Topic 5 - Water Cycle And Insecurity: EQ1 Flashcards
What type of system is the global hydrological cycle?
A closed system
What type of system is a drainage basin?
An open system
What is residence time?
The time during which water remains within a body of water before continuing around the hydrological cycle
What are flows (fluxes)?
Measurements of the rate of flow between stores
What are stores (stocks)?
Places where water is held
What is an example of a store?
Lake
What is blue water?
Water that is stored in rivers and lakes
How much of Earth’s water is considered freshwater?
2.5%
How much of Earth’s water is stored in the oceans?
96.5%
How much of Earth’s water is accessible for humans?
0.007%
What conditions are needed for precipitation to form?
Air cooled to saturation point with relative humidity of 100%
Condensation nuclei to facilitate the growth of droplets
A temperature below dew point
What are the 5 key influencing factors on the a hydrological system?
Amount of precipitation
Type of precipitation
Intensity of precipitation
Seasonality
Variability
What are the 3 types of variability affecting a hydrological system?
Secular Variability
Periodic Variability
Stochastic Variability
What is Secular Variability?
Long Term, e.g. as a result of climate change trends
What is Periodic Variability?
Happens in annual, seasonal, monthly or diurnal context
What is Stochastic Variability?
Results from random factors e.g. a thunderstorm or lightning strike
What are the 3 types of rainfall?
Relief/Orographic
Frontal/Cyclonic
Convectional
What is Precipitation?
The input into a drainage basin system. It includes all forms of moisture entering:
Hail, snow, dew, frost, sleet, rain
What is Interception?
The storage of water when it lands on vegetation (or structures like buildings) before it reaches the soil. It’s a temporary store before evaporation or stemflow
What is Surface Storage?
The storage of water on the surface including puddles, ponds and lakes
What is Soil Storage?
The storage of water in soil. Water is held in the small gaps between soil particles
What is Groundwater Storage?
The storage of water in the ground rocks of permeable rock. The water is held in cracks (limestone), bedding planes (sedimentary rock) or pores (chalk)
What are Aquifers?
Rocks with lots of groundwater storage
What is Channel Store?
The storage of water in the river channel
What is Vegetation Store?
The storage of water in the vegetation. Plants and trees take up water through their roots and water is stored here
What is Surface Run-off?
The horizontal flow of water over the surface of the land either in little channels or over the whole surface
What is Stemflow?
The downwards flow of water moving downwards from interception storage to the surface
What is Soil Throughflow?
The horizontal flow of water moving through soil (between the particles) towards the river
What is Infiltration?
The downwards movement of water from the surface into the soil
What is Percolation?
The downwards movement of water from the soil to the permeable ground rock
What is Groundwater Flow.
The horizontal movement of moving through the rocks (cracks/bedding planes/pores) slowly towards the river. This is the movement of water below the water table sideways to the river
What is River Channel Flow?
The movement of water in the river channel moving towards the sea
What is Evaportaion?
The output of water when water is heated and turned from a liquid into a gas
What is Transpiration?
The output of water where moisture is taken into plants through their roots, moved to the leaves by capillary action and then evaporates from the leaves into a gas
What is Evapotranspiration?
The combined output of water from evaporation and transpiration
What is River Discharge?
The output of water from a river channel out to sea
What physical factors cause variation within the drainage basin?
Interception
Infiltration
Surface run-off
Percolation
Evapotranspiration
River Discharge
What human factors cause variation within the drainage basin?
Cloud Seeding
Urbanisation
Dam Construction
Groundwater Abstraction
What are the inputs in a water budget?
Precipitation
Water Diversion
Groundwater flow
Surface water flow
What are the outputs in a water budget?
Evapotranspiration
Water Diversion
Groundwater flow
Surface water
Surface run-off
What is Field Capacity?
The normal amount of water that can be held in the soil
What is Potential Evapotranspiration?
The amount of water that could be lost by evapotranspiration if there was sufficient moisture available
What is Actual Evapotranspiration?
The amount of water that is lost through transpiration (release from leaves) and evaporation (heating of water on surfaces) to the atmosphere
What is Soil Moisture Surplus?
When the soil moisture from the soil stores is being used by vegetation/humans as the precipitation rate is less than evapotranspiration
What is Soil Moisture Rechrge?
When moisture from precipitation infiltrates and percolates in the stores to repay the soil moisture utilisation/defecit
What is Soil Moisture Defecit?
There is not enough water left in the soil to match potential evapotranspiration. Rivers run dry and drought ensues.
What is the equation to calculate a Water Budget?
P = Q+E +/- Storage Change
What is a River Regime?
Indicate the annual variation of discharge of a river at a particular point
What unit is used to measure a River Regime?
Cumecs
What Factors affect a River Regime?
Size of the river
Precipitation
Temperature
Geology and Soil
Vegetation
Humans
