✅3.1.1.2 - The Water Cycle Flashcards
Gas —> Liquid
Condensation
Liquid —> Gas
Evaporation
Liquid —> Solid
Freezing
Solid —> Liquid
Melting
Solid —> Gas
Sublimation
Gas —> Solid
Deposition
What is precipitation?
Transfer of water form the atmosphere to the ground. It can take the form of rain, snow ,hail, dew etc
What is interception?
Water intercepted and stored in the leaves of plants
What is throughflow?
Water flowing through soil towards the river channel
What is infiltration?
Transfer of water from the ground surface into soil where it may then percolate into underlying rocks
What is percolation?
Water soaking into rocks
What is groundwater flow?
Transfer of water very slowly though rocks
What is latent heat?
The energy required to change the state of water by breaking hydrogen bonds between molecules
What is hydrogen bonding?
A strong intermolecular force between the H+ of one water molecule and the O 2- of another , holding them together
What is surface tension?
How the molecules on the surface of water behave and how tightly they are held together by hydrogen bonds
What is atmospheric water?
Water found in the atmosphere mainly water vapour with some liquid water and ice crystals
What is cryospheric water?
The water locked up on the Earth’s surface as ice
What is the hydrosphere?
A discontinuous layer of water at or near the Earth’s surface waters, groundwater held in soils and rock and atmospheric water vapour
What is oceanic water?
The water contained in the Earth’s oceans and seas but no including such inland seas as the Caspian sea
What is terrestrial water?
This consists of groundwater, soil moisture, lakes, wetlands and rivers
Which is the largest store of water?
Oceanic water
Where is most of the freshwater on Earth stored?
In the Antarctic and Greenland ice sheets
What are inputs into the drainage basin?
Precipitation
Energy from the sun
What are stores in the drainage basin?
Lakes Soil/Ground water Interception/vegetation River flow Surface flows
What are transfers in the drainage basin?
Ground water flow
Percolation
Transpiration
Precipitation
What are the outputs from the drainage basin?
River discharge
Evaporation
Water vapour
What is the fastest movement of water through the drainage basin?
Along the surface where there are relatively few obstacles in the way of the water
How fast is water movement though soil?
Somewhat slow, but varies more as clay soils retain water, slowing it down, but aerated soils and woodland channels allow it to move faster
What is the slowest form of movement in the drainage basin?
Groundwater flow, as it can be held for millennia
How much of the water on Earth is available for use by humans?
2.5%
What is soil storage?
The amount of water stored in the soil
What is vegetation storage?
The water stored in plants as they take it up from the soil
What is transpiration?
Water lost from plants through stomata, released back to the atmosphere
What is infiltration capacity?
The point where the soil becomes saturated
What is water balance/budget?
The balance between inputs and outputs within the drainage basin
What is the river’s regime?
As discharge levels rise and fall, often showing an annual pattern
What is the formula for water balance?
Precipitation (P) = discharge (Q) + evapotranspiration (E) +/- changes in storage (S)
What is stemflow?
The portion of precipitation intercepted by the canopy that reaches the ground by flowing down stems, stalks or trees.
What are the factors impacting the soil moisture budget?
Precipitation
Potential evaporation
What is potential evaporation?
The amount of evapotranspiration that could occur if there was sufficient water available in the system
What is the formula for river discharge?
River discharge = cross sectional area x velocity
What is water surplus?
When precipitation exceeds evapotranspiration
How does drainage basin shape affect the shape of a storm hydrograph?
Basins with a more circular shape have flashier hydrographs because each point is roughly equidistant from the channel
How do slope angles affect the shape of a storm hydrograph?
Drainage basins with steep sides have flashier hydrographs because water flows more quickly down steep slopes
How does drainage density affect the shape of a storm hydrograph?
Basins with a lot of surface stream tributaries have flashier hydrographs because all the water arrives at the same time
How does antecedent (prior) rainfall affect the shape of a storm hydrograph?
If the basin in already saturated, overland flow increases, so water moves quickly and peak discharge is higher, so flashier hydrographs
How does rock type affect the shape of a storm hydrograph?
If a rock is impermeable, overland flow will be higher, so lag time is reduced and the hydrograph is flashy
How does vegetation cover affect the shape of a storm hydrograph?
More vegetation leads to a subdued hydrograph because they intercepts and holds rainfall, slowing its path to the river channel
How does amount and intensity of precipitation affect the shape of a storm hydrograph?
Heavy storms with a lot of water entering at once produce flashy hydrographs. Slower lag time is precipitation is slow
How does drainage basin size affect the shape of a storm hydrograph?
Larger basins catch more precipitation and so have higher peak discharge. Smaller basins have shorter lag time, as water doesn’t travel as far
How does deforestation affect the shape of a storm hydrograph?
Reduces interception and lack of roots reduces infiltration rats, leading to rapid overland flow and flashy hydrographs
How does afforestation affect the shape of a storm hydrograph?
Opposite effect of deforestation, also decreases soil erosion, so less sedimentation of the channel, therefore increasing its capacity and reducing flooding
How does agriculture affect the shape of a storm hydrograph?
Ploughing allows infiltration, subdued hydrographs. Terraces stop water movement downhill, subdued hydrographs. Grass crops increase infiltration, subdued hydrograph
How does growth of urban areas affect the shape of a storm hydrograph?
Flashy hydrographs: impermeable surfaces, floodplains, water moved directly into river, loss of green spaces and vegetation
How does soft engineering flood management affect the shape of a storm hydrograph?
Some schemes attempt t reduce flashiness of hydrographs. Afforestation increases interception and infiltration, subdues discharge
How does water abstraction affect the shape of a storm hydrograph?
Reduces the base flow and so more water must reach the channel before it reaches bankfull capacity and floods
What is the base flow?
The normal day to day discharge of the river
What is the impact of deforestation on the water cycle?
New vegetation generally has fewer leaves and shallower roots, so uses less water
So less water evaporates from the land surface to be returned to the atmosphere
More water runs off the land and stream flow is increased
Amount of rainfall may decrease or river discharge will increase
What is the impact of agricultural soil drainage on the water cycle?
Heavy machinery can work the land without compaction, leading to more overland flow
The insertion of drains increases rate f through low in the soil
Can increase likelihood of flooding as discharge becomes more flashy and peak discharge increases
Soils can be eroded and soil water decreases
What is the impact of water abstraction on the water cycle?
Sinking water tables can make rivers less reliable, as their flows are maintained in the dry season by springs, that dry up when the water table falls
Ground water levels fall and saline intrusion can occur, contaminating water supplies
Precipitation and rainfall don’t replace water used
What is El Nino?
A cycle of warn and cold temperatures measured using sea surface temperatures of the tropical Pacific
What is El Nino caused by?
Strong extensive interaction between the ocean and atmosphere
How can El Nino affect the water cycle?
Can cause droughts and global declines in evapotranspiration despite rising temperatures. Reduced precipitation leads to lower soil/ground water levels
How can tropical storms affect the water cycle?
Increased rainfall and storm surges over the and can lead to greater river discharge and saturated ground
How can drought affect the water cycle?
Causes reduction in water stores in rivers and lakes
Vegetation dies back or is destroyed by fires, affecting transpiration, interception and infiltration
Groundwater flow becomes more important as a long term transfer, soils dry out
