The city is frequently beset by floods

Canaletto's pictures are extremely accurate since he used a camera obscura to project the image onto a canvas before tracing the contours with a pen.

"We can measure today in the picture what the tide level was some three centuries ago," said Dr Dario Camuffo, a climate change specialist working with the Italian National research council on the project.

By mapping the tide levels in the past it is hoped that they will be able to predict, and prevent, flooding.

Rising sea levels

"You can do a projection with the information from the past because the past is the key to interpreting the future," Dr Camuffo said.

Venice's problems are two-fold, it is falling victim to rising sea levels brought on by global warming, and the subsidence of the soil supporting the city.

The people of Venice have been angry at the authorities' failure to act over the city's problem with flooding.

A plan to create giant flood defences devised in 1994 and approved by an international panel of experts was blocked by environmentalists.

They say shutting the lagoon during high tides would have catastrophic consequences.