Scientists have entered the struggle to save Venice from sinking into the surrounding lagoon - for if the present rate is unchecked the ancient Italian waterway city could be irrepairably damaged and almost uninhabitable within a few generations.

The danger, revealed by scientists several years before the November 1966 floods which damaged Venice, were highlighted during the floods -- which put the famous St. Mark's Square three feet (about one metre) under water.

Several recognised factors are contributing towards the situation. The level of the sea is slowly rising; the increasing numbers of motorboats on the City's waterways cause stronger and stronger waves which are gradually eroding away building foundations; large-scale industrial pumping away of underground water is producing cavities which are causing the ground to sink; too much tidal water moving at too great a speed is coming down the deep oil-tanker channel excavated ten years ago; and land reclamation has interfered with the natural damming effects of sand bars and mud banks which help slow down the tides.

Now, Venice's regional government, in co-operation with the nearby University of Padova, is employing scientists and technicians to seek methods of accurately analysing some of the known damaging factors. A giant, accurate model of the Malamocco estuary, one of the lagoon's three great openings into the sea, has been built in a University laboratory, and the lagoon's tidal patterns are reproduced artificially. A computer has been linked to the model's various hydraulic measuring instruments and equipment, and is analysing the all-important tidal flows, trying to establish their cause and effect. Then, when scientists can more easily understand the situation, they may be able to produce plans to counter-act the damage - and save one of the world's most admired cities.

SYNOPSIS: Ten years ago St. Mark's Square in Venice was under three feet of water following floods -- and the famous ancient waterway city suddenly took heed of scientists' warnings that it was slowly sinking. Various recognisable factors are causing the damage -- and if allowed to continue unchecked, Venice could be almost uninhabitable within a few generations.

One of the problems is the deep channel in Venice's lagoon dug for oil tankers ten years ago. This altered the natural tidal flow -- and now too much water moving at too great a speed during tides is causing the water level to gradually rise. So a giant, accurate model of the Malamocco estuary area -- one of the lagoon's three great openings to the sea -- has been built in a laboratory at the nearby University of Padova. The project, designed to try and establish the exact cause and effect of the tidal problem so remedial measures can be undertaken, was set up by the regional government of Venice and the University itself. The model reproduces the exact pattern of the estuary sea-bed, and artificially-controlled flooding of the model enables measuring instruments and a computer to analyse the water's exact behaviour. The complex and expensive model was originally developed by Italian hydro-technicians and West German electronics engineers. The model -- using hydraulic equipment -- is matched by another using pure mathematical measurement, to produce comparable results.