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Project Mose: Venice: Problems The Main Cause Behind The Erosion of Islands

The main problems facing Venice are frequent flooding from high tides known as acqua alta, the sinking of the city, and deterioration of historic buildings. To address this, Project MOSE was developed to install movable barriers across the three inlets to the lagoon. When tides reach dangerous levels, compressed air will raise the steel gate barriers to prevent flooding into the city. However, there are concerns this could interfere with Venice's natural waste removal system and increase toxic chemicals in the waters.

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Shubhangi Singh
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57 views

Project Mose: Venice: Problems The Main Cause Behind The Erosion of Islands

The main problems facing Venice are frequent flooding from high tides known as acqua alta, the sinking of the city, and deterioration of historic buildings. To address this, Project MOSE was developed to install movable barriers across the three inlets to the lagoon. When tides reach dangerous levels, compressed air will raise the steel gate barriers to prevent flooding into the city. However, there are concerns this could interfere with Venice's natural waste removal system and increase toxic chemicals in the waters.

Uploaded by

Shubhangi Singh
Copyright
© © All Rights Reserved
Available Formats
Download as DOCX, PDF, TXT or read online on Scribd
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Venice: problems

The main cause behind the erosion of Islands :-


1. the first great escape was during the 1966 flood (the same rainy year when Florence was hardly
hit as well). On that occasion 16.000 Venetian ground-floor apartments were abandoned.
2. The progressive sinking of the town, with more frequent acqua alta (high water) phenomenons.
3. The increasing maintenance costs of its houses, old, often in bad conditions and constantly
under attack by damp.

Acqua alta

 Acqua alta - high water - is another problem for Venice.


It happens in November-December, mostly as a result of an interaction between tides and Sirocco (a
warm wind blowing from north Africa).
 To fight back acqua alta, the city is now building a big engineering project called Mose, which is
a system of big movable barriers able to lift up when the tides exceed a certain level, so to prevent
the water from flooding the town.

PROJECT MOSE
The construction of 79 steel gates to be installed along the sea floor at the three inlets of the lagoon

BACKGROUND -The Mose dams were designed in 1984 and were supposed to come into service in 2011

 The design plan for Project MoSE (Modulo Sperimental


Elettromeccanico) includes seventy-eight hinged steel box
gates placed throughout the inlets at Lido, Malamocco, and
Chioggia. The gates will first be flooded in seabed caissons.
When the tides reach 110 centimeters air will flow through
the gates, emptying the water, and allowing the gates to pivot
upward.
 System developed that foresees the barriers of mobile gates, able to isolate the lagoon
from the sea during the events of high tide.

 The integration of these interventions defines an extremely functional defense system


that guarantees the quality of the water, the protection of the morphology and the
landscape, the maintenance of the port activity.

Barrier stays on seabed until high tides and storm Air is pumped into each hollow gate to raise the
are forecast barrier

Gates move independently, allowing barrier to deal


with the rough seas.
CHALLENGES

One challenge in the project was trying to predict the right amount of barrier height to accommodate
for sea level rise.

fter consultation with the United Nation's Intergovernmental panel on Climate change, a 60 cm sea-level
rise was accounted for the same.

CONSTRUCTION OF GATES

The 300-ton gates will be 4m to 5m thick, 22m to 30m in length, and 20m wide. Hinges in the gate will
have a spherical shape and will be made up of ducts for air compression. The Caissons will be placed on
piles in trenches with dimensions of up to 60 meters in length, 10 meters in depth, and 45 meters in
width. The soil at each inlet will be strengthened with jet grouting and the ground around the caissons
will be secured with rock mattresses.

CONFIGURATION

There are 4 defense barriers: 2 at the inlet of Lido (the one closest to Venice which is twice the size of
the other two and is made up of 2 channels with different depths) which are respectively composed of
21 gates and one in the north channel of 20 that in the south channel, the two barriers are connected to
each other by an intermediate island.

1 barrier formed by 19 sluice gates at the port mouth of Malamocco and 1 barrier of 18 gates at the port
mouth of Chioggia.

At the port mouths of Lido and Chioggia, take shelter and small navigation basins allow the admission
and transit of pleasure boats, rescue vehicles and fishing boats even with the sluice gates in operation.
At the mouth of Malamocco a navigation basin was built for the transit of ships, so as to guarantee the
operation of the port even with the sluice gates in operation. The cliff outside the mouth of Malamocco
also has the function of creating a basin of calm waters that facilitates the entry of ships into the
navigation basin, to the sluice gates.
OPERATION
When they are inactive, the floodgates are full of water and lie completely invisible in housings placed in
the backdrop. In the event of a particularly high tide hazard which could cause flooding of the territory,
compressed air is introduced into the sluices which empties it from the water. As the water exits the
sluice gates, rotating around the axis of the hinges, they rise up to emerge and block the flow of the
incoming tide in the lagoon.

Compressed air is being pumped Gates rotating around the hinges as the water is expelled

Ultimately isolating the lagoon from the sea

CONSTRUCTION ELEMENTS

Each gate is made up of a metal box-like structure bound by two hinges to the housing box. Each gate is
20 m wide and has different lengths proportional to the depth of the mouth channel where it is installed
(Lido-Treporti: 18.6 m and Malamocco: 29.6 m) and variable thickness (Lido-Treporti: 3.6 m and
Chioggia: 5 m). The average closing time of the port inlets is about 4/5 hours (including the maneuver
times for the opening and closing of the sluice gates).
The housing caissons are the elements that form the basis of defense barriers: they house mobile sluice
gates and systems for their operation. They are connected by tunnels that also allow technical
inspections. The connecting element between the barriers and the territory is represented by the
shoulder boxes. They contain all the systems and buildings necessary for the operation of the sluice
gates.

DEMERITS

o Concerns about interference with normal tides can increase the levels of toxic chemicals, such
as mercury, in the waters of Venice.
o Since Venice does not have sewers, most of their household waste flows into the canals and is
washed out into the ocean twice a day with the tides. May affect city's natural waste system.

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