The impacts of sea level rise in the Venice’s lagoon
Venice sits in a lagoon, separated from the Adriatic Sea by a series of barrier islands. Centuries of human intervention — including the diversion of rivers, widening of the lagoon’s entrances and dredging of channels to accommodate shipping, and the draining of mudflats for construction and agriculture — have disrupted the lagoon’s equilibrium with the sea .
Sea level rise (SLR) represents the main threat for the survival of Venice, emerging today only 90 cm above the Northern Adriatic mean sea level.
Sea level rise is a significant consequence of climate change and global warming. At present Venice is sinking at 0.05 cm/year and the 25 cm of SLR occurred over the 20th century has increased the flood frequency by more than seven times. During the 21th century, global average sea level is expected to rise considerably faster that in the 20th  and the flooding events of 110 cm above datum or more could increase to 20–250 times per year with respect to the present annual frequency of 4 times .
MOSE: a barrier to hold back the tide
Finally, in 2001 the Italian government decided to put into action the most ambitious of the engineering solutions known by its Italian acronym of MOSE (MOdulo Sperimentale Elettromeccanico, Experimental Electromechanical Module). The project is an integrated system consisting of rows of mobile gates situated in the three inlets through which water enters and leaves the lagoon. Gates are inserted into their concrete foundations on the bed of the Venetian lagoon and are able to be opened and closed separately to control the flow of water and temporarily isolate the Venetian Lagoon from Adriatic Sea tides of up to 3 meters (9.8 ft) .
The Consorzio Venezia Nuova , made up of a group of national and local construction companies, is responsible for the work on behalf of the Ministry of Infrastructure and Transport – Venice Water Authority. Construction began simultaneously in 2003 at all three lagoon inlets and the gates are expected to be fully operational between 2018 and 2020, later than the originally anticipated 2016 completion date. The MOSE project is estimated to cost €5.5 billion, up €1.3 billion from initial cost projections .
To support and control the billionaire capital investment for the construction of the gates, Consorzio Venezia Nuova instituted the MOSE control center. The center has been simulating the control of the gates since 2011, collecting data that enables the creation of mathematical and statistical models that can be entered into the decision support system. The factors being considered are wind, water level, waves, pressure and fresh flood from the rivers .
Supporters and opponents of MOSE are still debating in local newspapers and media. The Venice Water Authority has done an important step forward to preserve a masterpiece of the human heritage from the impacts of climate change and sea level rise, but more actions need to be taken considering that we only have predictions of what those impacts could be in the next century.
First of all, the Venice Water Authority has to make sure that no further delays will affect the completion of the project. Secondly, additional measures suggested by many scientists should be put in place, such as narrowing the large canals that enter the city’s harbor, reinforce the coastal, raise special quaysides to protect historical buildings from high floods, and improve the pavement of the lagoon .
Furthermore, once the MOSE gates will be fully operational, Venice Water Authority should consider to add more resources to the MOSE control center so that it can operate 24 hours a day and manage flood emergency promptly.
Finally, Italian Turism Authorities should run sensitization campaigns and raise funds from global organizations and private funds to support the Venice’s cause. A successful example is the UK-based Venice In Peril Fund that supports restoration and conservation work in the city. In the words of the chairman of the fund Jonathan Keates, “If the thought of Venice sinking captures the imagination, then it should be as a wakeup call to save the city as an essential basis of the civilization we cherish. The world owes huge debts to Venice, including modern systems of democratic government and the printed book.” (793 words)
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- Windsor, Antonia, “Inside Venice’s bid to hold back the tide”, The Guardian Retrieved 2015-06-24, [https://www.theguardian.com/cities/2015/jun/16/inside-venice-bid-hold-back-tide-sea-level-rise], accessed October 2016
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