion and deposition create very pronounced meanders.
Levees
Levees are raised banks of deposited material found along the banks of the river. When the river floods and spreads out over the floodplain, the heaviest material is deposited close to the river.
Over time and after many periods of flooding this deposited material forms levees along the banks of the river.
Delta
A Delta is a triangular shaped piece of land which is formed at the mouth of the river. As the river enters the sea it drops off all the remaining material it is carrying. This material builds up to form new land. The river is forced to break up into smaller channels called distributaries.
