Water Cycle Flashcards
What is the systems approach with regards to water?
systems approach studies hydrological phenomena by looking at balance of inputs/outputs, and how water is moved between stores/flows
What is an open and closed system in terms of water?
- open system is one that transfers inputs and outputs of water to external systems e.g. drainage basin
- closed system is one with fixed amount of water with no external inputs/outputs, amount of water remains constant e.g. the hydrological cycle - earth can be considered closed as fixed amount of water -1385 million km3
What is blue and green water?
blue water - water stored in rivers, lakes (surface water 0.01% of all water) groundwater (1.1% of all water) in liquid form
green water - water stored in soil/vegetation e.g. cacti (biological water - 0.0001% of all)
What is the residence time of groundwater compared to atmospheric moisture?
groundwater - 10,000 years
atmospheric moisture - 10 days
How much water does the USA use?
260 gallons per person per day
How many dont have access to safe drinking water?
1/5
How often does a child die of a water-related disease?
every 15 seconds
What kind of water isnt renewable?
- fossil water not considered renewable e.g. many aquifers under Sahara Desert
How much of the worlds water is freshwater?
2.5%
How much freshwater is locked in ice?
2/3
What three things must be present for rainfall to be created?
- air cooled to saturation point (due to altitude) with humidity of 100%
- condensation nuclei (e.g. dust particles) to facilitate water droplet growth
- temperature below dew point (point where dew can form)
In what ways can precipitation vary?
- amount of precipitation
- type of precipitation
- seasonality
- intensity of precipitation
- variability
- distribution of precipitation within a basin
What are the different types of precipitation?
- orographic/relief (cloud rises altitude to reflect over mountain, causing precipitation)
- frontal (warm air rises over cold air when they meet, higher altitude causes precipitation)
- convectional (sun sends heat/light to earth, causing evaporation, cloud formation and precipitation)
What are the main types of interception?
- interception loss (when water is retained by a plant)
- through fall (water drops from leaves)
- stem flow (water trickles along branches/trunk)
How much do coniferous trees intercept compared to deciduous?
coniferous - 25-35%
deciduous - 15-25%
What does the rate of infiltration depend on?
- how long rainfall lasts - infiltration capacity decreases with amount of rainfall
- amount of water already in soil
- soil texture - sandy soils have bigger capacity than clay
- vegetation cover (varies throughout the year)
- soil surface/compaction
- slope - steep slopes encourage overland flow, smaller slopes encourage infiltration
What are the factors affecting rate of evaporation?
- sunlight hours
- temperature
- humidity
- wind speed
- size/depth of water
- vegetation cover
- surface colour