The modern rain dance: Cloud seeding
Weather was a phenomenon we thought we could never control. Until now. Cloud seeding is a growing business in the world’s dry and well-off regions.
For centuries mankind has looked to the skies in the hope for rain to quench people’s thirst, the lands and alleviate drought. During the dry months Native American tribes used to perform rain dances, wearing jewelled headdresses and special clothing to invoke the clouds and bring rain to an entire community. In ancient China, shamans – believed to be in contact with spirits that control rainfall and flooding – would perform sacrificial rain dance ceremonies during droughts.
Fast forward thousands of years and rather than having to dance, prey or sing for water, humans found a way to engineer rain to where it was needed. Known more broadly as weather modification, the process of cloud seeding or rain enhancement involves dispersing material – salts or silver iodide crystals – into clouds to encourage rainfall. Surprisingly, the process was actually discovered by accident.
It started with a bang. According to the Texas Weather Modification Association (TWMA), it was during the 1861- 1865 Civil War that an engineer called Edward Powers observed that it often rained where major battles had taken place. At the time clouds seemed to be invigorated whenever smoke, dust and other particulates from conflict were put into the air.
Since then, from 1891 in Texas various experiments took place, with strategically placed dynamite, through to ground based generators to disperse agents such as silver iodide. More recently, aircrafts have been kitted out to release hygroscopic and glaciogenic materials, including dry ice.
Cloud seeding then became so popular in Texas in the 1950s and 1960s that legislation was introduced requiring any activity to require a license issued by the state’s water agency.
TWMA says that since 2004, targeted areas saw an increase of 13 per cent in total rainfall. That may not initially sound like a huge difference yet the association claims for every dollar invested into weather modification programs, the return is roughly USD 19 with the potential state-wide impact upwards to USD 38. This is based on an analysis done in conjunction with the Texas A&M Agrilife Extension Center. The returns were calculated based on “reducing the need to irrigate”, according to TWMA.
Radar and satellite data, together with meteorological observations are used to help time cloud seeding activities
Selected materials are dispersed into the atmosphere by flying aircraft at an altitude of 5,000 feet above the cloud base
Silver iodide (Israel) or sodium chloride (UAE) accelerate the creation of ice particles in the cloud. Previously, small drops of rain at the bottom of clouds would not be heavy enough to fall as rain. When turned to ice crystals through seeding, they fall to earth as rain, due to their added weight
In Israel, water company Mekorot believes its cloud seeding efforts increase rainfall on average between 10-15 per cent, generating between 30-40 million cubic metres per annum. Estimates suggest this costs the company USD 1.5 million per year.
In the UAE, although cloud seeding is in much earlier development, authorities have higher expectations and believe it can enhance rainfall by as much as 30-35 per cent. Early tests in the Al Quaa region showed monthly rainfall at 136mm after seeding but 29.9mm previously. Costs are estimated at USD 1 per cubic metre of water delivered.
In Texas, TWMA says targeted cloud seeded areas have seen an increase of 13 per cent in rainfall. USD 1 invested into cloud seeding has an estimated return on investment of USD 19 based on saving irrigation costs.
Meanwhile, at the same time during the 1960s Israel carried out three cloud seeding experiments, followed by extended seeding programmes in the north of the country from 1975.
During the winter months between November and April, the country was seeding clouds with silver iodide in an effort to increase the amount of water that falls into the Sea of Galilee and its surrounding watershed.
"It is believed that cloud seeding may add as much as 18 per cent to the rainfall over the Sea of Galilee watershed and about 10 per cent to what falls on the lake itself."
Israel’s national water company, Mekorot, believes such efforts have increased rainfall on average between 10-15 per cent - generating additional water of between 30-40 million cubic meters per annum into the sea “at a very low cost”.
“By the 1960s, Israel had put a lot of resources into testing rain-cloud seeding and developed world-renowned expertise in how and when to seed,” said author and businessman Seth Sigel, in his book, Let there be water: Israel’s solution for a water-starved world. “It is believed that cloud seeding may add as much as 18 per cent to the rainfall over the Sea of Galilee watershed and about 10 per cent to what falls on the lake itself. The technique may be adding as much as ten billion gallons of water a year to the lake. At a cost of only USD 1.5 million for the annual Mekorot cloud-seeding operation, this is very inexpensive water.”
Fiddling with nature
Today estimates from the World Meteorological Organization suggest there are over 80 cloud seeding projects taking place around the world, in more than 52 countries. Cloud seeding has turned into a big business. Take the project list of Weather Modification Inc. – one of the world’s largest private aerial cloud seeding companies. From Indonesia, to Burkina Faso and Saudi Arabia, not to mention the 30+ projects in North America – it’s clear other countries are looking to the skies as a solution to increasing water scarcity.
However, the activity of fiddling with weather patterns and intercepting water on route to where nature intended it to go, has attracted its fair amount of criticism over the years.
Three researchers – Prof. Zev Levin, Prof. Noam Halfon and Prof. Pinhas Alpert – from Tel Aviv University’s Department of Geophysics and Planetary Sciences wrote a paper entitled ‘Reassessment of rain enhancement experiments and operations in Israel including synoptic considerations’.
Featured in an Elsevier journal called Atmospheric Research, the work analyzed 50 years of data on cloud seeding in Israel but said that the resulting increase in rainfall was down to changing weather patterns. It concluded that: “Re-analysis of the cloud seeding experiment and operations in Israel shows that seeding has not produced the expected enhancement in rainfall.”
According to the researchers, when comparing the seeded area with an “unseeded adjacent area to the south” it showed “no difference with even slightly higher values in the unseeded area”.
“This suggests that seeding had little or no effect on total precipitation on the ground”, the paper said.
Efforts in the Emirates
Later to the game, the United Arab Emirates (UAE) is also trying its hand at cloud seeding. Last year the UAE Research Program for Rain Enhancement Science was launched. Overseen by the National Centre for Meteorology and Seismology (NCMS), to date more than 110 cloud seeding test flights have been launched. It is hoped water supplies, with the majority currently supplied by desalination, could be boosted by 5 per cent.
Results published to date are positive. In April 2013 monthly rainfall in the Al Quaa region of Abu Dhabi was recorded at 136mm following cloud seeding. This compared to a monthly average of 29.9mm between 2003 and 2014 without rain enhancement, according to NCMS.
Speaking to WaterFront, Alya Al Mazroui, programme manager for the UAE Research Program for Rain Enhancement Science (UAEREP) says cloud seeding costs USD 1 per cubic metre of water produced, which she says is “cost effective” when compared to desalination. She believes cloud seeding can enhance rainfall by 30-35 per cent.
“We are now in an arid region: we have average below 100mm annual rainfall rate with a big pressure on our total annual water use in the country. Add to this our current water recharge rate is low. We are looking for a more sustainable approach – we are addressing water security issues through the programme.”
Omar Al Yazeedi, director of research, development & training department at the NCMS adds: “The goal here is to increase the rain – no matter where it is of course it will be beneficial for animals, for agriculture, for recharging the water in aquifers and for the benefit of people.”
Others remain skeptical of the work, questioning how the enhanced rain will be collected and used. After all, unless seeded clouds rain over crops or water reservoirs, what use is the additional water if it’s lost in the desert?
"It is hoped water supplies, with the majority currently supplied by desalination, could be boosted by 5 per cent."
“Cloud seeding is usually for agriculture,” says David Lloyd Owen, managing director of independent consultancy, Envisager. “For the UAE to encourage agriculture in its area would be rather indulgent and probably pretty expensive. For piped water, there is the challenge of gathering the rain and getting it to the pipes. Catchment systems need to be able to gather water through groundwater and deserts tend to be poor in this respect. So, this is something of a challenge here.”
As part of the UAE research programme, a grant of USD 5 million is offered over a three-year period to be shared by up to five winning proposals. Earlier this year three scientists from Japan, the UAE and Germany shared the funding:
Masataka Murakami, visiting professor from the Institute for Space- Earth Environmental Research, Nagoya University (Japan), for his work on precipitation enhancement in arid and semi-arid regions.
Linda Zou, professor of chemical and environmental engineering from the Masdar Institute of Science and Technology (UAE), for her work on using nanotechnology to accelerate water condensation.
Volker Wulfmeyer, managing director, professor, and chair of physics and Meteorology at the Institute of Physics and Meteorology in the University of Hohenheim (Germany), for his work on cloud seeding optimization.
Since Edward Austin’s early observation during the American civil war of conflict-induced rain, cloud seeding methods continue to evolve to this day. Some will continue to argue that we should not be meddling with nature. Others believe if the technology is available, we should take advantage of it and deliver rainwater to where it is most needed. The weather and rainfall by their very natures are unpredictable. Recent investment from the Middle East into cloud seeding research should help to keep the momentum up. Yet getting additional rainwater through to residents’ taps comes with its own unique challenges.
"Catchment systems need to be able to gather water through groundwater and deserts tend to be poor in this respect. So, this is something of a challenge here.”
Water efficiency can potentially have a large impact at the level of a municipality or across a sector such as agriculture, progressively and sustainably reducing water used while still making social and economic development possible.
Make no mistake – an increase in available water supply will always play an important role in ensuring water security, especially in developing countries where there is a backlog in the development of this infrastructure. However any increase in supply which is not accompanied by a concomitant process of improving water use efficiency (value added per unit of water consumed) is likely to be futile in the medium term, with water scarcity returning once the newly supplied water becomes fully allocated.
Hence a short “health warning” should accompany any proposal to increase supply (cloud seeding included): Your supply solution should not be consumed in excess and should form part of a comprehensive programme aimed at reducing demand and improving water-use efficiency. Failure to heed this warning may result in you facing water scarcity again sooner than you think.
- The full version of this article appears in issue #2 of the Stockholm Waterfront Magazine that can be found here: http://www.siwi.org/wp-content/uploads/2016/08/WF-2-2016-web-2.pdf