The drainage basin Flashcards
Drainage basin:
- (1) system
- AKA (2) can be any size
- (3) within the global hydrological system
1 - open
2 - local hydrological system
3 - subsystem
Define ‘drainage basin’
The area of land drained by a river and its tributaries
Name five factors that affect the drainage basin
Climate Soil Geology Relief Vegetation
How does climate affect the drainage basin?
Affects the rate of evaporation, precipitation and vegetation growth
How does soil affect the drainage basin?
Clay - impermeable due to particle size so stores water
Sand based - through flow and infiltration
How does geology affect the drainage basin?
Chalk and Sandstone allows aquifers as water soaks into them
Pervious (limestone) allows water to flow but not into the rock
Caves and stalagmites
How does relief affect the drainage basin?
Orographic rainfall affects run off as a steeper slope will reduce infiltration
Name four human impacts on the drainage basin
- Deforestation
- Urbanisation
- Agriculture
- Mega dams
How does deforestation affect the drainage basin?
Less interception so rain falls directly on the soil > compaction > less EVT
How does urbanisation affect the drainage basin?
Less infiltration capacity
How does agriculture affect the drainage basin?
Water needed for irrigation, pasture compact soil, arable removes nutrients and requires heavy machinery
How do mega damns affect the drainage basin?
Increased EVT and reduces water downstream
Amazonia:
- (1)% destroyed in the last 50 years
- Trees are ‘(2)’ act as carbon sinks
- (3)% of rainfall is recycled from trees
- (4)% of intercepted water is EVT
- Contains (5)% of the world’s rainforest
1 - 20 2 - green lungs 3 - 50 4 - 75 5 - 60
How does the El Nino Southern Oscillation affect the Amazonia?
Droughts and forest fires
Why is run-off into the Amazon problematic?
Aquifer depletion and soil erosion
Name the only input of the drainage basin system
Precipitation
Name the five flows in the drainage basin system
Infiltration Percolation Through flow Run off Groundwater flow
Name four stores in the drainage basin system
Surface store
Interception
Soil moisture
Channel store
Name the three outputs in the drainage basin system
Transpiration
Evaporation
River discharge
Define ‘percolation’
When water flows through the soil by the force of gravity
Where is precipitation heaviest and why? What affects precipitation?
Tropics due to the Intertropical Convergence Zone and places that get monsoons
ITCZ - high solar radiation causes rapid convection of warm air
Also affected by continentality (distance from sea) and land relief
Why could precipitation act as a store? What affect does this have on precipitation distribution?
E.g. snow takes longer to form
Not evenly distributed across drainage basin
Name the seven fluxes (flows)
Interception Infiltration Direct run off Saturated over land flow Through flow Percolation Ground water flow
What affects interception?
- Size of the leaves (vary throughout the year)
- Deciduous (loses its leaves during the winter)
What affects infiltration? (mm/hr)
- antecedent soil moisture
- soil compaction
- slope angle
Name four factors that affects the volume of evaporation
- Hours of sun
- Air movement
- Albedo
Where is the Amazon River located?
South America
Amazon river regime:
- (1)km long
- (2) km squared basin
- Snowmelt from the (3)
1 - 6,308
2 - 6 million
3 - Andes Mountain Range
Where is the Yukon river?
North America (Canada and Alaska)
Yukon river regime:
- (1)km long
- (2)km squared drainage basin
- (3) climate through a mountain range
1 - 3,540
2 - 850,000
3 - Tundra
Where is the river Nile?
North Africa through 11 countries
Nile river regime:
- (1) climate
- 1970 construction of (2) dam reduced flow by (3) and changed seasonal flow
1 - Warm and arid
2 - Aswan
3 - 65%
