What will save Venice

The aqueous city of Venice, suspended between sky and water, is by its very nature sustained and at the same time threatened by its own environment : the salty water of its vast and beautiful lagoon. The ancient Republic of Venice knew the key role that a sustainable management of this fragile body of water played in the city for the circulation of people and goods.

The lagoon of Venice today measures 500 squared kilometers also thanks to four main interventions: the diversion of the rivers that were flowing into the lagoon, the reinforcement of the barrier islands of Lido and Pellestrina – defended by a very innovative sea wall called Murazzi – the construction of the big outer breakwaters at the three openings of the lagoon, and at last the excavation of the navigable channels connecting the port of Venice to these openings. The first works started at the beginning of the 17th century.

In a few centuries, these interventions created a deepening of the channels. Consequently a larger amount of cube meters entered the lagoon, creating higher tides and acqua alta (floods). To these artificial interventions we also need to add the tendency of Venice to subside (1,3 mm per year) and the general sea level rising (1,3 mm per year).

The city of Venice has been therefore more frequently and severely flooded between the 20th and 21st centuries. It was in fact at the beginning of the new century that, after many national and international debates, the Italian central government decided to built a gigantic movable flap watergate called MOSE – MOdulo Sperimentale Elettromeccanico (Experimental Electromechanical Module) at the three lagoon mouths. These water gates would be activated when the high tide coming in from the open Adriatic sea were to be forecasted at a critical level.

MOSE should protect Venice and the lagoon from high tides up to 3 meters (9.8 feet) and it is part of a larger project, toghether with the raising of quaysides and the maintenance of the whole lagoon, including vital elements such as the salt marshes.

The construction of the three dams started simultaneously in the year 2003 and, after numerous delays, costs overruns and big corruption scandals, we could finally perform the first test on July 2020. The original deadline was 2011…On October the 3rd 2020 Mose was successfully activated for the first time and we could at last enjoy a dry San Marco square ! The MOSE itself costed 7 billions Euros and its maintenance will cost 100 million Euros per year, a fabulous cost at the expenses of the Italians !!

This year, Mose was activated already 4 times when the tide got over 130 cm above the MSL (mean sea level) and between the 4th and the 6th of December for nearly 40 hours ! However, since San Marco Square gets already flooded at 110 cm MSL, the dams will in a couple of years be activated when the water will reach 110 cm only. In 2019 the level of the lagoon water went above the level 110 cm 28 times (50 hours of flooding) with 12% of city under water. Luckily this year we had a dry November. We are now facing a paradox in which most of the shop-keepers located in low-lying areas wish that high tides reach the 130 cm level more often, so that the city can stays dry. A dilemma is not yet solved!

Photos: Peggy Choucair // Cristina Utrera