Venice - Lagoon: The MOSE System for the Defence Against High Waters
Venetian Lagoon Defense System
Overview of the Venetian Lagoon and Inlet System
- The Venetian lagoon connects to the sea through inlets, where a new defense system called "Mose" is being implemented to combat increasing high water events.
- The Malamok inlet is framed by two long jetties, serving as a critical point for this defense mechanism.
Structure and Functionality of the Defense System
- A breakwater, approximately 1,300 meters long, serves dual purposes: reducing tidal currents' intensity and protecting the navigation lock from wave motion.
- Underwater mobile gates are central to the defense system; they consist of metal gates hinged at their base that can rise to isolate the lagoon from high sea levels.
Construction and Operation of Mobile Gates
- Special protective paint is applied to gates to withstand marine conditions; inside, a modular metallic structure enhances resistance against waves.
- When tides exceed 1 meter and 10 cm, compressed air expels water from the gates causing them to rise and block seawater entry into the lagoon. Once water levels normalize, they return to their original position.
Management of Flood Events
- Fixed structures like outer breakwaters help reduce flood frequency; mobile barriers are expected to be used only 3 to 5 times annually under current sea level conditions.
- Precise procedures govern gate operations considering various factors such as river flow and wind effects on water levels in the lagoon. There are four rows of gates across different inlets with varying numbers based on depth requirements.
Specifications of Gate Structures
- Gates vary in size: lengths range from 18 to 28 meters with thicknesses between 3.6 and 5 meters; all have a uniform width of 20 meters for consistency across installations.
- At full operation, these gates form a continuous barrier capable of sustaining up to two meters difference between sea and lagoon levels, ensuring protection even amid significant sea-level rises over the next century.
Impact on Port Activities