A Weblog monitoring coverage of environmental issues and science in the UK media. By Professor Emeritus Philip Stott. The aim is to assess whether a subject is being fairly covered by press, radio, and television. Above all, the Weblog will focus on science, but not just on poor science. It will also bring to public notice good science that is being ignored because it may be politically inconvenient.

Sunday, September 11, 2005

Should New Orleans be abandoned as a city?.....

Should New Orleans now be abandoned as a city? This is a far more serious question than many might wish to admit.

Even at its foundation, in 1718, there were those who doubted the viability of the chosen site. The French coloniser, Jean-Baptiste Le Moyne de Bienville, located the pioneer settlement on a rare piece of higher ground that lay along the flood-prone banks of the lower Mississippi. But the site was completely surrounded by swamps. Nevertheless, in 1792, it became the capital of French Louisiana, replacing, perhaps somewhat ironically in the light of recent events, Biloxi. For a long time, development was wisely confined to what little higher ground existed, which constricted the old town, the 'Crescent City', as it was known, to an arc of land. Yet, as the city inevitably grew and expanded, there was no choice but to move on to the swamps, trapped between the Mississippi River and Lake Pontchartrain. In order for this to happen, the city had to be defended against the river, the lake, and the sea by artificial dykes, or levées, and canals.

In 1910, the engineer, A. Baldwin Wood, drained the city, so that heavy rain water had to be pumped into the canals that flow into Lake Pontchartrain. Unfortunately, this was accompanied by groundwater pumping, which caused subsidence, with the result that much of the city currently lies in a 'bowl', 2 metres below normal sea-level. Indeed, models show that the central city can all too easily be turned into a lake, up to 9 metres deep.

The city is thus open and vulnerable to four major problems, quite independent of any direct physical damage from a hurricane:

(a) the breaching of the levées, allowing water to flood into the 'bowl-shaped' core;

(b) direct flooding of the centre by extremely heavy and concentrated rainfall;

(c) direct flooding from the mighty Mississippi overtopping its banks; and,

(d) the failure of the pumping mechanisms and the canals.

Tragically, as we know all too vividly, Hurricane Katrina, and the accompanying storm surge, caused three of these to happen simultaneously.

Can, therefore, New Orleans ever be environmentally and economically viable as a modern city?

In answering this crucial question, we must face up to six tough facts:

(i) the city will always remain at risk of serious direct flooding from the Mississippi River, as occurred in 1927;

(ii) the city will always remain at risk of serious flooding from hurricane-driven storm surges, as occurred in 1965, and with Hurricane Katrina;

(iii) to defend a reconstructed city in any meaningful way will demand levées that can withstand a Saffir-Simpson Category 5 Hurricane and storm surge; a totally new, above-ground pumping system; the re-development of swampland to absorb the incoming energy of the storm surge; better defences against direct Mississippi flooding; and a completely different style of urban infrastructure. The cost will be astronomic;

(iv) eternal vigilence against hurricanes, with undiminished maintenance of the new levées, canals, and pumping systems;

(v) a totally dedicated and uncorrupt local, state and federal government with a shared approach that never flinches at spending what will be always be required to maintain, and to improve, the defences of the city; and,

(vi) the issue of 'global warming' is irrelevant. Category 3-5 Hurricanes will continue to strike, on a regular basis, come what may.

Although it may be possible, in theory, to defend the city in purely engineering terms, in the light of the above, is this ever going to be possible in long-term economic and, above all, political terms?

If the answer to the above question is a realistic 'No!, then New Orleans, as a major centre of population and industry, has to be abandoned by design. It may still be possible to maintain a small 'tourist' centre, based on the old French/Spanish core, but that will be little more than a theme-park to the past.

Accordingly, the people of New Orleans should be given every assistance to start a new life elsewhere in the South, while the city itself should cleansed and then left to the swamps.

Yet, 'New Orleans', as a dream and an icon, will never be lost. It will live on in legend, in music, and in plays - a rickety-old Street Car fulfilling many desires that once rattled its way through history, until the rusty rails were swamped by the tides of time.

The memory will surely gild the ruin in the mud.

See also: 'A sad truth: cities aren't forever' (The Washington Post September 11).


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