Strange coincidence: Last week I was interviewing an archaeologist about why London was founded in what was clearly a flood zone. This was only a few days before Manhattan was inundated by the huge tidal surges of hurricane Sandy. The answers to my questions, and their relevance, were quite telling.
Around 45 A.D. Roman surveyors sailed across the English Channel and into the broad estuary of the Thames. The dynamics of what they saw were similar to what the Dutch surveyors of New York harbor found many centuries later.
In both cases, a vast and turbulent body of water lay outside natural defenses that suggested that an inner haven could be built around a harbor—and that this haven might one day become a metropolis.
In the case of London, the North Sea, dividing Europe from the east coast of the British Isles, narrowed into a funnel at the English Channel. Storms barreling down the North Sea forced surges into the Thames estuary that, unchecked, could flood low-lying areas as far as 60 miles upriver.
In New York, the Atlantic had two ways of surging toward the island of Manhattan—through the western neck of Long Island Sound and through the Verrazano Narrows.
The Romans wanted a site that would lie at the center of a road system to supply all their garrisons as they conquered ancient Britain. They settled on a place where the Thames could be easily bridged and where a hill provided enough elevation for a small city to be free of flood risk—the city they called Londinium.
There’s a long and intriguing story about why this first iteration of London flourished until around 400 A.D. and then totally disappeared (which was why I was talking to the archaeologist). But over the centuries, as London evolved into the first world city, it was better to be living on the high ground than down by the river—without any engineered embankments, it remained prone to being inundated by surges from the North Sea, particularly on the south side of the river which was low marshland.
Eventually, as it became obvious that both the British seat of government at Westminster and essential parts of the infrastructure, like the tube, were becoming vulnerable to increasing water levels, it was decided to end the game of chance in which the capital risked catastrophe.
In 1982 the Thames Barrier opened. It’s a system of ten enormous steel gates, sited in Woolwich, where the estuary narrows into the serpentine course it takes through the most densely populated parts of London. The Barrier looks weird. Each gate is topped by a five-story apparatus that looks like the cowl of a medieval suit of armor.
Since it was established, the Thames Barrier has been called to action more than 100 times, saving the city from serious storm damage. On current estimates of future rises in sea level and the increased frequency of storm surges, the Barrier should be good until 2070. After that, London will need even mightier gates on its river.
As a result of the security provided by the Barrier, it was possible for London to build a vast second financial district around CanaryWharf, where once a network of docks served the old maritime power. And beyond this powerhouse have come other prospering new quarters and the infrastructure to support them.
It’s not exactly rocket science to see that that one prudent step taken in the 1980s has repaid its cost many times over, and is responsible for the fact that as I write this I can sit alongside the replica of Shakespeare’s Globe theater on the south bank of the Thames knowing that, at least for some decades to come, London will never face the terrible damage inflicted on Manhattan this week.
Belatedly, after years of ignored warnings from experts, there is talk of putting barriers near the Throgs Neck Bridge, under the Verrazano-Narrows Bridge and at a narrow channel between Staten Island and New Jersey. How much longer will we have to wait?
Courtesy: iStock Photo