JEFFREY A. THORNTON
As we approach the 21st century, many countries face increasing shortages of freshwater. Even traditionally water-rich countries in Europe and North America are feeling the effects of past abuses of freshwater supplies, while in the water-poor countries of the inter-tropics, critical shortages are developing into incipient or actual crises.
As a result, water resource managers are increasingly looking to the past, not in a spirit of nostalgia, but to blend technologies born out of a traditional need to conserve water with futuristic materials and techniques.
A joint effort
UNEP has responded by drawing up a compendium of traditional and modern approaches to protecting, rehabilitating and harvesting freshwater sources other than surface and groundwater reserves that are commonly considered the only reserves of freshwater available to the modern world. They include techniques for obtaining freshwater from saline water, wastewater and even fog, and draw on concepts and methods dating back to the earliest days of humankind.
The series of books, a joint effort from UNEP's Water Branch and its International Environmental Technology Centre, is being published under the title Alternative Technologies for Freshwater Augmentation*. So far,
UNEP has completed source books for five regions: Africa, Asia and the Pacific, Central and Eastern Europe, Latin America and the Caribbean, and small island developing states. A sixth volume for Western Asia is under way.
Many of the technological approaches outlined prove to be common to all regions, although with distinctive geographical variations. For example, the harvesting of rainwater runoff from rooftops or similar hard surfaces for domestic and garden use is worldwide, though the technique varies to meet local architectural demands ranging from the thatched roofs of the South Pacific to the flat rooftop patios of Latin America. All that is required is a system of guttering and a collection vessel - the proverbial rain barrel. Materials can range from all-natural bamboo and wood to high-tech PVC.
In agriculture, too, techniques such as the use of planting beds or pits and terraces designed to retain moisture also prove to transcend regional boundaries. Whether known as zai, fanya-juu, or waru waru these methods of cultivation all aim to keep rainwater or irrigation water on the land rather than contributing to erosive runoff that degrades water quality in rivers, lakes and coastal waters. These traditional techniques may not mix well with 'modern' mechanized agriculture but they are proving effective in the cultivation of some high-value crops as well as augmenting household food supplies.
Other technologies discussed are more region-specific. For example, the highly engineered approaches to distribution, system maintenance, and wastewater treatment are particularly relevant to urbanized regions such as Europe and Latin America.
The books pay special attention to regional methodologies. For example, the traditional stone spouts that were constructed around natural springs in the Himalayan foothills of India and Nepal are now being restored for use as village water supply points. In Latin America, the recent development of underground 'impoundments' that collect and store water within dry river beds has its origins in traditional water-harvesting methods developed in the Chaco region of sub-Andean Argentina and Brazil. In Europe, the reintroduction of dam-building beavers is increasing natural infiltration from rivers into aquifers that augment groundwater supplies (on which many urban centres depend), at the same time reducing flooding and restoring degraded wetlands.
At the other end of the technological scale, the books cover complex and modern technologies, such as reverse osmosis and wastewater reclamation, which require skilled personnel and precision engineering. These, it is acknowledged, are best-suited to municipal networks or industrial enterprises. The importance of water conservation and ways of extending the availability of existing water resources are also discussed.
The source books emphasize methodologies that work - old and new, engineered and non-engineered, high-tech and appropriate-tech. All have been tried and tested in the field, even if some of the alternative technologies are best described as 'still experimental'. The authors supply contact names and addresses of agencies and individuals who are willing to discuss a range of technologies and traditions, many of which were abandoned more than 50 years ago in favour of highly engineered sources. Their practical experience demonstrates once again that old is not always worse.
* Available from UNEP's International Environmental Technology Centre, 1091 Oroshimo-cho, Kusatsu City, Shiga 525, Japan.
Jeffrey A. Thornton is Managing Director of International Environmental Management Services in Wisconsin, United States of America.