Water Scarcity: Definition, Causes and Solutions

Water scarcity refers to a condition where water demand is greater than supply. This imbalance is caused by water pollution, pressure from water-intensive agriculture, population pressures, and climate change effects on water sources.

Water scarcity has grave impacts on human health, but also on plants, animals, and the planet as a whole. It also poses a threat to food security. A 2014 paper by Wada et al., in Nature, estimates that water scarcity can be significantly reduced by 2050 if stakeholders commit to improving agricultural water productivity, improving irrigation efficiency, improving domestic and industrial water-use intensity, limiting the rate of population growth, increasing water storage in reservoirs, and increased desalination of seawater in coastal water-stressed regions.

What is Water Scarcity?

Water scarcity is an excess of water demand compared to supply, according to the UN Food and Agriculture Organization. UN-WATER defines water scarcity as the lack of water availability “due to physical shortage or scarcity in access due to the failure of institutions to ensure a regular supply or a lack of adequate infrastructure.” Water scarcity may arise due to local ecology and arid conditions, or poor-quality management and infrastructure.

Four billion people live in “conditions of severe water scarcity at least 1 month of the year”, according to a 2016 article from the Twente Water Center in the Netherlands. 4.8 billion to 5.7 billion people could be living in extreme water scarcity by 2050, according to a team of researchers led by Peter Burek of the International Institute for Applied Systems Analysis in Austria.

Water scarcity leads to wider contamination and transmission of diseases such as cholera, diarrhea, and typhoid, as people seek alternative, improperly treated water sources. It forces animals to abandon their natural habitats, plants to soak up more moisture leaving less water in streams and soil, and it destroys entire ecosystems such as wetlands and glacier-dependent regions.

To prevent risks of water scarcity, the Solar Impulse Foundation stresses the importance of sustainable water management practices, reclaiming water for reuse, and spreading awareness. Sustainable water management includes conservation, desalination, and smart irrigation systems. Rainwater harvesting, recycling water, pollution control, and improved sewage systems are components of reclaiming water to combat water scarcity.

What are the Types of Water Scarcity?

The two types of water scarcity are as follows, according to a 2008 study by the FAO.

1. Economic water scarcity
2. Physical water scarcity

Economic water scarcity occurs due to inadequate water infrastructure and is a result of insufficient financial, technical, and political resources or poor governance. Physical water scarcity is a result of local ecological and geographical conditions such as lack of river volume in arid regions or insufficient rainfall.

1. Economic Water Scarcity

The FAO defines economic water scarcity as “a situation caused by a lack of investment in water, or a lack of human capacity to satisfy the demand for water”.  According to the IPCC, economic water scarcity can also occur when infrastructure is available but “water distribution is inequitable”. All should have the human right to water and not every water should be on the list of the most expensive water in the world. Mark Giordano, a water management expert at Georgetown University, says that economic water scarcity “has to do with the scarcity of financial and political wherewithal”.

Factors that lead to economic water scarcity include a lack of investment in infrastructure or technology to draw water and transport it safely to consumers and businesses. This is a result of a lack of financial resources, and ineffective governance, which may be exacerbated by political and ethnic conflicts.

The FAO states that approximately 1.6 billion people suffer from economic water scarcity. In a 2020 study led by Lorenzo Roza at the University of California, Berkeley, researchers estimated that 15% of global croplands also lack water for this reason.

The water crisis in Flint, Michigan from 2014 to 2019 is one of the clearest examples of economic water scarcity. Failure to maintain the municipal water system and cost-cutting measures that switched it to an unsafe source meant the tap water became unusable and dangerous. This video gives a quick explanation of how the Flint water crisis happened.

2. Physical Water Scarcity

Physical water scarcity is caused by inadequate natural water resources to meet consumer demand and for the proper functioning of natural ecosystems. Physical scarcity occurs when water demand exceeds 75% of river flows for all uses, according to Volume 8 of The World’s Water from the Pacific Institute. Although physical water scarcity is caused by natural terrain, weather, and geography, manmade factors can exacerbate it. For instance, The Water Project notes that the Colorado river basin has been depleted due to excessive allocations, overuse, and mismanagement.

According to the FAO, effects of physical water scarcity include environmental degradation, water and land pollution, a decline in groundwater levels, and greater inequity in water distribution.

International Water Management Institute (IWMI) estimates in 2007 suggested that 1.2 billion people worldwide live in areas of physical water scarcity while another 500 million are approaching such a situation. Estimates by the IPCC suggest that as many as 4 billion people could be pushed toward physical water scarcity if the worldwide average temperature rises by 4°C due to global warming. UNICEF estimates that 4 billion already live in areas where there is water scarcity for at least one month per year.

What are the Causes of Water Scarcity?

The causes of water scarcity are the following items.

1. Water Pollution
2. Agriculture
3. Population Growth
4. Climate Change

1. Water Pollution

Water pollution is one of the primary causes of water scarcity. Chemicals, oil, industrial wastes, fecal matter, pesticides, and fertilizers can make water unfit for consumption. These can have immediate effects or steadily build up in the environment over many years. These pollutants can also seep into underground aquifers, spoiling reserves.

Researchers estimated that water pollution directly or indirectly affects between 700 million and 1.36 billion people, according to a January 2020 article in the journal Nature by lead author Ting Ma of the Chinese Academy of Sciences.

One of the worst affected parts of the world for water pollution is the Niger River Delta around Port Harcourt, Nigeria. Hundreds of oil spills per year, together with natural gas flaring and illegal refining of crude oil that spews toxic chemicals into the environment, have produced an ecological disaster. Combined with economic underdevelopment which results in fecal contamination of water, researchers at the University of Port Harcourt stated that there is a need “for urgent interventions to improve the quality of drinking water for the people of the Niger Delta.” This video from Bloomberg shows the devastating effects of water pollution in the Niger Delta region.

India is another country with major water pollution problems that creates water scarcity problems. The Ganges River has virtually every type of water pollution including dumping of untreated sewage, gray water from homes and commercial buildings, agricultural runoff, industrial waste products, animal carcasses, and partial or fully burned carcasses from funeral rites. Egypt’s Nile River and Jakarta, Indonesia’s waterways are among the other regions with serious pollution problems.

2. Agricultural Uses of Water

Agricultural uses of water are a major contributor to water scarcity, especially in countries where there is large-scale food production such as India, China, Australia, Spain, and the United States.

The World Wildlife Fund (WWF) estimates that 70% of the world’s freshwater is used in agriculture. 60% of this is lost due to leaks in irrigation systems and the use of water-intensive crops. Pesticides and fertilizers can also contaminate water sources leading to worsening water scarcity. This map from a 2016 article by Moghaddam et al. in the journal Desalination and Water Treatment shows the percentage of water that is used for agriculture by country.

In a 2020 study by Roza et al., researchers found that agricultural use of water can result in both physical water scarcity as well as economic water scarcity. In the case of agricultural economic water scarcity, despite sufficient freshwater resources, certain regions lack institutional capacity resulting in underperforming crop yields. Roza estimates that “0.14 to 0.23 billion hectares of rain-fed croplands (mostly in Sub-Saharan Africa, Eastern Europe, and Central Asia)” are not irrigated because of economic water scarcity. The paper estimates that 28% to 38% of global croplands are facing economic water scarcity. Nigeria, Ukraine, Russia, Romania, and Kazakhstan, account for half of global calorie production and lie in economic water-scarce areas.

In terms of reducing water supply, NITI Aayog in India reports that 70% of Indian freshwater is contaminated, primarily due to agricultural run-off.

3. Population Growth Effects on Water

Population growth and the related economic development, industrialization, and shifting dietary patterns have led to unsustainable levels of water consumption, according to the FAO. Demand for more goods, shelter, and water-intensive crops has expanded sharply as countries develop, leading to greater pressure on the water supply. The FAO reports that global water use has grown at twice the rate of population growth during the previous century. Estimates suggest that by 2050 the world’s population will require one billion additional tons of cereals per year and 200 million tons of meat. The Beef Cattle Research Council calculates that one kilogram of beef requires nearly 16,000 liters of water.

The biggest water scarcity problems will likely occur in the countries with the greatest population growth. Estimates of the number of people living with water scarcity in 2050 from a 2021 article in the journal Nature, together with population growth estimates from the World Bank strongly suggest that the positive relationship between population growth and water scarcity will continue. Egypt, the Philippines, and Indonesia are forecast to see the greatest increases in water scarcity alongside rapid population growth, as illustrated in this chart.

4. Climate Change Effects on Water

UN-WATER states that “water is the primary medium through which we will feel the effects of climate change.”

Research by the Columbia Climate School finds that as there is more carbon dioxide in the atmosphere, plants are likely to get larger while growing seasons will be extended. This would result in the retention of more water over time which could have the net result of reducing moisture on land.

Climate change will drastically alter the distribution of precipitation. In the United States, the Midwest is expected to get wetter, while the Southwest, southern Great Plains, and Southeast may experience longer droughts. The National Climate Assessment notes that additional precipitation has “increased sediments and contaminant concentrations'' which could pollute lakes, reducing water availability.

In part due to climate change, Harvard University found that by 2071, almost half of the freshwater basins in the United States may not be able to supply their monthly demand. Higher temperatures and evaporation rates could also increase the demand for water in many areas, furthering water scarcity issues.

Glaciers are frozen reservoirs that provide reliable water supply to millions of inhabitants in India, China, the United States, and South America. The World Glacier Monitoring Service recorded a loss of ice volumes in glaciers for the 33rd year in a row in 2020. Glacier expert Mauri Pelto reported in the State of the Climate in 2019 that glacier loss has accelerated every decade since the 1980s. In Greenland, this is a result of warmer water below as well as circulation of warmer air above glaciers.

By 2100, the IPCC estimates that a third of the 56 large-scale glacierized catchments, particularly in Central Asia and the Andes, will experience an average annual run-off of over 10%. This is expected to impact 1.5 billion people.

This video is from “The Last Tropical Glaciers” project led by Svalbarði environmental advisor Heïdi Sevestre. It shows one of the last six high-altitude glaciers in Colombia, the rare ecosystems that rely on them, and the rapid melt they are undergoing.

What are the Impacts and Harms of Water Scarcity?

The impacts and harms of water scarcity include damage to people, plants, animals, and the planet as a whole. The effects of water scarcity on plants and animals often go unnoticed, but they also impact people and the planet as a whole.

On People: Water scarcity leads to wider contamination and transmission of diseases such as cholera, diarrhea, and typhoid, as people seek alternative, improperly treated water sources. Water scarcity also threatens crop production and food security which can lead to chronic illnesses and malnutrition. Research by Allianz, the multinational financial cooperation, finds that several industries such as mining and food and beverages are under threat due to increased water scarcity, which could eventually slow economic growth. Experts from UN-WATER add that changes in the availability of water and precipitation “have already proven to trigger refugee dynamics and political instability”. Low-income communities are the most likely to face threats of water scarcity and food insecurity. According to the Global Water Institute, 700 million people could be displaced due to water scarcity by 2030.

On Plants: Water scarcity caused by climate change leads to a mixture of opposite effects according to a paper authored by Justin Mankin from Columbia University’s Lamont-Doherty Earth Observatory. As CO2 increases, photosynthesis will require less water, reducing the demand for water by plants and increasing the efficiency of food production. However, as temperatures rise, growing seasons will get longer, and plants in the mid-latitudes will absorb more water, leaving less water in streams and soil. In a 2016 study by Imadi et al., plants experiencing a deficit of water decreased photosynthesis and showed signs of gradual deterioration.

On Animals: Water scarcity forces animals to exit their natural habitats, often toward areas inhabited by humans, according to the African Wildlife Foundation. Greater contact with other species accelerates the spread of infectious diseases among wildlife and livestock. Greater contact with humans increases the number of animals that are killed. Research by the Columbia Climate School finds that toxic runoff (such as from fertilizers) into water bodies can harm fish by encouraging algal blooms which reduce the oxygen supply in the water.

On the Planet: Water scarcity damages the planet as a whole because of the harm it causes to entire ecosystems, especially wetlands. Not only do many species thrive in wetlands, they also provide ecological services such as water filtration and storm protection which are hampered when there is a lack of water. The Aral Sea is an example of a damaged ecosystem that has rapidly shrunk and deteriorated leaving behind a salty and polluted habitat. This resulted in food shortages and decreased life expectancy among human populations in the surrounding regions. As climate change intensifies, water scarcity will too, leading to more severe droughts and floods. Glacier loss will accelerate, threatening the water security of downstream ecosystems and communities.

What Are Some Facts and Statistics about Water Scarcity?

These are some important facts and statistics about water scarcity.

• UN-WATER states that about 4 billion people experience severe water scarcity during at least one month of the year. This is forecast to increase to 4.8–5.7 billion in 2050, of which about 69% will live in Asia.
• 1.2 billion people, or one-sixth of the world’s population, live in “severely water-constrained agricultural areas” today.
• 700 million people worldwide could be displaced by intense water scarcity by 2030.
• World Wildlife Fund (WWF) research shows that nearly 2.4 billion people lack adequate sanitation, and are exposed to water-borne diseases. Of these, nearly two million children die every year due to poor water quality leading to diarrheal diseases alone.
• 2012 estimates from the United Nations are that groundwater withdrawals have tripled during the last half-century, particularly in China, India, and the United States.
• The World Resources Institute (WRI) forecasts that investing a mere 1% of global GDP could ensure water security for everyone by the year 2030.

Which Countries are the Most Affected by Water Scarcity?

The countries most affected by water scarcity are the Maldives, Yemen, Jordan, Israel, Qatar, Saudi Arabia, Bahrain, Egypt, the UAE, and Kuwait, according to a report by the USAID Water Management Initiative published in 2018 which was based on the Falkenmark indicator of national water scarcity.

Water scarcity can be difficult to compare between countries because there are different indicators used and each landscape, ecology, and institutional arrangement is unique. Indicators include baseline water stress, interannual water variability, and water security risk index among others. Justin Mankin, a research scientist at Columbia University states that “allocating water is politically contentious, capital-intensive and requires really long-term planning”.

The following map from IWMI and Earthscan displays water scarcity in countries around the world, distinguished by the type of scarcity (i.e., physical or economic water scarcity). The areas marked in orange show physical scarcity due to a naturally low base of water supply and desert-like arid conditions. Purple areas show economic water scarcity. Water scarcity in the Middle East and North Africa is mostly physical water scarcity. Countries in these regions often import agricultural goods to save water and use desalination technology.

Economic water scarcity is particularly acute in Sub-Saharan Africa, parts of India and Nepal, and some Andean regions of South America.

Water scarcity in Africa is physical and economic, according to a 2013 article by Hua Xie and colleagues from the International Food Policy Research Institute. The scarcity of water in Cape Town, South Africa during the 2017 and 2018 water crisis was an example of both physical and economic water scarcity as drought was combined with population growth and government failure to manage and develop sufficient supplies. This shows the complexities of identifying the underlying causes of water scarcity.

The causes of water scarcity in India include excessive depletion of groundwater reserves, pollution due to industrial development, a high degree of contamination, and hydrological mismanagement, according to a 2018 article by Circle of Blue chief correspondent Keith Schneider.

Water scarcity in the US is focused on the arid western states. There is heated competition for water from the stressed Colorado River Basin because of water-intensive agriculture in California, and fast population growth in Nevada, Utah, and Arizona. Physical water scarcity is compounded by economic scarcity due to contentious water-sharing arrangements between the states which were formed long ago in very different demographic and socio-economic circumstances.

This picture shows the Colorado River entering the Grand Canyon in Arizona. 7 US states and 2 Mexican states rely on the water from this system, with intensive agriculture and growing cities situated amidst the vast arid landscape.

What are the Possible Solutions to Water Scarcity?

Possible solutions to water scarcity include improved water management, awareness campaigns, new water technologies, recycling water, better agricultural policies, water pricing, desalination, and climate change mitigation programs. Experts, organizations, and governments are all proposing and trying different solutions.

Expert-proposed solutions to water scarcity include those from Peter Gleick, a global water expert at the Pacific Institute. He emphasizes improving existing agricultural policies as has been done in California to reduce water consumption. He also advocates shrinking corporate global water footprints and shifting to sustainable manufacturing, particularly in the bottled water sector.

Kristine Diekman is a professor of media theory at Cal State San Marcos and documents local water crises in California. She endeavors to spread awareness around water scarcity via documentaries, data visualization, and easily accessible GIS maps. She also advocates water conservation methods.

Dr. Upmanu Lall of the Columbia Water Center has developed AWASH, a model to allow the general public to explore various water supply and demand scenarios locally. He sees the potential to “start changing things from the bottom-up”.

Organization-proposed solutions to water scarcity include those from the Columbia Climate School for whom the primary tools to address water security include increasing water storage, improving irrigation systems, and selecting water-efficient crops. Usage of renewable sources of power such as wind and solar use less water than conventional power plants.

The WWF advocates water stewardship and the use of the Water Footprint Network to estimate the impacts of withdrawal. The organization also recommends the preservation of wetlands. The WWF and the Intergovernmental Panel on Climate Change (IPCC) stress the need to conduct river basin assessments and design international conventions which keep in mind climate change adaptation to protect water reserves.

Fluence, a leading company in the decentralized water and wastewater treatment space, emphasizes physical infrastructure such as water reuse systems, storage, and desalination, on top of conservation techniques. They support the importance of aquifer recharging and restoration of watersheds using native plant species.

Another important area is water reuse and recycling, and the use of ZLD (zero liquid discharge) systems. In these systems, water is used, treated, and reused within a closed-loop without any discharge. Recycled water can be used in various industries including irrigation of food crops, landscaping, recharging of groundwater, toilet flushing, and industrial processes. PepsiCo’s Frito-Lay plant in Arizona is the first facility in the United States to produce drinking quality reused water which is deployed in the food production process, saving costs, meeting regulatory requirements, and alleviating water scarcity. This graphic shows the basic process for how a ZLD reusable water system works.

Inspire Clean Energy, a clean energy provider in the United States, highlights the importance of engineering technologies such as smart irrigation systems to prevent losses. They also suggest economic solutions such as new water pricing strategies, and social solutions that bring recycling technology and water-saving appliances to the customer.

UNICEF’s multi-pronged approach to tackling water scarcity includes identifying new water resources via remote sensing and field surveys, improving the efficiency of distribution networks, promoting the reuse of wastewater, developing new technologies, managing aquifer recharge, rainwater harvesting, and promoting education on water scarcity issues via schools and community outreach.

Government-proposed solutions to water scarcity often come in the form of infrastructure. Countries like the UAE, Cyprus, Saudi Arabia, and Malta employ desalination systems to treat brackish water. The UAE spends over $3 billion annually on such technologies.

Zaragoza in Spain focuses on water conservation and developed the Water Saving City project which reduced per-capita water consumption by 51 liters per year. Marrakech in Morocco has successfully developed a participatory groundwater management system.

Both the United States and European nations are trying to improve the monitoring of distribution infrastructure using smart valves and leakage detection. A 2013 report by the Center for Neighborhood Technology showed that 16% of water supplied in the US is lost via leaks. In Europe, this is estimated to be causing a loss of approximately 80 billion euros a year.

Other solutions that countries are implementing to alleviate water scarcity include green infrastructure systems in Peru and Vietnam, to integrate natural water solutions for managing stormwater. Namibia, China, and the United States have implemented wastewater recycling methods, while China is developing smarter, bio-engineered crops that are more resilient.

Which Organizations are Working against Water Scarcity?

Organizations working against water security include the following groups.

• UN-WATER facilitates partnerships between UN members and international organizations on water issues. The organization focuses on informing policy choices, monitoring and reporting on key trends in water management, and spreading awareness through campaigns.
• The United Nations Food and Agriculture Organization (FAO) focuses on furthering an understanding of water scarcity and building a conceptual framework that also integrates the importance of agricultural activities and food security. The FAO hosts the Global Framework for Action to Cope with Water Scarcity in Agriculture in the Context of Climate Change (WASAG). This is an initiative bringing together a variety of government, non-profit, and private groups to help agriculture adapt to water scarcity.
• The International Water Management Institute (IWMI) is a multinational “research for development”’ organization with a vision of a ‘water-secure world’. The organization focuses on water and land management challenges in developing countries.
• The World Wildlife Fund (WWF) is a leading conservation organization that restores species and natural habitats. One of the organization’s key focus areas is freshwater resource protection.
• The World Resources Institute (WRI) is an international environmental research and policy development group. They work to create solutions to water security problems by providing data and analytical tools to assist decision-makers.

Other organizations working to solve water scarcity problems include The Water Project, WaterAid, The Stockholm International Water Institute, Columbia Water Center, the World Water Council, and the Global Water Institute.

What Are Some Concepts Related to Water Scarcity?

Some concepts related to water scarcity are the following items.

• Water stress: This is an “outcome of water scarcity” and refers to poor quality and limited accessibility to water.
• Water risk: This is the “probability of an entity” experiencing a harmful water-related event. Water risk is gauged differently from sector to sector, distinguishing it from water stress and water scarcity.
• Water security: This is the “capacity of a population to safeguard sustainable access to adequate quantities of acceptable quality water”, according to UNICEF. This applies to water for sustaining livelihoods, socio-economic development, and preservation against water pollution.