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Water scarcity (closely related to water stress or water crisis) is the lack of fresh water Water resources to meet the standard water demand. There are two types of water scarcity. One is physical. The other is economic water scarcity. Physical water scarcity is where there is not enough water to meet all demands. This includes water needed for to function. Regions with a desert climate often face physical water scarcity. Central Asia, West Asia, and North Africa are examples of arid areas. Economic water scarcity results from a lack of investment in infrastructure or technology to draw water from rivers, Aquifer, or other water sources. It also results from weak human capacity to meet water demand.Caretta, M.A., A. Mukherji, M. Arfanuzzaman, R.A. Betts, A. Gelfan, Y. Hirabayashi, T.K. Lissner, J. Liu, E. Lopez Gunn, R. Morgan, S. Mwanga, and S. Supratid, 2022: Chapter 4: Water. In: Climate Change 2022: Impacts, Adaptation and Vulnerability. Contribution of Working Group II to the Sixth Assessment Report of the Intergovernmental Panel on Climate Change H.-O.. Cambridge University Press, Cambridge, UK and New York, NY, USA, pp. 551–712, doi:10.1017/9781009325844.006. Many people in Sub-Saharan Africa are living with economic water scarcity.IWMI (2007) Water for Food, Water for Life: A Comprehensive Assessment of Water Management in Agriculture. London: Earthscan, and Colombo: International Water Management Institute.
There is enough freshwater available globally and averaged over the year to meet demand. As such, water scarcity is caused by a mismatch between when and where people need water, and when and where it is available. This can happen due to an increase in the number of people in a region, changing living conditions and diets, and expansion of irrigation. Climate change (including droughts or floods), deforestation, water pollution and wasteful use of water can also mean there is not enough water. These variations in scarcity may also be a function of prevailing economic policy and planning approaches.
Water scarcity assessments look at many types of information. They include green water (soil moisture), water quality, environmental flow requirements, and Virtual water. Water stress is one parameter to measure water scarcity. It is useful in the context of Sustainable Development Goal 6. Half a billion people live in areas with severe water scarcity throughout the year, and around four billion people face severe water scarcity at least one month per year. Half of the world's Metropolis experience water scarcity. There are 2.3 billion people who reside in nations with water scarcities (meaning less than 1700 m3 of water per person per year).
There are different ways to reduce water scarcity. It can be done through supply and demand side management, cooperation between countries and water conservation. Expanding sources of usable water can help. Reclaimed water and desalination are ways to do this. Others are reducing water pollution and changes to the virtual water trade.
The FAO defines water stress as the "symptoms of water scarcity or shortage". Such symptoms could be "growing conflict between users, and competition for water, declining standards of reliability and service, harvest failures and food insecurity". This is measured with a range of Water Stress Indices.
A group of scientists provided another definition for water stress in 2016: "Water stress refers to the impact of high water use (either withdrawals or consumption) relative to water availability." This means water stress would be a demand-driven scarcity.
Water is scarce in densely populated Desert climate. These are projected to have less than 1000 cubic meters available per capita per year. Examples are Central and West Asia, and North Africa). A study in 2007 found that more than 1.2 billion people live in areas of physical water scarcity.Molden, D. (Ed). Water for food, Water for life: A Comprehensive Assessment of Water Management in Agriculture. Earthscan/IWMI, 2007, p.11 This water scarcity relates to water available for food production, rather than for drinking water which is a much smaller amount.
Some academics propose a separate type of water scarcity termed ecological water scarcity though some publications argue that this falls within the definition of physical water scarcity. It would focus on the water demand of ecosystems, referring to the minimum quantity and quality of water discharge needed to maintain sustainable and functional ecosystems. Results from a modelling study in 2022 show that northern China suffered more severe ecological water scarcity than southern China. The driving factor of ecological water scarcity in most provinces was water pollution rather than human water use. Text was copied from this source, which is available under a Creative Commons Attribution 4.0 International License
The United Nations Development Programme says economic water scarcity is the most common cause of water scarcity. This is because most countries or regions have enough water to meet household, industrial, agricultural, and environmental needs. But they lack the means to provide it in an accessible manner.United Nations Development Programme (2006). Human Development Report 2006: Beyond Scarcity–Power, Poverty and the Global Water Crisis . Basingstoke, United Kingdom:Palgrave Macmillan. Around a fifth of the world's population currently live in regions affected by physical water scarcity.
A quarter of the world's population is affected by economic water scarcity. It is a feature of much of Sub-Saharan Africa. So better water infrastructure there could help to reduce poverty. Investing in water retention and irrigation infrastructure would help increase food production. This is especially the case for developing countries that rely on low-yield agriculture. Providing water that is adequate for consumption would also benefit public health. This is not only a question of new infrastructure. Economic and political intervention are necessary to tackle poverty and social inequality. The lack of funding means there is a need for planning.
The emphasis is usually on improving water sources for drinking water and domestic purposes. But more water is used for purposes such as bathing, laundry, livestock and cleaning than drinking and cooking. This suggests that too much emphasis on drinking water addresses only part of the problem. So it can limit the range of solutions available.
"Water stress" is a criterion to measure water scarcity. Experts use it in the context of Sustainable Development Goal 6. A report by the FAO in 2018 provided a definition of water stress. It described it as "the ratio between total freshwater withdrawn (TFWW) by all major sectors and total renewable freshwater resources (TRWR), after taking into account environmental flow requirements (EFR)". This means that the value for TFWW is divided by the difference between TRWR minus EFR.FAO (2018). Progress on level of water stress - Global baseline for SDG 6 Indicator 6.4.2 Rome. FAO/UN-Water. 58 pp. Licence: CC BY-NC-SA 3.0 IGO. Environmental flows are water flows required to sustain freshwater and estuarine . A previous definition in Millennium Development Goal 7, target 7.A, was simply the proportion of total water resources used, without taking EFR into consideration. This definition sets out several categories for water stress. Below 10% is low stress; 10-20% is low-to-medium; 20-40% medium-to-high; 40-80% high; above 80% very high.
Indicators are used to measure the extent of water scarcity. One way to measure water scarcity is to calculate the amount of water resources available per person each year. One example is the "Falkenmark Water Stress Indicator". This was developed by Malin Falkenmark. This indicator says a country or region experiences "water stress" when annual water supplies drop below 1,700 cubic meters per person per year. Levels between 1,700 and 1,000 cubic meters will lead to periodic or limited water shortages. When water supplies drop below 1,000 cubic meters per person per year the country faces "water scarcity". However, the Falkenmark Water Stress Indicator does not help to explain the true nature of water scarcity.
A successful assessment will bring together experts from several scientific discipline. These include the hydrological, water quality, aquatic ecosystem science, and social science communities.
Rivers and lakes provide common surface sources of freshwater. But other water resources such as groundwater and glaciers have become more developed sources of freshwater. They have become the main source of clean water. Groundwater is water that has pooled below the surface of the Earth. It can provide a usable quantity of water through springs or wells. These areas of groundwater are also known as aquifers. It is becoming harder to use conventional sources because of pollution and climate change. So people are drawing more and more on these other sources. Population growth is encouraging greater use of these types of water resources.
About half of the world's population currently experience severe water scarcity for at least some part of the year. Half a billion people in the world face severe water scarcity all year round. Half of the world's Metropolis experience water scarcity. Almost two billion people do not currently have access to clean drinking water.
A study in 2016 calculated that the number of people suffering from water scarcity increased from 0.24 billion or 14% of global population in the 1900s to 3.8 billion (58%) in the 2000s. This study used two concepts to analyse water scarcity. One is shortage, or impacts due to low availability per capita. The other is stress, or impacts due to high consumption relative to availability.
With the increase in global temperatures and an increase in water demand, six out of ten people are at risk of being water-stressed. The drying out of wetlands globally, at around 67%, was a direct cause of a large number of people at risk of water stress. As global demand for water increases and temperatures rise, it is likely that two thirds of the population will live under water stress in 2025.
According to a projection by the United Nations, by 2040, there can be about 4.5 billion people affected by a water crisis (or water scarcity). Additionally, with the increase in population, there will be a demand for food, and for the food output to match the population growth, there would be an increased demand for water to irrigate crops. The World Economic Forum estimates that global water demand will surpass global supply by 40% by 2030. Increasing the water demand as well as increasing the population results in a water crisis where there is not enough water to share in healthy levels. The crises are not only due to quantity but quality also matters.
A study found that 6-20% of about 39 million are at high risk of running dry if local groundwater levels decline by a few meters. In many areas and with possibly more than half of major this would apply if they simply continue to decline.
Economists and others have argued that a lack of property rights, government regulations and water subsidies have given rise to the situation with water. These factors cause prices to be too low and consumption too high, making a point for water privatization.Segerfeldt, Fredrik (25 August 2005), "Private Water Saves Lives" , Financial Times.Zetland, David (1 August 2008) "Running Out of Water" . aguanomics.comZetland, David (14 July 2008) "Water Crisis" . aguanomics.com
The clean water crisis is an emerging global crisis affecting approximately 785 million people around the world. 1.1 billion people lack access to water and 2.7 billion experience water scarcity at least one month in a year. 2.4 billion people suffer from contaminated water and poor sanitation. Contamination of water can lead to deadly Diarrhea such as cholera and typhoid fever and other waterborne diseases. These account for 80% of illnesses around the world.
Subsidence is another result of water scarcity. The U.S. Geological Survey estimates that subsidence has affected more than 17,000 square miles in 45 U.S. states, 80 percent of it due to groundwater usage.
Vegetation and wildlife need sufficient freshwater. , and are more clearly dependent upon sustainable water supply. Forests and other upland ecosystems are equally at risk as water becomes less available. In the case of wetlands, a lot of ground has been simply taken from wildlife use to feed and house the expanding human population. Other areas have also suffered from a gradual fall in freshwater inflow as upstream water is diverted for human use.
In 2000, the world population was 6.2 billion. The UN estimates that by 2050 there will be an additional 3.5 billion people, with most of the growth in developing countries that already suffer water stress. This will increase demand for water unless there are corresponding increases in water conservation and recycling. In building on the data presented here by the UN, the World Bank goes on to explain that access to water for producing food will be one of the main challenges in the decades to come. It will be necessary to balance access to water with managing water in a sustainable way. At the same time it will be necessary to take the impact of climate change and other environmental and social variables into account.
In 60% of European cities with more than 100,000 people, groundwater is being used at a faster rate than it can be replenished.
Until recently, groundwater was not a highly used resource. In the 1960s, more and more groundwater aquifers developed. Improved knowledge, technology and funding have made it possible to focus more on drawing water from groundwater resources instead of surface water. These made the agricultural groundwater revolution possible. They expanded the irrigation sector which made it possible to increase food production and development in rural areas.Giordano, M. and Volholth, K. (ed.) 2007. The Agricultural Groundwater Revolution. Wallingford, UK, Centre for Agricultural Bioscience International (CABI). Groundwater supplies nearly half of all drinking water in the world.WWAP (World Water Assessment Programme). 2009. Water in a Changing World. World Water Development Report 3. Paris/London, UNESCO Publishing/Earthscan. The large volumes of water stored underground in most aquifers have a considerable buffer capacity. This makes it possible to withdraw water during periods of drought or little rainfall. This is crucial for people that live in regions that cannot depend on precipitation or surface water for their only supplies. It provides reliable access to water all year round. As of 2010, the world's aggregated groundwater abstraction is estimated at 1,000 km3 per year. Of this 67% goes on irrigation, 22% on domestic purposes and 11% on industrial purposes. The top ten major consumers of abstracted water make up 72% of all abstracted water use worldwide. They are India, China, United States of America, Pakistan, Iran, Bangladesh, Mexico, Saudi Arabia, Indonesia, and Italy.
Goundwater sources are quite plentiful. But one major area of concern is the renewal or recharge rate of some groundwater sources. Extracting from non-rewable groundwater sources could exhaust them if they are not properly monitored and managed.Foster, S. and Loucks, D. 2006. Non-renewable Groundwater Resources. UNESCO-IHP Groundwater series No. 10. Paris, UNESCO. Increasing use of groundwater can also reduce water quality over time. Groundwater systems often show falls in natural outflows, stored volumes, and water levels as well as water degradation. Groundwater depletion can cause harm in many ways. These include more costly groundwater pumping and changes in salinity and other types of water quality. They can also lead to land subsidence, degraded springs and reduced baseflows.
Many aquifers have been over-pumped and are not recharging quickly. This does not use up the total fresh water supply. But it means that much has become polluted, salted, unsuitable or otherwise unavailable for drinking, industry and agriculture. To avoid a global water crisis, farmers will have to increase productivity to meet growing demands for food. At the same time industry and cities find will have to find ways to use water more efficiently.
Business activities such as tourism are continuing to expand. They create a need for increases in water water supply and sanitation. This in turn can lead to more pressure on water resources and natural . The approximate 50% growth in world energy use by 2040 will also increase the need for efficient water use. It may means some water use shifts from irrigation to industry. This is because thermal power generation uses water for steam generation and cooling.
The United Nations' FAO states that by 2025 1.9 billion people will live in countries or regions with absolute water scarcity. It says two thirds of the world's population could be under stress conditions. The World Bank says that climate change could profoundly alter future patterns of water availability and use. This will make water stress and insecurity worse, at the global level and in sectors that depend on water.
Scientists have found that population change is four times more important than long-term climate change in its effects on water scarcity.
The International Resource Panel of the UN states that governments have invested heavily in inefficient solutions. These are mega-projects like , canals, aqueducts, pipelines and water reservoirs. They are generally neither environmentally sustainable nor economically viable. According to the panel, the most cost-effective way of decoupling water use from economic growth is for to create Systems ecology water management plans. These would take into account the entire water cycle: from source to distribution, economic use, Water treatment, Reclaimed water, reuse and return to the environment.
In general, there is enough water on an annual and global scale. The issue is more of variation of supply by time and by region. Reservoirs and pipelines would deal with this variable water supply. Well-planned infrastructure with demand side management is necessary. Both supply-side and demand-side management have advantages and disadvantages.
The more developed countries of North America, Europe and Russia will not see a serious threat to water supply by 2025 in general. This is not only because of their relative wealth. Their populations will also be more in line with available water resources. North Africa, the Middle East, South Africa and northern China will face very severe water shortages. This is due to physical scarcity and too many people for the water that is available. Most of South America, Sub-Saharan Africa, southern China and India will face water supply shortages by 2025. For these regions, water scarcity will be due to economic constraints on developing safe drinking water, and excessive population growth.
In Nigeria, some reports have suggested that increase in extreme heat, drought and the shrinking of Lake Chad is causing water shortage and environmental migration. This is forcing thousands to migrate to neighboring Chad and towns.
Even with the overpumping of its aquifers, China is developing a grain deficit. When this happens, it will almost certainly drive grain prices upward. Most of the 3 billion people projected to be added worldwide by mid-century will be born in countries already experiencing water shortages. Unless population growth can be slowed quickly, it is feared that there may not be a practical non-violent or humane solution to the emerging world water shortage.Brown, Lester R. (8 September 2002) Water Shortages May Cause Food Shortages. Greatlakesdirectory.org. Retrieved on 27 August 2013.
It is highly likely that climate change in Turkey will cause its southern river basins to be water scarce before 2070, and increasing drought in Turkey.
The west coast of North America, which gets much of its water from glaciers in mountain ranges such as the Rocky Mountains and Sierra Nevada, is also vulnerable.Schoch, Deborah (2 May 2008) Water shortage worst in decades, official says , Los Angeles Times.
Some countries have already proven that decoupling water use from economic growth is possible. For example, in Australia, water consumption declined by 40% between 2001 and 2009 while the economy grew by more than 30%.
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