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A river runs over it

Think the Amazon River is the largest river on Earth? Technically, you’d be right but the river with twice the amount of water than the Amazon can be found in the sky.

Atmospheric rivers are long, narrow bands of concentrated water vapor that produce major amounts of rainfall. They exist on a global scale, transporting moisture from the tropics to the higher latitudes.

And they can have a huge effect on the way you live. “Atmospheric rivers are responsible for important impacts throughout the Earth’s middle and polar latitudes, such as flooding, influence on water resources, and melting of polar ice sheets,” explains Kyle Mattingly of the University of Wisconsin.

IMAGE: Unsplash
Like a hurricane
but not

Atmospheric rivers are not big hurricanes. Read more›››

Although they share many features (high winds and lots of rain originating from the tropics), atmospheric rivers are sustained, moving bands of moisture with wide-spread impact. Think a jet stream, but wet, and closer to the ground.

Hurricanes, on the other hand, are rapidly rotating storm systems that concentrate their water content into precipitation over a much smaller area. Hurricanes take heat from the tropics to the poles, which plays an important role in regulating global climate; atmospheric rivers take moisture out of the tropics and spread it around the world.‹‹‹ Read less

A 1998 paper from Yong Zhu and Reginald Newell, the researchers who coined the term, says on any given day, atmospheric rivers account for over 90 percent of the global north-south water-vapor transport.

There are typically three to five rivers present within a hemisphere at any given time, and any single one can carry a greater flux of water than the Amazon River. For context, that’s about 6,592 cubic kilometers of water every year, or more water than the next seven largest independent rivers combined. It’s just water vapor instead of liquid water.

These rivers in the sky help replenish reservoirs and redistribute water in the Earth system, but they can also be detrimental to the places they deposit water.

Extreme weather events such as severe flooding and high winds are now found to be associated with atmospheric rivers. These elongated tendrils of moisture stretching from the tropics poleward act as conveyor belts, feeding huge amounts of tropical moisture into existing weather systems, intensifying the rainfall. Record-breaking rainfall is often associated with an atmospheric river making landfall.

However, this water content doesn’t just fall out of the sky on a whim. The rivers pass through various atmospheric conditions on their journey, and where conditions are right for precipitation, water is released as rain or snow. Mountainous regions are particularly effective at squeezing moisture out of these sky rivers as wind travels up their sides.

A NEW ANCIENT PHENOMENON

Despite earning a name only in 1998, atmospheric rivers have been meandering through the skies for millions of years — they’re not new. So why are atmospheric rivers making a splash in the current zeitgeist?

Climate change, of course.

Plus, it’s a useful and versatile term, says Mattingly. “The ‘rivers in the sky’ metaphor helps to vividly communicate these scientific ideas to the public. In places such as California, where they have major impact, the concept helps people connect weather they experience personally with processes operating at much larger scales in the climate system.”

Understanding atmospheric rivers is key to improving weather forecasts for better managing water resources and predicting flood risk. However, atmospheric rivers are also influenced by climate change.

Previous work has examined the relationship between weather patterns and atmospheric-river development, but with climate change, these features may become more variable — and therefore harder to predict. This could mean a less reliable source of precipitation for those areas depending on the water redistribution, but could also mean extreme flooding in other places.

To those living in the Middle East, huge amounts of rainfall are pretty rare and would likely be welcomed to recharge oases, water crops and wash away the dust that accumulates in cities. The reality can be much more detrimental than beneficial, unfortunately.

A global phenomenon, atmospheric rivers have far-reaching influences on weather patterns and natural disasters. IMAGES: Unsplash and Pexels

Although a large body of research has shown the impacts of atmospheric rivers on weather-related natural disasters over the western United States and Europe, little is known about their mechanisms and contribution to flooding in the Middle East.

However, a rare atmospheric river was found responsible for the record floods of March 2019 in Iran that damaged one-third of the country’s infrastructure and saw the death of 76 people. This river started its 9,000-kilometer journey in the Atlantic Ocean before making landfall over the Zagros Mountains. It needed special conditions to make this trek across North Africa, including anomalously warm sea-surface temperatures.

What do we know is a symptom of global warming? Rising sea temperatures. The moisture transported by this rare atmospheric river was equivalent to more than 150 times the accumulated flow of the four major rivers in the region: the Tigris, Euphrates, Karun and Karkheh. Even now, people are still wrestling with the aftermath.

It was a rare atmospheric river for 2019. But like hurricanes, atmospheric rivers are projected to grow longer, wider and wetter in a warming climate. Several recent studies have modelled how atmospheric rivers will change in the coming decades: The planet warms, more water evaporates and a wetter atmosphere makes for stronger storms.

BLOWING HOT AND COLD

Challenging our understanding of atmospheric-river genesis is the increasing activity in the polar regions. Atmospheric rivers developing near the poles transport large amounts of moisture and heat and have been playing a significant role in short-duration but high-volume melt events over the Arctic and Antarctic in recent years.

There are several reasons for this, explains Mattingly. “Research to date has shown that atmospheric rivers can increase ice melt by enhancing the water-vapor greenhouse effect, releasing condensational latent heat into the air over the ice, forming bands of cloud that reflect heat back to the surface, and providing more water to the cyclones ahead of which they develop. In addition, atmospheric rivers are closely related to the atmospheric fronts over the Southern Ocean, which, in turn, reinforce subantarctic cyclone dynamics.”

The number and intensity of cyclones around Antarctica over the past few decades have increased as the storm tracks shift toward the pole under enhanced greenhouse-gas concentrations.

In the largest calving event from the Amery Ice Shelf since 1963, an iceberg 1,636 square kilometers with an estimated weight of 315 billion tons broke away from its glacier in September 2019.

Melting polar ice is concerning enough, but global warming and atmospheric changes could lead to more such calving events.

Atmospheric rivers can increase ice melt by enhancing the water-vapor greenhouse effect.

– Kyle Mattingly, University of Wisconsin

Cyclogenesis, the formation of cyclones, is a major factor in this, and an increase in the frequency and intensity of atmospheric rivers in the region will only exacerbate the problem. It’s not just calving events we need to be worried about.

Despite their distance, the sand dunes of the Sahara and the ice caps of the Antarctic are linked by global atmospheric phenomena. CREDIT: Anas Albounni, KUST Review

“Our analysis of the polynya event in September 2017, where a body of unfrozen ocean appeared within a thick body of ice during Antarctica’s winter, shows that the atmospheric rivers that initiated this were the most intense on record,” Mattingly says. “Surprisingly, these atmospheric rivers resulted in the highest amount of snowfall on record over the study area, but because of the warm temperatures, it was this warm snow that enhanced the ice melt and inhibited refreezing.”

It may be rare now, but under a warmer climate, atmospheric-river activity is expected to intensify considerably: a scary thought when we now know it can melt the sea ice in the middle of the Antarctic winter.

It’s not all bad, though. Within the sea-ice zones of both hemispheres these polynyas act as oases, enabling marine mammals such as walruses, narwhals and belugas to overwinter.

Some polynyas, such as the North Water Polynya between Canada and Greenland, occur at the same time and place each year. Animals can adapt their life strategies to this regularity, with polynyas in McMurdo Sound in the Antarctic providing a vital winter feeding place for the Cape Royds penguin colony.

IMAGE: Unsplash
A bad year for oysters

Aside from crazy weather, atmospheric rivers can have unexpected secondary consequences. Read more›››

In 2011, there was a massive wild Olympia oyster die-off in Northern California. These oysters were sensitive to the low salinity levels caused by excess freshwater dropped into the ocean from the sky by the 20 atmospheric rivers that passed through the region between October 2010 and September 2011.

It is yet to be seen what other marine life may be affected by an increased frequency in atmospheric rivers. ‹‹‹ Read less

The problem arises in the intensification of the atmospheric rivers affecting a larger area than that of the natural polynya, which may prevent sea-ice growth around the polynya and contribute to keeping it open even after the river moves on.

Jonathon Wille, postdoctoral researcher at the Université Grenoble Alpes, is also investigating the impacts of atmospheric rivers on Antarctica.

“The Antarctic continent, like many deserts in the world, receives a large percentage of its yearly precipitation from just a few intense events,” Wille explains. “They may be rarer here, but they still have a major influence on the surface-mass balance of the ice sheet and are responsible for 10 to 20 percent of the total snowfall across East Antarctica.

“This may seem a modest percentage, but this contribution to the snowfall budget has been driving parts of the positive annual snowfall trends in some areas and the negative trends in others. Atmospheric rivers also control the year-to-year variability of precipitation across most of the ice sheet.”

Given this link, increased future atmospheric river activity would result in higher snowfall accumulation on the Antarctic continent. Combine this with Mattingly’s results showing it was snow that melted the sea ice, and we have a problem.

CLOSER TO HOME

If Antarctica feels too far flung to worry about, you can always turn your attention to the European Alps.

Over the past four decades, there has been a pronounced reduction in the snow depth in the Alps, says Diana Francis, senior research scientist at Khalifa University, and, for once, it’s not a warming planet that is directly to blame. A new atmospheric river route has appeared, originating in the eastern Atlantic Ocean and drifting over the Sahara Desert on its way to Europe, bringing desert dust with it.

“Dust may actually play a bigger role in melting snow than ambient air temperature,” Francis explains. “It’s estimated that a single dust event in March 2018, where Saharan sand blew in over the Caucasus Mountains, may have shortened the snow-cover duration by up to 30 days, with this effect even more pronounced at higher elevations.”

Cryoconite is dust made up of microscopic mineral and organic particles that are carried by the winds and fall on the ice. IMAGE: Shutterstock

The dust magnifies the snowmelt in a number of ways.

Dust may actually play a bigger role in melting snow than ambient air temperature.

– Diana Francis, senior research scientist at Khalifa University

For starters, airborne dust enhances the radiative effects of the water vapor in the atmospheric river, meaning the air can hold higher amounts of moisture, and the dust particles can act as cloud-condensation nuclei, promoting the development of clouds that then rain on the mountain snow.

Then, there’s the dust that is deposited on the snow. Dust on the snow impedes the albedo effect, where the white snow reflects the UV radiation back, reducing the heat and keeping things cool.

Dust-covered snow can’t do this, with the darker surface absorbing a larger fraction of the incoming solar radiation, causing it to melt. Drastically, in fact, as Francis confirms the snow-albedo feedback in response to Saharan dust can lead to the snow melting up to 38 days earlier than normal.

That’s not all.

Mineral dust on snow and ice can provide nutrients to the microalgae that grow there. That might not sound so bad, but when microbes grow in abundance they can cause holes in the ice and snow cover, called cryoconite holes.

Among the 21 countries in the MENA region, Iran, Egypt and Saudi Arabia have benefited the most from this phenomenon.

– Mehry Akbary, assistant professor at the University of Tehran

The microalgae tend to concentrate at the bottom of these holes, creating a dark mass, which further reduces the albedo effect. As the snow melts, more of the darker material is exposed on the surface, creating a vicious circle.

The jet streams that zoom over the Earth often bring dust to northern latitudes, but with new atmospheric rivers lending a hand, alpine skiers won’t get much opportunity to enjoy the slopes.

But again, it’s not all bad. In a world without atmospheric rivers, drought would reign supreme. Atmospheric rivers are crucial to rebalancing water distribution around the planet, and while an increase in rain may be devastating, no rain at all would be just as bad. A better understanding of the future of rivers in the sky may also help water-resource managers on the ground.

THE GOOD NEWS

Mehry Akbary, assistant professor at the University of Tehran, thinks her findings on the development of atmospheric rivers in the Middle East and North Africa could be used to compensate for the shortage of water resources in this desert region.

The MENA region lies at the interface of the subtropics and mid-latitudes, and its geographical location means there is significant uncertainty about the magnitude of future changes to precipitation in much of the region.

However, because atmospheric water vapor will increase with increasing temperatures, researchers from Jet Propulsion Laboratory, University of Balamand Dubai, University of California and California State University say in their 2020 paper, confidence is high that precipitation extremes will increase in frequency and intensity throughout the MENA region.

Akbary thinks this could be more beneficial than detrimental, though. “As the most arid deserts of the world are located in the MENA region, atmospheric rivers can be counted as good sources of precipitation. Among the 21 countries in the MENA region, Iran, Egypt and Saudi Arabia have benefited the most from this phenomenon.”

Atmospheric rivers account for more than 30 percent of the total rainfall across the MENA region, with some areas seeing almost half their precipitation from rivers in the sky. “I believe if water storage systems are suitable, this huge amount of rainfall could be stored for coming droughts,” Akbary says.

Desertification may be kept at bay by the live-giving moisture in atmospheric rivers. CREDIT: Anas Albounni, KUST Review

In models simulating the year 2100, calibrated to represent a high-emissions future, we can see increases in atmospheric-river frequency in the North African coast, Turkey and Iran. This doesn’t mean the rest of the region will dry up: on the contrary, there is an expected increase in precipitation for the Arabian Peninsula.

From the Horn of Africa to the United Arab Emirates, more rain is coming. More water for a parched land can only be welcomed, but locals need to prepare for the accompanying high winds and flooding potential.

Mattingly thinks the largest impact from more frequent atmospheric rivers will be their effects on flooding and water resources. “More intense atmospheric rivers will lead directly to more intense floods in the future, and we are already seeing examples of extreme floods in recent years that were likely exacerbated by the fact a warmer atmosphere can hold more water vapor.

Although more rainfall might help replenish water resources in some areas, wetter and warmer atmospheric rivers will also present challenges to water managers in the future. For example, in areas such as the western U.S. that are heavily dependent on snow pack for their water resources, atmospheric rivers are expected to bring more rain to the region, rather than snow, which will likely result in depleted snow packs and stressed water resources during the dry summer months.”

In general, water managers are working to be more flexible in their approach to managing resources in the future.

– Kyle Mattingly, University of Wisconsin

It’s not all doom and gloom, though, Mattingly is keen to point out. “I do think that in general, water managers are working to be more flexible in their approach to managing resources in the future. California is, again, a good example, because in the past few years they have had to deal with a few wet seasons against the backdrop of a long-term drought and overall warming that has depleted reservoirs and snow packs. The challenge seems to be to develop approaches that conserve the water delivered quickly during more intense rain events to help ride out drought years.”

Models from around the world agree: Atmospheric rivers will become more frequent and intense as the planet warms. The researchers behind these models also agree: Knowing how atmospheric rivers develop and move – and what they may pick up along the way – is an important step toward accurately predicting them and their associated rainfall.

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UAE team among winners of
global FoodTech Challenge

A team from the UAE is one of four winners of the second edition of the global FoodTech Challenge in Abu Dhabi.

The team from Dubai-based agritech company Revoltech uses electromagnetic fields to speed up the freezing process, which allows food to be preserved for up to 50 years.

Other companies sharing the win with Revoltech are:

  • Aguagrain — Creating a soil improver made from organic waste that can absorb 30 times its weight in water, supplying water and food to crops. It requires no fertilizers.
  • Sustainable Planet — Developing a plant-based protein that can be grown in salt water, with 20 times less water than other protein isolates require.
  • Orbisk — Using AI technology to quantify food waste to reduce food-waste cost, water waste and carbon emissions.

The Abu Dhabi Ministry of Climate Change and Environment started The FoodTech Challenge to encourage sustainable food production and address food waste.

The winners of the 2022 FoodTech Challenge will share a U.S.$2 million prize. The prize also includes start-up incentives, mentorship programs and grants. Close to 700 applicants from 79 countries applied for this year’s competition.

Others who have won the award have had success bringing their projects to life.

One of the winners from the first edition was Ryan Lefers of Saudi Arabia-based Red Sea Farms. Red Sea Farms builds sustainable technologies to grow food in such harsh environments as deserts.

For prospective participants in future FoodTech competitions, Lefers advises, “Carve out time to wholeheartedly invest in the process of the FoodTech Challenge because ultimately, it is an investment in your business. It is worth it to create a thoughtful application and to engage fully in all of the mentor sessions,” in an interview with FoodTech Challenge.

Global food insecurity is on the rise. The World Food Programme estimates 345.2 million people in the world will be food insecure in 2023 — double what it was in 2020.

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Making it rain

Linda Zou is a UAE researcher who uses nanotechnology to develop new materials for cloud seeding, a weather-modification technology that improves the chances a cloud will produce rain. She talked to the KUST Review about her work and the future of cloud-seeding technology.

CREDIT: Khalifa University
Linda Zou

Linda Zou is a professor in the Khalifa University Department of Civil Infrastructure and Environmental Engineering and the head of the Nano and Water Laboratory. This interview has been edited for space and clarity.

QUESTION: Walk us through the basics of cloud-seeding technology and what should people who aren’t familiar with cloud seeding know.

ANSWER: The sun shines and water vapor rises up from the Earth’s surface, and these tiny water vapors will keep on rising and finally condense to become either rain or snow.

In the presence of small particles as nuclei, water vapor condenses, turning into small liquid droplets. And that droplet will hit another small droplet during the falling process, and then they form a larger droplet. The size grows and grows. When the drops reach the lower part of the atmosphere, they’re too big, too heavy, and they fall as rainfall. And unfortunately the availability of this sort of small seeding nuclei in the atmosphere is unpredictable. It could be naturally occurring particles such as volcano ashes, dust particles or pollens. But when you need it you can’t guarantee you’ll get it.

Cloud seeding is to spread artificial seeding materials by using aircraft, flying over the bottom of suitable clouds and releasing the seeding materials, and an updraft will carry them into the cloud, to start the condensation and turn the water vapor into water droplets artificially. And this is the cloud-seeding process.

Q: How important is it to the world to tap that atmospheric moisture?

A: The World Meteorological Organization (WMO) did a survey and reported more than 45 countries are practicing some sort of weather modification. Cloud seeding is one of the major (weather-modification) technologies. This implied the advancement in the cloud-seeding materials could have a wider impact to combat the water-shortage problem globally.

Q: Is cloud seeding used primarily in desert countries or are a broad range of countries practicing it?

A: (Cloud-seeding) is technology-driven; commonly you need aircraft fleets. Countries like the US, South Africa and some European countries are very active, particularly in agricultural protection, as well. (Countries may have) a different purpose: Russia is more interested in hail-suppression. China has dry regions. For many decades, the science behind this water-related process hasn’t had much innovation, UAE is driving innovation through its UAE Rain Enhancement Science Program.

CREDIT: Anas Albounni, KUST Review
AI and nowcasting

Cloud seeding can increase a region’s rainfall, but knowing when the conditions for cloud seeding are optimal can be difficult. Read more›››

Now, researchers who recently won a U.S.$1.5 million grant from the UAE’s National Center of Meteorology think they can help by tapping into artificial intelligence.

Luca Delle Monache, deputy director of the Center for Western Weather and Water Extremes (CW3E), Scripps Institute of Oceanography at the University of California, San Diego, in March received the three-year grant of the UAE Research Program for Rain Enhancement Science (UAEREP) for the project using a hybrid machine-learning framework for enhanced precipitation nowcasting.

Nowcasting in meteorology is describing the present or predicting the very near-future weather conditions. Khalifa University’s Ernesto Damiani, Linda Zou and Hussam Al Hamadi will gather data and create a prototype artificial intelligence system for data fusion and weather nowcasting for the project.

Alya Al Mazroui, UAEREP director, says the work will continue the organization’s role in advancing rain-enhancement technology, as well as “promoting the UAE’s status as a prominent hub for rain-enhancement research and helping the world tackle the challenges posed by the scarcity of potable water.” ‹‹‹ Read less

Q: That leads into the next question: What are some of the problems and limitations that your work is looking to solve?

A: The kind of seeding material adopted around the world heavily depends on atmospheric relative humidity. That means the seeding material released is only activated or useful at very high relative humidity. So a lot of cases you release (the seeds), and if it isn’t very humid conditions, it’s not useful. So because I’m thinking on the science of the interactions between materials and atmospheric relative humidity, I can see that there’s room to improve.

Q: And your proposal is to change the seeding material?

A: Yes. I proposed three ideas: Each has been investigated and concept is realized. The first is to change the surface of the material to make it more reactive (so it can work) at a lower relative humidity. Instead of 75 percent or higher, now we can use it at 65 percent.

To achieve this, we used nanotechnology to engineer a material that is activated in much broader relative-humidity conditions. Because the structure is so porous, water will melt easily, forming larger droplets, increasing the probability that it will work.

Secondly, a bioinspired hydrophilic/hydrophobic pattern was created on the seeding material to enhance the interaction with water vapor; thirdly, a porous 3D nanocomposite was developed to promote ice nucleation and growth for cloud-seeding in cold clouds.

Q: Old-technology cloud-seeding materials might be harmful to the environment. That’s another problem you’re looking to solve?

A: There are different types of seeding material used. Various salt particles are used for warm clouds; their environmental effect is less of concern. But the one you hear about is mostly silver iodide, which is mostly for cold clouds – for ice- and snow-making. Over longer periods of application, silver iodide may pose some toxic effects. It is not used in my research project, as the design of novel seeding material is to steer away from potential harmful materials.

RELATED: Climate change promises uncharted waters for scientists studying atmospheric rivers

Q: Some of your materials are inspired by natural adaptations in biological organisms. What would you say is the value of looking to nature to solve problems?

A: Nature has evolved over millions of years. Every biological system that thrives today is the positive result of evolution. Modern analytical tools enable scientists to look at the details of biology at the biochemistry level and have more understanding on how they work. This newly gained knowledge helped us to mimic the biological mechanism in designing nanomaterials. Although we’re not able to replicate biological mechanisms, I can be inspired and learn from their principles.

Cloud-seeding materials are spread by airplanes but can also be released by balloons and drones. CREDIT: UAE Program for Rain Enhancement Science
Cloud seeding
and beyond

The United Arab Emirates’ rain-enhancement operations began in the 1990s and were developed in cooperation with such international organizations as the United States’ NASA and National Center for Atmospheric Research. Read more›››

According to the UAE Program for Rain Enhancement Science, the Emirates now have more than 60 networked weather stations, five specialized aircraft used for seeding and an integrated radar network.

Other benefits from cloud-seeding research include increased understanding of cloud microphysics; cloud dynamics and thermodynamics; the physical chain of events that lead to cloud formation and rainfall; and how cloud-condensation nuclei and ice nuclei interact with clouds.

Research impacts include improved cloud-seeding materials and delivery methods and helping meteorologists better nowcast and forecast the weather. ‹‹‹ Read less

Q: What would you say are the biggest challenges to seeding clouds?

A: One of the major problems is all cloud-seeding operations are carried out in the open atmosphere. All the conditions cannot be controlled as in a closed system.

Secondly, all clouds are different at a time and they’re also varied and unpredictable. These make the evaluation of cloud-seeding effects difficult. But we accept this unpredictability. And if the seeding materials become more and more efficient, the probability (of success) is higher for any given cloud conditions.

Q: Some of your work focuses on ice and snow instead of rain. How are these approaches different?

A: It’s different and it’s the same in some regions. Clouds that form at a few thousand meters above us are in sub-zero temperatures. Precipitation at that altitude will be ice. But when ice falls down to the earth, if it falls down in cold regions it will be snow. If it falls down to the warm regions such as UAE it will melt into rain.

So for clouds with sub-zero temperatures, different techniques have to be used. The sub-zero clouds’ conditions are different. The water vapors are oversaturated in some cold clouds, so their relative humidity is like more than 100 percent but they stay as supercooled water vapor. So at this stage if (the supercooled vapor meets) a suitable ice nuclei it will form ice crystals and grow rapidly as an ice explosion, as an avalanche of ice crystals.

So I also investigate to develop this type of ice nuclei. The ice nucleus is often silver iodide. Why? the possible theory behind is that its crystal structure is similar to the ice. So crystal grows on the other crystal due to their crystal framework lattice matching. So it’s very different from the droplets, a different mechanism.

And as we said with the silver iodide there are some problems but there aren’t many alternatives. So I designed an alternative material. This material can also help create artificial snow at ski resorts. It works well in cloud-chamber experiments.

Q: Can you describe that material?

A: The novel cloud-seeding material has a shell/core structure, it has a sodium chloride core, which is covered by a nanometer thickness of titania particles. This structure offers a synergistic effect on condensation at lower relative humidity and forms larger water droplets: Both are important to increase the probability of rainfall.

Q: Is this the sort of technology that would be used to control undesirable weather, like preventing hail?

A: Yes. That’s the case in some European countries, to protect agriculture industry from extreme weather attack, such as hail and frost.

Whether the precipitation falls as rain or snow depends on the air temperature. CREDIT: Shutterstock

Q: What impact would you say cloud-seeding will have on climate change?

A: I think this is a very important question. It is in the broader spectrum of climate-change strategies. If we got more water as rainfall through cloud-seeding, it would be cooling the weather and replenish the ground-water aquifer. There would be less demand for air-conditioning, less demand for desalinization. It has very positive effects.

Q: So what’s the next frontier? What’s the next exciting development?

A: The next frontier will be scaling up the production, making the seeding materials more available. Apart from airplane, the seeding materials can be released by other methods such as balloons, or drones. In addition, it can also migrate into surface-water-harvesting applications, like catching fog.

Q: Is there anything we haven’t covered that you want people to know?

A: The UAE Research Program for Rain Enhancement Science is appreciated because they provide us funding on my research project. I really wish that this will have a ripple effect. We need to transform the novel seeding materials into commercial-scale production and wider application. We have started working on that. I need government and industry support on this direction. If this becomes commercially technology, more countries and regions will benefit.

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Sea, salt and sun:
Desalination’s brighter future

If you’re ever lost in a desert, finding a water supply is key to your survival. Understandably, this is difficult in a desert as there is neither enough rainfall nor open-water sources, such as rivers or lakes, to reliably support the people inhabiting these areas. What many desert regions do have, however, are coastlines with access to plenty of salty seawater.

Enter desalination.

Desalination is a brilliant way to make fresh water. Seventy percent of the world is covered with water, but only 1 percent of that is potable. The solution? Take the salt out of the sea.

In the United Arab Emirates, even the groundwater is saline, in some cases up to eight times as salty as the surrounding seawater. Although this brackish groundwater can be used in irrigating salt-tolerant plants like date palms, everything else needs that water to be desalinated.

IMAGE: Anas Albounni, KUST Review
A harsh legacy of waste

“Historically, water availability has always been considered fundamental for human civilizations to evolve and flourish, from the early Mesopotamian age to the current rapidly growing cities in the Middle East. Read more›››

“Over time, wasteful water use, mismanagement and significant environmental challenges have triggered severe depletion and degradation of the available freshwater resources, with adverse effects on human health, living conditions, and social and economic prosperity.”

Tom Pankratz, Global Water Intelligence‹‹‹ Read less

In many ways, the Middle East is on the cutting edge of sustainability because the governments there were forced to confront water scarcity from the get-go. The evolution of water conservation and sustainability in this region is a result of a multi-pronged approach, involving rethinking city planning, efficient water use and innovative solutions to providing clean water.

A PERFECT FIT

Desalination plants are found in abundance in the Middle East: The U.S. Geological Survey says 70 percent of the world’s desalination plants are located in this area, found mostly in Saudi Arabia, the UAE, Kuwait and Bahrain. This makes sense: These countries are water-strapped but oil-rich. An energy-intensive clean-water-production technique is a perfect fit.

This oil won’t last forever, though. And the world is already feeling the effects of global warming and climate change thanks to rampant use of fossil fuels in applications including desalinating water for desert populations. The solution? “Renewabilize” it. And luckily, the Middle East also has plenty of renewable energy to spare: sunshine.

RELATED: Desalination has social benefits – and costs, too

But first, how does desalination work?

The most popular method is reverse osmosis, where large quantities of seawater are pushed through a semipermeable membrane to remove the salt from the water. Think of this membrane as a very fine sieve that catches salt and other impurities.

Although this is an effective means to desalinate seawater, it is driven by very high hydraulic pressure and requires robust pumping and expensive pretreatment. In Saudi Arabia’s Eastern Region, for example, the seawater first needs to be filtered for oils, greases and jellyfish.

IMAGE: Shutterstock
What to do
with the brine?

Brine is a high-concentration solution of salt in water and is a byproduct of many industrial processes, including desalination. The simplest way to dispose of brine is to return it to the ocean, but high localized brine concentrations raise seawater salinity and alkalinity, creating an environmental risk. Read more›››

Another common way to dispose of brine is to use evaporation ponds, where the water is evaporated and the salt is collected for use in other processes. Unfortunately, neither method is a fully environmentally friendly approach, and untreated brine can be corrosive and toxic if disposed of improperly.

A collaborative work between King Abdullah University of Science and Technology, Saudi Arabia, and Khalifa University of Science and Technology, UAE, saw the design of a solar crystallizer that uses solar energy as the main energy source to heat and evaporate the brine. This follows the same concept as an evaporation pond, except the condensate from the evaporated brine is collected as fresh water.

This sounds like an obvious solution to reducing the water loss, but the amount of salt in the water can affect the performance of the materials in the crystallizer, so the team needed to design a new device in which the water-evaporation surface and the light-absorption surface are separated by an aluminum sheet with high thermal conductivity. The bottom and inner walls absorb the solar energy, while the outer wall performs the evaporation and crystallization parts of the process.

The research team says the high thermal conductivity of the aluminum separator conducts the heat generated at the bottom of the device to the walls for water evaporation, resulting in a “high solar-to-vapor performance.” They believe this is a simple but promising strategy to provide a low-cost and sustainable solution for treating industrial brine, especially in small- to medium-size applications.‹‹‹ Read less

SEAWATER: SEE WATER

Desalination is an energy-hungry process. According to Richard Muller, professor of physics at the University of California, Berkeley, it will always take one kilowatt hour or more of energy to desalinate a cubic meter of seawater.

RELATED: Khalifa University is a hub for desalination research

But Corrado Sommariva, founder and CEO of the Middle-East-based Sustainable Water and Power Consultants, says the desalination sector has been experiencing a revolution in the past five years and believes the process can be powered by renewable energy, particularly solar.

The cost of desalination from reverse osmosis has fallen dramatically in recent years, with much of this decrease in price stemming from streamlining processes and cheaper electricity, he notes, and as solar power looks set to become the cheapest form of electricity, moving to a renewable-power supply seems inevitable.

Tom Pankratz, editor of the US Water Desalination Report, confirms: “Desalination is more energy-intensive than other water-treatment processes, so there’s a growing interest in using renewable energy to reduce a plant’s operating costs and its environmental footprint. In many places, especially in the Middle East where desalination is the primary source of water, renewable energy is often much less expensive – even with the abundance of fossil fuels in the region.

”In theory,” he says, “any form of renewable energy could power desalination, but solar power is generating the most attention. Helpfully, the arid regions that need desalination the most are also the ones blessed with abundant sunshine.

IMAGE: Anas Albounni, KUST Review
Solar stills:
A classic solution

Sometimes the old ways are the best ways. Read more›››

The oldest desalination technology is the solar still, a simple device that uses sunlight to purify water.

Salt water is placed in the still and an angled piece of glass or plastic is placed above. The sunshine evaporates the water, which then condenses on the surface above before running down the surface to collect in a separate trough.

The impurities and salt remain in the bottom of the still and the water in the trough is clean, pure drinking water.

If you do find yourself lost without a clean water supply, you can make a solar still from a sheet of plastic lining a hole in the ground, a mug to collect the clean water, and another plastic sheet on top anchored with a rock to create the angled surface.‹‹‹ Read less

“Solar farms are sprouting up in more and more areas in the Middle East, and their power generation gets priority to feed into the grid,” Sommariva says. “For at least six hours a day, power tariffs as low as 1 U.S. cent per kilowatt hour are available to utilities from photovoltaic plants as the amount of electricity being generated by these plants will shortly outstrip grid demand during certain hours of the day. Photovoltaic power offers the chance to both operate desalination plants as potable-water generators and grid-energy absorbers and buffers.”

A TOUGH BALANCE

The journey of electricity from the power plant to our homes and businesses is not always a smooth one. Grid operators are faced with the complex task of balancing the amount of electricity fed into the grid against the amount of electricity consumed to keep the power system stable. But as more intermittent renewable-energy sources of electricity, like solar and wind, are fed into the grid, this balancing act becomes even more challenging.

Pankratz notes that it’s no coincidence renewable-energy desalination plants are being implemented in Saudi Arabia and the UAE, where some of the largest solar photovoltaic power plants are also being built.

“For larger plants, it is often infeasible to locate a large wind- or solar-energy power plant near a coastal seawater desalination plant. In these cases, it is usually more practical and cost-effective to build the wind or power plant farther inland, and feed the energy into an electrical grid that can be distributed to the desalination plant and other facilities,” Pankratz says.

“This approach not only ensures that the desalination plant and energy plants are located where they are most cost-effective, but it also eliminates, or lessens, the need for large batteries to store the energy during the night or low-wind conditions.”

AN INGENIOUS BATTERY

Sommariva believes solar-power-driven desalination plants could also act as an electricity-storage system, using the excess electricity produced by photovoltaic plants, rather than continuously running fossil-fuel plants, to desalinate water. Connecting the desalination plant to the renewable-power grid could be the solution to two problems facing the region: renewable-energy storage and drinking-water shortage.

In theory, any form of renewable energy could power desalination, but solar power is generating the most attention.

– Tom Pankratz, editor of US Water Desalination Report

“If the industry could simply move away from the traditional concept of steady water generation mainly dictated by a lack of storage, we could imagine a desalination plant able to operate in a sustainable and flexible manner: producing when excess power is available in the grid from photovoltaic production and curtailing desalination when the grid is in peak mode,” Sommariva says.

Additionally, producing water when excess power is available from solar power and curtailing production when the grid is in peak mode does not require any dramatic changes to infrastructure, except an increase in storage capacity for the resultant potable water. As Sommariva points out, additional water-storage capacity is part of the strategic development in the region anyway.

“If the industry could simply move away from the traditional concept of steady water generation mainly dictated by a lack of storage, we could imagine a desalination plant able to operate in a sustainable and flexible manner: producing when excess power is available in the grid from photovoltaic production and curtailing desalination when the grid is in peak mode,” Sommariva says. Additionally, producing water when excess power is available from solar power and curtailing production when the grid is in peak mode does not require any dramatic changes to infrastructure, except an increase in storage capacity for the resultant potable water. As Sommariva points out, additional water-storage capacity is part of the strategic development in the region anyway.

CAPTION: Solar power-driven desalination plants could also act as an electricity-storage system. IMAGE: Anas Albounni, KUST Review

“It is necessary that policy makers start seeing desalination not only as a water producer but also a potential energy buffer and indirect storage system,” he says, adding that all of the desalination plants in the Gulf region and worldwide have the opportunity to smart retrofit and develop a net-zero-energy operational process.

CONTINUED IMPROVEMENTS

The potential use of renewable energy for desalination is hardly a new idea. Reported since the mid-1990s, a few conventional water-treatment plants in the United States have integrated solar power for water treatment, including a Massachusetts plant in 2009.

IMAGE: Anas Albounni, KUST Review
Managing
the resources

Previous poor water management and unsustainable agriculture practices in the Middle East have exacerbated desertification, and water scarcity is becoming severe in countries including Jordan and Yemen. Read more›››

Agriculture, industry, urbanization and population growth are all fueling the demand for more water, while climate change decreases supply day by day.

As the UN Food and Agriculture Organization points out, for every 1 degree Celsius of global warming, 7 percent of the world could see 20 percent of renewable water resources dry up. More frequent and severe droughts, combined with crops needing more water in higher temperatures, will put further pressure on dwindling water supplies.

According to the Water Project, other concerns with the future of desalination plants in the Middle East focus on the improper dependency they will cause, instead of encouraging alternate forms of water and energy to be explored and conservation of fresh water.‹‹‹ Read less

New renewable-energy technologies are becoming available for desalination applications as well. For example, an Australian pilot project utilizing wave-power technology for seawater desalination using submerged buoys began operating in 2015.

Despite the challenges, many researchers are working to improve desalination so it can reach more people and address climate change without contributing to it. The Global Clean Water Desalination Alliance has set a goal for 20 percent of new desalination plants to be powered by renewables between 2020 and 2025. Currently, the global share of renewable energy used in desalination is just 1 percent.

Sommariva does point out that the main challenge in pivoting to renewable-energy-powered desalination is retiring or converting traditional thermal-desalination assets.

“These plants have a residual economic life of several decades,” he explains. “Not to mention they are substantially energy-intensive. But desalination is a technology that is fast developing.”

There haven’t been any major recent breakthroughs in the technology, he adds, but the process is seeing a steady rate of improvements that are fine-tuning the process for ever-increasing efficiency.

A GROWING APPROACH

Already, stakeholders in the desalination industry are beginning to turn to renewables.

Dubai Electricity and Water Authority is planning to power its desalination plants with solar power by 2030, pushing for increased efficiency and large-scale integration of renewable energy in its water-production processes.

CAPTION: The desalination triangle: When the oil runs out, can the sunlight step in to power the process? IMAGE: Anas Albounni, KUST Review

In Port August, Australia, one desalination plant uses solar power to provide potable water for its tomato farm. In fact, in Western Australia, all new desalination plants must use renewable energy.

“All of the large Australian seawater desalination plant operators have contracts with renewable energy providers who supply energy into the local grid in an amount equal to that required by the desalination plant, in a cost-offset arrangement,” Pankratz adds.

Both the King Abdullah Economic City and the King Abdulaziz City for Science and Technology in Saudi Arabia are supplied by solar-powered seawater desalination plants, taking water from the Red Sea. Also in the United Arab Emirates, one Masdar plant in Ghantoot produces desalinated water using a solar-powered solution. The company behind this plant, Mascara Renewable Water, is now developing similar projects in Mauritius, Cape Verde, South Africa, Morocco and Vanuatu.

OTHER PROJECTS

There have also been several small-scale trials across the Middle East, Spain and India bringing together concentrated solar power and seawater desalination. Pankratzs says there are on-going research projects looking into using other forms of renewable energy too, including those from wave power, geothermal and biomass sources, and even from the energy contained within salinity, chemical and pressure gradients.

“There is absolutely a real future for this, and it’s happening now,” he says. “Renewable-powered desalination is proving itself in plants in the GCC and around the world. It’s happening on a local scale too, with hundreds of small, renewable-energy desalination plants under construction in island communities and off-grid locations in developing countries such as Kenya, Madagascar, Mozambique and Nigeria.”

As the planet faces an uncertain water future, desalination will continue pumping out freshwater for thirsty cities. And as renewables become increasingly mainstream and technology prices continue to fall, renewable energy will become an economically viable option as well as the environmentally friendly solution.

It’s not all bad though.

Renewable-powered desalination is proving itself in plants in the GCC and around the world.

– Tom Pankratz

Desalination can provide sufficient quantities of water as and when needed, which can significantly enhance the water security of a nation, while also supporting regional stabilities by evading any conflict over water resources. This also means there are a plethora of opportunities for society to benefit from desalination technologies.

Local employment opportunities during the construction and operation of desalination plants are one such benefit, but easy access to cheap water also means more work and education opportunities for women, who otherwise typically bear the often expensive, time-consuming and physically taxing burden of collecting and carrying water in the poorest communities.

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Civil planning in the age of pandemics

COVID-19 was not the first pandemic to force changes in how we live: Communicable diseases have transformed urban planning before.

The Black Death outbreak in 14th century Europe saw narrow public squares transformed into larger public spaces better integrated with nature. The cholera outbreak in 19th century London prompted improvements to water-management infrastructure. And during the Spanish flu, residents eschewed cramped public transport in favor of walking in uncrowded streets.

Many of the practices in architectural and urban design prevalent now have evolved from similar measures taken throughout history to safeguard the health, hygiene and comfort of city dwellers. Now, researchers are turning their attention to suburbia.

Cities have to learn how to balance the competing demands of social distancing, preserving the economy and promoting people’s well-being.

– Khaled Alawadi

The team from Khalifa University says accessibility and walkability are crucial aspects for pandemic-proofing neighborhoods. The findings, published in Sustainable Cities and Society, suggest suburbs can provide better pedestrian accessibility with the right combination of structure and design.

Future pandemics may bring more lockdowns, says Khaled Alawadi, associate professor in the KU Department of Civil Infrastructure and Environmental Engineering, and open spaces will be vital.

“Cities have to learn how to balance the competing demands of social distancing, preserving the economy and promoting people’s well-being. … We argue that suburban design in the post-pandemic era should facilitate a balanced density level that is higher than the suburban norm but lower than that of traditional compact cities.”

A heavy Western influence

Despite the vast majority of the population continuing to reside in suburbs, retrofitting efforts to promote walkability and transit-oriented development are mostly limited to city centers. In GCC countries and the UAE in particular, suburbanization is the dominant development trend: suburbs occupy more than 50 percent of Abu Dhabi’s urbanized land and 40 percent of Dubai’s urban area.

Because suburbs are likely to continue to be the primary features of urban development, the researchers argue that suburban design should be rethought, instead of vilified, discarded or ignored. Their work integrates morphological mapping, urban-network analysis and forgotten urban-form elements such as alleys into designing future suburban areas. They focused on neighborhoods in Abu Dhabi and Dubai, examining the structural and physical layouts of both cities that resemble neighborhood typologies common in Western cities.

The grids and fragmented layouts that comprise the diverse set of neighborhoods in Abu Dhabi and Dubai are the same applied in city planning around the world.

– Khaled Alawadi

“Both cities have a history of inviting and hiring consulting firms and foreign architects who were all trained in Western countries,” Alawadi says. “The grids and fragmented layouts that comprise the diverse set of neighborhoods in Abu Dhabi and Dubai are the same applied in city planning around the world.”

The need to rethink suburban design stemmed from the need to confront climate change, long before the emergence of the novel coronavirus. Suburbs have been harshly criticized for their social, economic and environmental impact, and in terms of physical planning ideals, one of the key criticisms is low pedestrian accessibility.

Detached, single-family housing — the primary form of the suburban landscape all over the world — has either been glorified as the icon of the American dream of vilified as a deplorable built environment, but the KU team argues suburbia should not be visualized as sprawling low-density settlements only.

“The potential to design suburbs in various forms and levels of density cannot be overlooked,” Alawadi says. “For example, new suburbs can be designed to feature interconnected street systems rather than fragmented and broken street networks. Accessibility plays a vital role in good urban form. Residents are more likely to walk or cycle when their local area is more accessible and the distance between origins and destinations is shorter.”

Increasing accessibility

Accessibility and mobility go hand in hand: Mobility can be defined simply as how far you can go in a given amount of time, whereas accessibility is how easily one can get there. Research shows that, at neighborhood scale, accessibility has a significant influence on urban living, spatial equity, public health and walkability.

Comparing Abu Dhabi with Dubai, the researchers found that Dubai is more accessible overall but particularly when its network of alleys is considered. This suggests that better accessibility can be achieved by linking street networks with alleys between buildings.

“Walking within neighborhoods for recreational, fitness and utilitarian purposes is indispensable in a post-pandemic world,” Alawadi says. “The COVID-19 pandemic revived old debates in urban planning but there is an almost unanimous consensus regarding the need for walkable neighborhoods in post-pandemic cities. People want easy access to outdoor spaces, public parks and other destinations to meet their daily needs. Redesigned suburbs with more suitable infrastructure for local accessibility have the potential to serve as a viable housing option for the post-pandemic world.”