Flood Defence System to Prevent Flooding around Italy

In one of AUMA’s (Germany) most prestigious flood defence projects, and the largest order to date for its Generation .2 product series, almost a thousand modular electric actuators are being installed in a major scheme to protect the Venetian Lagoon in Italy. The high technology structure, known as Mose, is in an advanced stage of implementation.

Forming part of a major plan for the physical and environmental restoration of Venice’s entire Lagoon basin, Mose links the defence of the City with the architectural heritage of historic buildings and the Lagoon’s ecosystem. Protection from high waters, and recovery of the Lagoon’s resources, are incorporated into the scheme. The measures to safeguard the Lagoon are being implemented as part of an integrated and systemic programme by the Consorzio Venezia Nuova, on behalf of the Italian State (Ministry of Infrastructure and Transport - Venice Water Authority).

Mobile barriers are being constructed to defend the Lagoon area, its inhabitants, towns, cities and historic/ artistic/environmental heritage from high waters: as a result of changes in the inter-relationship between water and land in the Lagoon, rising water levels have become more intense and frequent over recent decades. To protect the Lagoon’s three inlets, 78 flood barrier gates with steel panels 20 m wide and up to 28 m long are secured to concrete foundations on the sea bed in four rows. Filled with water under normal conditions, the gates lie flat on the sea bed. If a tide of more than 1.1 m is predicted, compressed air triggers the gates to rise in sequence to produce an artificial dam.

AUMA actuators were chosen by ITALVALV to aid automation of the dam’s barrier gates. The Italian valve designer and manufacturer selected AUMA’s Generation .2 AUMATIC actuators: the actuation technology was integrated by ITALVAV into its emergency system which operates high performance control ball, butterfly and globe valves, required for on-off and modulating services.

Key reasons cited for selection of AUMA’s adaptable valve automation products included zone 2 explosion protection, required to protect against methane gas leaks. Reliability of performance is ensured with plug housing incorporating fail safe technology within the power supply and feedback system. And, as a result of using AUMA’s new generation products, full flexibility of control is afforded with redundant Profibus DP communication, in combination with conventional and analogue (4 - 20 mA) controls.

The mobile barriers for the Mose are made up of rows of independent gates consisting of a metal box structure fastened to a housing caisson by means of two "hinges". In normal tidal conditions, the gates are full of water and rest on the seabed, completely invisible and with no impingement on the fundamental exchange of water between sea and Lagoon. In the event of danger from flooding, compressed air is pumped into the gates, emptying them of water. The gates, which function only for the period of the high water event, rise and emerge, blocking the inflow of the tide into the Lagoon.

A total of 981 AUMA actuator and gearbox combinations are being installed as part of the Mose scheme over an 18 month period.