An estimated 13,000 km3 of water vapor exists in the sky, some of which may be caught by cloud seeding and the collection of water from fog and mist. For almost a century, remote populations in Chile, Morocco, and South Africa have employed vertical mesh nets to gather fog, and there are potential fog harvesting sites on every continent.
Advancements in materials and indigenous knowledge have aided in the development of highly productive, low-cost, and ecologically beneficial systems for collecting potable water – more than 20 liters per square meter of mesh on a dense fog day. At a cost of less than $250 per square meter of mesh that will last more than a decade, 75,000 liters per square meter may be generated for approximately 33 cents per liter.
Experts explain how many different "unconventional water sources" there are.
Even if only a portion is tapped, it can assist fulfill the world's rapidly expanding freshwater demands.
According to UN and partner water experts, now is the moment to tap into Earth's diverse and plentiful unconventional water sources, including the millions of cubic kilometers of water in deep land-based and seabed aquifers, icebergs and fog, and the ballast holds of thousands of ships.
Unconventional Water Resources, a new book published by Springer and compiled by experts at the UN University's Institute for Water, Environment, and Health (UNU-INWEH), the UNU Institute for Integrated Management of Material Fluxes and Resources (UNU-FLORES), and the UN Food and Agriculture Organization (FAO), claims that these potential supplies can help many of the 1 in 4 people on the planet who face water shortages for drinking, sanitation, agriculture, and economic development.
The book highlights the potential of various types of unconventional water resources, such as tapping offshore and onshore deep groundwater, reusing water, physically moving water to water-scarce areas, and more, based on the most recent information and data and with contributions from renowned scientists, practitioners, and experts from around the world.
“As climate change worsens and with population rising worldwide, water shortages are a top threat to human development and security, making this authoritative analysis of unconventional water resources both timely and important,” says UNU-INWEH Director Vladimir Smakhtin.
“Harnessing the potential of unconventional water sources could benefit billions of people,” says the book's principal editor, UNU-INWEH Deputy Director Manzoor Qadir. “These sources will be essential to building a future in arid areas.”
The book divides unusual water sources into six categories:
1) Harvesting water from the air with cloud seeding and fog collectors
A total of 13,000 km3 of water vapor exists in the sky, some of which may be caught by cloud seeding and the collection of water from fog and mist. (A cubic kilometer of water is equivalent to 400,000 Olympic swimming pools, and yearly worldwide freshwater demand is currently projected to be around 4,600 km3 - nearly the same as the capacity of North America's Lake Michigan or 1.7 times that of Africa's Lake Victoria.)
Cloud Seeding or Rain Enhancement
Cloud seeding may increase rainfall by up to 15% under the correct conditions, and studies demonstrate that rain augmentation can be done at a fair cost-benefit ratio. Rain augmentation is being planned by an increasing number of nations in response to water shortages and other societal requirements.
Fog Harvesting
For almost a century, remote populations in Chile, Morocco, and South Africa have harvested fog with vertical mesh nets, and there are potential fog harvesting sites on every continent. Advances in materials and indigenous knowledge have aided in the development of highly productive, low-cost, and ecologically friendly systems for collecting potable water — more than 20 liters per square meter of mesh on a dense fog day. At a cost of less than $250 per square meter of mesh that will last more than a decade, 75,000 liters per square meter may be generated for approximately 33 cents per liter.
2) Desalination
Desalination produces around 100 million cubic meters of water every day, enough to feed about 5% of the world's population. By 2030, this volume is expected to quadruple, while costs are expected to drop by half. Desalination's new improvements will certainly make it the cheapest unconventional water supply option on the planet, especially in low-income nations where desalination production is still a long way off.
While desalination is still an energy-intensive process, new technologies such nanoparticle augmented membranes and forward osmosis are lowering energy use by 20 to 35 percent. Meanwhile, desalination generates massive amounts of brine, a pollutant that is becoming increasingly problematic in areas where it is released. In the next decade, new technologies that extract salts, magnesium, and other metals from brine to produce economically viable goods may be able to balance the expense of desalinated water production.
3) Reusing water
Municipal wastewater
Advanced municipal wastewater treatment systems provide a supply of water while also conserving high-quality surface and groundwater.
In high-income nations, roughly 70% of municipal wastewater is treated nowadays, compared to only 8% in low-income ones. Untreated city wastewater is estimated to be 171 km3 per year, with much of it thrown into the environment, lowering water quality in many regions of the world.
In a number of nations, treated wastewater is increasingly being utilized to recharge subterranean aquifers that produce drinking water. Treated wastewater satisfies 40% of Singapore's demand and supplies 25% of Windhoek, Namibia's potable water supply. San Diego, California, and other US towns get some of their drinking water this way, while Israel and other countries get up to a quarter of their agricultural water from treated wastewater.
People and legislators still have a hard time accepting reclaimed wastewater.
Agricultural drainage water
Irrigated areas account for just one-fifth of all cultivated land, but they generate 40% of global food. Irrigated agriculture is at least twice as productive per unit of land than rainfed agriculture, since it allows for crop variety and production intensification. Through improved conservation and reuse of irrigated agricultural drainage water, even more food may be grown with the same quantity of water. Because drainage water is always more salty than the irrigation water from which it is created, it needs special attention and treatment.
Salt-tolerant plants and new kinds are making it easier to cultivate food in saline environments. Cyclic and blended management strategies involve one farm using irrigated drainage water from another and a third field using that drainage water combined with freshwater. Solar evaporation can be used to collect water and salt from super-saline drainage.
4) Tapping fresh and brackish groundwater offshore and onshore
Although much of it is brackish, the volume of sustainable groundwater might be as large as 5 million km3 (salty). There is a lot of fresh to brackish water on the seafloor along the shorelines.
Offshore
Aquifers at shallow depths on continental shelves throughout the world contain large amounts of water (approximately 300,000-500,000 km3). These aquifers, which were formed millions of years ago when sea levels were much lower, are less than 100 kilometers offshore.
Ancient Syrians built an inverted funnel over a submerged spring offshore to feed roughly 1,500 liters per second to the city of Tyre some 3,000 years ago. Exploratory drilling off the coast of the United States in the 1970s produced no oil or gas but discovered large volumes of fresh to brackish water. New marine electromagnetic research tools are now able to produce comprehensive photographs of freshwater off the coast. When these photos are paired with horizontal drilling technology, it is possible to produce commercially significant amounts of freshwater that can be piped to shore for at least 30 years. There have been no offshore freshwater resources developed to yet.
Inshore Continental Brackish Groundwater Resources
The volume of brackish or salty water in deep inland aquifers is believed to be in the millions of cubic kilometers. As shallow freshwater supplies have dwindled, brackish water reverse-osmosis desalination facilities for drinking water have exploded across the United States. Desalinated water derived from brackish water is also utilized to grow high-value crops in Israel and Spain.
By employing electromagnetic surveys to locate relatively plentiful fresh / brackish water sources and installing desalination units there, the high costs associated with desalination can be reduced. Improving the efficiency of these facilities will allow farmers to use desalinated water more widely. Deep subsurface aquifers, for example, can contain hot brackish water that can be desalinated after being utilized for geothermal heating in greenhouses and aquaculture operations, lowering total expenses.
5) Micro-scale capture of rainwater that would otherwise evaporate
Evaporation and surface runoff generally lose over 90% of precipitation in arid areas. Rainwater collecting in micro-catchments offers a unique chance to capture water for agricultural production and local needs. It's an old approach that includes everything from rooftop and cistern collection to agricultural and landscape systems like contour ridges, bunds, minor runoff basins, and strips.
Even in extremely arid places, collecting rainfall from three-quarters of the land and applying it on the remaining quarter of the land will typically supply enough water for cattle drinking and shrub production.
6) Moving water physically to water-scarce areas in ships’ ballast holds, or towing icebergs
Ballast water
Ships transport over 90% of the world's products and discharge around 10 billion tons of ballast water (10 km3) each year. All ships of 400 gross tons or more must have onboard treatment options to desalinate ballast water, remove invasive aquatic organisms and unhealthy chemical compounds, and make it usable for other economic activities like irrigation, according to the International Convention on the Control and Management of Ships' Ballast Water and Sediments. This water might be marketed to arid-region port towns.
Oil tankers and liquefied natural gas (LNG) ships docked in Abu Dhabi, United Arab Emirates, might, according to one research, send their ballast water to an onshore water treatment facility. Treated ballast water might be sold by ports with onshore desalination plants.
Each year, more than 100,000 icebergs from the Arctic and Antarctic melt into the ocean, containing more freshwater than the world consumes. Iceberg harvesting for freshwater has been explored for a long time, but it is not considered feasible. Icebergs, on the other hand, are towed to provide water to 700 people in Qaanaaq, Greenland. In Newfoundland and Labrador, iceberg towing is used to avoid accidents with offshore oil and gas facilities, as well as for freshwater and other purposes.
Due to the enormous loss of water volume and the danger for ice disintegration while towing, long-distance iceberg towing has never been tried. However, if the icebergs to be towed are large enough, i.e. 125 million tons, a financial feasibility analysis of towing icebergs to Cape Town, South Africa, reveals that it is an economically viable alternative. According to research, wrapping icebergs in a net and subsequently a mega-bag would likely prevent breakage and limit melting. Other difficulties include converting an iceberg into drinking water at its destination and dealing with the environmental consequences.
Additional comments
“The stark fact is that conventional water provisioning approaches relying on snowfall, rainfall, and river runoff are not enough to meet growing freshwater demand in water-scarce areas. Water scarcity is expected to intensify in regions like the Middle East and North Africa (MENA), which has 6% of the global population but only 1% of the world’s freshwater resources. Climate change adds to this complexity, creating uncertainty and extended droughts, mostly in arid areas," said Vladimir Smakhtin, Director, UNU-INWEH .
“Water-scarce countries need a radical rethink of water resource planning and management that includes the creative exploitation of a growing set of viable but unconventional water resources for food production, livelihoods, ecosystems, climate change adaptation, and sustainable development.”
Manzoor Qadir, Deputy Director, UNU-INWEH, added: “Water scarcity is ranked among the top 5 in terms of impacts on livelihoods and human wellbeing. By 2030, humanity’s annual global water requirements will exceed current sustainable supplies by 40%, according to one analysis, and almost half of all countries (87 out of 180) are projected to become water-scarce by 2050.”
“The time has come for humanity to tap into the vastly under-used unconventional water sources. Our book stresses, however, that national water policies and action plans to tap these sources will first require local assessments of the environmental trade-offs. And a prerequisite for that in many places will be greater institutional and human capacity to evaluate potential unconventional water source uses, including comprehensive cost analyses. Innovative financing mechanisms will also be needed.”
According to Sasha Koo-Oshima, book co-Editor and Deputy Director, UN FAO: “The increasing pressures on water resources requires a new era of water management, one that addresses barriers to efficient water management and ensures that water in all its forms is monitored and accounted for, including its value to food, ecosystems, and health, and its role in supporting food security and basic needs of humanity and economic development.”
Reviewed by Lilit
on
May 30, 2022
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