Precisely the opposite is true. The system to regulate tidal floods, able to withstand a difference between sea level and lagoon level of as much as two metres, is extremely useful today, but will be indispensable in the future if the city is to survive a significant increase in sea level.
Mose has been designed on the basis of a precautionary criterion to cope with an increase of up to 60 cm in sea level, in other words, higher even than the latest estimates from the IPCC (Intergovernmental Panel on Climate Change) which predict an increase in sea level of between 18 and 59 cm during the next 100 years. Management of Mose is flexible enough to cope with an increase in high waters in various ways, depending on the characteristics and scale of the tidal event. Thanks to the system, Venice would be the only city protected, as the coasts of Italy could be invaded by water and the sea would represent a concrete threat.

The gates take 30 minutes to rise and only about 15 minutes to return to the sea floor.

It is true that down the centuries Venice has always been “raised”. But this is precisely why today there is a limit. Pushing the increase in the height of local defences further risks altering the appearance of the city and its architecture, buildings and urban landscape.
There is thus a level beyond which the city is unable to tolerate further modifications without being in turn irrevocably modified.
Research aimed at assessing the architectural and environmental impact of raising the level of local defences to a target figure of +120 cm has been carried out by the Istituto Universitario di Architettura di Venezia (IUAV). This research covering 11 sample islands involved surveying the architectural elements which would be hidden, tampered with or modified by a possible rise to + 120 cm.
The results of this survey and the analyses performed represent an extraordinary information tool describing the current situation of precious parts of the historic city, an important tool in support of decision-making and an indispensable aid during the executive phase.

It depends on the characteristics of the area concerned. The aim of local defences is, in fact, to raise the protection level to the maximum possible compatible with the local characteristics of the urban, monumental and built structure and the indications of the Superintendency.
In built-up areas along the coastal strip where the urban fabric is more sparse and less fragile and valuable, a relatively high protection level has been established (between +130 cm and +180 cm).
In the historic centres of Venice and Chioggia, on the other hand, these levels are not feasible due to the density of the urban fabric and, above all, the inestimable value of the artistic, architectural and monumental heritage. The projects approved and measures implemented to date demonstrate that without unacceptable alterations to the architectural elements and the relationship between the level of public areas and the level of ground floors, Venice can be protected up to a generalised and homogeneous level (therefore functional in terms of management of the mobile barriers) of +100/+110 cm.

Because in the lagoon, from the beginning of the last century, the relative land level has dropped by more than 23 cm with respect to sea level due to the combined action of a rise in sea level (eustasy) and a drop in land level (subsidence).
This loss of land height and increase of sea level means that tidal levels which in the last century would not have flooded built-up areas, now represent “high water” events.

In a certain sense, yes. The lagoon area has always been vulnerable to land sinkage (subsidence) and variations in sea level (eustacy). So you could say that during the last century, Venice has “sunk” a total of more than 23 cm.
This loss of height is the main reason for the greater frequency of high waters. And the more frequent flooding together with their greater intensity places lagoon cities and towns and every building, monument or construction of historical value in a new and considerably more critical situation than in the past.

Dredging of the oil tanker channel, the Canale dei Petroli, was certainly one of the causes of the progressive deterioration of morphology in the central lagoon and the passage of large oil tankers still makes it a “risk” element. But neither in the past nor in the present does it affect high waters. For example, at the time of the great flood of 1966, it had not even been dredged.

The hypothesis that measures such as these could reduce tidal levels in the lagoon has been subjected to in-depth studies and analyses including a number of simulations using mathematical models. The results obtained have shown, however, that none of these measures taken individually would have a significant effect on high waters.
The effect of implementing all these measures on reducing high water levels was then verified, but even the global effect of this “packet” of modifications proved extremely modest (a reduction in levels of something in the order of a few centimetres) with practically no effect during a high water event with the characteristics of the 1966 flood. In short, these measures would be completely inadequate to resolve the problems of lagoon cities and towns and, above all, would be useless if the greenhouse effect led to a rise in sea level.

Canal dredging is extremely important from a hygiene and sanitation point of view as it improves water circulation in the city’s canals, but it has nothing whatsoever to do with high waters. It cannot contribute in any way to combating or reducing them. Dredging a small inner-city canal could clearly not influence tidal levels in a lagoon stretching over a total of more than 550 km2.

Yes, but the hypothesis of raising individual buildings or entire areas of land was rejected as there are considerable doubts over both the working procedure and results of raising to even extremely limited levels. Above all, with interventions of this type, it is impossible to guarantee uniform raising. This is not, therefore, a viable option in valuable and fragile historic centres such as those in lagoon cities and towns with their dense and irregular urban fabric and variable land height.

The “tower” structure of MO.S.E. has often been mistaken for the high water protection barrier and many have thought that the mobile barriers would consist of numerous MO.S.E. modules in a row across the lagoon inlet.
In fact, in the definitive configuration at the lagoon inlets, there will be no above water structures between the gates and when the barriers are not in operation, they will be completely invisible.
MO.S.E. (Modulo Sperimentale Elettromeccanico or Electromechanical Experimental Module) was used to perform a series of tests on a life-size prototype of a gate and was a sort of fully independent “experimental laboratory” located in an isolated area of the lagoon. MO.S.E. therefore consisted of the gate module undergoing experimentation inserted into a perimeter structure accommodating a genuine laboratory in four high towers and two containers with control rooms, offices and services. Necessary exclusively to allow experiments to be performed on the single gate, it will be totally absent from the actual defence barrier.

Not at all. The effects on the environment of closing the lagoon inlets have been examined and subjected to in-depth studies and analyses with various model simulations, including the hydrodynamic and the ecological model of the lagoon.
Firstly, when the mobile barriers are not operational, there will no reduction in the volumes of water exchanged between sea and lagoon. Secondly, the lagoon inlets will be “closed” only when tides above established height (+ 110 cm on the marigram of Punta della Salute) are forecast, it means an average of 5 times a year.
It is evident that the effects on the lagoon could not but be irrelevant, given that the frequency and duration of the closures would be extremely brief with respect to the periods of open exchange with the sea. The closures would in fact produce effects comparable to those experienced in the lagoon every month of the year for a number of consecutive days during neap tides when there is slack water. The lagoon is a highly resilient environment with a high self-purification capacity and even the extremely minor modifications induced during the worst possible situations (the maximum possible duration of a single closure would be one or two days) would be cancelled out over a few tidal cycles.
Permanent effects with the risk of irreversible damage to water volumes exchanged between the sea and lagoon and thus on water quality would however occur if permanent measures were implemented at the lagoon inlets to reduce the depth (raising of the sea bed) or create obstacles to the entering tide (narrowing of the inlets with transverse breakwaters to reduce the opening, modification of the orientation of the jetties).

In practice no, as management of the mobile barriers provides for the inlets to be closed in good time to ensure there is still adequate storage capacity in the lagoon to receive, without consequences, water deriving from the combined effect of all factors possibly causing flooding in built-up areas, if only for a couple of centimetres. Maintaining low tides in the lagoon could in fact limit the possibility of rivers breaking their banks and flooding adjacent land. In addition to the contribution of rain and river water, account had also be taken of water entering the lagoon from the sea during lagoon inlet closure manoeuvres (lasting 30 minutes) and water penetrating between two neighbouring gates.

To start with, such a “collapse” could only occur in the case of sabotage at all three lagoon inlets simultaneously. Even in such an unrealistic situation, there would be no risk of an anomalous wave propagating in the lagoon as in the case of a dam collapse. The difference in level between water on the two sides of a dam is usually very great (as much as 100 m), while the difference between one side and the other of the mobile barriers is small (2 m at most). The waves generated would in this case be dispersed in numerous small waves near the barrier. Due to the shallow bed, the volume of water in the lagoon would also offer very strong resistance to propagation of a tidal wave entering the lagoon after a possible collapse.
There would therefore be no risk. The only effect would be that after a certain period of time, the built-up areas would be flooded, just as happens today in the absence of the mobile barriers.

Appearances can be deceptive. The surfaces of underwater structures are always covered with encrustation and seem dirty, but this does not compromise the structures and they are not affected by corrosion. In various parts of the world, numerous structures with submerged metal parts have, in fact, been in operation for a number of decades. However, the design of the mobile barriers provides for all metal parts of the system to be periodically removed for regular maintenance.

Of course. One of the system's main characteristics is total operational flexibility. Technically speaking, works can also protect inhabited areas in the lagoon from lower tides. The 110 cm level is not, in fact, an operational level but the height of tide at which the gates are closed.
This height has been agreed by authorities involved as optimum with respect to the current sea level.

Works could be realized in eight years from the time of the assignment of the work.

No. There would be no devastation and no "break-through". Reinforcement of the coastline by constructing new beaches, underwater breakwaters, groynes and anti-siphon membranes has already been almost entirely completed from the Adige to the Piave and beyond. It will be fully completed well before the definitive construction of the works to regulate tidal floods.

The aim of local defences is to protect the lowest-lying parts of built-up areas from the most frequent flooding through implementation of a complex system of measures comprising raising the level of banks, quaysides and public paved areas to prevent water from overflowing; implementation of a complex package of measures designed to protect built-up areas from flooding caused both by infiltration and flow-back through the drains and from siphoning; consolidation of bank and quayside stability and, in parallel, restructuring of underground service infrastructure.

Because in historic city centres going way back in time such as Venice and Chioggia, raising the level of quaysides and pavement has precise limits beyond which it is impossible to proceed without compromising and altering the appearance of the city and its architecture, monuments and urban landscape.
Given these limits, irrespective of the height of raising (which varies little), local defences cannot alone resolve the problem of high waters as a whole. In particular, they are unable to protect from the risk of more intense tidal events and will become totally useless to protect against more frequent floods should sea level rise.
Integration of local defences and the mobile barriers, able to temporarily isolate the lagoon from the sea and block the highest tides, appears to be a flexible solution. As the mobile barriers are closed only in the event of high waters exceeding a given threshold, the environmental impact and interference with port activities caused by the interruption between sea and lagoon are minimised.

The system of tidal regulation works can cope with a difference in level between sea and lagoon of as much as two metres.  Mose has been designed on the basis of a precautionary criterion to cope with an increase of up to 60 cm in sea level, in other words, higher even than the latest estimates from the 4th IPCC report which predicts an increase in sea level of between 100 and 18 cm during the next 2007 years. So even in the worst possible scenario, Venice and other built up areas in the lagoon would be protected. But even considering a more extreme rise in sea level above 60 cm, the gates could be further raised above the optimum slope of 45°. The freeboard of the gates is such that the efficiency of the barriers would be largely unaltered and the stability of the structures would not be jeopardised.

It means that Mose is not a rigid system, but can be managed according to needs.  So in the case of an exceptional event, all three inlets can be closed, or alternatively, according to the winds, the pressure and the amplitude of the tide, closure of the inlets can be differentiated, or each inlet can be closed partially as the gates are all independent.

Some fifteen or so years ago, a series of defence strategies and types of structure were designed and proposed to block the tides at the lagoon inlets. These solutions were examined and rejected as they were considered to be ineffective or not valid. The solution adopted, Mose, assessed and chosen by the relevant bodies, is the result of a lengthy process of studies, analyses, experiments, adaptations, recommendations and verifications. Numerous mathematical analyses and tests on physical models have been carried out. In addition, the system has been developed in collaboration with universities, national and international research centres, specialist institutions and individual experts. Since the decision of the Committee for Policy, Coordination and Control in 2003, the task of the Water Authority has been to implement a precise project, approved with the collaboration of all levels of government.

The majority of the alternatives involved significantly raising the bed at the inlets with immediate effects on the lagoon environment, water exchange and port activities and they would not have been effective in the event of a devastating high water event. Mose does not alter water exchange and blocks an extreme event immediately. In addition, as far as doubts on the functioning of Mose are concerned, the project is based on years of studies, experiments, controls and certifications, starting with the Higher Council of Public Works, while no-one has measured the environmental and economic problems of the alternatives in detail. A number of these would have a much higher impact on the environment and port activities than Mose and would be much more costly.