Understanding Our Natural World: River Environments Flashcards
(31 cards)
The Drainage Basin
4 marks
Area of land that is drained by a river and its tributaries. When a droplet of water falls onto the land (as precipitation), gravity will make sure that the water is pulled downhill to the sea.
When a droplet of water falls onto the land (as precipitation)
(2 marks)
Gravity will make sure that the water is pulled downhill to the sea.
The Water Cycle (Hydrological Cycle) - simplified
4 marks
Water is recycled through the process of; evaporation, condensation and water transfers such as surface runoff.
Amount of the worlds water contained within oceans and seas.
1 mark
97% of the worlds water is found in oceans/seas.
Amount of the world’s water found in ice.
1 mark
Ice holds 2% of the world’s water.
Amount of the world’s water found on land and in the atmosphere (air)
(1 mark)
1% of the world’s water is found on land and in the atmosphere.
The Water Cycle (in order)
10 marks
- Evaporation
- Water vapour is blown over the land
- Evapotranspiration; air rises, cools and condenses
- Precipitation
- Surface runoff/overland flow
- Infiltration
- Percolation and throughflow
- Groundwater flow
Major Component of the Water Cycle
1 mark
Drainage Basin System
Interrelationships within the Drainage Basin System
17 marks
Inputs: Precipitation
Store: Surface storage, Interception, Soil moisture
Transfer: Stemflow, Infiltration, Percolation , Channel flow, Surface runoff, Throughflow, Groundwater flow
Output: Evapotranspiration, River discharge
Inputs of Drainage Basin System
2 marks
How water is introduced into the Drainage Basin System - Precipitation.
Inputs of Drainage Basin System (Simplified)
1 mark
Precipitation
Stores of Drainage Basin System
7 marks
How water is stored or held for a period of time within the DB System - Interception (by vegetation), Soil Moisture, Surface Storage (lakes), Groundwater storage
Transfers of Drainage Basin System (Simplified)
7 marks
Stemflow, Infiltration, Percolation , Channel flow, Surface runoff, Throughflow, Groundwater flow
Transfers of Drainage Basin System
8 marks
A process or flow of water from one place to another in the DB System - Stemflow, Infiltration, Percolation , Channel flow, Surface runoff, Throughflow, Groundwater flow
Outputs of Drainage Basin System (Simplified)
2 marks
Evapotranspiration, River Discharge
Outputs of Drainage Basin System
4 marks
How the water is released either back to the sea or back into the atmosphere -
Evapotranspiration, River discharge
How does a river change course downstream?
2 marks
A river changes shape as it flows from its Source to its Mouth.
Long Profiles are made up of
12 marks
- Source
- Upper part of River - has larger bedload, more roughness, turbulence & friction.
- Watershed
- Lower part of River - has greatest cross-section, highest hydraulic radius, greatest velocity & discharge.
- Mouth
The Source of a River
3 marks
Is often, but not always, in an upland area.
Near the source, a river flows over steep slopes with uneven surfaces.
Near the River’s Source
4 marks
- River flows over steep slopes with uneven surfaces. Often moving over a series of waterfalls and rapids.
- There is more Vertical Erosion here as the river flows downhill, using its energy to overcome friction.
Vertical Erosion
3 marks
Occurs as a river flows down steep slopes, cutting down towards the river bed and carving out steep-sided V-shapes valleys.
As the river approaches the mouth
7 marks
- Gradient of the slope becomes less steep, flowing over flat land as it approaches the sea.
- Velocity and energy increase due to increased discharge
- Performs more Lateral Erosion making the Channel wider/smoother meaning less turbulence and friction.
As the river approaches the mouth more Lateral Erosion takes place.
What does that mean for the Channel?
(3 marks)
Makes the Channel wider/smoother meaning less turbulence and friction making water flow more efficient.
As the river moves from the source to the mouth
1 mark
Both the depth and width of the river increase.
