The Water Cycle EQ3

renewable water resources/reserves

a combination of both internal water (from precipitation) and external water (i.e. flowing into country from upstream source or a lake shared with another country)

water stress

experienced when renewable reserves are between 1000 and 1700 m3 per person per year; likely to lead to restrictions on use eg. hosepipe bans.

water scarcity

renewable reserves between 500 and 1000 m3 per person per year (basic need UN). not all demand met, conflict likely. resources used unsustainably and river flows depleted

absolute water scarcity

renewable reserves below 500m³ per person per year. widespread shortages and severe rationing

physical causes of water insecurity

macro scale: climate variability, saltwater encroachment at coast, el Niño

micro scale: geology, relief

climate variability

variable precipitation across the globe. around the equator and at mid-latitudes there is more rain (low air pressure, air rises) eg. Amazon (>2000mm per year) but at subtropics there is less rain (high air pressure, air sinks) eg. Sahel (200-800mm per year)

evaluation - hugely important factor on global scale

saltwater encroachment

saline water intrudes inland or seeps into the ground due to sea level rise (up to 1m by 2100) caused by anthropogenic climate change as well as increased groundwater abstraction. threatens ecosystems eg mangrove forests and SIDS (Small Island Developing States) eg Maldives

evaluation - only affects coastal areas and SIDS (not global) but is growing

el Nino

reversal of wind directions that brings changes to normal weather patterns, floods in places and droughts in others that usually wouldn’t expect it eg. Eastern Australia - The Big Dry, rainfall decreases due to reversal of wind direction

human causes of water insecurity

over abstraction, water contamination from agriculture, industrial water pollution, anthropogenic climate change

over abstraction from rivers, lakes and groundwater aquifers

cuts off input of water and too much output

eg. Aral Sea - Soviet Union blocked rivers draining into sea by building dams and over abstracted for irrigation. Also an area of high evaporation

evaluation - dependent upon human actions can be very significant and difficult to reverse. est.18 countries using groundwater unsustainably for irrigation eg. USA, China, India (big grain producers) - lead to issues of food security

water contamination from agriculture

increased use of pesticides and fertilisers enter hydrological system and affects marine ecosystems eg. 2022 - all rivers in UK gone beyond EU regulations on water quality (however UK is an anomaly of developed countries)

evaluation - depends on management of use of fertilisers and rivers, link to Kuznets Curve (worst in emerging)

industrial water pollution

waste and other pollutants enter rivers due to lack of environmental regulations and waste treatment facilities specifically in developing + emerging - 90% of waste water in developing cities discharged into rivers untreated eg. 1980s Huangpu River, Shanghai turned black for 100 days, 40% of China’s rivers dangerously polluted

evaluation - biggest issue in developing and emerging as begin to industrialise and urbanise - link to Kuznet’s curve

finite water resource

a water resource that has a limited supply and cannot renew itself quickly enough for human timescales

rising demand comes from

increasing population , improving living standards , industrialisation and agriculture - leading to increasing risk of water insecurity

water availability gap

concept that in developing nations there is a greater likelihood of people facing water shortages; in developed nations up to 10 times the water per person is used

embedded water

water used to grow crops or produce manufactured goods; virtual water that is effectively imported when farm products/manfactured goods are imported

physical water scarcity

issue of water availability - not enough precipitation to meet demand

eg. Middle East, North Africa (Sahel)

economic water scarcity

issue of access to safe/clean water - people cannot afford water as well as lack of infrastructure to transfer, store and treat water (common in developing)

more than 600 million people lack access to safe clean drinking water

eg. Central/sub-Saharan Africa, SE Asia

consequences of scarcity

industry, energy supply, agriculture, sanitation and health and food preparation

industry

rapid industrialisation (common in emerging countries) leads to an increased demand as well as contamination of rivers and groundwater therefore degrading the environment

over 20% of freshwater withdrawal is for industry and energy production

energy supply

water is needed for HEP and for cooling of thermal + nuclear power stations. countries that rely heavily on HEP (Norway, NZ) are affected by changing rainfall patterns due to climate change

demand for water for energy production predicted to increase by 400% from 2000-2050

agriculture

water needed for rain-fed crops and irrigation systems. lack of water leads to crop failure and therefore food shortages and issues surrounding food security (particularly for developing), more of an economic impact for developed countries

by 2050 food production will need 140% more water

eg. California - almost 1mill acres of cropland fallowed in past 2 years

sanitation & health and food preparation

water needed to maintain human health. lack of sanitation leads to outbreak of diseases, greatly affecting social development and ability to escape poverty.

1.6mill children die every year due to infections from waterborne diseases

2006 - WHO estimated only 59% of global pop. has access to adequate sanitation systems

environmental problems from inadequate water - Aral Sea

Shrinking of sea meant water became saltier an plants became salty, then the animals that ate these plants died. The edge of former sea dried out and desertified, winds carry salt and dust from dried out sea bed (area becomes more arid). only ½ of bird species remains

this was an unsustainable use of water however north could be saved but south may dry up completely

economic problems from inadequate water - Aral Sea

collapse of fishing industry that formerly employed 60,000 people causes large-scale unemployment and less fish for food. land has become infertile so cannot grow crops - food insecurity. Soviet Union took water for irrigation for cotton so benefitted them but completely negative for locals

conflicts - only actual example

1967 - 6 day war between Israel, Syria, Jordan over Jordan River

conflicts - The Nile

• Nile catchment shared by 10 countries

• Egypt relies on the Nile for 98% of its freshwater

• 1959 agreement between Egypt and Sudan gives Egypt 2/3 and Sudan ¼ - unfair to Ethiopia

• situation will worsen for Egypt if countries upstream choose to intensively exploit water - Ethiopia beginning to build dams for HEP affecting downstream flows

• Nile Basin Initiative - work together in managing resources with help of World Bank but cannot agree

techno fixes - water transfers eg S to N China

½ of China’s pop. and 2/3 of farmland is in the North however 80% of water supply in the south. Beijing has the same water scarcity as Saudi Arabia (100m³). Imbalance between supply and demand

• largest intra-basin transfer scheme in the world.

• costs c. $100bln

• up to 25blnm³ transported over 2 routes (western + central, eastern planning)

• water travels c. 1000km

water transfer pros

• helps redistribute water from area of greatest supply to area of greatest demand

• reduces risk of water shortages in Beijing and helps secure economic development

• reduces pressure on groundwater supplies in north

water transfer cons

• high costs of scheme ($100blnto build) - farmers unable to afford high costs of water + continue groundwater use

• increased risk of scarcity in south (in 2011, reservoir dropped 4m below ‘dead level’)

• passes through industrial area so may become polluted

• worsening water quality affecting ecosystems

techno fixes - mega dams eg 3 Gorges Dam

• largest dam scheme ever constructed (1.3 miles wide)

• located on Yangtze River (south china)

• overall cost $59bln

mega dams pros

• generates renewable energy (HEP)

• large scale energy production - 8x Hoover Dam output (18000 MW)

• 400 sq miles reservoir behind to store water

• helps control flooding on lower Yangtze

mega dams cons

• 1.3m people relocated

• facilities (factories, mines) that were flooded released certain toxins into water

• decomposing vegetation releases methane when water passes through turbines

techno fixes - desalination plants eg Singapore

• 5 desalination plants in operation

• accounts for approx. 30% of water supply

desalination pros

• costs reduced due to technological breakthroughs thanks to research and investment by TNCs

• reduces pressure on limited supply of freshwater

• energy intensive but uses solar energy

desalination cons

• each plant requires its own power station and not all rely on renewable energy

• vast amounts of brine (v. saline water) produced which is harmful when reintroduced to natural coastal ecosystems

• relatively new technology so we do not know what the long term impacts will be

sustainability

futurity - will it last?

environment - is it eco-friendly?

equity - does it benefit everyone?

public participation - is it bottom up?

smart irrigation

reducing irrigation at specific stages of crop growth without impacting yield

6-year study in North China Plain found smart irrigation reduced water use by 25%

evaluation-significantly reduces use of water, even if demand increases it can still be met which then improves future food security, doesn’t require many resources (low tech) so can be used in developing countries

river restoration

Kissimmee River, USA - >100km² of river channel restored (largest in world) - previously straightened but returned back to original path

evaluation-good for environment however river will now flow naturally so cannot be applied in urban areas and now cannot build on land surrounding river due to flood risk

wetland restoration

eg Aral Sea - dam built in north with World Bank funding to restore wetland - water level risen by 4m and salinity level dropped, settlements become closer to shore, fish catches increase (52 tons to 11000 tons)

evaluation-mostly positive for north however south (historically the larger part) being sacrificed

integrated drainage basin management

where a framework (agreement) is put in place including all stakeholders to plan policies that manage the basin to ensure everyone has fair access to water whilst ensuring long term environmental sustainability