Water Cycle Flashcards
Give the biggest contributor to global water storage - percentage what is its pH?
The oceans - carry 96.6 % of the water (saline)
pH-8.2
Of the non saline water on earth describe different stores and the magnitude
30% as aquifers - deep storage in porous rocks
69% in the crysophere - various ice forms
1% in lakes rivers, the atmosphere and people
Give 5 stores of water in the cryosphere
Sea ice - ross ice shelf Ice sheets - e.g. Antarctic ice shelf larger than USA Alpine glaciers Ice caps Permafrost
State the residence time of the following stores Groundwater Oceans Lakes Soil mositure Atmosphere
Groundwater - 10,000 years Oceans - 3600 years Lakes - up to 10 years Soil mositure - around 4 weeks Atmosphere- 10 days
What is dew point temperature?
Temperture at which the air is fully saturated with water vapour, at this temperature condensation will occur
E.g. Around condensation nuclei
Leads to rain formation
Give three causes of precipitation
Relief rain - warm air pushed over hills
Different temperatures meet less dense rises
Warm localised surfaces
Describe the formation of clouds at the sides of the equator
High temperature at the equator and low pressures lead to evapotranspiration.
Air rises and condenses
What is the term for gaseous water immediately freezing ?
Sublimation
Describe the cryospheric processes in the water cycle
Snow fall freezes in layers and becomes compressed
Ice forms in huge sheets
Ageing around 400,000 years
Glaciers will have an equilibrium line between the points in summer and in winter
Describe the flows within the drainage basin scale of the water cycle
Infiltration - surface water into soil due to capillary action and gravity
Percolation - water through faults in rocks
Through flow - where water flows through the soil layer
Overland flow - when ground is impermeable water flows along the surface
Ground water flow - underground through aquifers
Channel flow - the water running within rivers
What is run off?
The volume of water that leaves the drainage basin
An output
Define drainage basin
The catchment area from which a river gets its water, separated by the water shed
Give the water balance equation
Precipitation = runoff + evapotranspiration + change in storage
Describe the sections of a flood hydrograph, when would a river be considered flashy?
Lag time - time between peak discharge and peak rainfall
Rising limb - where discharge is increasing after a rainfall
Bas flow - initial and final discharge of the river
A river is flashy when the rising limb is steep and the lag time is short
What is discharge measured in?
Cross sectional area X velocity
So M^3 S^-1
Why may run off vary?
Vegetation - type and amount, more evapotranspiration from more trees means soil is further from field capacity therefore more infiltrates
Rainfall - high intensity rainfall cause greater runoff
Topography - steep sided = greater runoff
Geology - some rocks are more permeable than others e.g. Granite vs chalk
Size and shape of river basin
What is a river regime?
The variability is discharge of a river throughout the course of a year
Describe natural causes that lead to variation within the water cycle
Precipitation
Seasonal variation - e.g ground may freeze
Biomass increases in summer
Ground becomes baked in summer so less permeable
Describe the farmings impact on the water cycle
Ploughing leads to increased infiltration, hence reduces lag time, but can lead to soil erosion therefore long term increase runoff
Crop planting increases evapotranspiration, but compared to previous conditions may be less evapotranspiration e.g. If rainforest deforested
Live stock trample the ground making it more compact
Ditch digging
Irrigation leads to increased runoff
Describe land use change as a human factor changing the magnitude of flows in the water cycle
Deforestation- less infiltration, as ground is more saturated, decay of plant matter produces loam that holds water, without this run off increases. Positive feedback loop where reduced evapotranspirstion can lead to less precipitation as less air within the atmosphere
Urbanisation - increases impermeable surfaces, plus urban drainage designed to remove water as quick as possible
Describe the role of water abstraction in changing the magnitude of stores and flows within the water cycle.
Water taken from aquifers
Aquifers v long term store that take ages to replenish
Where level drops below water table the aquifer becomes contaiminated with saline water
