Why is Venice flooded? Is this just climate change? Is plate tectonics involved?

Question

Venice is located near the African and Eurasian plate boundaries, so is flooding caused by subduction?

Answer 1

Venice was built on a river

Answer 2

It's not just erosion.  Mud gradually loses water, until it's stone a few million years later.  Organic matter in the mud gradually decays.  Pilings sink into the mud.

My guess is that subduction contributes, but negligibly.  It's slow compared to the other processes.

Answer 3

Venice was intentionally built on a group of islands in a lagoon.   At the time it was built this was a good defence from anyone trying to attack the city.   This is why Venice was such a powerful city some centuries ago.  

Venice is sinking because too many people were digging artesian wells around the edge of the lagoon for water for the local industries.  River controls to stop flooding into the lagoon also stopped the silt build up required to keep the foundations of the city stable.  Venice is built on wooden piles driven through the mud with stone placed on top.   The dropping water levels of the aquifer below the city caused Venice to start sinking.   Flooding is also caused when the Adriatic sea raises water higher than the city quays.  Installing artesian bores were banned from the area in the 1960's.  Italy is looking at putting in high tech gates at the entrances to the lagoon that will automatically block the sea should the water level rise enough to flood the city.  They expect this to be working by 2011.

So in short,  Venice is sinking due to mans mismanagement of natural resources and not to geological forces.

Answer 4

Actually Venice is built on a river delta. All the material that makes up the delta is flood debris. This makes the material pretty soft and easily eroded. So venice is sinking partially because its built on mud. Also when they instituted flood controls the land lost the ability to replenish itself. Venice is at sea level so a few foot rise in sea level will be devastating, but the current flood problems are all just inherent in poor planning.