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 from the atmosphere to the ground. It can take the form of rain, snow, hail, dew etc
What is interception?
Precipitation intercepted and stored in the leaves of plants
What is throughflow?
Through flow is water flowing through soil towards the river channel
What is inflitration?
Infiltration is the transfer of water from the ground surface into soil where it may the percolate into underlying rocks
What is percolation?
Water soaking into rocks
What is groundwater flow?
Transfer of water very slowly through 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, groundwater held in soils and rock + atmospheric water vapour
what is oceanic water?
The water contained in the Earth’s oceans and seas BUT NOT including inland seas e.g. 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? (2)
-Precipitation
-Energy from the sun
What are the stores in a drainage basin? (5)
-Lakes
-Soil/ Groundwater
-Interception/vegetation
-River flow
-Surface flows
What are transfers in the drainage basin? (4)
-Ground water flow
- Percolation
-Transpiration
-Precipitation
What are the outputs from the drainage basin? (3)
-River discharge
-Evaporation
-Water vapour
What is the fastest movement of water through the drainage basin?
Fastest movement is along the surface where there are relatively few obstacles in the way of the water
how fast is water movement through 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 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 or stalks
What are the factors impacting the soil moisture budget? (2)
-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?
precipitation exceeds evapotranspiration
How does drainage basin shape affect the shape of a storm hydrograph?
Basins with a more circular shape = flashier hydrographs because each point is roughly equidistant from the channel
How do slope angels affect the shape of the storm hydrograph?
Drainage basis with steep sides have flashier hydrographs because water flows more quickly down steep slopes
How does drainage 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?
Basin already wet = water table high, soil saturated, so low infiltration/percolation,peak discharge higher, so flashier hydrograph
Basin dry = low water table, unsaturated soils, so high infiltration/percolation, so subdued hydrograph
How does rock affect the shape of a storm hydrograph?
If a rock is impermeable, overand 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?
Bare = flashy (deciduos in winter, low levels of interception, rapid movement through system)
Forest = subdued (deciduous in summer, high levels of interception and slower passage through the system: more water lost to evaporation from vegetation surfaces)
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 if 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. = flashy
smaller basins have shorter lag time, as water doesn’t travel far = subdued
How does deforestation affect the shape of a storm hydrograph?
Reduces interception and lack of roots reduces infiltration rates, 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 inflitration, subdued hydrographs
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 to reduce flashiness of hydrographs.
- Afforestation increases interception and inflitration, subdues discharge
How does water abstraction affect the shape of the 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 returns 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 drain increases rate through flow 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 on the dry season by springs, that dry up when the water table falls
- Ground water fall and saline intrusion can occur, contaminating water supplies
- precipitation and rainfall doesn’t replace water used
What is El Nino?
A cycle of warm and cold temperatures measured using sea surfaces 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 land can lead to greater river discharge and saturated ground
How can drought affect the water cycle? (3)
-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
What is surface runoff/ overland flow?
the flow of water that occurs when excess stormwater, meltwater, or other sources flows over the earth’s surface.
What is chanel flow?
the movement of water within the river channel.
What are the main stores of water? (4)
Oceanic
Lithosphere - outermost layer of earth e.g crust and upper mantle
Cryosphere - frozen parts of earths surface e.g ice caps
Atmospheric - air that surrounds earth
How much water is stored in the lithosphere?
1.7% of all water on earth
Captures water for the longest period of time
How much water is stored in the hydrosphere?
71% - approx 3% fresh
How much water is in the cryosphere?
2.1% - less than 1% is in all living plants and animals
How much water is in the atmosphere?
0.001% of water on earth
What are the global factors that drive changes in water storage? (3)
- Climate change
- Cryospheric processes
- Cloud formation and causes of precipitation
How are clouds formed? (3)
- When water molecules join together
- Frequently noticed at altitude when air temp falls to where condensation of invisible water vapour occurs, or where humidity content has risen such that water vapour can’t remain in that state and condenses
- As molecules grow, clouds formed with the tiny water or ice particles kept aloft by rising air currents
How does precipitation occur? (4)
- When water molecules within a cloud combine and become too big
- Process is call coalescence
- If droplets fall, velocity is greater than the cloud’s updraft velocity, precipitation will occur
- Faster the cloud moves upwards, rain, snow or hail will fall from the cloud
Long timescale effects of cryospheric processes?
Snow falling on glaciers and ice sheets becomes compressed and enters long term storage, forming layers of ice
Short timescale effects of cryospheric processes?
- Snow accumulated during winter adds to mass of glacier or ice sheet - in summer, melting occurs or ice calves
What impact will climate change have on the cryosphere? (4)
- Will get smaller as snow and ice melts
- Sea ice less likely to form
- River flow will increase initially due to glacier-melt, maybe leading to localised flooding of flood plains
- Loss of glaciers may cause water shortages in certain communities e.g. Himalayas
What impact will climate change have on the hydrosphere? (3)
- River flow and ocean levels likely to increase
- Increased evaporation likely to increase
- Increased evaporation likely to regulate rate of sea level rise, sea levels likely to be much greater, leading to threats to coastal communities from more frequent flooding and infiltration of saline water into lithosphere at the coast
What impact will climate change have on the atmosphere? (4)
- Increased evaporation likely to occur as conditions become warmer - increased atmospheric moisture content
- Greater precipitation rates as cloud formation occurs more regularly
- Increased heavy rainfall as atmospheric water reaches a new equilibrium state
- More intense flooding
