Blog

Water Stress

Water stress: Lack of reliable, cost effective water supplies in a region.

Water stress occurs when demand for water exceeds the amount available during a certain period, or when poor quality restricts its use. Therefore, when a country’s water consumption is more than 10% of its renewable freshwater rate it is said to be water stressed.

During the 20th Century water consumption has increased by 600% due to population growth and economic development:

  • Farming uses 70% of all water and in LEDCs this is up to 90%
  • Industrial and domestic use has to compete with farming needs as a country develops
  • Daily domestic water use on average is 47 litres per person in Africa, compared with 578 litres in the USA

This has led to the development of a world water gap with 1.4 billion lacking clean drinking water and 12% of the world’s population consuming 85% of the world’s water.

  • Half the world’s rivers are badly pollution or no longer flow all year.
  • Population growth by 2025 will demand a 20% increase in water supplies.

 

Agriculture

  • Major user of water.
  • Currently uses 69% of the world’s freshwater supply.
  • Some forms of agriculture are less water-efficient than other.
  • While water storage and irrigation systems do make agriculture more productive, they can also be wasteful of water.
  • Poor management of such systems can lead to problems of evaporation, seepage, salinization and fertiliser pollution.

 

Industry

  • The proportion of water used globally by industry rose slowly during the twentieth century mainly in the developed countries.
  • Coming decade, more rapid global rise due to large-scale industrialisation in countries such as India and China.
  • Generally, a much more efficient user of water than agriculture, but there are some significant exceptions, such as paper manufacturing.
  • Caused significant water pollution problems.

 

Domestic

  • Smallest category of consumption, using only 10% – but varies from country from country,
  • Most developed countries need at least 100,000 litres of water per person per year,
  • In most African countries it is less than 50,000 litres,
  • Global domestic demand seems to have doubled every 20 years.
  • Poor access in Africa that is limiting growth in demand there.

 

 

Pressure on water supplies

Bluewater flow: visible part of the system, namely water running on the surface and supplying rivers or travelling underground, recharging aquifers.

Water stress occurs when the demand for water exceeds the amount available during a certain period, or when poor quality restricts its use, the country’s water consumption is more than 10% of its renewable freshwater supply has less than 1700m3 per person.

Water scarcity = when the annual supply of water per person falls below 1000m3

Two types of scarcity:

Physical scarcity: when more than 75% of a region’s river flows are being used, demand exceeds supply.

Economic scarcity: when development of blue water flow sources is limited by human and financial capacities – people cannot afford water even when it is readily available.

 

Rapid economic growth in India and China is putting pressure on water supplies.

India

  • 4% of the world’s freshwater but 16% of its population.
  • Demand will exceed supply by 2020, as urban water demanded is expected to double and industrial demand to triple.
  • 43% of precipitation never reaches rivers or aquifers.
  • Water tables are falling rapidly as 21 million wells abstract water.

 

China

  • 8% of the world’s freshwater but 22% of the population.
  • 2/3rds of cities do not have enough water all year round.
  • Stress levels expected to occur by 2030.
  • China uses irrigation to produce 70% of its food.
  • Annual population growth rate is about 2.5% in Beijing.
  • Water table has been lowered in some areas by 40m.

case study: the water problems of the beijing-tianjin region

Salt water incursion: the pollution of coastal groundwater by inflowing sea water.

Beijing may run out of water: wells drying up, groundwater and rivers becoming polluted and ground subsidence worsens.

Physical causes:

  • Northeast China, where Beijing is located, is prone to floods and in recent years, droughts.
  • Most precipitation falls between July and September, sometimes more than half of it within 3 days.
  • Several wet years can be followed by several dry years.

Human causes:

  • Population of 16 million making it 2nd largest city.
  • Tianjin (population: 11 million) is a major port with heavy industry, commerce and developing services.
  • Beijing and Tianjin annual population growth is stabilising after government efforts to reduce family size, but rural-urban migrants continue to arrive.

 

Water supply:

  • Beijing draws 60% of its water supply from aquifers, which are overexploited, but water quality is acceptable.
  • In late 1970s and early 1980s, a series of droughts led to increased demands for irrigation water.
  • This lowered the water table in some areas by as much as 40m.
  • Some wells were pumped down to the bedrock.
  • Much of Beijing has subsided by between 0.5m and 1m per year because of all this abstraction.
  • Tianjin relies on groundwater for about 30% of its water supply, but salt water incursion makes the water salty.
  • Surface water supply depends on 5 major rivers which enter the Hai He river system.
  • Upstream withdrawals and contamination of these rivers have a negative effect on downstream cities.
  • Beijing also makes Tianjin’s water problems worse by the scale of its abstractions and pollution.

 

Demand for water:

  • Water demand in Beijing-Tianjin region is currently 4.9billion m3 and continues to rise.
  • Agriculture account for about 65% of demand, although the use of water saving technologies means irrigation demands are levelling off.
  • Industrial output in region has increased more than six-fold in 20 years.
  • Demand has not risen as fast as this as industries have become more water efficient and recycle their waste water and there has been a shift from heavy to high tech industry.
  • Fastest rate of increase is in domestic water use: consumption has risen tenfold in the last 50 years and now averages 240 litres per person per day.

Asia and the pacific

  • 1/3 of Population lacks access to safe drinking water, 500,000 diarrhoea related infant deaths each year.
  • Level of bacterial waste from human sources is ten times greater than recommended levels.

Overuse:

  • Agriculture accounts for 90% of freshwater withdraws in S Asia.
  • Aquifer depletion is Asia has led to a drop-in water availability per capita from 10,000m3 in 1950 to 42,0003 in 1990s.
  • Withdrawals in West Asia far exceed natural replacement rates.

africa

Poverty and water scarcity:

  • 25 countries will face water stress/scarcity by 2025.
  • Over 300 million people lack access to safe water, nearly 51% of people in sub-Saharan Africa without a safe water supply.
  • Lack of groundwater protection from agricultural uses makes up 88% of total water use.

 

europe/central asia

  • Increasing water consumption, with half of Europe’s cites over-exploiting their ground water reserves.
  • Declining water quality in countries with groundwater pollution.

latin america and the carribean

  • Ground water contamination and depletion from increasing release of heavy metals, nutrients, chemicals and hazards wastes from mining, agriculture and industry.
  • Poor sanitation because only 2% of sewage produced in Latin America is treated – typhoid and cholera are common diseases.
  • Economic scarcity with conflict over access and use of water.

north america

  • Aquifer depletion steadily increasing due to population growth and urban growth and expansion of irrigation and industry e.g. cotton farming in Texas.
  • Water pollution from agricultural runoff has contaminated ground and surface waters.