Water Cycle Flashcards
Which county receives the most rain in England?
Cumbria
What is the global hydrological cycle?
A system that describes how water moves between different stores on Earth
What type of system is the global hydrological cycle? Open or closed?
Closed
Inputs = Outputs
Which two energies drive the global hydrological cycle?
Solar energy - Heats water and causes evaporation
Gravitational potential energy - Water moves by gravity. Rain falls down to the ground and then runoff and groundwater flow move it down hill
Where is most freshwater on earth found?
In the cryosphere
Glaciers and polar ice
66% of freshwater in the cryosphere
Only 04% of freshwater in in streams, lakes etc
What are fluxes?
Processes by which water moves between stores
What is the global water budget?
The balance between inputs and outputs in the global hydrological cycle
What is residence time?
How long water stays in one store
What is the ITCZ?
Inter-Tropical Convergence Zone
What happens in the ITCZ and why is it important in the global hydrological cycle?
Due to high solar radiation levels in the tropics, evaporation is high
This water vapour is transported towards the ITCZ where it cools and forms clouds
The rain then causes the water to be transferred again
What kind of system is found in drainage basins? Open or Closed?
Open
Water can move between basins
Inputs are not determined by outputs
What are the 3 ways that water can flow when it falls as precipitation?
Infiltration - flows into the ground and causes ground water recharge and throughflow
Surface Runoff - Water runs over the surface, faster than throughflow
Evaporation - Water is evaporated back into the atmosphere
What is interception?
Where plants or buildings catch the water before it reaches the ground and has a chance to infiltrate
What is percolation?
Where water flows through rocks as groundwater and becomes stored in aquifers
What factors of a drainage basin affect flow rates?
Relief - Steeper relief will increase runoff rates
Climate - more frequent rain increases the change of saturation and therefore runoff
Vegetation - increases interception and reduces runoff rate
Geology - impermeable rock will increase chance of saturation and therefore runoff
Land use - more impermeable surfaces (urban areas) will increase runoff rate
Drainage density - more tributaries reduces runoff rate
What are antecedent conditions?
The weather conditions prior to an event
What are the 4 human activities that impact a drainage basin
Over Abstraction - causes ground to dry up
Deforestation - reduces interception and absorption so causes flooding
Urbanisation - more impermeable surfaces mean increased runoff and increased flood risk
Reservoirs - Disrupts the natural water cycle by changing residence times in each store
What is the Water budget?
The balance between inputs and outputs in an area
What is field capacity?
The maximum amount of water soil can hold
What does a water deficit do to the field capacity?
Reduces it
as the ground becomes dried out out it becomes less able to quickly absorb water
In terms of the field capacity of an area, what is a water surplus?
When the soil is saturated above the field capacity
Leads to Hortonian overland flow
How does a flash flood occur?
Very dry antecedent conditions (drought)
A very quick and heavy rainfall
The dry soil is unable to absorb the water
What are the factors affecting river discharge?
Characteristics of the Basin (shape, geology, soil type)
Inputs and Outputs
Climate
Human Intervention
What is a river regime?
The annual pattern of a rivers flow
What are the two types of river regime?
Simple - a river experiences consistent seasonal variations, its predictable
Complex - A river crosses several relief and climatic zones and can be affected by human activity (e.g damming)
What two activities can increases the complexity of a river regime?
Damming
Irrigation
What is a storm hydrograph?
A graph showing the events of a single storm
Shows: Discharge, Precipitation, Lag time
What are planners’ roles as a player in the hydrological cycle?
They decide if the proposed development will affect flood risk
They weigh up the importance of environmental factors against the importance of economic development in an area
What are SuDS?
Sustainable Drainage Systems
Give some examples of SuDS used in the UK
Green Roofs Infiltration Basins Permeable Pavements Rainwater Harvesting Soak-away Filter Drains Detention Basins Wetlands
What are the 4 types of Drought? explain what they mean
Meteorological Drought - Reduced precipitation compared to ‘normal’
Agricultural Drought - Insufficient water for irrigation of crops
Hydrological Drought - Permanent stores (e.g lakes) dry up
Socio-economic Drought - Impacts the health of the population and the quality of life (e.g famine)
Name a case study of a natural drought and describe the impacts of it
Brazil 2014-15
Caused by high-pressure systems diverting rain north
Impacts: water rationing HEP stopped Reservoirs dried up Increase in global coffee price by 50%
Why is the Amazon essential for regulating global weather?
It recycles rainfall and generates flows of moisture
This allows the weather to remain consistent
More deforestation will lead to an increase in extreme weather
What is the case study for an area that is experiencing drought due to deforestation?
The Amazon
