Water Flashcards
What percentage of the world’s water is freshwater?
2.5%
What percentage of the world’s water is easily accessible for use by humans?
1% of freshwater
What is the duration that water is in a store called?
Residence time
What is the boundary of a drainage basin called?
Watershed
What are the inputs of a drainage basin?
Precipitation
What are the outputs of a drainage basin?
Evaporation
Transpiration
Discharge
What are the flows of a drainage basin?
Throughflow Groundwater flow Channel flow Infiltration Percolation Surface Runoff
What physical factors influence the drainage basin?
Relief Soil Biomass Geology Climate
What human factors influence the drainage basin?
Deforestation/Afforestation
Urbanisation
River management
Land use
Define river regime
The change in river discharge through the year
What are the characteristics of a storm hydrograph?
Storm event, lag time, rising limb, falling limb, peak discharge
What is a Hadley Cell?
Rising air due to solar heating is replaced by air mass from other latitudes, creating a cycle
Which way do the trade winds go in El Nino?
West to East (reversed)
How does El Nino affect Australia?
Droughts
How does El Nino affect South America?
Low pressure and flooding
Which way do the trade winds go in La Nina?
East to West (intensified)
What is the progression of drought?
Meteorological, hydrological, agricultural, famine
How is meteorological drought defined?
A period of time with less than a certain amount of precipitation
How is hydrological drought defined?
The effect of precipitation deficit on a drainage basin’s fluxes and stores of water
How is agricultural drought defined?
Soil moisture is insufficient for crop growth and production
How is famine drought defined?
Decline in availability or access to food caused by drought
What is the water balance equation?
P = Q + E ± S
What does P stand for in the water balance equation?
Precipitation
What does Q stand for in the water balance equation?
Runoff / river discharge
What does E stand for in the water balance equation?
Evapotranspiration
What does S stand for in the water balance equation?
Soil moisture and groundwater storage
What “drives” the water cycle?
Solar Power
How much of the world’s water is in the oceans?
97%
How much of the world’s water is in the atmosphere?
0.001%
How much of the world’s water is in the biosphere?
0.003% of freshwater
How much of the world’s water is in the cryosphere?
69% of freshwater
How much of the world’s water is groundwater?
30% of freshwater
How much of the world’s water is surface water?
1.2% of freshwater
Which water stores are non-renewable?
Fossil water, cryosphere
What are the causes of drought?
Precipitation deficit, ENSO, global warming
Define fossil water
Water that infiltrated millennia ago under different climatic conditions to now, which has been stored since then
How does human activity increase drought risk?
Global warming
Over-abstraction of ground- and surface-water
What factors increase uncertainties in the hydrological cycle?
Global warming
ENSO
How does climate change affect the hydrological cycle?
Size of cryosphere, reservoirs/lakes, soil moisture
Rates of runoff and stream flow
Drainage basin inputs/outputs
What defines water stress?
Below 1,700 m³ / person
What defines water scarcity?
Below 1000 m³ / person
What causes water stress and scarcity?
Imbalance between water supply and demand
What is drip irrigation?
Gradually but directly dripping water to the plants’ roots, reducing evaporation
What is grey water?
Relatively clean waste water from the bathroom (NOT toilets) and kitchen appliances
What is rainwater harvesting?
Accumulating and storing rainwater for reuse, disallowing surface run-off
What is catchment?
Storing rainwater in large reservoirs
How does La Nina affect Australia?
Increased rainfall
How often are El Nino/La Nina events?
Anywhere from 2-7 years
Unpredictable
What does ENSO stand for?
El Nino-Southern Oscillation
How does La Nina affect South America?
Drought
How does La Nina affect North America?
Drought in the southwest
