Water Cycle

Question 1

Give the biggest contributor to global water storage - percentage what is its pH?

Answer 1

The oceans - carry 96.6 % of the water (saline)

pH-8.2

Question 2

Of the non saline water on earth describe different stores and the magnitude

Answer 2

30% as aquifers - deep storage in porous rocks
69% in the crysophere - various ice forms
1% in lakes rivers, the atmosphere and people

Question 3

Give 5 stores of water in the cryosphere

Answer 3

Sea ice - ross ice shelf
Ice sheets - e.g. Antarctic ice shelf larger than USA
Alpine glaciers 
Ice caps 
Permafrost

Question 4

State the residence time of the following stores
Groundwater 
Oceans 
Lakes 
Soil mositure 
Atmosphere

Answer 4

Groundwater - 10,000 years
Oceans - 3600 years
Lakes - up to 10 years
Soil mositure - around 4 weeks
Atmosphere- 10 days

Question 5

What is dew point temperature?

Answer 5

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

Question 6

Give three causes of precipitation

Answer 6

Relief rain - warm air pushed over hills
Different temperatures meet less dense rises
Warm localised surfaces

Question 7

Describe the formation of clouds at the sides of the equator

Answer 7

High temperature at the equator and low pressures lead to evapotranspiration.
Air rises and condenses

Question 8

What is the term for gaseous water immediately freezing ?

Answer 8

Sublimation

Question 9

Describe the cryospheric processes in the water cycle

Answer 9

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

Question 10

Describe the flows within the drainage basin scale of the water cycle

Answer 10

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

Question 11

What is run off?

Answer 11

The volume of water that leaves the drainage basin

An output

Question 12

Define drainage basin

Answer 12

The catchment area from which a river gets its water, separated by the water shed

Question 13

Give the water balance equation

Answer 13

Precipitation = runoff + evapotranspiration + change in storage

Question 14

Describe the sections of a flood hydrograph, when would a river be considered flashy?

Answer 14

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

Question 15

What is discharge measured in?

Answer 15

Cross sectional area X velocity

So M^3 S^-1

Question 16

Why may run off vary?

Answer 16

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

Question 17

What is a river regime?

Answer 17

The variability is discharge of a river throughout the course of a year

Question 18

Describe natural causes that lead to variation within the water cycle

Answer 18

Precipitation
Seasonal variation - e.g ground may freeze
Biomass increases in summer
Ground becomes baked in summer so less permeable

Question 19

Describe the farmings impact on the water cycle

Answer 19

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

Question 20

Describe land use change as a human factor changing the magnitude of flows in the water cycle

Answer 20

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

Question 21

Describe the role of water abstraction in changing the magnitude of stores and flows within the water cycle.

Answer 21

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