This environmental expert describes balanced, comprehensive strategies that can transform urban blight into green cities.

Within cities, poor citizens face the worst environmental consequences. In low-income settlements, services such as water, sewage, drainage and garbage collection are often non-existent. Lacking the resources to purchase or rent housing, between one-third and two-thirds of urbanites in developing countries become squatters on dangerously steep hillsides, flood-prone riverbanks and other undesirable lands.

But cities can not be blamed for global environmental deterioration, despite the magnitude of their environmental and population problems. In reality, dense settlement patterns are necessary to preserve open spaces for other uses. Cities cause environmental problems, but also hold the key to their reduction and ultimate solution.

At the Mega-Cities Project, we are working to promote and encourage innovative and successful solutions to these common problems, recognizing that the best ideas are seldom "overnight sensations." Rather, they are ideas, experiments and experiences that evolve into successes over years, sometimes decades. But the critical environmental problems threatening health and well-being for so many urban dwellers around the world compel us to speed the process by which successful innovations are recognized and imitated by other cities.

The three case studies that follow reveal the transformative potential of local solutions. Two experiences have been extremely successful and have been replicated many times over, while a third had mixed results. They each contain valuable lessons about the promise and pitfalls of implementing environmental innovations and the factors that contribute to their success or failure.

The Zabbaleen Environment and Development Program: Cairo

In Cairo, a partnership formed by local, national, and international actors has successfully transformed a community through the Zabbaleen Environment and Development program. Since the program began in 1981, quality of life has improved in a formerly neglected community; thousands of jobs have been created as an improved municipal waste collection and recycling system has been implemented. At the intersection of poverty and the environment, the Zabbaleen Environment and Development program fashioned productive solutions.

Greater Cairo generates thousands of tons of solid waste per day. The municipal sanitation force shares management of the waste with a traditional, private-sector collection system run by two historically poor, marginalized social groups, the Wahis and the Zabbaleen With more than a century in Cairo's garbage trade, the Wahis control the collection routes and contracts with homeowners. The Zabbaleen pick up waste and transport it to their settlement on the city's fringe, where it is sorted and recycled, or used for animal fodder.

A community with little or no organization or power, the Zabbaleen enjoyed few basic services when the program began almost 20 years ago, and suffered from environmental devastation, little economic opportunity, lack of education, and a host of other problems endemic to urban slums. The Zabbaleen Environment and Development Program has made significant improvement in this community with the backing and funding of partners including the Moqattam Garbage Collectors' Association, known as the Gameya, and numerous governmental and non-governmental organizations.

The ZEDP had two primary objectives: to improve the living conditions and build the capacity of the Zabbaleen; and to create a more efficient solid waste management system for Cairo. Today the most visible transformation is the community's physical appearance, resulting from substantial government improvements in community infrastructure. There are now approximately 1,500 houses in the settlement, many of which are multi-story, concrete-block structures, more than double the some 700 one-story shacks in the area in 1981. The number of inhabitants has almost tripled over 12 years, rising from 5,881 in 1981 to 16,600 in 1993.

New infrastructure, clean-up projects and the organization of a composting plant are all ZEDP projects which have helped to improve the overall cleanliness of the settlement. In turn, public health has improved, with infant and child mortality decreasing from 240 per thousand in 1979 to 117 per thousand in 1991.

Health and environmental benefits initiated in the ZEDP have had wider effects in greater Cairo. The Route Extension Project, funded by the NGO, Oxfam, brought 8,000 more homes into the Zabbaleen collection system, helping to create a much cleaner city overall. Recycling programs born of ZEDP have significantly reduced the environmental burden of waste disposal. The ZEDP composting plant mentioned above now produces fertilizer that is free of chemicals and harmful contaminants.

The economic benefits are also numerous. Household income has increased twenty times over the past ten years. Recycling activities and projects created a diversified urban economy and additional income. Women and children have been relieved of the long and arduous process of sorting, and are free to engage in various other income-generating, educational and recreational activities.

The ZEDP has served as a model for other cities, notably Manila, Philippines. Payatas is a vast squatter area in the north of the city, and at its heart is a 13-acre open dump site, home to 40 percent of the city's trash, and to 4,000 men, women and children who forage daily in search of anything that can be eaten or sold. After consultations with Cairo's ZEDP, the Payatas Environmental Development Program (PEDP) is now working to attack the many problems surrounding the area's waste collection system.

The driving vision behind the PEDP, as with the ZEDP in Cairo, is to create a sustainable community for the waste pickers, while simultaneously integrating them into a more effective waste management process for the city.

The Paid Self-help Reforestation Project: Rio De Janeiro

Rio de Janeiro is home to nearly 11 million people, the second largest metropolitan population in Brazil. Lacking suitable planning structures to rein in growth, uncontrolled development and overly rapid expansion have strained the environment and outgrown the city's ability to provide basic services to the people.

The poor inhabitants of Rio, many of whom live in informal squatter settlements called favelas, suffer more than their share of these problems. Many of these squatter communities are located on hillsides denuded decades ago by logging and coffee cultivation. Rapid population expansion on this exhausted soil worsened already poor conditions. In this terrain, water-saturated soil can cause landslides and rock-falls; compacted soil causes excessive runoff and flooding; and the ever-present mud is a habitat for disease-carrying mosquitoes. In the 1970s, when Rio experienced rapid, uncontrolled growth, flooding could kill hundreds of favela residents every year.

In response to this problem, the Municipal Secretariat of Social Development (SMDS) in 1986 created an integrated program to reverse urban deforestation and its consequences and to improve the socio-economic conditions in the favelas. In collaboration with community groups and technical advisers, SMDS staff designed a scheme that addressed drainage, sewage, reforestation and environmental education in the favelas. To address the economic problems of the residents, the plans also relied upon the use of paid local labor, recruited and managed by community leaders.

The SMDS developed the reforestation program for an initial 25 favelas with implementation occurring over several years. The first stage included site-selection with community consultation. Then, appropriate tree species were selected and seedlings cultivated. At the same time, sites would be prepared with the construction of access roads, ditches, canals and terracing. Planting began on a schedule of ecological succession to prepare the soil for the forest in the making. Members of the community then performed two to three years of critical maintenance, paid by SMDS. These stages of the Self-Help Reforestation Program were implemented over three to four-year periods, depending on the site.

This payment to the people of the fevelas is perhaps the most innovative aspect of Rio's reforestation project. Unemployed or underemployed favelados are paid by the municipal government for cultivating seedlings, planting, watering, greenhouse maintenance, and all the assorted tasks required for a reforestation effort. Administrative costs have been significantly reduced in the dissemination of these wages by a community-based foreman. The trust that this system has generated in the community has helped the reforestation program win acceptance of other residents as the city expanded the effort into other favelas.

Though an innovative attempt at reforestation, the program was not without setbacks. Despite community participation and awareness about the need for reforestation, some residents still cut down the fledgling trees out of desire for fuel wood and land for grazing. Without a strong educational component, the trees stand little chance of remaining untouched. The project also suffers from a chronic lack of political will among civic leaders toward financing such ventures.

Still, the Rio Paid Self-Help Reforestation Program has been a success in several respects. Fruit from the planted trees improved residents' diets, and the local community members learned about the benefits of protecting the environment. Residents at the bottoms of the hills have also benefited from the reduced risks of floods, erosion, landslides and rockslides from heavy rainfall.

Flora and fauna have returned to the re-forested areas, with bird-carried seeds adding to the biodiversity of the growing forests. Fruit trees have contributed to a greater diversity in the diets of favela residents. Water springs were regenerated, especially in the reforested areas in the west of the city, where fish and amphibians can now be found.

The program also brought an important improvement in quality of life. Since many residents were migrants from the countryside, planting and tending fruit trees restores a strong cultural connection to their agricultural past. Ultimately, the project instills a sense of community participation and raises political consciousness among the favela residents.

As a result of its initial success, the Self-Help Reforestation Project has been established citywide, currently operating in 60 neighborhoods. It also has been replicated in other Brazilian cities. Reducing risk and improving the quality of life for favela residents, this top-down program has successfully involved poor communities in a partnership which benefits both the city and the low-income settlement. This partnership is the root of the program's success both as a reforestation project and as a poverty alleviation project.

Integrated System for the Recycling of Organic Waste (SIRDO): Mexico City

In contrast to the two experiences above, SIRDO is a striking example of how the over-reliance on technology to solve urban problems can fail when there is insufficient attention to social dynamics and the needs of a community.

In Mexico City, over three million residents lack basic sewerage and drainage infrastructure, and those that are connected to the municipal system suffer from inadequate and outdated service. As for solid waste, the city produces over 10,000 tons of rubbish and 200 tons of industrial toxins every day, most of which are dumped in open pits, landfills and illegal deposits. This vast quantity of mismanaged waste has dire consequences for the city's water supply.

Upon invention in the 1970s, the Integrated System for the Recycling of Organic Waste (or SIRDO, its Spanish acronym) seemed a good alternative for sewage disposal. The SIRDO is a technical method for the treatment of organic solid waste and/or black and gray domestic waters through filters and fermentation in solar heated chambers. (Toilets discharge black water; sinks, showers and laundries discharge gray water.) The SIRDO essentially collects the sewage from households, allows the waste to decompose in a tank, and creates an organic fertilizer.

Theoretically, a working SIRDO would enable a community to cut its production of waste, lessen its demand on municipal water supplies, and generate income. In practice, SIRDO installations have been beset with technical, institutional, and economic problems and marked by controversy.

El Molino, a neighborhood in the southeast of Mexico City, had no sewage system, so SIRDOs were proposed, and financed through a grant from the National Popular Housing Fund. Technical problems -- such as clogged pipes and incomplete decomposition -- plagued the project from the outset. After a series of delays and an exchange of accusations of fraud and mismanagement between the community and project managers, the SIRDO was abandoned. The community was eventually connected to the main municipal sewer system.

SIRDOs were implemented in some places with less disastrous results than in El Molino, and success hinged on the degree to which the systems were properly integrated with the needs and capabilities of communities. In Tepepan, another Mexico City neighborhood, the planners and architects were from the community, and were knowledgeable, responsible partners in every aspect of the SIRDO's implementation, adaptation and use. They had the necessary training and resources to make design changes, maintain the SIRDOs, and educate and train their fellow-residents in the system's purposes, functions and requirements. The whole community felt connected to the technology's implementation and responsible for its success.

These conditions are rarely, if ever, replicable on a large scale in poor urban communities lacking the resources and the sophisticated knowledge necessary to meet the SIRDO's installation and maintenance needs. Technology and human beings interact. If this human element is not taken into account, if people are forced to adapt to technology rather than control it, then technology is likely to fail. Technological solutions must be responsive to that community's needs, capabilities, limitations and existing conditions. Putting communities at the center of a technical innovation is critical to making that innovation sustainable.

Conclusion

Based on the research and analysis of the hundreds of environmental and other types of innovations which the Mega-Cities Project has identified over the past 12 years, we have drawn six basic lessons.

• Urban environmental, social, and economic sustainability is essential for global sustainability. Concentrating human populations in cities is an environmental necessity to create economies of scale and resource efficiencies. Dense populations leave open space for either agriculture or natural wilderness areas. Creating circular systems that recycle water and waste of these concentrated populations is the key to reversing our global environmental deterioration

• Alleviating urban poverty is essential to ensuring urban environmental regeneration. The urban poor tend to occupy the most ecologically fragile and service-deprived areas of our cities. Without alternative locations to settle and sufficient income to cook and keep warm, their survival will increasingly be pitted against environmental needs.

• A strong civil society and grassroots initiatives are essential for lasting solutions to poverty and environmental degradation. The most creative and resource-efficient solutions to urban problems tend to emerge at the grassroots level, closest to the problems being solved. Without local participation, even the best ideas are doomed to failure.

• To reach scale, it is essential to transform "micro" solutions into "macro" impact. While small may be beautiful, it's still small.

• Urban transformation cannot take place without changing the old incentive systems and "rules of the game." Local innovations can never achieve scale without cross-sectoral partnerships involving government, business, NGOs, academia, media, and grassroots groups. We need to create a climate conducive to experimentation, mutual learning, and collaboration.

• The sustainable city of the 21st Century must have social justice, political participation, economic vitality, and ecological regeneration. Only with all these social elements in place can our cities be truly sustainable for the 21st Century and beyond.