Are we ready for the flood?

Piazza San Marco (Source: Archivio Storico Comunale — Celestia)

Introduction

The historical center of Venice is composed by 118 islands connected by 354 bridges and divided by 177 canals. The shape and the land on which Venice stands required the solution to various problems in building construction and urbanism of the city, such as the consolidation of the foundations obtained by planting wooden poles in the unstable soil of the lagoon islands. The city, unfortunately, is slowly sinking due to the natural subsidence of the territory and to the sea level rise caused by natural causes, but in latest years mostly by human induced global warming. The Forecasting Center and Reports of Venice Tides estimated in 26 cm (average of the last ten years) the total loss of elevation of the city from 1897 (year of the definition of zero elevation, all values are recorded at the Punta della Salute Venice Station and refer to the 1897 tidal datum point), divided in the following contributions:

  • Subsidence, +12 cm (natural and human causes)
  • Sea Level Rise, +14 cm
The table shows the percentage of flooding connected to high tides. The bar chart shows the ten-year frequency of tides >=110cm. High waters since 1966, the year of the great flood, more than 110 cm have been 191, while between 1926 and 1965 had been 21.
Source: Centro previsioni e Segnalazioni Maree
Signs in St. Mark’s square of the “Aqua Granda”(Venetian dialect expression to remember the big flood) in 1966"
These graphics show the increase of global temperatures and the rising of sea levels (source: AR5, SPM, p. 3)

M.O.S.E.

I reckon that even though I had fun going to school wearing high boots through the flooded city, what I did not enjoy was being awoken during the night from the siren announcing the high tide (imagine owners of ground floor shops), but luckily the government had something in store for Venice.

THE HUMAN FACTOR

So the Mose project on paper seemed to be perfect: innovative, environmentally friendly, hidden underwater. Despite protests of environmentalists regarding the impact of the massive project; Even though in 2009 the European Commission-Environment, taking into account the mitigation and environmental restoration adopted by the Italian Government, dismissed an environmental infringement procedure brought to Italy; Despite protests against construction and the fact that operating and maintenance costs would have been at the expense of the Italian government - costs that the associations opposed to the project said would have been much higher than other systems with which other countries (Netherlands, United Kingdom) had faced similar problems - the project finally took off in 2003 (let me remind you the first Special Law was issued in 1973), and the money started to come. A lot of money.

1. Beaches reinforced 2. The intervention on the north pier of Malamocco 3. The intervention on the banks of the Zattere (Source: https://www.mosevenezia.eu/)
High Tide in St. Mark Square (Source: https://www.mosevenezia.eu/)

FLOOD BARRIER SYSTEMS FROM A TRANSNATIONAL PERSPECTIVE

As we already saw the Mose itself is a transnational project from the very first phase, where the best engineers showed their projects, to the end (just think that when the European commission dismissed the environmental infringement procedure, unlocked 1.5 billion of European founds). Project was also presented at the UN building. The presentation was part of the event ‘Saving and Preserving World Heritage Cities: Venice and Dubrovnik’, where the two sister cities on both sides of the Adriatic have been confronted on the challenges of preservation of historical heritage in relation to the opportunities offered from mass tourism and the problems posed by climate change.

1. Surge Barriers on the River Thames protect 125 square kilometres of central London from flooding caused by tidal surges. 2. The Oosterscheldekering, one of 13 ambitious Delta Works series of dams and storm surge barriers, designed to protect the Netherlands from flooding from the North Sea. (Source: https://www.mosevenezia.eu/)

CONCLUSIONS

The seas of the Earth are rising, a direct result of a changing climate. Oceans temperatures are increasing, leading to ocean expansion. And as ice sheets and glaciers melt, they add more water. As humanity experiences the early effects of a rapidly changing climate, policymakers focus on two primary responses: mitigation, and adaptation, or modifying infrastructure or behavior to adjust to climatic change.

Peak global mean temperature, atmospheric CO2, maximum global mean sea level (GMSL), and source(s) of meltwater. Light blue shading indicates uncertainty of GMSL maximum. Red pie charts over Greenland and Antarctica denote fraction (not location) of ice retreat. (Source: A Dutton / Science.)
Climate Central has launched its first animated map, Seeing Choices, which allows viewers to see the long-term sea levels locked in by different amounts of carbon pollution, contrasting scenarios of 0°C through 4°C of global warming.

UPDATE 14/11/19

Two days ago, November the 12th of 2019, Venice experienced the highest Acqua Alta after the flood of 1966: a tidal wave of 187cm with winds up to 100 kmh.

the force of the tidal wave inside the historical center of Venice
The historical center of Venice completely flooded.
The historical center of Venice completely flooded.

UPDATE OCTOBER 2020

In the last weeks the city of Venice experienced new tidal waves up to 130 cm.

M.O.S.E. barriers in function. On the left the lagoon (70 cm tide) on the right the Adriatic Sea (130 cm tide).

--

--

Get the Medium app

A button that says 'Download on the App Store', and if clicked it will lead you to the iOS App store
A button that says 'Get it on, Google Play', and if clicked it will lead you to the Google Play store
Mario Pavanini

Law graduate. Expertise in IT Law, Privacy and Administrative Law.