Water Cycle 2 Flashcards
Explain the importance of the inter-tropical convergence zone
zone of convergence at the thermal equator where trade winds meet
- low pressure belt and migrates with the changing position of the thermal equator.
How does the ITCZ cause heavy rainfall
-steep angle of sun over tropical oceans -> intense solar radiation -> high evaporation
-trade winds transfer water vapour -> ITCZ -> strong convectional currents lift air -> cools, condenses -> clouds -> heavy rain
What is the ITCZ
narrow zone iof low pressure near equator
-where northern & southern air masses converge
How does the thermohaline circulation work
-ocean water in polar region is colder, more salty & denser in tropics so it sinks
-cold sinking water draws in warmer water from ocean surface above, which in turn draws water across surface from Tropics
-movement of water from Tropics draws cold water up from oicean bottom to be warmed again
How does the thermohaline circulation work
-ocean water in polar region is colder, more salty & denser in tropics so it sinks
-cold sinking water draws in warmer water from ocean surface above, which in turn draws water across surface from Tropics
-movement of water from Tropics draws cold water up from ocean bottom to be warmed again
Why are polar regions importanat
2/3 of Earth’s freshwater locked up in cryosphere -> as temp remains below freezing (ice sheets)
global climate warms -> frozen cryosphere water melts -> adding to hydrological cycle
Why are drainage basins referred to as catchment areas
as they catch all precipitation falling within watershed
How do drainage basins lose water
-evaporation, evapotrabspiration
-surface runoff to sea
-percolation into groundwater stores
What prevents the oceans from drying out
-global water budget
-oceans lose water through evaporation -> regain water from precipitation
-surface runoff makes up the difference known as the balance -> if balance was disturbed -> oceans would receive more water
Why does the warming of the global climate lead to an increase in water in the global hydrological cycle
2/3 water locked up in cryosphere
-as global climate ^ frozen cryosphere water melts -> sea -> adding to closed hydrological cycle
Name the 3 pathways water takes when precipitation occurs
-name 2 reasons why these pathways may be delayed
-reach land surface then infiltrate
-run off surface as overland flow (surface runoff)
-be evaporated- taken back into atmosphere
delayed:
-water intercepted -> plants/ buildings before evaporating/ inflitrating into surface
-some water infiltrates & percolates through rocks underneath groundwater -> may be stored as aquifers
explain the physical factors that affect the flow of interception in the drainage basin
- rate of interception dependant on two physical factors: precipitation and vegetation
- interception greatest when rain is lightest and of short duration as the dry leaves and stems have the greatest water storage capacity, if intensity increases then interception is less effective as more will drop off
- denser types of vegetation such as coniferous forests intercept more water than sparser deciduous trees, especially in winter when deciduous lose their leaves
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explain the physical factors affecting infiltration
1) precipitation intensity - infiltration-exces
explain the physical factors affecting infiltration
1) precipitation intensity - infiltration-excess overland flow will occur when rainfall intensity exceeds infiltration capacity, meaning that the water flows over the surface and infiltration is reduced
2) vegetation cover- roots help to break up the soil, increasing the infiltration rate
3) soil and rock type- infiltration rates will increase as porosity and permeability increase
4) water table depth- as the water table rises during prolonged rainfall the soil will become saturated, reducing infiltration
5) slope gradient- as gradient increases, more water will flow over the surface, reducing infiltration
explain the physical factors that affect the rate of percolation and groundwater flow
the permeability of the rock and the angle of the rock strata as a steeper gradient will allow gravity to operate more effectively
- the rate of P and GWF increases with porosity, impermeable rocks like granite prevent any percolation
- areas with permeable rock will absorb the water and create groundwater storage and an aquifer (a permeable rock which shotes water)
- porosity relates to the total volume of pore spaces and is greatest in coarse-grained rocks such as sandstone, while pervious rocks such as limestone have joints and bedding planes along which water can flow
how do you calculate a water budget?
precipitation = discharge + evapotranspiration + - change in storage
P = Q + E + - S
what are water budgets?
show the annual balance between inputs (precipitation) and outputs (evapotranspiration) in any given area
what are the different parts of a water budget?
monthly temperature
potential evapotranspiration
precipitation
water surplus
soil moisture utilisation
soil moisture deficiency
soil moisture recharge
what is soil moisture surplus?
precipitation exceeds than potential evapotranspiration
- soil water store is full -> soil moisture surplus for plant use, runoff and ground water recharge.
what is soil moisture utilisation?
potential evapotranspiration exceeds precipitation
-more water evaporating from ground surface & transpired by plants than is falling as rain
-soil moisture -> used up by plants/ lost by evaporation
what is soil moisture deficiency?
deficiency of soil water -> store is used up
potential evapotranspiration exceeds precipitation.
plants must adapt to survive- irrigation is needed
what is soil moisture recharge?
precipitation higher than potential evapotranspiration, soil water starts to fill again
what is field capacity?
when soil is full of water & cannot hold any more.
what is potential evapotranspiration?
amount of water lose through evaporatiojn & transpiration in any given period
what is infiltration capacity?
max rate at which the water can be infiltrated
What is effective rainfall
amount of precipitation remaining after evaporation
What is a river regime
annual pattern of flow
Name the 2 types of river regime
-simple regimes -> where river experiences period of seasonally high discharge followed by low discharge
-complex regimes -> where larger rivers cross several different relief and climatic zones, therefore experience the effects of different seasonal climatic events
Provide an example of complex river regimes
-amazon, brazil
-high flow: wetter season
-low/ no flow: drier season
-seasonable variability: moderate variability- fed by Andean rivers
-human influences: increasing
What are the major influences in the river regimes in the amazon, Brazil
-rainforest climate
-seasonal precipitation- rainfall in every month but divided into higher and lower rainfall seasons
-evapotranspiration levels very high
What is a hydrograph
a graph showing the discharge of a river at a given point over a period of time
What is a storm hydrograph
shows how river responds to a particular storm & displays both rainfall and discharge
What is the rising limb on a storm hydrograph
line on a storm hydrograph which shows the discharge rise up to its peak discharge