LONDON — For the first time in more than three decades, scientists from around the world are meeting this weekend to discuss how to reduce the risk of flood waters overwhelming the celebrated Italian canal city of Venice.

Around 100 scientists from a variety of disciplines are expected to attend a four-day conference that begins Sunday at Cambridge University's Churchill College.

"Everybody knows that Venice gets flooded. Not everyone knows that this is a drastically deteriorating situation," said a statement by Venice in Peril, a British group which funds research and organized the conference.

High water regularly floods St. Mark's Square and other parts of Venice, forcing people to tread on raised walkways. The city itself is sinking, the level of the Adriatic is rising and high tides are becoming more frequent.

Venice in Peril says that around 1900, the city's central St. Mark's Square was flooded about 10 times a year; now it is about 100 times and the group believes the implications of climate change on the ancient center are only beginning to be understood.

There has been no international meeting on the subject since a UNESCO gathering in 1969, three years after a major flood deluged Venice.

In May, Italian Premier Silvio Berlusconi inaugurated an ambitious $4 billion scheme, dubbed the "Moses" project after the Biblical figure who parted the Red Sea, to cut flooding.

Over the next eight years, hinged barriers will be built on the seabed that will be raised when high tides threaten the city.

Conservationists worry that the barriers will disturb the ecology of the lagoon.

"The closed lagoon and the architectural and physical infrastructure of Venice mean that water quality and ecological issues have to be confronted," Venice in Peril said, citing loss of natural sediment, the degradation of wetland areas, and the movement and storage of pollutants within the industrialized lagoon.

At the conference, scientists will look at ways to protect other coastal locations that face possible flooding, including parts of London along the River Thames; the Russian city of St. Petersburg, Chesapeake Bay in the United States and the Dutch city of Rotterdam.