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South Africa's award-winning rainfall enhancement programme may soon be back on track
RainmakingIt is estimated that, withoutappropriate water resourcemanagement interventions, by 2020, South Africa’s water reserves will have diminished to the point that the country could be classified as a water-scarce, arid state.

As a result, a renewed effort is being made by the Department of Water Affairs and Forestry (Dwaf) and the South African Weather Service (Saws) to reinstate South Africa’s award-winning rainfall enhancement programme, which has been dormant for the last six years.

This is according to chairpersonof the World Meteorological Organisation (WMO) expert team on weather modification andresearcher at Saws Dr Deon Terblanche, who tells Engineering News in an exclusive interview that this programme could increaserainfall in target areas by approx-imately 24%.

However, Terblanche elaborates that, although South Africa hasbeen the global leader in rainfall enhancement technology for the last two decades, owing to a lack of field activities for a number of years, the country is rapidly losing its capabilities in this field.

“An attempt is currently being made by Saws and Dwaf to possiblyresume hygroscopic flare cloud-seeding activities.

“This can be evidenced from a meeting that was held last week between the two governmentbodies.” While it is too soon to reflect on the outcome of these discussions, Terblanche notes that it is hoped that they will eventually lead tothe adoption of an initiative that will develop the scientific research that was conducted in South Africaduring the past two decades into useful technology.

    Background
Terblanche tells Engineering News that South Africa’s involvement in rainfall enhancement technology began in 1980 when chronic water shortages in the economic industrialheartland of South Africa, arising from excessive demand on limitedwater resources, first promptedresearch into weather modification as a potential means of augmentingrainfall, river flow and reservoir storage.

In particular, rainfall enhancement was initially identified and pursued as a viable option forresearch and development by Saws, Dwaf and the Water Research Commission (WRC), which pro-vided the funding and projectmanagement expertise.   The research team that initially pursued this initiative consisted of a group at the Bethlehem weather office in north-eastern Free State, CloudQuest, a private company in Nelspruit that conducted theexperiments and a significantportion of the scientific research, and the University of South Africa (Unisa), which provided statistical expertise and analysis of results.

Terblanche explains that, during the 1980s, there were two significant randomised seeding experiments in South Africa, which attempted to test the hypothesis that glacio-genic seeding of mixed-phased cumulus clouds, with either silver iodide or dry ice, would enhance precipitation from such clouds.

“The emphasis of this research was on the understanding of natural processes in small cumulus storms to determine the effects of seeding clouds with dry ice particles,” says Terblanche.

“Although results at times seemed promising, they were never entirely convincing.” However, the amalgamation of these forerunner projects in 1990, with reformulated goals, provided the foundation for a new research initiative: the National Precipitation Research Programme (NPRP).

The NPRP was, in turn, transformed into the South African Rainfall Enhancement Programme (Sarep) in 1997.

Terblanche explains that the NPRP-Sarep spanned a decade of research and development and field activities between 1990 and 2000, which saw South African rainfallenhancement technology based on hygroscopic seeding advance from the conceptual through the experimental to one that has been evaluated semioperationally, with a con-siderable degree of success.

The NPRP component of theresearch was initially conducted within an area ranging in altitude from 800 m to 1 800 m, character-ised by continental atmosphericconditions and encompassinga large part of south-western Mpumulanga and north-eastern Free State.

With the transition to Sarep, field research and operations were translocated northwards to the Tzaneen-Polokwane area of Limpopo, where the altitudinal rainfall regimes are similar to those of the NPRP experi-mental area.

Terblanche elaborates that up to five aircraft were employed duringvarious stages of the research, which were variously instrumented and used for cloud physics research, rainfall measurements at cloud base and cloud seeding operations.

During this period, a database of 127 storms was created, of which 62 were seeded using hygroscopic flare technology.

Terblanche explains that the seeding methodology involves a process whereby cumulus clouds are made to ingest hygroscopic smoke particles by means of pyrotechnic flares mounted on aircraft, which enhancesthe process of droplet formation and precipitation development in clouds.

“The results of the field experiments conducted during the decadeindicated that seeded cloudsyielded 24% more precipitationthan unseeded clouds,” says Terblanche.

“Moreover, this research gives South Africa the opportunity toenhance rainfall to increase river runoff by up to 10% in certainspecific circumstances.” Despite these positive results, former scientist and researcher of the WRC involved in Sarep, Dr George Green, tells Engineering News that, during the late 1990s, the WRC stopped its funding of theprogramme as field experiments proved to be quite costly.

“Sources of funding thenincluded the Limpopo Departmentof Agriculture, Dwaf and the National Department of Agriculture, with the WRC playing a coordi-nating role together with the Dwaf-appointed Sigma Consulting Engineers.” “However, by 2000, continued funding from these sources was no longer available, resulting in thediscontinuance of hygroscopicflaring field activities.” In addition, by 2000, Dwaf changed its national water priorityfrom rainfall enhancement toaddressing the basic water needs of South Africa by first using theavailable water resources.

Despite efforts by the then Dwaf director-general, Mike Muller, to move the science that had been developed in the previous decade into application, his suggestionsremained ‘up in the air’.

“In particular, I had insisted that the next step should be to designa catchment level intervention that would aim to demonstrate thathygroscopic flaring technologycould cost-effectively produceuseful water, such as additional rainfall in an area where it could be captured by a dam,” Muller tells Engineering News.

“This would require moreattention to the delivery technology,which included using unmannedaircraft, as well as identifyingregions where it could be applied.

“Another application option would be to find commercial users such as the forestry industry or highveld rain-fed agriculture, which could benefit from increased rainfalldispersed over large areas.” Despite the lack of action on these suggestions, Muller stressed that systems are in place within Dwaf to review the role technologycan play on a regular basis and to ensure communication betweenthe role players.

Significantly, this has paved the way for renewed dialogue between Saws and Dwaf to explore possibil-ities of resuming rainfall enhancement as the rapid growth of the economy and subsequent commercial and industrial demand on South Africa’s water resources arecompelling Dwaf to turn itsattention back to rainfall enhancement.

It is believed that, if the prelimi-nary discussions between Dwaf and Saws are successful, the WRC should retain a significant role as the programme moves from research into development.

In addition, skills scatteredbetween Saws, the private sector and local universities will have to be mobilised to resume work on the technology of which Dwaf is the custodian.

Award
Despite the lack of field activities for the last six years, South Africa has remained the global leader in rainfall enhancement technology for the last decades.

However, other countries, such as the US, the United Arab Emirates (UAE) and France, are actively usingthe technology first developedby South African scientists in the 1980s.

In particular, Green tells Engineering News that the National Centre for Atmospheric Research (NCAR) in the US has been furthering research in this area.

“But active South Africancollaboration in the NCAR programme has ensured that South Africa has not entirely lost theposition of leadership that was once its sole domain,” says Green.

Significantly, South Africa’s role in the development of this crucial rainfall enhancement technologywas recently recognised by the President of the UAE.

The Department of Atmospheric Studies of the Ministry for Presi-dential Affairs of the UAE and the WMO signed an agreement on the establishment of a special prizefor excellence in advancing the science and practice of weather modification in May 2003.

The prize is intended to assist in fostering further research into weather modification.

To this end, in February this year, the South African national precipitation research and rainfall enhancement programme won the second prize of $200 000 for thedesign and execution of a successful weather experiment involving the revolutionising concept based on hygroscopic nuclei injection and radar tracing software.

“This international recognition is seen as a boost to the South African water sector, and the prize money will be used to further the science of rainfall enhancement and build capacity in the field,” concludes Terblanche. 

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Published: 2006/09/29
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Author: jade davenport
Portfolio: Staff Writer
E-mail: newsdesk@engineeringnews.co.za