British and Italian scientists have started work in the Venice Lagoon on a project designed to prevent the city sinking into the sea.

Venice is regularly swamped by high tides and floods, which struck again this week.

The research, funded by the European Union, aims to find out how the Lagoon functions before the construction of a �2bn barrier of steel gates similar to the flood barrier on the River Thames.

The sea levels rise faster than the sinking of the city but together it is a double whammy

Professor David Paterson

The British team, led by Professor David Paterson of St Andrews University, has begun a three-year project to map tidal flows and marine life.

The team is using satellite technology and the latest remote sensing techniques.

Professor Paterson said: "Venice has been settling and the water is obviously rising as well because of global changes.

"The sea levels rise faster than the sinking of the city but together it is a double whammy."

Artificial marsh

Dubbed Project Moses, the engineering project to create the barrier - which will be raised from the sea bed to shut off high tides - remains intensely controversial and years behind schedule.

The salt marshes in the lagoon already provide a natural defence by helping to stabilise tides and slow down destructive waves.

Venice's St Mark's Square floods regularly

Professor Paterson thinks there is merit in another plan to strengthen Venice's outer defences by floating artificial marshes in the Lagoon.

Twice this week, the city's St Mark's Square has been engulfed by high tides.

The water slowly seeps out from under the stones in the piazza, the lowest point in Venice.

In 1966, when the city was hit by the most serious flooding in its history, the water rose 1.8 metres.

Some scientists fear that sea levels will rise by over 18 inches this century, which could prove catastrophic.

Others believe that in 50 years' time there could be daily flooding in some areas.