Water efficiency I: Cities
by Katherine Waser
Water management has always been important to cities: any large aggregation of humans must deal both with obtaining water for drinking, industry and agriculture, and with disposing of wastewater. Historically, though, as long as population numbers and population density were relatively low, water management was not a serious problem even in dryland cities. This is no longer the case. With increasing urbanization and explosion of population numbers in megacities, particularly in developing countries, water management has become a crucial challenge, especially in light of the dwindling availability of new water resources to develop. This is leading to new ways of thinking about water provision and use. Writing in the February 2001 issue of the Scientific American, internationally recognized water expert Peter H. Gleick said, "At the outset of the new millenium, however, the way resource planners think about water is beginning to change. ... The challenges we face are to use the water we have more efficiently, to rethink our priorities for water use and to identify alternative supplies of this precious resource." (Gleick 2001)
The articles in this issue of the Arid Lands Newsletter provide four discrete examples of how these challenges are being met, in various urban contexts, by specific governmental agencies, NGOs, and individuals. First, we visit the city of Windhoek, the capital of Namibia, sub-Saharan Africa's most arid country. Windhoek's growth has long outpaced the capacity of its underlying aquifer to supply its water needs. Currently, the city obtains as much as 70% of its potable water from far-away dams established on ephemeral rivers. Given this precarious situation, Windhoek has long taken a lead in exploring the potential of reclaiming domestic sewage for drinking water purposes. In this article, Petrus L. Du Pisani briefly describes Windhoek's water history and the evolution and design of its new Goreangab Water Reclamation Plant: the first plant in the world to reclaim domestic sewage water for drinking water purposes. While the author dwells primarily on the technical aspects of the plant's design, implicit in his article is the understanding that finding long-term, city-wide, publicly acceptable solutions to severe problems of water availability must inevitably involve top-down planning by governmental agencies. Bottom-up initiatives alone are not enough. In the case of Windhoek, the city government has been directly involved in such planning for more than 40 years.
From arid Windhoek, we jump to the coastal city of Chennai in southeastern India. Chennai is, in fact, tropical rather than arid, with an annual rainfall of about 1300 mm (~47.2 inches). But -- as in most drylands -- the rains do not come evenly and gently throughout the year. Instead, they come in heavy downpours that last a few days, during the two yearly monsoons (June-September and more predominantly, October-December). As author Sekhar Raghavan explains, much of this rainwater simply runs off into the sea, a tendency that has grown as the city has grown and paved over more and more soil. Meanwhile, the city's increasing pumping of groundwater is depleting the water table, posing both short-term problems of water availability and the long-term danger of seawater intrusion into these aquifers, which could ultimately render them unusable. Mr. Raghavan, a private citizen with a strong belief in rainwater harvesting, is a founding member of the Akash Ganga Trust. As he describes, this local NGO promotes rainwater harvesting in numerous ways, including the establishment of the Rain Centre, a "one-stop information and assistance center on rainwater harvesting." He also describes the local and state governments' substantial involvement in promoting (and indeed requiring) rainwater harvesting.
The third article takes us to an inner-city neighborhood in the South African city of Johannesburg. Here, the climate is semi-arid, with the city receiving approximately 713 mm (~28.5 in) of rainfall a year. As in Chennai, the rains do not fall evenly year-round. Drought is a common occurrence. As in Windhoek, Johannesburg relies largely on surface water from far-away dams. And, like both of the preceding cities, Johannesburg's rapid growth is putting huge strains on its water and sewer systems. Against this background, author Richard Holden describes the water-saving measures being implemented in his own inner-city household. Over the past 3-1/2 years, by means of using dry sanitation, greywater recycling and rainwater harvesting, the household has reduced its monthly average water use to about 18 kiloliters (~4,755 gallons) per month -- a substantial savings over the average monthly Johannesburg household use of about 30 kl (~7,925 gal) per month. What's more, the household has achieved these changes with low-cost, low-maintenance techniques that are well within the reach of other households. Here, the focus is on what individuals can achieve with a little bottom-up "activism:" not only have the residents improved their own lives and well-being, they also provide a model for other individuals who may need just a bit of a push to implement water efficiency measures in their own households.
The fourth and final article, which brings us to arid Tucson, Arizona, provides a similar example of bottom-up activism. As author Tom Brightman explains, in this case it's activism as practiced among a loose-knit community of neighboring households that have pooled resources in a common backyard. Here, all of the households share a washing machine, clothesline space, a solar-water-heated shower, and garden plots and fruit trees watered by rainwater runoff and greywater. The individuals in these households not only save money with all of these devices; they find their lives greatly enriched by the community engendered by their shared use of resources around their "backyard well."
And here, surely, is the real point: water and community are inextricably linked. Historically, human beings have always needed water to support community, and cities have always tended to arise where water is particularly available. Now, as pressures on existing water resources grow, we need greater community involvement and mindfulness at all levels to use that water as efficiently as possible. As Peter Gleick (2001) puts it, "The history of human civilization is entwined with the history of the ways we have learned to manipulate water resources." These four articles provide exciting examples of how, in the face of growing water scarcity, we are learning to manipulate our water resources more efficiently and wisely both as individuals and as municipalities. In the end, if these trends succeed, they may go a long way toward ensuring that when it comes to water, we will all have enough.
Gleick, Peter H. Making every drop count. Scientific American 284(2): 40-45.
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