EQ1 - Indicative mock content Flashcards
What is ‘the drainage basin?’
It is a sub-system within the water cycle which operated on a system of inputs and outputs of water, stores and fluxes. Another name for it is the catchment.
What are the main stores of the drainage basin?
Groundwater
soil moisture
interception
surface storage
what are the main fluxes within the drainage basin?
Percolation
infiltration
throughflow
surface runoff
groundwater flow
What is the one input into the drainage basin?
precipitation
Wht are the ranked impacts on precipitation?
Amount
Intensity
Distribution
Seasonality
How does amount of precipitation impact the drainage basin?
Amount - low levels = low infiltration, groundwater and surfacewater levels. Egypt = 200mm rain annually. Sandy soil.
How does intensity of precipitation impact the drainage basin?
Intensity - high intensiy = high levels of surface storage due to exceeded soil moisture capacity. Flood risk - Orographic rainfall in Scottland.
How does distribution of precipitation impact the drainage basin?
Unequal distribution = unequal river regimes and channel volumes. Nile starts in Mediterranean conditions, in Egypt, then travels to desert regions of Ethiopia
How does seasonality of precipitation impact the drainage basin?
Impacts soil saturation, groundwater levels, runoff levels. Asian monsoon season is from April - September.
What is orographic rainfall?
Rainfall occurring over land with high/mountainous ground. Causes a rain shadow on the leeward side of the mountain range, as clouds are forced up. Occurs in N and W of the UK.
What is frontal rainfall?
Rainfall produces by the colliding of hot and cold weather fronts. Hot air rides above the cold air, creating the conditions for a weather front. Occurs over all of the UK, and is associaed with cyclonic weather.
What is convectional rainfall?
Rainfall that occurs in the SE of UK in summer. The evapo. of the ocean leads to the build up of condensed air over land. When the weight of this cloud reaches sufficiency, and precipitation nuclei are present, it rains.
What ranked factors impact infiltration?
1) duration
2) vegetation
3) soil porosity
4) slope angle
how does duration impact soil porosity?
duration of rainfall will increase the amoount of moisture in soil before turning, and decreasing due to the capacity of soil being reached.
how does vegetation impact infiltration?
infiltration increases with more veg. curved slope negatively due to time increase
how does soil porosity impact infiltration?
infiltration increases with mroe soil porosity. Perfect positive increase.
how does slope angle impact infiltration?
Highe the slope, less infiltration there is.
What are the ranked outputs of the drainage basin?
4) Transp.
3) Evapotransp. (ET)
2) Potential ET
1) Evapo.
What is potential ET?
The amount of wter that would evapotranspire from the earth if there was an unlimited supply of water.
What is ET?
The combined effect of evaporation and transpiration.
What is Transpir.?
Loss of water through stomata to the atmosphere.
Impacted by:
- veg cover
- growing season
What is evaporation?
The most important factor. increased by:
- high temp
- high wind
- low veg cover
What are the ranked human factors that influence the drainage basin?
1) Urbanisation
2) Deforestation
3) conversion to grassland
4) Afforestation
How does urbanisation inpact the drainage basin?
Paving over of soil prevents infiltration. 1/3 of London has been paved over since 1900. Leads to faster runoff This has led to huge sewer issues, 10,000 fish died from sewer leakage in 2021.
how does Deforestation impact the drainage basin?
Stops throughfall, interception, interception loss, and transpiration. Leads to intense flooding because of quicker soil capacity reach. in Togo, 60% of its forests have been cut down, which has led to flooding.
How does conversion to grassland impact the drainage basin?
It removes vegetation, and increases soil compression from cattle. Also introduced a monoculture. This has been happening in the Amazon, where 20% of the original rainforest has been converted.
How does afforestation impact the drainage basin?
Introduces soil compression due to planting which has a negative impct for 30 years, until plant roots boar away at the soil until it reaches its maximum soil capacity. China has been trying to do this with its ‘Great Green wall,’ - 1 bil trees
What are the ranked physical factors which impact the drainage basin?
1) climate
2) vegetation
3) geology
4) soils
How does climate impact the drainage basin?
impacts veg. present
impacts the main inputs and outputs, evapo. & precip. = amount and type
How does vegetation impact the drainage basin?
overland flow, infiltration, transpiration, and interception.
how does geology impact the drainage basin?
the permeability of rock impacts percolation, groundwater levels, groundwater flow, throughflow.
how does soil type impact the drainage basin?
porosity impacts moisture capacity levels, thoughflow rates, groundwater levels, surface runoff levels.
What is a water budget?
The annual balance of inputs for a volume of water.
What is the shape of the global water buget?
From 90 - 40 degrees, there is a positive water budget, because there are low pressure systems with temperate zones causing regular precipitation.
40 - 10 degrees = a negative water budget due to high pressure systems causing less precipitation within the Hadley cell.
What is the difference between annual runoff levels in Africa and in S. America?
Africa = 74
S. America = 395
What is the difference between base flow levels in Africa and S. America?
Africa = 40
S. America = 223
What challenges do the different runoff and base flow levels cause?
Drought in Africa because of similar levels of evaporation to runoff.
Flood in S. America because of large difference in evapotrans. levels to runoff levels.
What is a soil buget?
The capacity of soil to intake moisture and retain it until peak capacity.
Explain the stages seen on the SE. UK water budget:
a) Surplus of water because it exceeds PET.
b) Soil moisture is used as PET increases, and exceeds precip.
c) groundwater is absorbed by soils and reaches peak PET levels
d) Precip. less than PET so plants have to adapt to survive.
e) soil moisture is recharged becaue of less PET and mroe precip.
f) groundwate is recharged by additional water.
What do soil water budgets tell us?
How to identify the challenges of:
- Deficiency and drought
- flood risk
- irrigation times
what are river regimes?
Annual variation in discharge from a river from a fixed position.
What impacts a river regime?
- climate
- topography
- geology
- vegetation cover
- precipitation
- human activity
How does climate impact a river regime?
Climate warming leads to glacier melt in Europe. This means that discharge is flashier in summer due to more loss from the cryosphere.
How does ocenic rainfall impact river regimes?
Oceanic rainfall is evenly distributed within Europe, this means that river regimes have lower discharge due to water not being distributed within the basin.
