Water

Question 1

What is the global hydrological cycle?

Answer 1

The global hydrological cycle is the circulation of water around the earth. It is a closed system of linked processes so there are no inputs or outputs. It is powered by solar energy in the form of heat and gravitational potential energy in allowing the downhill flow of water and fall of precipitation .

Question 2

What are the Stores?

Answer 2

Stores are reservoirs where the water is held- the four main stores are glaciers, oceans, surface run off and the atmosphere.

Question 3

What are the Flows?

Answer 3

Flows are the transfers of water from one store to another: oceans and atmosphere (precipitation and evaporation)

Question 4

What is the global water budget?

Answer 4

The global water budget takes into account all the water that is held in stores and flows of the global hydrological cycle.

Question 5

What is the resistance time?

Answer 5

The average time a molecule of water will append in these stores.

Question 6

What is fossil water ?

Answer 6

Fossil water is ancient, deep groundwater made from pluvial periods in the geological past

Question 7

What is the cryosphere made up of?

Answer 7

The cryosphere is made up of areas of the world where water is frozen into snow and ice

Question 8

What are the inputs and outputs of the hydrological cycle?

Answer 8

main input: precipitation, output: evaporation, transpiration and discharge

Question 9

What is the drainage basin?

Answer 9

A drainage basin is an area of land drained by the river and its tributaries. The boundary of the river is the watershed

Question 10

How do physical factors affect the drainage basin?

Answer 10

Climate: influences the amount of precipitation as well as the amount of evaporation and also impacts vegetation type
Soils largely affect the relative importance of the different flows within the system and directly impact the amount of infiltration
Geology affects the types of flows within a system as well as percolation and groundwater flow
Vegetation impacts interception, infiltration, surface flow and transpiration rates
Relief affects water flows- impacts amount of precipitation and slopes can affect the amount of run off

Question 11

How do human factors affect the drainage basin?

Answer 11

humans accelerate its process
River management- construction of storage reservoirs holds back the river flow, and abstraction of groundwater for irrigation lowers water tables
Deforestation- the clearance of trees reduce evapotranspiration but increases infiltration and surface run off
Changing land use- agriculture, arable and pastoral: compaction of soil by livestock increases overland flow and pastoral to arable- ploughing increases infiltration by loosening and aerating the soil- Amazon

Question 12

What is a river regime?

Answer 12

A river regime is the annual variation in the discharge or flow of a river at a particular point

Question 13

What is the character of a river regime influenced by?

Answer 13

• The size of the river
• The amount of precipitation
• Temperature (meltwater and evaporation)
• Geology and soils- permeability and porosity
• Type of vegetation cover: wetlands can hold water and release it slowly into the river
• Human activities to regulate river discharge

Question 14

What are the main features of a storm hydrograph?

Answer 14

• Once the rainfall starts, the discharge begins to rise- rising limb
• Peak discharge is reached some time after the peak rainfall because the water takes time to move over and through the ground to reach the river
• The time interval between peak rainfall and peak discharge is known as lag time
• Once the input of rainwater into the river starts to decrease, so does the discharge; this is shown by the falling limb
• Eventually the river’s discharge returns to its normal level, or base flow

Question 15

What is meteorological drought?

Answer 15

Deficiency in rainfall

Question 16

What is hydrological drought?

Answer 16

Where there is reduced stream flow, lowered groundwater levels and reduced water stores

Question 17

What is the physical causes of drought?

Answer 17

• lack of precipitation over a prolonged period of time

Question 18

What is El Nino and La Nina?

Answer 18

Normal conditions in the Pacific Basin
In a non-El niño year, the trade winds blow from east to west along the equator
The air pushes the warm water westerwards
Thermocline, upwelling,
Warm, moist air rises, cools and condenses, forming rain clouds
Conditions during an El Niñ​o event
The trade wind pattern is disrupted - it may slacken or even reverse and this has a knock-on effect on the ocean currents
Air circulation loop reversed
La Niña - La Niña events may sometimes, but not always, follow an El Niño event. They involve the build-up of cooler-than-usual subsurface water in the tropical part of the Pacific. This situation can lead to severe drought conditions, particularly on the western coast of South America. Very strong air circulation and very warm water moving east-west.

Question 19

What is Desertification?

Answer 19

the process by which once-productive land gradually changes into a desert-like landscape. It usually takes place in semi-arid land on the edges of existing deserts

Question 20

How does human activity contribute to drought?

Answer 20

population growth
overgrazing
over-cultivation
deforestation

Question 21

What are the impacts of drought on ecosystem functioning?

Answer 21

• wetlands
• forests

Question 22

What are the meteorological causes of flooding?

Answer 22

intense storms which lead top flash flooding
prolonged, heavy rainfall
rapid snowmelt

Question 23

How can human actions exacerbate flood risk?

Answer 23

-urbanisation (permeable surfaces, dams, ploughing)
-river mismanagement- (channelisation, dams, embankments)
-deforestation

Question 24

How can damage from flooding have environmental impacts?

Answer 24

• recharged groundwater stores
  -increased connectivity between aquatic habitats
  -soil replenishment
  -trigger breeding, migration

Question 25

How can damage from flooding have socio-economic impacts?

Answer 25

-death and injury
-water-borne diseases
-trauma
-property damage
-transport and communications disruption
-communication disruption
-destruction of crops
-disturbance to every day life (work)

Question 26

How does climate change affect inputs and outputs within the hydrological cycle

Answer 26

Precipitation: a warmer atmosphere has a greater water-holding capacity, widespread increases in rainfall intensity are expected more than large increases in total amounts, tropics and high latitude areas,
Evaporation and Evapotranspiration: increase over large areas of Asia and North America, transpiration linked to vegetation changes, which in turn are linked to changes in soil moisture and precipitation

Question 27

How does climate change affect stores and flows?

Answer 27

Stores : more low flows (drought) and high flows (floods) , increased run off and reduced infiltration
Flows: reservoirs: storage decreasing as temperatures decrease, soil moisture increase with precipitation, permafrost: methane released, releasing more groundwater, snow: decrease, spring melt earlier, glacier ice: glacier retreat, less accumulation, decreasing store, ocean: sea level rise

Question 28

How does climate change resulting from ENSO cycles and global warming increase the uncertainty in the system?

Answer 28

• increases in annual temp lead to great evaporation from reservoirs
• impact of oscillations is leading to increasingly unreliable patterns of rainfall
• more frequent cyclone and monsoon of droughts as a result of global warming
• increased intensity and frequency of droughts
• depleted aquifers- problems with groundwater
  -decreasing rainfall in many areas
  -loss of snow and glaciers as a store threatens many communities in mountain areas

Question 29

How does the growing mismatch between water supply and demand lead to a global pattern of water stress and scarcity?

Answer 29

• accessible surface water is a scarce resource, under increasing pressure as a result of population growth and economic development
• water insecurity experienced though many countries
  -growing mismatch relates to the distribution of freshwater resources (water availability) and the distribution of the demands for water. These do not coincide- leading to water insecurity

Question 30

What are the physical causes of water scarcity?

Answer 30

• climate
  -evaporation and evapotranspiration
  -discharge into the sea
  -saltwater encroachment at the coast

Question 31

What are the human causes of water scarcity?

Answer 31

• contamination of water by agricultural, industrial and domestic pollution
  -over-abstraction from rivers, lakes and aquifers and the acute need to replenish these dwindling stores
• all factors exacerbated by global warming and climate chanage

Question 32

How is the finite water resource facing pressure?

Answer 32

• population growth
  -economic development
  -rising living standards

Question 33

What are the three main pressures increasing the risk of water insecurity?

Answer 33

• diminishing supply
  -rising demands
  -competing demands from users

Question 34

What are the causes of economic water scarcity?

Answer 34

• occurs when the use of blue water sources is limited by lack of capital, technology and good governance
  -in the developed world, much of the water supply industry there us now in the hands of private companies
  -in the developing world, supplying safe water in areas of physical scarcity can be difficult and costly
  -charities such as WaterAid set up programmes to help reduce the extent of economic water scarcity

Question 35

What is the importance of water supply for economic development and human wellbeing?

Answer 35

• economic development is one of the main drivers of the increasing demand for water
• agriculture: 3,770 km of water withdrawn each year, 20% of world’s land is under full irrigation
  -industry and energy: just over 20% of all freshwater withdrawals worldwide are for industrial and energy production - half to HEP or as cooling water in thermal and nuclear power stations. water pollution is an issue
  -domestic use: rising standards of living and an increasing per capita consumption of water. safe water is a fundamental human need- water is an effective medium for the breeding and transmission of range of lethal diseases such as typhoid, cholera and dysentery

Question 36

What are the potential conflicts to occur between users within a country, and internationally over local and transboundary water sources?

Answer 36

• when the demand for water overtakes the available supply and there are key stakeholders desperate for that water, there is potential for conflict (water wars)
• within countries, conflicts can arise between the competing demands of irrigation, energy, industry, domestic use and recreation
  -when countries share the same river or drainage basin - transboundary water sources- causes international tension in the competition for water

Question 37

What are the pros and cons of the techno-fix of hard engineering schemes?

Answer 37

• water transfer schemes involve the diversion of water from one drainage basin to another either by diverting a river or constructing a large canal to carry water from one basin to another
  -China’s South-North Transfer Project
• Mega Dams: nearly 60% of the world’s major rivers are impeded by large dams, perhaps most notably the Colorado, Nile and Yangtze, immense costs, high evaporation losses, disruption of the downstream transport of silt and the displacement of people
• Desalination: the process by which dissolved solids in sea water are partially or completely removed to make it suitable for human use

Question 38

What are the more sustainable schemes of restoration of water supplies and water conservation?

Answer 38

• smart irrigation
• hydroponics
  -recycling of greywater
  -rainwater harvesting
  -filtration technology
  -restoration

Question 39

What are the different players in reducing water conflict risk?

Answer 39

• Integrated Water Management Schemes- emphasised the river basin as a logical geographical unit for the management of water resources
• Water sharing treaties and frameworks- the Helsinki rules, UNECE, EU Water Framework Directive