The lagoon in 1000.
The lagoon in 1500.
The lagoon in 1700.
The lagoon in 1000.
The lagoon in 1500.
The lagoon in 1700.
The history of Venice has always been closely linked to coping with its water, as is shown by the constant changes in the lagoon over the centuries. As we can see the lagoons in 1000, 1500, 1700 etc., showed morphological changes caused by the various interventions made in that era. Apart from the historic views of the lagoon’s conformation, we should concentrate on the recent dynamics that characterize the current situation and problems of the lagoon’s balance.
Professor of hydraulics – Padua University
It is commonly presumed that the only problem facing the Venetian lagoon is defending it from the floods. In reality that is just one of the problems we should consider and perhaps it is not the most difficult to solve because the real problem is how to preserve the lagoon’s environment. Above all in the last few decades the lagoon’s environment has drastically changed and we are now facing phenomena that are slowly but relentlessly transforming the lagoon from lagoon to inlet. This is the problem that must be faced and dealt with.
From this view point I believe that the results that we have achieved from sophisticated math models and the experimental, cartographic examination of the lagoon over the past 200 years are very significant. The Denaix lagoon, 1811, still had extensive shoals and relatively deep water. In the centre the water was 50cm deep, today the water is 1metre 50cm. deep. This one metre difference is decidedly superior to what eustatic movement or subsidence could have caused.
The real cause is the work that man has carried out in the Venetian lagoon since 1800. First the wharves were built at the harbour entrance and later on the navigable canals and most importantly the Malamocco-Marghera Canal. During an ebb-flow a large quantity of fine material is expelled from the lagoon and carried out to sea being removed forever from the exchange balance of sediment between the sea and the lagoon.
The mechanisms that contribute to this large loss of sediment are mainly the motion of the waves which carry the fine sediment into the centre of the lagoon and then are slowly carried by the sea currents towards the mouths and then expelled into the open sea. If we want to reduce this phenomenon there are two paths to take. One is to reintroduce the fine sediment into the Venetian lagoon to balance the present situation where virtually no sediment is being brought from the rivers and the second is to reduce the effects of the movement of the waves. The movement of the waves is caused by the wind, fetch phenomenon, boating and fishing and clam fishermen.
1800 - 2000 - - rev. 0.1.7