BY THE year 2000 about 8 percent of the most heavily populated cities in the world will be located in delta and coastal regions. And although there is no concrete evidence that global warming will cause sea levels to rise, experts are estimating a rise anywhere from 10 centimeters (4 inches) to a catastrophic 150 cm (59 inches) over the next century.
Recognizing this threat, the Venice City Council, the University of Ca Foscari, the University Institute of Architecture, and the consortium Venezia Nuova founded Venice's international center "Cities on Water" in 1989.
Among the many cities that have participated in annual meetings are Boston; Glasgow; Osaka, Japan; Sydney; Rotterdam; and Oslo.
Membership is subject to approval, but is open to cities, research institutions, government organizations, and technical agencies. Honorary committee members include the United Nations Environment Program, the Organization for Economic Cooperation and Development, the World Bank, and the World Meteorological Organization.
Operations are supported primarily by contributions - both financial and scientific - from members and from public and private institutions.
The center has two goals. The first is to become a permanent center for the exchange of information on cities' project experiences as well of analysis, diagnosis, and treatment methods for common problems.
The second goal is to promote studies and research by universities and scientific institutes. These studies will provide information on subjects of interest to all cities located on water.
Through a "think-globally, act-locally" strategy, the Center focuses on several issues key to coastal cities - the characteristics of the cities themselves, water quality, water-level control, waterfront areas, transportation, water-resource management, and the protection of vulnerable areas.
The first annual meeting focused on rising sea levels, and revealed that solutions do not always lie in traditional construction measures such as dikes, seawalls, and movable gates. Although these methods are the most visible and therefore often politically popular, their inflexibility can have many unforeseen consequences.
Thus the center follows projects involving experimental solutions to these hard-defense systems. One such project is in the south of the Netherlands, where solid-stone or concrete bulwarks have been replaced with soft-defense systems. Based on the idea of "building with nature," the project is forming a new coastline through a flexible integration of land in sea, and water in land.
By taking into account the effects of tides, currents, river overflow, waves, wind, and gravity on the loose sand and clay in the area, coastal designers have been able to use these forces to create a new coastal dynamic and equilibrium. In addition to protection against the expected rising sea level, the resulting coastal structures have been designed to improve safety in times of unexpected flooding.
For this and all other such projects, one of the greatest obstacles is the uncertainty of a future sea-level rise. This makes it very difficult to answer questions about the cost-benefit analysis of such enterprises within the boundaries of either traditional or current economic frameworks.