Robert Costanza, William Mitsch, and John Day, three ecologists with long experience with wetlands, New Orleans, and ecological economics, have an editorial in the journal Ecological Engineering on Creating a sustainable and desirable New Orleans (pdf). Their arguement is a more ecological version of the vison of a new bright green city presented by Alan AtKisson in his post Dreaming a New New Orleans.
Costanza et al write:
The Federal government has pledged over US$ 100 billion for the New Orleans and Gulf coast region to be rebuilt after this terrible (but predictable) tragedy. The question is not if but how it should be rebuilt. What was there can simply be replaced, but this would merely be setting the pins up to be knocked down again by a future big hurricane, the destructive powers of which are increasing worldwide, probably due to global warming. In addition, sea level is rising and New Orleans continues to sink, making the city even more vulnerable over time.
What is needed is a new vision of a truly New Orleans—one that can provide a sustainable and high quality of life for all of its citizens while it works in partnership (not in futile opposi- tion) with the natural forces that shaped it. This New Orleans can serve as a metaphor and a model for the sustainable devel- opment of western industrial society more generally.
The built capital of New Orleans has been radically depleted and must be rebuilt. We can recreate the vulnerable and unsustainable city that was there, or we can reinvent New Orleans as a model of a sustainable and desirable city of the future. To do this, we need to redesign and restore not only the built infrastructure, but also the social, human, and natural capital of the region. How do we do this and what would a truly sustainable and desirable New Orleans look like? Here are some of the elements of a sustainable vision:
1. Let the water decide: Building a city below sea level is always a dangerous proposition. While parts of New Orleans are still at or above sea level, much of it had sunk well below sea level since the first quarter of the 20th century. It is not sustainable or desirable to rebuild these areas in the same way they were before. They should be either replaced with coastal wetlands which are allowed to trap sediments to rebuild the land (see below), or replaced with buildings that are adapted to occasional flooding (i.e., on pilings or floats). Wetlands inside the levees can help clean waters, store short-term flood waters, provide habitat for wildlife, and become an amenity for the city. Coastal wetlands outside the levees should be rebuilt so that the city has both wetlands and levees to protect the city.
2. One should avoid abrupt boundaries between deepwater sys- tems and uplands. Gentle slopes with wetlands are the best division, and avoid putting humans, particularly those who have few resources to avoid hydrologic disasters, in harm’s way. Of course the abrupt boundaries of the levees are nec- essary, since wetlands alone cannot protect the city, but we need to use both as appropriate.
3. Restore natural capital: Coastal wetlands in Louisiana have been estimated to provide US$ 375/acres/yr (US $940/ha/yr—these and all subsequent figures have been converted to US$ 2004) in storm and flood protection services. Hurricane Katrina has shown this to be a large underestimate. Restoring Louisiana’s coastal wetlands and New Orleans levees has been estimated to cost US$ 25 billion. Had the original wetlands been intact and levees in better shape, a substantial portion of the US$ 100 billion plus damages from this hurri- cane probably could have been avoided. Prevention would have been much cheaper and more effective than recon- struction. In addition, the coastal wetlands provide other ecosystem services which when added to the storm pro- tection services have been estimated to be worth about US$ 5200/acres/yr (US$ 12,700/ha/yr). Restoring the 4800 km2 (480,000 ha) of wetlands lost prior to Katrina would thus restore US$ 6 billion/yr in lost ecosystem services, or US$ 200 billion in present value (at a 3% discount rate).
4. In order to do this we should use the resources of the Mississippi River to rebuild the coast, changing the current system that constrains the river between levees, and allow the resources of freshwater, sediments, and nutrients to flow into the deeper waters of the Gulf. Diversions of water, nutrients, and sediments from the Mississippi are a major component of the LCA plan. These planned diversions should be greatly expanded in order to allow more rapid restoration of the coastal wetlands. Levees are necessary in some locations, but where possible the levees should be breeched by structures in a controlled way to allow marsh rebuilding.
5. We should restore the built capital of New Orleans to the highest standards of high-performance green buildings and a car-limited urban environment with high mobility for everyone. New Orleans has abundant renewable energy sources in solar, wind, and water. What better message than to build a 21st-century sustainable city running on renewable energy on the rubble of a 20th century oil and gas production hub. In other words, New Orleans should be built higher, stronger, much more efficient, and designed to make extensive use of renewable energy. One can imag- ine a new pattern for the residential neighborhoods of New Orleans with strong, multistory, multifamily buildings surrounded by green space, each with enough water and fuel storage for several weeks, and operating principally on wind and solar energy.
6. We should rebuild the social capital of New Orleans to 21st-century standards of diversity, tolerance, fairness, and justice. New Orleans has suffered long enough with social capital dating from the 18th (or even the 15th) century. To do this the planning and implementation of the rebuilding must maximize participation by the entire community. This will certainly be difficult for a number of reasons, including the historical antecedents of racism and classcism in the region, and the fact that much of the population has been forcibly removed from the city. But it is absolutely essential if the goals of a sustainable and desirable future are to be achieved.
7. Finally, we should restore the Mississippi River Basin to min- imize coastal pollution and the threats of river flooding in New Orleans. Upstream changes in the 3 million km2 Mississippi drainage basin have significantly changed nutrient and sediment delivery patterns to the delta. Changes in farming practices in the drainage basin can improve not only the coastal restoration process, but also improve the nation’s agricultural economy by promoting sustainable farming practices in the entire basin.