In the face of the water crisis

The demand for drinking water is soaring while the global supply is dwindling. A global water crisis can be avoided with the help of technologies that already exist, but they must be implemented quickly

by Peter Rogers

I have a friend who lives in a middle-class neighborhood in New Delhi, which is one of the richest cities in India. Although the area receives a considerable amount of rain each year, he wakes up in the morning to the sound of a megaphone announcing that the water in the faucets will only flow for the next hour, and hurries to fill the bathtub and other containers to store water for the whole day. These times of scarcity, typical of New Delhi, are mainly due to the decision of those in charge of water in India to divert large amounts of water up rivers and reservoirs and use them to irrigate crops.

On the other hand, Benny, who lives in arid Phoenix, wakes up to the sound of the sprinklers irrigating the green suburban lawns and golf courses. Although Phoenix lies in the middle of the Sonoran Desert, it has an almost unlimited supply of water. The region's politicians allowed the agricultural water to be diverted to the cities and suburbs, and used in running water Purified for watering gardens and other non-drinking uses. (See: A special project for the science website - water problems in the world)

As in New Delhi and Phoenix, all over the world the influence of the policy makers on the way water resources are managed is great. The importance of the wise application of this power of influence is increasing because in many places in the world the demand for drinking water is greater than the supply, and it does not seem that this trend will change soon. Although the problem is known and recognized, this does not diminish its severity: currently one in six people, that is, more than a billion people, has difficulty obtaining fresh water that is safe to drink. According to data published by the United Nations, by 2025 there will be a shortage of drinking water in more than half of the world's countries. The distress may arise, among other things, from the demand for water quantities that are greater than the available or safe supply for drinking by the population or from a shortage, literally. By the middle of this century three quarters of the earth's inhabitants may suffer from a lack of fresh water.

Scientists predict that water shortages will become more common mainly because the world's population is growing and many people are getting richer (and increasing the demand for water) and because global climate change is increasing aridity and reducing water supplies in many areas. Also, many water sources are at risk due to deficiencies in sewage disposal, release of industrial pollutants, runoff of fertilizer materials and infiltration of seawater into aquifers following the drop in the level of groundwater. Since the lack of access to drinking water can lead to hunger, disease, political instability and even war, failure to take steps in this regard can cause far-reaching and serious consequences.

Fortunately, we know to a large extent what technologies and policies are necessary to preserve the drinking water available today and to ensure its continued supply in the future. In this article I will review some measures that seem particularly effective. Now is the time to act. Governments and authorities at all levels must formulate and implement practical plans to implement the political, economic and technological measures that have the power to provide security for the water sector today and in the decades to come.

The sources of the shortage

In order to solve the world's water problem, one must first understand how much fresh water each person consumes, and to know the factors that decrease the supply and increase the demand in different parts of the world. Malin Falkenmark of the "International Water Institute in Stockholm" and other experts estimate that a person consumes a year, on a global average, 1,000 cubic meters (m40) of fresh water, or about XNUMX% of the volume of an Olympic swimming pool, for drinking purposes, hygiene and growing food for a living The satisfaction of these needs depends greatly on the place of residence, since the distribution of water sources in the world is not uniform at all.

An adequate supply of water is difficult, especially in dry, undeveloped or developing countries with a large population, since the demand is high and the supply is small. Rivers such as the Nile, Jordan, and Yangtze are overexploited, and the flow in them is low for long periods of the year. The aquifers beneath New Delhi, Beijing and other developing urban areas are also being depleted.

At the same time, the lack of fresh water is becoming common even in the developed countries. Many cities in northern Georgia and large areas of the southwestern United States, for example, suffered from a water shortage after several years of drought. This problem is illustrated by the two artificial lakes, Mead and Powell, which are fed by the Colorado River, which carries too much load. Year after year these receding lakes record the height of the peak water in a series of chalk lines on the high canyon walls that bound them, much like marks on the sides of a bathtub.

golden rule

Not only the location determines the availability of water in a certain place, the ability to pay is also very important. According to an old saying that originated in the western United States, "Water usually flows downhill, but it always flows uphill toward money." That is, when the supply is low, those in power will divert the water to profitable uses at the expense of less profitable uses, and hence the wealthy gain water and the others do not.

Such arrangements leave the poor and the non-human consumers of water, i.e. the animals and plants in nearby ecosystems, without adequate allocations. Furthermore, even the best intentions can go awry due to the economic reality described in the proverb above.

Evidence of the correctness of the adage can be found in what happened in one of the most efficiently managed drainage basins in the world - the Murray-Darling River basin in southeastern Australia. A few decades ago, the farmers and the government allocated the river water to the human consumers, the vine growers, the wheat growers and the sheep breeders in a sophisticated way based on fairness and economy. The regional water management agreement allowed those concerned to trade both water and the rights to use it. He also made sure to allocate a significant portion of the water resources to the ecosystems in the area and the life that inhabits them. These are key "consumers" that are often overlooked, even though their proper health is essential to the well-being of the entire region. For example, aquatic and marsh plants, large and small, often help remove human waste from the water flowing in the ecosystems where they grow.

However, it turns out that the planners did not allocate enough water for the benefit of the environment. The signs of this shortfall allocation can be seen in drought years, and especially during the long drought that has caused heavy damage in the region in the last six years. The areas surrounding the drainage basin of the river have dried up and caught fire from the terrible fires that have occurred there recently.

The economic players in the arena got their share, but they did not give their opinion on the needs of the natural environment, which was severely damaged when the drought brought the water supply below the red line. Now the members of the Murray-Darling Basin Commission are trying to extricate themselves from the disastrous results of the misallocation of the total water resources.

In view of the difficulty in wisely allocating the water resources within one country, imagine how difficult it is to do this in international river basins such as the Jordan drainage basin, which is shared by Israel, Jordan, Syria, Lebanon and the Palestinian Authority, who claim their share of the shared, but limited, supply in the region So thirsty for water. The struggle for fresh water contributed to the civil and military conflicts here. Only thanks to continuous negotiations and compromises made has this tense situation not yet gotten out of control.

the degree of demand

Like the supply, the demand for water also varies by location. Demand does not only increase as the population increases and the growth rate increases, but also as the level of income increases: the rich generally consume more water, especially in urban and industrial environments. The affluent also typically require services such as sewage treatment and increased agricultural irrigation. In many cities, and especially in the relatively dense regions of Asia and Africa, the demand for water is rising at a rapid rate today.

Besides the level of income, the price of water also plays a role in dictating demand. In the 90s, for example, when my colleague and I did a computer simulation of global water consumption from 2000 to 2050, we found that the total global demand for water would exceed 3,350 cubic kilometers, a little more than the volume of Lake Huron (the fifth largest lake in the world and one of the largest lakes of North America - the editors), to 4,900 cubic kilometers (a cubic kilometer is equal to the volume of 400,000 Olympic swimming pools), if water prices and income levels remain as they were in 1998. But the demand will almost triple (increase to 9,250 cubic kilometers) if in the poorest countries the income per capita continues to grow until it is equal to that of the countries where the income per capita is moderate today, and if the governments of these countries do not adopt a special policy to limit the use of water. This increase in demand will greatly increase the pressure on water sources. The results we received are in line with the "International Water Management" (IWMI) forecasts, based on the "business as usual" scenario, or "sit and do it", obtained in the study "Water for food, water for life" done by the director in 2007.

How to spend less

There is no doubt that due to the importance of economic considerations and the level of income in water matters, it is worthwhile to adopt a reasonable pricing policy that will encourage savings among domestic and industrial consumers. In the past, the price of fresh water in the United States and other economic powers was too low to encourage consumers to save: as is often the case when exploiting a natural resource, few care about waste when the commodity is so cheap that it seems to be given almost for free.

Increasing water prices where possible is therefore at the top of the treatment prescription I recommend. This is a very logical step in developed countries, and especially in large cities and industrial areas, but also in developing countries. Higher water prices can, for example, encourage the implementation of measures such as the systematic circulation of potable water ("gray water") that is not suitable for drinking. They can also spur the water authorities to set up recycling and reclamation systems.

Raising prices can also persuade municipal and other authorities to reduce the amount of water being lost by improving the maintenance of water transport systems. One of the serious effects of water prices that are too low is that not enough money is collected for future development and preventive maintenance. In 2002, the US State Comptroller's Office (GAO) reported that most domestic water suppliers were delaying maintenance of their infrastructure due to budget constraints. Instead of detecting leaks early and preventing serious failures, they usually repair main pipes only after they burst.

However, repairing and renewing the water infrastructure in the United States and Canada to reduce waste would be an expensive operation. In 2007, the accounting firm Booz Allen Hamilton calculated that these two countries would need to invest $3.6 trillion in their water systems over the next 25 years.

Another important strategy for saving water is focusing on the biggest consumers. This approach marks irrigated agriculture as a main goal: the amount of fresh water that can be saved in agriculture is much greater than that which can be saved in any other field of activity. If there are no technological improvements in agricultural irrigation methods, in 2050 farmers will need almost double the amount of water to meet the global demand for food (4,000 cubic kilometers compared to 2,300 cubic kilometers today), according to a study done by the IWMI.

However, even a modest 10% improvement in irrigation efficiency will save more water than the amount of water lost by all other consumers combined to evaporation. Such an improvement can be achieved with a few simple steps: plugging leaks in the water supply infrastructure, using reservoirs that lose less water and streamlining the irrigation operations themselves.

The agreement between municipal water suppliers in Southern California and environmental farmers who are members of the "Imperial County Water Plant" is an example of a creative effort to save water. The group of municipal suppliers finances the lining of leaking irrigation canals with sealing materials, and the water saved will be diverted to municipal needs.

According to a different approach to saving irrigation water, in the non-irrigation seasons, water intended for irrigation will be injected into underground reservoirs. In most places in the world the rains, snows and flow to the rivers reach their peak outside the growing season, when the demand for irrigation water is lowest. Therefore, the basic task assigned to the water managers is to transfer water from the season of the year when the supply is the greatest to the season of the greatest demand - when the farmers need water to irrigate their fields.

The most common solution is to store surface water using dams, but a significant part of this exposed water evaporates and is lost. Underground storage will greatly reduce water loss due to evaporation. In order for such storage to be feasible, engineers must first find large underground reservoirs that are convenient to fill with surface water and pump back to the surface when needed. Today, such "banks" are already being used in Arizona, California and other places.

Another way to reduce the demand for irrigation water is to increase the use of drippers. Drip irrigation reduces consumption because the water flows to the seal only in the root zone, either by percolation from the soil above them or directly. The demand for fresh water in agriculture can also be reduced thanks to investment in the development of new varieties of drought- and drought-resistant crops and varieties that can be irrigated with brackish water and even salty water.

Considering the increase in the demand for agricultural produce, resulting from the increase in population and income per capita, it is doubtful whether the water managers will succeed in reducing the amount of water directed to irrigation today. But streamlining irrigation and increasing productivity in agriculture can curb the demand for water in this sector and keep it from exceeding the reasonable range.

Additional steps

It is possible to help curb the demand for irrigation water in arid areas without impairing their ability to meet the full demand for food in the future by injecting "virtual water" into these places. The concept describes the water required to produce food or goods. If they sell these food and goods to the arid regions, they will not have to produce them there and use the local water. The supply of goods and foodstuffs is therefore equivalent to the supply of water to the dry area, that is, it is a virtual supply of water.

The concept of "virtual water" may at first sound like an exercise in accounting and nothing more, but the supply of goods, based on their virtual water content, helps many arid countries avoid using their water for agricultural purposes, and frees up large amounts of water for other needs. The idea of ​​virtual water and the expansion of trade also resulted in the resolution of many conflicts between countries suffering from water shortages. Jordan's virtual water import, for example, through goods reduces the risk that it will get into a conflict with Israel over water.

The volume of trade in virtual water in the world is greater than 800 billion cubic meters of water per year, an amount ten times greater than the amount of water in the Nile. Easing trade in agricultural products and reducing protective tariffs, which today hinder the transfer of food products between countries, can significantly increase the mobility of virtual water in the world. Free agricultural trade could truly double the annual virtual water supply in the world today to 1.7 trillion cubic meters.

Whatever the benefit to the world from trading virtual water, the inhabitants of the growing cities need real water - for drinking, bathing and sanitation. The ever-increasing demand for water-based municipal sanitation services can be reduced by switching to dry or water-efficient facilities, such as dry toilets equipped with composting and urine separation systems. With this technology, the urine is diverted for agricultural use, and organic manure is produced instead from the other excretions for improving the soil. The principle of operation is similar to that of a compost pile in the garden. These facilities use aerobic (aerobic) bacteria to break down the excrement and turn it into non-toxic, nutrient-rich organic compost that can be used by farmers. These techniques can be used safely even in fairly dense urban areas, as demonstrated by the systems installed in the Gebers residential project in one of the suburbs of Stockholm and many other pioneering projects.

Basically, the civil engineers can use this technology to disconnect the water supply from the sewage systems, a principle that, if more widely applied, could bring about significant savings in fresh water. Furthermore, the recycled waste can reduce the use of fertilizers derived from fossil fuels.

Besides reducing the demand for fresh water, the opposite approach, increasing the supply, is also a crucial element in solving the water problem. Only about 3% of all water on earth is fresh water, and the rest is salty. But there is a way desalination which are intended to take advantage of this vast source. Recently, the cost of the most energy-efficient desalination technology – reverse osmosis using membranes – has dropped considerably, and now many coastal cities can rely on this source of drinking water.

In reverse osmosis, the salty water is introduced into one of two cells separated from each other by a semi-permeable membrane (which only allows water to pass through), and fresh water is flowed into the other cell. After that, a fairly strong pressure is applied to the salt water cell, and over time the pressure forces the water molecules to pass through the membrane into the fresh water cell.

The engineers achieved the reduction of the cost with the help of a variety of solutions, including a more efficient membrane for filtering the water that requires less pressure, and therefore also less energy, and modularization of the system, which facilitates the construction of the desalination facilities. Large desalination plants that use the new, more economical technology have already been built in Singapore, Tampa, Florida, and Ashkelon.

Today, scientists are working on reverse osmosis filters made of carbon nanotubes, which allow more efficient separation and reduce costs by another 30%. This technology, which has already been used in prototype facilities, is getting closer to the level of commercial use. However, despite the improvements in terms of energy consumption, the reverse osmosis method is still limited because it is energy intensive. The availability of energy at a reasonable price is therefore very important for a significant increase in desalination with this method.

Return on investment

Naturally, preventing future water shortages involves investing a lot of money. Booz Allen Hamilton's analysts estimate that in order to satisfy all the world's fresh water needs by 2030, an investment of approximately one trillion dollars per year will be required in the application of existing technologies for water conservation, in the maintenance and replacement of infrastructure, and in the construction of sanitation systems. There is no doubt that this is a huge amount, but it is not that big if you compare it to other expenses. This is actually only about 1.5% of the annual global gross domestic product (GDP), or per capita - about $120 per person, and it seems that this expenditure is possible.

Unfortunately, from the end of the 90s until today, the rate of investment in water facilities is less than the total GDP in most countries of the world. If there is a crisis in the coming decades, it will not result from a lack of knowledge but from short-term vision and a refusal to invest the necessary funds.

However, there is at least one reason for hope: the most populated countries, whose water infrastructure needs are the greatest, India and China, are the two countries whose economic growth is the fastest. The continent that is expected to suffer more from water shortages is Africa with its billion inhabitants. Africa is where the least amount of money is spent on infrastructure, and it cannot spend big. It is therefore very important that the richer nations provide more funding and help this effort in Africa.

The international community can reduce the risk of a global water crisis if it is able to give its collective opinion on this challenge. No need to invent new technologies. We only need to speed up the application of existing techniques for the conservation and enrichment of water sources. Solving the water problem is not simple but possible, if we start acting immediately and persist in it. Because if we don't do that, the thirst in the world will be great.

key concepts

The world's fresh water resources are in danger due to an increase in demand from all sides. The increase in population requires more and more water for drinking, personal hygiene, sanitation, food production and industry. On the other hand, more and more years of drought are expected due to climate change.
Policy makers must find a way to provide water without harming the natural ecosystems from which it is taken.
Today there are simple technologies that can help prevent water shortages and ways to increase the supply, such as improved desalination methods.
But governments at all levels must already set policies and invest in infrastructure to save water.

There is a lot of water, but not always in the right place

120,000 cubic kilometers of precipitation, almost ten times the volume of Lake Superior in North America, falls from the sky each year. This huge amount would easily be enough for all the needs of the inhabitants of the earth if the water came in the places and times people need it. But much of this water cannot be stored, and the rest is not evenly distributed.

Where does the rain flow?

More than half of the amount of precipitation that falls on land cannot be stored because the water evaporates from the soil or evaporates from plants. This water is called green water. The rest of the water drains into sources of blue water that humans can use directly: rivers, lakes, swamps and aquifers. Agricultural irrigation is the single largest human use of this flowing water. The cities and industry use only tiny amounts of the total fresh water resources, but the high local demand they create sometimes dries up the water sources in their surroundings.

The water sources today

Large areas in North America and southern and northern Eurasia enjoy an abundance of water. in contrast,

There are places that suffer from a "physical" water shortage, more or less severe, that is, in these places the demand is greater than the supply. Other places, including central Africa and parts of the Indian subcontinent and Southeast Asia, suffer from "economic" water scarcity, meaning they have enough water, but access to it is limited due to poor technical training, governance failures, or insufficient funding.

About the author

Peter Rogers holds the Gordon McKay Chair in Environmental Engineering and teaches urban and regional planning at Harvard University, where he received his doctorate in 1966. Rogers is a senior consultant at the "Global Water Partnership", an organization whose goal is to improve water management in the world. He won scholarships from the "Twentieth Century" Foundation and the Guggenheim Foundation.

Climate pressure and population growth

Models that examined the effects of climate change, population growth and economic growth on water availability in 2025 show that climate change alone may lead to water shortages in many places, but population growth is even more dangerous. If coordinated actions are not taken to conserve water, the increase in population and climate change will together cause a world-wide distress.

Save water for irrigation

Irrigation of fields and orchards consumes huge amounts of water. Reducing the water consumption for irrigation by 10% will save a greater amount of water than is consumed by all the other sectors combined. Plugging leaks in the water supply system for agriculture, storing water under the ground to reduce evaporation, using drippers and choosing crops that need less water can bring about the required savings. The photo below shows water from the Colorado River flowing through open irrigation canals in the famous agricultural area of ​​Imperial Valley in California.

Network

The lifestyle a person chooses determines how big his footprint will be on the water system, that is, what is the volume of fresh water needed to produce the goods and services he consumes. To find out your personal footprint on the water economy: www.waterfootprint.org

raise the price of water

In the United States and other economic powers, it is customary to charge a very low price for water, and consumers have no reason to save. Only a few bother to save on a commodity that seems to be provided almost for free, however valuable it may be. The price increase will encourage savings and investment in less wasteful water infrastructure.

The necessary investment in the water sector

2005 to 2030 (in trillions of dollars)

Asia and Oceania – 9.0

Latin America – 5.0

Europe – 4.5

United States and Canada – 3.6

Africa – 0.2

The Middle East – 0.2

The maintenance of the water infrastructure is necessary to prevent actual deterioration, leaks and break-ins. At the same time, the growing populations and the growing populations need to develop new and efficient water supply systems. To preserve fresh water sources, the developed countries and some less developed countries must invest trillions of dollars in the maintenance and construction of efficient infrastructures, in their own and other countries, in the next 25 years.

to flow "virtual water"

Virtual water is the water consumed for the production of a food item or other product, and in fact it is embodied in this item. The production of a kilogram of wheat, for example, requires about 1,000 liters of water, so each kilogram of wheat contains, virtually, 1,000 liters of water. Exporting wheat to the land that is stored frees its inhabitants from diverting water to grow wheat, and reduces the pressure of demand on local sources.

Switch to water-efficient sanitation systems

Urban and suburban sewage services consume a lot of water, about 100 cubic kilometers worldwide. Economical toilets can subtract quite a bit from this amount. The residents of the Gebers residential project in the suburbs of Stockholm demonstrate to the world the use of a system that works like a composting facility in the garden. First, the urine is separated from the feces and used for liquid soil fertilization in agriculture. The rest is recycled into fertilizer in a compost tank using microorganisms. The application of this technology is safe even in fairly dense cities and suburbs.

Take advantage of the advantages included in the desalination technology

97% of the world's water is salty. New desalination plants, cheaper to operate, can help provide water to population concentrations near the sea. Basically, you apply pressure to salt water and force the water molecules in the salt water to pass through a selective membrane to another container where fresh water is obtained. Although the filtration process usually consumes a lot of energy, the next generation of membranes and other innovations can reduce the amount of energy required.

Savings:

Shame every bit

There are some small steps that can also ease the world's difficulties a little, if enough people adhere to them persistently. Here are some suggestions:

Instead of throwing in the trash, collect the organic waste for a compost pile.

Use an efficient dishwasher and washing machine and only run them when they are full.

Install a two-volume flushing tank for the toilet (which allows flushing with less water).

Use a shower head with a flow limiter and use the bath water to water the pots or the garden.

Water the lawn early in the morning or in the evening to reduce the amount of water wasted due to evaporation.

And more on the subject

Balancing Water for humans and nature: The new Approach in Ecohydrology. Malin Falkenmark and Johan Rockström. Earthscan Publications, 2004.

Water Crisis: Myth or Reality? Edited by Peter P. Rogers, M. Ramón Llamas and Luis Martínez-Cortina. Taylor & Francis, 2006.

The World's Water 2006–2007: The Biennial Report on Freshwater Resources. Peter H. Gleick et al. Island Press, 2006.

Water for Food, Water for life: A Comprehensive Assessment of Water Management in Agriculture. Edited by David Molden. Earthscan (London) and International Water Management Institute (Colombo), 2007. Available at http://www.iwmi.cgiar.org/Assessment