It is now widely recognized that cities play a vital role in social and economic development in all countries. Urbanization builds diversified and dynamic economies which raise productivity, create jobs and wealth, provide essential services, and absorb population growth, and become the key engines of economic and social advancement. Thus, efficient and productive cities and towns are essential for national economic growth and welfare; equally, strong urban economies generate the resources needed for public and private investments in infrastructure, education, health, and improved living conditions.

ABIDJAN:With 19% of Cote d'Ivoire's population, Abidjan generates 27% of GDP, houses 80% of the country's industry, and provides over half of secondary and tertiary sector employment.

COLOMBO: The Urban area is the most important industrial, commercial and administrative centre in Sri Lanka. It has the largest employment density and is the major distribution centre for imports as well as exports.

CONCEPCION: The Bio Bio region, of which Concepcion is the capital, accounts for 10% of Chile’s GDP; over one-third of regional GDP is generated by the industrial sector.

DAKAR: Dakar generates 68% of Senegal's GDP and its workers account for 66% of the national wage bill. 80% of the country's industries are located in the metropolitan region. In resource use, it consumes three-quarters of the country's piped water and 40% of its charcoal.

DURBAN: Durban is the busiest port in Africa. It accounts for 55% of provincial economic output and 9% of South Africa's GDP. It is also the country's top year-round tourist destination.

DURBAN: Durban is the busiest port in Africa. It accounts for 55% of provincial economic output and 9% of South Africa’s GDP. It is also the country’s top year-round tourist destination.

KATOWICE: the agglomeration is the primary source of key raw materials for the Polish economy, the centre of heavy industry and the country’s major source of electric power. It produces 15% of national GDP with 10% of the Polish citizenry on 2% of the country’s land mass.

MANILA: economically, Metro Manila is the industrial, financial and commercial centre of the country. 65% of the Philippines’ large industrial firms were located in the metropolis. This includes 90% of the meat processing capacity, 90% of electronics production and 45% of paper mill output. While there is a national policy encouraging industries to locate outside of Manila, it is estimated that the metropolis’ industrial sector will continue to grow at 9% annually.

However, the development potential of cities is increasingly threatened by environmental deterioration. Aside from its obvious effects on human health and well-being, environmental degradation directly impedes socio-economic development. Water and air and soil pollution, for example, impose extra costs on business and industry, and on households as well as public services. Inefficient use and depletion of natural resources raises input prices and operating costs throughout the economy, and also deter s new investment. Heightened risk from environmental hazards has the same effect. In terms of impact, it is usually the poor who suffer most cruelly and directly from environmental degradation, although the lives and health of all urban residents can also be affected. Failing to deal with the problem today, moreover, leads to much greater problems (and cost) in the future. For development achievements to be truly "sustainable", cities must find better ways of balancing the needs and pressures of urban growth and change with the needs and constraints of the environment.

COLOMBO: Conservative estimates suggest that the annual costs of environmental degradation in the Urban Area by the year 2002 could be Rs. 3.3 billion in lost property value, Rs. 1.9 billion in lost fish sales, Rs. 778 million due to traffic congestion, and Rs. 315 million in additional health care costs.

IBADAN: Lack of environmental management has hampered Ibadan's development potential in two important ways. First, much of the city has no storm drains, sewers or gutters. This lack of drainage, combined with shallow valley floors, increasing impermeabilization, and poor solid waste management, has resulted in at least ten costly and destructive floods in the last 70 years. Second, inadequate water supply, water pollution, poor refuse disposal, crowded and substandard housing, contam inated food, and disasters such as the flooding have heightened health risks for Ibadan's residents. As an extreme example, a cholera epidemic claimed over 10,000 victims in the early 1970s.

ISMAILIA: Several environmental factors may limit Ismailia’s development potential. Allocating land to potential industrial investors at 75% below the market price could lead to overconsumption of critical land. Failure by the growing agricultural sector to adopt water conserving irrigation methods could create serious pressure on water resources and hamper growth. Worsening lake and other pollution may have negative economic consequences through loss of tourism and recreation opportu nities, depletion of fishery resources and deteriorating public health.

KATOWICE: the agglomeration is relatively well off in terms of income and employment when compared to the rest of the country but much worse off in terms of quality of life. Relatively high infant mortality rates are caused by dust fall, ambient levels of lead, tar, phenols and other chemicals. Children suffer from anaemia, gastro-intestinal diseases, encephalic changes, chromosome damage, and problems with the peripheral nervous system. Environmental degradation results in about 2000 cases of excess mortality annually along with high morbidity rates.

There are many encouraging signs, however, that environmental deterioration is not a necessary or inescapable result of urbanization and economic change. Some cities seem to have had success in striking the right balance - in finding development paths which are more effectively attuned to their relevant environmental resources and hazards. Unfortunately, other cities seem to have failed to come to grips with the requirements of sustainability and are suffering severe environmental and economic damage as a result.

DURBAN: Prior to initiation of a more general EPM process, Durban successfully implemented a programme to preserve its ecologically valued lands, known as the Durban Metropolitan Open Space System (D'MOSS). D'MOSS was approved by the City Council in 1989; the Parks Department began implementation several months later. Implementation is gradually proceeding as public land is consolidated and private land is acquired in order to link nine parks in an ecologically connected network.

GOTHENBURG: The municipality has a long history of successfully solving environmental problems. For example, the city energy company developed a district heating system that uses energy from the sewage water with the help of heat pumps, reuses waste heat from oil refineries and burns natural gas. By phasing out oil as a fuel, the city has reduced carbon dioxide emissions per capita and lowered sulphurous emissions by 94% since 1984.

MANILA: Three-month average lead concentration used to exceed the standards by 2.2 times. However, ambient lead levels have now fallen to within standards following the replacement of high-lead gasoline with low-lead fuel in mid-1993 and the introduction of unleaded gasoline in early 1994.

Indeed, mounting evidence from cities around the world shows that the fundamental challenge has to do with urban governance: learning how to better plan and more effectively manage the process of urban development, avoiding or alleviating problems while realizing the positive potentials of city growth and change. New and more positive approaches to urban management can help to mobilize and effectively apply local resources - of all kinds.