Hydrological Cycle Flashcards
Name the 3 parts of the hydrological cycle
Stores - oceans
Fluxes - rivers , water moving
Process- the mechanisms which drive the fluxes
What kind of cycle is it
Closed
What goes in must come out
One input and many outputs
Amount of water never changes
What happened to the hydrological cycle in the last ice age?
Sea levels fell by over 140 m due to more water stored in the cryosphere
What is isostatic rebound?
Land rises out of ocean due to previous ice coverage pressing it down into the ocean over the thousands of years land slowly comes back up
What is the biggest store of water?
The ocean
What percentage of freshwater do ice caps hold?
70%
What percentage of groundwater represents freshwater
30%
What are the smallest freshwater stores
One percent for rivers and soil moisture. And 0.1% for the atmosphere.
What is blue water
Visibly part of the cycle
Rivers, lakes
What is green water
Water stored in vegetation and soil generally seen as I visible
Describe what type of system The ground basin is
On a small scale the drainage basin is an open system as it has external inputs and outputs that cause the amount of water to vary over time
What is a confluence
A confluence is where a tributary meets the main flow of water
How does water travel
Downstream
The slope angle effects the speed of water
What is the catchment area
The area of land which catches the rainfall
Usually on a hill
What is watershed
The area of land which channels precipitation
Top of the river is the ____
Source
Top of the river is the ____
Source
Bottom of the river is the _____
Mouth
What is overland flow
When the water is not absorbed by the ground it goes off as overland flow
What is orographic rainfall
Air is forced to rise over over a barrier
E.g clouds rising over Pennines
This then forms clouds and rain.
The leeward side (downwind) recipes relatively less rainfall (rain shadow )
What are the 7 impacts on the drainage basin
Amount of precipitation
Type of precipitation
Seasonality
Intensity
Variability of precipitation e.g. climate change
Distribution of precipitation e.g. larger basins localised storm events impact on only part of the basin
What impacts the drainage basin
Amount of precipitation
Type of precipitation
Seasonality
Intensity
Variability of precipitation e.g. climate change
Distribution of precipitation e.g. larger basins localised storm events impact on only part of the basin
Name the three types of rainfall
Orographic
Cyclonic
Conventional
Cyclonic rainfall
Warm air is lighter and less dense
Forced to use over cold denser air
Rises and cools can no longer hold water vapour so condenses and forms rain
Occurs when warm moist air comes into contact with cool dry air
Conventional rainfall
Occurs in the tropics and uk summer
Heat radiation heats land, this heats the thin layer of air above land , this warms , expands and rises
As it rises it cools condenses and falls as rainfall
Rain shadow
On the side facing away from prevailing winds (leeward side), this area of land that has relatively less rainfall
Infiltration
The rate at which water enters the soil/ground this varies considerably depending on the vegetation type e.g. different trees have different infiltration rates, coniferous forests intercept about 25 to 35% of annual rainfall however deciduous only intercept 15 to 25%
What factors affect infiltration rate
Amount of rain already in the ground
Soil texture (sand and clay intercept at vastly different rates)
soil compaction
type of vegetation (trees versus pasture)
slope angle
What is through flow
Flows through the land under ground
What is percolation
Water infiltrates ground and goes into rocks under ground
Channel flow
Channel flow is the main body of water
Describe evapotranspiration
-A combination of evaporation and transpiration
-the most crucial element of moisture loss especially in areas such as arid and semi arid areas like Spain.
-It is often difficult to distinguish between what is transformation and evaporation therefore they are combined.
Describe how soil texture impact the drainage basin
The rates of infiltration are different depending on soil types
Sandy -good
Clay based-poor
Silt —average
The porosity of these impact upon the rate at which water infiltrates
What factors affect infiltration rates?
Vegetation type and cover
how much water is already in the soil
Compact
Slope angle
Why does Interception affect the drainage Basin
Type of vegetation and density results in different interception levels
Deforestation and afforestation both have significant impacts
How does groundwater affect the drainage basin
Grandma is used a lot in warm countries to irrigate crops
UK no longer uses much groundwater since the manufacturing moved elsewhere, meaning flooding is more common as there is more water in the groundwater
Five factors which impact the rate of infiltration
Climate
soil
geology
relief
Vegetation
Name the 4 human factors that impact the water cycle
Cloud seeding
Urbanisation
Dam construction
Groundwater abstraction
Define river regime
The annual variation in discharge from a river
What factors influence the river regime
Climate
Snowmelt
Geology
Human activity
Dam construction
Rainfall regimes
Deforestation
What factors affect the shape of a storm hydrograph
Basin size
Drainage density
Precipitation intensity
Precipitation duration
Bain shape
Natural vegetation
Land use
Snowfall
Soli type
Basin relief
Rock type
Evapotranspiration
What are the 4 drought types
Meteorological
Hydrological
Agricultural
Food deficit
What is the El Niño southern oscillation
It is an oscillation of the ocean atmosphere system in the tropical pacific
It has major impacts on global weather
What happens during El Niño
Winds across the pacific change direction
They blow west to east
This changes weather patterns around the pacific
Occurs every 3-6 years however getting more regular
Describe what happens during an El Niño year
Air pressure over west coast of South America is low
Air pressure over Australia is high
The regular trade winds over pacific are disrupted and warm water sloshes eastwards
No cold upwelling on South American coast
What are the consequences of an El Niño year
The warm water back eastwards prevents the cold upwelling of nutrient rich water which plankton feed off
This attracts anchovy’s
What are the teleconections of El Niño
Reduced hurricane activity in south central America
Droughts in Brazil
Floods in Kenya
Fires in indonisia
What is el Nina
It is exaggerated version of normal conditions - increased natural disasters
Warm water eastwards causes sea levels to rise by 1m
Strong uplift of air around Indonesia and Philippines causes heavy rain
