The water Cycle and water insecurity EQ1 Flashcards
Define the hydrological cycle
A closed system (definite amount of water) in continual circulation where water can change forms and moves between stores.
What is the hydrological cycle powered by?
Solar energy and gravitational potential energy
Name the hydrological cycle input
Precipitation
Name the hydrological cycle outputs
Evaporation
Evapotranspiration
Transpiration
River Discharge
Name the hydrological cycle flows
Infiltration Throughflow Percolation Stem flow Base flow Channel flow Surface runoff
Name the hydrological cycle stores
Interception Vegetation storage Surface storage Soil moisture Groundwater storage Channel storage.
Define flux
The rate of movement between stores
Define percolation
movement of water from the soil to the bed rock
Define precipitation
Moisture in any form, the only input in the hydrological cycle.
Define interception
Temporary storage as water is captured by plants, buildings and hard surfaces before reaching the soil.
Define groundwater storage
Water held within permeable rocks also known as aquifers
Define Channel storage
Water held in rivers and streams
Define infiltration
Water entering the topsoil. Most common during snow or heavy rainfall.
Define throughflow.
Also, know as interflow.
Water seeping naturally through the soil below the surface, but above the water table
Define percolation
The downward seepage of water through rock under gravity, especially on permeable rocks such as sandstone and chalk.
Define stem flow
Water flowing through plant stems or drainpipes
Define groundwater flow
Also known as base flow, slow-moving water that seeps into river channels.
Define surface runoff
Also called overland flow, when water runs over impermeable, saturated or frozen ground.
Define evapotranspiration.
The combined effects of evaporation and transpiration
Define River discharge
The volume of water passing a certain point in the channel over a certain amount of time.
Define channel flow
The volume of water flowing within a river channel.
Define hydrosphere
The combined mass of water below, on and above the earth’s surface.
What is the biggest water store?
The ocean containing 97% of water. However, it is unusable for humans as it is saline. But can be used for certain industries and supports marine life with 90% of marine life living close to the shore.
What is the cryosphere?
Water stored in a solid-state.
What is blue water?
Visible water such as rivers, streams and ground water in liquid form.
What is green water?
Parts of the water cycle that are not visible such as vegetation or soil moisture.
What is residency time?
The average amount of time a water molecule will spend in a store.
List the water stores in order of longest to shortest residency time
Cryosphere groundwater Oceans lakes soil moisture rivers atmospheric water
How long does water spend in each store?
Cryosphere 1000 to 10 000 years groundwater 2 weels to 10 000 years Oceans 4 000 years Soil moisture 2 weeks to 1 year lakes 10 years rivers 2 weeks atmospheric water 1.5 weeks
What percentage of Earth’s water is freshwater?
2.5%
Where is the majority of freshwater located?
69% in glaciers
30% in ground-water storage.
What is thermohaline circulation?
When water circulates globally between the tropics and the poles to regulate temperature.
Colder, saltier polar water sinks as it is dense pulling in warmer water from the tropics.
Ensures Earth water does not get too hot for life.
What is the albedo effect?
dark surfaces absorb solar radiation whilst white surface reflect solar radiation meaning they a cooler, this stops the icecaps from melting.
What is the Intertropical convergence zone?
ITCZ
Areas with the highest rates of evaporation and precipitation.
Moves seasonally due to the Earth’s axis tilt
Caused by collided southern and northern air masses. Air rises rapidly so cools and condenses.
Disadvantages and advantages of rivers and lakes
\+Easily extracted for use. \+The biggest store we can use \+Potable -Easily polluted -Under 1% of the available freshwater.
DIsadvantage and advantages of the cryosphere
+freshwater (69% of total fresh)
+Albedo effect regulate temperature
-Hard to access as drilling is difficult and the area is protected for environmental reasons.
Advantages and disadvantages of the ocean
+ Supports marine life with 90% of life living close to shore
+ largest area for evaporation which drives precipitation.
- saline so not potable, desalination is expensive.
What is the average usage of water in the UK?
The average person in the UK uses 3,400 litres of water a day.
What percentage of public water supplies in England and Wales comes from groundwater storage?
35%
Advantages and disadvantages of ground water storage
+ 5th largest store
+ easily accessible freshwater store, unconfined aquifers provide water for human consumption, irrigation and industry.
- easily polluted by landfills and fertilisers
- over-extraction can cause the store to run dry.
- confined aquifers are unaccessible.
Saudi Arabi water usage statistic
In Saudi Arabi half of public water is provided by desalination.
Define a drainage basin.
An open sub-system within the hydrological system. Normally an area of land within two high relief points that are drained by a river and its tributaries.
Also referred to as catchment areas.
Drainage basin size
Drainage basins vary hugely in size from a small stream to international rivers.
The largest drainage basin is the Amazon which drains 7mil km2.
What are the physical factors affecting a drainage basin?
climate soils geology relief vegetation
How does climate effect the drainage basin?
Main influence on precipitation e.g orographic rainfall.
Affects the rates of evaporation.
Indirectly effects the vegetation in the area altering infiltration rates.
How does soil type effect the drainage basin?
Changes the rate of through flow and infiltration.
Impermeable surface can lead to more surface runoff.
Variable soil moisture storage.
Indirectly impacts the type of vegetation.
How does geology effect the drainage basin?
Indirectly alters soil formation.
Impacts percolation and groundwater flow altering aquifer levels.
How does relief effect a drainage basin?
Altitude effects preciptation rates as higher altitudes have colder air so can carry less moisture causing preciptation, also effects relief rainfall.
Slopes increase the rates of surface runoff and decrease the rates of infiltration.
How does vegetation effect a drainage basin?
More vegetation means more interception, less infiltration, less overland flow and more transpiration.
What are the human factors effecting the drainage basin?
cloud seeding deforestation afforestation dam building land use irrigation manufacturing channelisation of rivers in urban areas.
How does cloud seeding effect the drainage basin?
Cloud seeding can increase the rate of precipitation. An expensive method to cause ice crystals by dispensing silver iodide into the atmosphere.
Used as part of The South African Rainfall Enhancement program. On average, from the 37 strorms that were treated, rainfall doubled.
How does deforestation effect the drainage basin?
Reduction in evapotranspiration rates.
Increase in surface runoff contributing to increased river discharge and flooding.
India has blamed deforestation in Nepal for increasing surface flow of water in India, contributing to the 6,000 deaths from the Himalayan floods in 2013.
how does afforestation effect the drainage basin?
Mature trees increase interception and transpiration, also improve soil fertility.
Immediately after planting trees there is an increase in surface runoff and sediment loss due to soil compaction from tractors.
How does farming effect the hydrological cycle?
Grazing animals compact soil increasing surface runoff.
Ploughing loosens soil can cause soil erosion.
Irrigation increases water demand.
Groundwater abstraction and China
Groundwater is used for 40% of farmland and 70% of drinking water.
Levels in arid North China Plain have dropped by one meter a year between 1974-2000.
Dam construction impact on the hydrological cycle impact.
Laker Nasser behind the Aswan Dam in Egypt has evaporation losses of 10-16bn m3 per year.
This represents 20-30% of the volume of the River Nile.
hos does latitude generally effect the drainage basin?
30-45 negative water budget deserts.
50-60 positive water budget,
Define water budget.
The annual balance between inputs and outputs in a drainage basin that leads to a surplus or deficit of water.
What does a water budget graph look like?
It has two y-axes to show the mean rate of precipitation and evaporation both as line graphs.
The x-axis records the month.
What key events are shown on a water budget graph?
Water surplus Soil moisture deficit soil moisture utilisation soil moisture recharge field capacity.
Label the key parts of a water budget graph
What is a water surplus?
When precipitation is greater than precipitation.
Define soil moisture utilisation
soil moisture deficit
soil moisture recharge.
Soil moisture starts to be used by plants
Soil moisture decreases as evapotranspiration is greater than precipitation, all stored moisture has been used by plants.
Soil moisture increases after a dry period when precipitation rates increase.
What is a river regime?
Annual variation in the discharge of a river, influence by groundwater levels, surface runoff, precipitation and tributaries.
What is the difference between a simple and complex river regime?
Simple river regimes have a seasonally high river discharge followed by a seasonally low, patterns are regular.
Complex river regimes occur when rivers are larger or are effected more by humans so their change in discharge is harder to follow.
What processes may affect a river regime?
Glacier / snowmelt
High summer evapotranspiration
tropical seasonal rains / monsoon seasons.
What is a hydrograph?
A graph showing the discharge of a river over a given period of time. compares rainfall (bar chart) to river discharge (line graph)
What factors affect the Yukon Alaska river regime?
Glacial melt in summer contributed to flooding in June 2021
50% of total precipitation falls as snow between November and March.
Higher altitude mountains receive more rain, around 150mm a year or precipitation.
What factors affect the Murray- Darling RIver Basin?
Crosses different biomes, the east is mainly temperate forests and grasslands so has a higher rate of orographic rainfall. West is blocked by mountains so is mainly desert.
Monsoon season in January.
Land use also varies, west of the basin being rangelands and used for farming, decreases land quality leading to agricultural drought, compact land reduces infiltration and aquifer recharge.
Factors effecting river regimes in Amazonia
20% of forest destroyed by deforestation.
Wet Season, 300 mm of rain, highest rates of precipitation in January to May.
Affected by the movement of the intertropical convergence zone, above in January not July.
What are the key features of a storm hydrograph?
rising limb - rapid increase in river discharge normally during or after rainfall.
lag time - the gap between peak rainfall and peak discharge
falling limb - the decreasing river discharge after peak discharge.
What does the term bankfull mean on a storm hydrograph?
When discharge breaches the channel capacity.
Any more water entering the system would cause the river to flood.
Factors affecting the shape of a storm hydrograph
Land gradient - steeper land decreases the rates of infiltration and increases surface runoff. Often causes a steeper rising limb.
Circular v optical (long narrow drainage basin) - in a circular drainage basin water takes longer to exit the drainage basin and enters the river faster. Rivers often have
Landuse - urbanisation - vegetation
Permeability
Duration and intensity of rainfall
