Everyone knows about Venice and its water troubles. Situated on the extremity of a closed-off part of the Adriatic Sea, the Italian city is frequently subjected to the encumbrance of fluctuations in water levels – where high water periodically floods the piazzas, and low water obstructs navigation due to shallower canals. Add tourism into the mix, and it’s no wonder Venice has been hit by waves of challenges when it comes to managing its water levels.

30 years of planning, 20 years of construction

For more than 20 years, DHI has worked with Venice to manage high water levels in the city. In the 1990s, the Italian government initiated the MOSE (Modulo Sperimentale Elettromeccanico, Experimental Electromechanical Module) project to protect the city from flooding. The project involved the complex construction of 78 gates submerged in the sea – each as tall as a five-story building – that can be raised to separate the lagoon from the Adriatic Sea during high sea levels. To support the operations at the MOSE gates, a decision-support system was set up based on MIKE Powered by DHI technology: MIKE OPERATIONS.

What does the decision-support system do?

Sea-level forecasting and defining the correct timing for closing and opening the gates are fundamental tasks for properly operating the gates and safeguarding the ancient city. This is what the MIKE-based decision support system does.

As decision on the closure is taken several hours in advance based on the predicted water level at peak surge, producing reliable forecasts is extremely important to reduce false alarms, erroneous closures or missed closures in case of underestimated water levels. It means that the forecast of high water level events, as well as the right information and warnings to be disseminated, need to be extremely accurate.

To achieve that, a wide range of hydraulic models, based on a statistical and physical approach, as well as machine learning technologies, are continuously operated by the system. A complex algorithm combines the model results with measured data, allowing decisions to be taken on barrier closing and opening maneuvers, and therefore on when and for how long the MOSE gates will be in operation.

The computerised decision-support system is the outcome of a close collaboration through the years between the technicians of DHI and Consorzio Venezia Nuova (CVN), the concessionaire of the Italian Ministry of Infrastructure and Transport for the implementation of measures to safeguard Venice and its lagoon.

Round-the-clock support for critical events

DHI’s Marine & Coastal team in Italy provides 24/7 support during the more critical forecasted events, being part of the task force working at the MOSE control room. The team was active 24/7 from 19 to 25 November 2022 when the second highest surge in the last century occurred in Venice, constantly supporting the MOSE operations. Forecasts were highly accurate due to a very recent activity addressing the improvement of calibration of the MIKE 21 models.

The climate change solution took 30 years to plan and 20 years to build. The MOSE system is unique as the barriers are hidden away in the sea, allowing ships to navigate freely and the lagoon to operate normally on most days. Thanks to MOSE, the people of Venice were spared from another flood catastrophe – one that they have been all too familiar with.

What about the future?

The MOSE system has been adapted and improved over the years to help Venice confront the changing climate. Sea levels will continue to rise, and MOSE has been designed to protect the city from tides of up to 3 metres. As long as the technical collaboration with CVN is in place, DHI will continue working at improving storm surge forecasts, targeting more accurate model predictions – and hopefully leveraging more reliable weather forecasting.