This article by prof. Han Meyer first appeared on Reuters The Great Debate UK on Aug 20, 2010. Han Meyer is Professor of Urban Design at Delft University of Technology. He has been a principal organiser of the 'Dutch Dialogues' with New Orleans since 2005 and is Editor of 'New Orleans-Netherlands: Common Challenges in Urbanised Deltas'.

In August 2005, Hurricanes Katrina and Rita devastated large swathes of the U.S. Gulf Coast and overwhelmed New Orleans causing what then-U.S. Secretary of Homeland Security Michael Chertoff described as "probably the worst catastrophe, or set of catastrophes" in U.S. history.

Katrina's punishing storm surge, strong winds and massive rainfall weakened flood protection infrastructure which then failed, flooding coastal areas of Louisiana and Mississippi, including 80 percent of New Orleans:

* Tragically, at least 1,836 people lost their lives, while a massive 1.3 million residents were evacuated, some never to return.
* The scale of the carnage is underlined by the fact that U.S. federal disaster declarations covered some 90,000 square miles, an area almost as large as the United Kingdom.
* The U.S. Geological survey has estimated that some 217 square miles of land was transformed to water by Katrina and Rita.
* The economic impact of the crisis has been estimated at some 150 billion pounds, with around 81 billion dollars in property damage alone.

The disaster was not only the costliest in U.S. history, but also served as a major warning for all urbanised deltas across the world of the need to maintain sufficient and efficient flood defences and water management systems.  As such, one of the biggest questions raised in New Orleans itself since 2005 has been how, and indeed whether, the city should be reconstructed and redeveloped given the threat it will continue to face from future hurricanes and catastrophic flooding.

This debate has not only prompted major interest from U.S. planners, engineers and designers, but also public authorities and politicians too, including Louisiana Senator Mary Landrieu, about international best practice, especially the pioneering 'Dutch tradition' of combining water management with urban development.

The Netherlands (with about 20 percent of its land area and 21 percent of its population located below sea level, and 50 percent of its land lying less than a metre above sea level) has long been famous for its flood protection systems.

Reflecting this expertise, and with the support of the American Planning Association, I have worked with Delft University of Technology since 2007 as part of a 'Dutch Dialogue' project in New Orleans to provide long-term recommendations for enhanced flood protection infrastructure, and reducing subsidence, restoring wetlands, and boosting ecosystem resiliency along the Gulf coast.

Far from New Orleans being a lost cause, our unwavering belief is that 'out of disasters can come wonderful things' and that the city can not only survive as a major urban centre, but also prosper and grow if it can get key fundamentals right.

What are these fundamentals?

In short, the essence is the combination of a ‘safety first’ strategy with an improvement of the quality of the urban environment.  A delta-city should not only be safe to live in, but also attractive and enjoyable.  The question is how to combine these two goals.

'Safety first' means in practice that the New Orleans area, in particular, has to better adapt to threats inherent in living in a subsiding delta, with protection against hurricanes, floods and excess storm water being the sine qua non for redevelopment.

Since 2005, crucial flood protection infrastructure around coastal Louisiana, the Mississippi Delta and New Orleans has been repaired.  However, this is just the start of what is needed.

Key amongst forthcoming, new safety initiatives is construction of three major storm surge barriers in New Orleans. Considering the city's intense rainfall, we have also recommended more storm storage.

Adding water-storage capacity will lower the risk from localised flooding during hurricanes and make it easier to actively manage the water table (and risks levels) just as in the Netherlands.

While safety first must be the priority, New Orleans can also adapt more effectively to a corollary 'Living with the Water' principle.  Thus, rather than seeing flood protection systems as being exclusively to keep the water out' or 'keeping it contained', it can re-secure the vibrant and prosperous future it deserves by better exploiting the economic, societal , and cultural gain of being, like Dutch settlements such as Amsterdam, a world leading 'water city'.

For instance, there are unique opportunities post-Katrina to create more amenities like canals, lakes, ponds, wetlands in and around New Orleans:

* Additional canal capacity exists in the city:  many old canals were covered or backfilled over the past century. Moreover, we have also encouraged the construction of new canals and other water storage systems with an 'urban feel' (comparable to that in the Netherlands) where people enjoy living near the water.
* Wetlands can also be created and restored to add robust ecosystems that are attractive, environmentally friendly, enhancing recreation and tourism, and improving sustainability.

To be sure, many in Louisiana and Mississippi believe that the process of reconstruction and redevelopment so far has been insufficient and patchy.  It is certainly true that, some five years later, many thousands of displaced residents continue to live in ‘temporary’ accommodation such as trailers, and, indeed as late as 2009, the New Orleans population of around 320,000 was only two thirds that of its 2005 size of 480,000.

Nonetheless, just as the Netherlands emerged more strongly after the cataclysmic storm surges of 1953 which killed around 2000 people, and flooded most of the southwestern part of the country, I am absolutely sure that a more vibrant, thriving and safer New Orleans is not only possible but also feasible.  Consigning the city to becoming an historical artifact (culturally, economically, socially and strategically) would be shortsighted and a major mistake.

This article by Joris Melkert appeared on Reuters The Great Debate UK on April 20th 2010. Joris Melkert, MSc BBA, is Assistant Professor in aerospace engineering at the Delft University of Technology.

Despite the announcement that air space could begin to re-open in Northern Europe, the Icelandic volcano eruption could prove to be a major turning point for the global airline industry with short- to medium-term questions already being asked by some about its future financial viability.

One of the biggest questions, which engineers will be grappling with right now, is whether there is a cost-efficient way to ‘design out’ the current problems that aircraft experience with dust clouds.

The short answer is that it may be possible to make modifications to aircraft engine cores to make them less sensitive to ash deposits.  However, such major engine development is a long term project so no solution will be in sight for at least a year.  Moreover, the expense of such an undertaking could be prohibitively costly for airlines right now.

The volcano eruption has cost the airline industry an estimated 200 million dollars each day.  Voicing the industry’s frustration and concern, the Air Transport in Europe (AEA) trade body warns that, without state aid, some airlines would have potentially gone out of business as soon as next week unless travel restrictions began to be lifted.

The crisis has been especially worrying for the industry for three main reasons.

•    First, because the economic downturn of the last two years has already left many airlines in a very financially precarious position with cash flow a major concern.

•    Second, because Eyjafjallajökull, the Icelandic volcano which has erupted, could potentially sputter on (perhaps intermittently) for months or even more than a year.

•    Third, because the recent transport chaos could be followed in swift succession by an eruption at Eyjafjallajökull’s much bigger volcanic neighbour, Katla, as happened the last time Eyjafjallajökull erupted in 1821 – 1823 and 1612.  If Katla were to erupt in a significant way, the potential for travel chaos and economic damage would much greater than has occurred so far.

The massive financial hit being taken by the airline industry has perhaps inevitably brought it into conflict with regulators.

The IATA, the body that represents the world’s airlines, has been particularly critical about the decision to ground airlines on the basis on what it purports is “a theoretical model which does not work… instead of using a system and taking decisions on facts and on risk assessment”.

The industry also points to the numerous airlines which have launched test flights and found that the ash in the atmosphere had neither caused damage to the aircraft nor threatened the safe conduct of travel.

However, long-term damage to aircraft engines may not be witnessed after just a handful of test flights. Moreover, the first duty of regulators must always be to put passenger safety first, and legitimate concerns do exist about flying in parts of Europe in current conditions.

When one knows where the dust clouds are, it is possible to avoid them by flying over or under them.  However, the problem with flying over is that it runs the risk of having to pass through them first.

The problem with flying underneath the clouds is that planes have to fly in air with a higher density with greater drag.  For every 5 kilometre drop in height, density doubles. Thus, when aircraft move down from a cruise altitude of 10 kilometres to 5 kilometres drag and thus fuel consumption will double. This is a serious obstacle for long-haul flights in particular.

In the short term, the best way forward will probably be for air space to be re-opened progressively based on the results of test flights with continuous monitoring of potential long-term damage to aircraft engines.

Once this current crisis is over, the key short to medium-term question for the airline industry will therefore be whether there is a cost-efficient way to ‘design out’ the current problems that engines experience with dust clouds.

This might become especially necessary if, as predicted, volcanic eruptions in Iceland and indeed elsewhere in the world become more frequent in coming years whilst world wide air traffic continues to grow.  At the end of the last ice age, for instance, the rate of eruption in Iceland was some 30 times higher than historic rates.

This is because the reduction in the ice load reduced the pressure in the mantle, leading to decompression melting there.  Since the late 19th century the ice caps in Iceland have been shrinking yet further, due to changing climate.  This will lead to additional magma generation, so we should not be surprised if more frequent and/or more voluminous eruptions start happening in the future.

Even if a technical solution isn’t possible to the aircraft engine core, it is unlikely that this will pose a mortal long-term threat to the industry.  With growing wealth, the global populace will want to travel more, despite concerns about global warming.  There will simply not be enough available capacity in surface transportation to meet this need.

While the short-term future of some airlines will therefore be a very rocky one indeed, growing global demand for long-haul travel in particular will ensure that the industry continues to exist and possibly prosper despite this week’s travel chaos.

Check out the website of the Faculty of Aerospace Engineering here.