2010 National Planning Conference: Delta Urbanism Symposium
Delta Urbanism Plenary
By Jim Schwab, AICP
APA Senior Research Associate
No two urbanized deltas are the same. That much was clear from the presentations of two Planners Press authors, Richard Campanella and Han Meyer, in a Monday morning session in which they discussed their respective new books, Delta Urbanism: New Orleans and Delta Urbanism: Netherlands. Nonetheless, both nations and the cities of New Orleans and Rotterdam have a great deal to learn from each other.
Campanella, a professor of geography at Tulane and author of numerous books and articles about the New Orleans region, began by explaining the differences among types of deltas, which can be wave-dominated, tide-dominated, or river-dominated. The Mississippi River falls into the last category because the enormous force of the river, draining a large portion of the North American continent, overwhelms the slack tides of the Gulf of Mexico. Since the Ice Age, it has dumped sediment that has gradually pushed out the continental boundaries and created the unique mix of wetlands that forms present-day southern Louisiana. Though that formation has been at least 7,000 years in the making, New Orleans has built an urban presence on the delta only in the last 300 years. Campanella went on to detail the rapid evolution of the city during those 300 years since the French began to settle the area in an attempt to control the Mississippi River valley.
But why choose such a vulnerable location? Campanella explained what he called "Bienville's Dilemma," the title of one of his earlier books, as a difficult choice between a good site, which would have been a safer location further upriver, and a good situation, which allowed more control and strategic advantage. Choosing the latter, founder Bienville left modern New Orleans with the dilemma it has faced ever since: how to make a livable location out of a great strategic situation that dictated a poor site. Campanella concluded by noting that this type of dilemma, if not this precise dilemma, probably affects much of delta urbanism around the world today. Deltas generally make vulnerable but highly valuable locations for cities, and the dilemma of the human race is how to create safety in addition to value along deltaic plains.
Meyer followed by noting that the Netherlands faces a substantially different situation in which the sea dominates the delta. The Rhine River, he noted, lacks the force of the Mississippi and would "appear to be a creak alongside it." Also, the Dutch have wrestled with the dilemmas of creating safe situations for nearly 1,000 years, during which they have learned much "by trial and error" and not through any one stroke of genius. Along the way, they have suffered numerous disasters, including major floods in 1840 and as recently as 1953, the latter being the closest Dutch equivalent to what happened in Hurricane Katrina, with many deaths and major damages.
Eventually, he said, they have realized that they must deal with three layers of the problem, from what lies underground, to the hydraulic infrastructure of their delta, to the occupied city above. That middle layer is the "fundamental layer that you must take into account" to succeed in creating a livable, safe environment. The Dutch have evolved complex approaches with different levels of safety for different regions based in large part on the density of population being protected.
But no approach is permanent, as conditions change over time. Meyer concluded by outlining four major reasons why the Netherlands today is seeking a new approach to its challenge of protecting development in a land increasingly below sea level:
- Subsidence, or the steady sinking of the land below sea level;
- Concern with the environment, i.e., worries about the impacts of engineering and hydraulic works and past protection efforts;
- The changing nature of urban waterfront development; and
- Climate change, producing sea level rise that may render previous flood protection levels insufficient.
Ultimately, Meyer concluded, solving these dilemmas by remedying the problems in that middle layer of hydraulic infrastructure will require the cooperative efforts of hydraulic engineering, urban design, and landscape architecture to accept common responsibility for the outcome.
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