Water Cycle Flashcards
5 Stores of Water
Cryosphere (2/3) Atmosphere (0.04%) Lithosphere (1.7%) Terrestrial (includes biosphere) (30%) Oceanic
Process of Condensation
Air cools, holds less water vapour
Dew point temperature
Water vapour loses energy to surroundings
Condensation nuclei needed
When does condensation occur?
Volume of air increases but no heat is added
Temperature of air reduces below dew point but volume remains constant
Process of Evaporation
Water uses energy from surroundings, latent heat, to become a gas
What does rate of evaporation depend on?
Amount of solar energy
Air temperature
Humidity of air (rate decreases close to saturation)
Availability of water
Cloud Formation
Evaporation Convection Air expands as it rises- lower pressure of atmosphere Saturation- dew point temperature Condensation When too heavy, precipitation occurs
3 way cloud formation begins
Topography- air forced to rise over hills
Sun’s energy heats ground- latent heat
Warm air meets cold air- warm air rises
Input in the Drainage Basin System
Precipitation
Flows/ Transfers in Drainage Basin System
Interception Stem Flow Surface Runoff Infiltration Through Flow Percolation Channel Flow Ground Water Flow
Storage in Drainage Basin System
Surface Storage Soil Water Storage Channel Storage Groundwater Storage Vegetation Storage
Outputs in Drainage Basin System
Transpiration
Evaporation
River Runoff
Water Balance Equation
P = Q + E + ΔS
P= Precipitation Q= Runoff E= Potential Evapotranspiration ΔS= Change in Groundwater Storage
P > Q + E
Positive water balance
ΔS increases
P < Q + E
Negative water balance
ΔS decreases
Natural factors impacting shape of a storm hydrograph
Size of drainage basin
Topography
Rock and soil type
Human factors impacting shape of a storm hydrograph
Agriculture Water abstraction Urbanisation Deforestation Water management strategies
Natural factors impacting the water cycle as a whole
Storms and precipitation
Seasonality
El Nino
Droughts
Human factors impacting the water cycle as a whole
Agriculture
Deforestation
Urbanisation
Water abstraction
Through Flow
Downslope movement of water through the soil (roughly parallel to ground)
Infiltration
Water soaking into the soils
Percolation
Water moving down into the water table
Groundwater Flow
Very slow, horizontal movement of water through rock
River Regime
Variability in a rivers discharge throughout the course of a year
What can influence a rivers regime?
Temperature
Precipitation
Drainage basin characteristics
Flashy Hydrograph
Short lag time
High peak discharge
Subdued Hydrograph
Long lag time
Lower peak discharge
How does the size of a drainage basin impact the hydrograph?
Large = increased peak discharge Small = decreased lag time
How does topography impact the hydrograph?
Steep = lag time reduced
How does rock and soil type impact the hydrograph?
Impermeable rock = increased run off = increased peak discharge
How does seasonality impact the water cycle?
Winter- ground freezes, impermeable + ice melt = large output
Reduced input of precipitation in summer
Less vegetation in winter = decreased interception and decreased store
More vegetation in summer = increased evapotranspiration and root uptake so peak discharge decreases
How does El Niño impact the water cycle?
Causes droughts
Decreased precipitation
Decreased global evapotranspiration
How does agriculture impact the water cycle?
Ploughing increases infiltration
Crops increase interception and evaptranspiration
How does deforestation impact the water cycle?
Decreases interception
Decreases biospheric water store
Sedimentation of river channel- decreases bank full capacity
How does urbanisation impact the water cycle?
Increased impermeable surfaces increases runoff
Drainage systems decrease lag time
How does water abstraction impact the water cycle?
Less reliable rivers
Decreased ground water and surface stores (particularly in dry seasons)
Ground water level decreased by 7m in London since 2000, due to population increase
