Wherefore art thou, MOSE

Dec 10 | News on the Rialto

The MOSE (the Italian word for Moses, and an acronym for Modulo Sperimentale Elettromeccanico) project has cost about 16 billion euros to construct and after thirty years, has finally started operating. It has successfully worked three times in early December 2020, and has saved residents in the city and the other areas of the Venetian Lagoon the costs and damage from the ever-increasing frequency of acqua alta.

​At the moment, the MOSE barriers are not activated unless the high tide is forecast for 130 cm or more. And on 8th December (a holiday in Italy), the maximum high tide was forecast was for 125 cm; therefore for there were no plans to operate them.

06a bocca di malamocco

As can happen, however, on the morning of the 8th, the predicted storm winds from the south-east and Croatia began instead to strengthen, with the unpredicted convergence of bora winds from the north-east. As this change arrived too late to put the Mose in motion, the resulting 138 cm tide caused great damage in the city.

The change of the weather caught the authorities out, and now questions are being asked as to why. As it takes over 3 hours to raise the 76 barriers of the MOSE (as the water that fills them normally is replace with air so that they rise), compounded by the fact that the instruction to action the Mose comes from Rome, the procedure will have to be reviewed to avoid a repeat in the future.

One of the unexpected consequences of the situation is that the lagoon is becoming a lake, as the two tides per day are not ‘flushing’ the water in the lagoon. Luckily boat movements are at a minimum at the moment, as pandemic conditions have put the tourist industry—maintained by the movement of people and goods by boat—on hold.

In numerous subsequent occurrences of acqua alta since 8 December, the gates have been in operation and Venice has been kept gratefully dry. We wait to see how matters develop and any future changes of how and when the MOSE will be called into action.