In order to know the precise degree to which the pavement needs to be raised to limit flooding and save the "Queen of the Adriatic" it is first necessary to undertake a comprehensive survey of elevations throughout the affected regions of the city (1,2,3).
With ample forecasting of an ensuing acqua alta, city workers scramble to erect an elaborate network of raised pedestrian walkways. Location priority is given to areas frequented by tourists for sightseeing (1) or shopping (2,3) rather than residential areas occupied by locals. Occasionally water levels rise to a level to cover the much more modest walkways often placed in those areas off the beaten tourist path (4).
Another acqua alta band-aid is the placement of metal barriers across the mouths of doorways to prevent ground floor flooding, especially in those buildings which owners leave unoccupied for much of the year,. Depending on the location and confidence of the owner, these barriers range from ankle (1) to mid-shin (2) to knee (3, 4) height and are even present on some of the major buildings along the Grand Canal such as the Ca' Pesaro museum (5) and the notorious Palazzo Dario (6).
Water Waste Treatment
Construction of a series of treatment wetlands on the island of Lazzareto Nuovo provides a new direction for how smaller lagoon communities can deal with their sewage. Nutrients present in the wastewater from restrooms (1) is removed by plants in treatment beds (2) before being discharged into the surrounding wetlands (3) for further polishing prior to entering the lagoon. It is somewhat ironic that this positive adoption of such innovative ecological engineering techniques based on living systems has occurred on an island so associated with death given that it was once a quarantine for the plague-ravaged city in the sixteenth century (4: garb worn by plague doctors now familiar as a carnival costume). It is also ironic that these remediation techniques that depend on contaminant-sucking plants should occur on the same island made internationally famous for the recent discovery of exhumed remains that had been imagined by the buriers to belong to a life-Sucking vampire.
Insula, the public works engineers in charge of repairing and raising Venice's pavements to protect the city from tidal flooding, has a number of projects underway (1). For those situated beside the open lagoon (2), steel barriers sometimes need to be erected and water pumped out (3,4) before work can begin on the fondamente (5). One of the most visible of these projects recently occurred in front of the Ducal Palace (6) where storage of equipment (7), new underground piping (8), pavement stones (9), and actual work areas (10) were a necessary inconvenience to pedestrians. Insula is at work in many other areas of the city lifting up (11) and removing (12) the old pavement, laying down temporary walkways (13), replacing aging infrastructure (14,15), and stockpiling old and new paving stones (16,17,18).
Emergency 'sausages' of sand-packed fiber are used to buttress the edges of saltmarshes against further erosion from motorboat waves (1) until such time as more substantial arrays of wooden stakes can be set in place (2,3,4). These resemble miniature fortifications in some frontier setting that are erected against hostile natives, in the present case, these being the operators of the speeding motorboats. Due to the diversion of inflowing, sediment-laden rivers from entering the lagoon. the ecosystem is now starved of bottom material needed for the natural replenishment of eroded saltmarshes. Restoration practices therefore involve the presence of large machinery (5,6,7,8) for the direct application of sediment that is either excavated and dumped or sucked up and sprayed upon the marsh. This built up material serves as the foundation (9) for recolonization by native grasses (10). However, the continual bombardment of waves or swells from boat wakes against the wooden fortifications (11: note the rolling waves) eventually breaks them apart (12,13) letting the invading water through the breaches to destroy the marsh once again (14).
The reclamation of an enormous landfill on the mainland in Mestre into the Parco San Giuliano, the largest park in the Venice lagoon, is a wonderful success story in the post-industrial reuse of derelict landscapes. Here locals can attend outdoor concerts, have picnics, engage in a variety of recreational activities (1,2,3,4,5), and observe wildlife in the wetlands constructed for stormwater treatment (6), all within site of the historic centre of Venice.
Floating wooden planks (1, 2) denote canal restoration that often accompanies drainage. This work involves closing bridges and sealing off both ends of the canal (3,4), moving pumps and other equipment into place (5), and buttressing any unstable building foundations (6) during draining of the section (7) containing decades of accumulated sediments (8,9) that have inhibited the natural cycle of tidal cleansing and which in consequence will be removed.
Repairs to buildings and courtyards, a ubiquitous feature throughout Venice, requires the presence of barges laden with construction material that blocks canals for months at a time (1). Renovation of the foundations for buildings located beside large canals involves the use of steel barriers to create dry-dock conditions and are often associated with Insula projects of raising pavement for flood protection (2,3,4,5,6). For repairs to other buildings, the small canal needs to be blocked and drained of water (7), thereby enabling workers access to reinforce the water ravaged foundations (8,9,10,11).
Millions of kilograms of boulders are now used to protect the shorelines of islands throughout the lagoon against motorboat waves (1), some of it being placed discretely behind wooden cribs (2,3) but most left in the open to become the new visual 'amenity' of the location (4,5). Out on the barrier island of Pellestrina, rock and concrete jetties thrust out into the Adriatic in attempt to stabilize the shoreline against erosion and longshore currents (6,7) at the same time as providing convenient places from which to swim for those locals and few knowledgeable visitors who refuse to venture to the filthy, crass beach at the Lido. The ultimate coastal defense system for Venice and its lagoon remains the massive bulwarks of reinforced stone, meters high and kilometers long, that armor the barrier islands (8,9).
Located in enormous buildings on the outskirts of nearby Padua are a group of hydrodynamic physical models that were instrumental in determining both how the Venice lagoon functions and the operation of the proposed MOSE floodgates. The lagoon model is a spectacular, to-scale creation that shows all the islands and channels (1) and, most importantly, can be filled with water (2,3) to study the mechanisms of the inception (4), spreading (5), and flood peak (6) of different acqua alta events. Other, first-generation models were built to study how the MOSE gates would operate from closure (7) through deployment (8) against simulated incoming tides. Further, detailed studies conducted in a massive wave-propagation tank (9) were useful for observing the oscillating behavior of the deployed gates (10, 11) in relation to being struck by oblique waves, and thereby became instrumental for recommending important design modifications. Finally, a group of Harvard-Ca'Foscari university students standing on yet another, this time outdoor, model at the testing site joke around by simulating their own barrier (12) against the flood of propaganda that they have been subjected to from various spokespeople of the MOSE project.
MOSE Flood Barriers
Massive building works for the accompanying jetties, breakwaters, and artificial islands that are underway in all three openings of the lagoon to the Adriatic, such as at the Lido (1, 2,3,4,5,6,7), are necessary to redirect inflowing tidal water to the protective MOSE barriers whose construction has taken over the eastern end of Venice (8).