Yes, Belvedere has a real flood risk, and it's concentrated on the low ground beside the Thames. About a quarter of the area's postcodes are in the highest river-and-sea flood zone. Over two hundred homes are rated at high risk from the river and the sea. The worst flood on record came when the sea broke through a defence. Up the hill, most of this stops being your problem.
On the Environment Agency's river-and-sea mapping, about 27% of Belvedere's postcodes are in Flood Zone 3, the highest-probability band, and about 1% are in Flood Zone 2. The two zones don't overlap. Zone 2 is the medium-probability fringe outside zone 3, which is why it's the smaller number here. The edge of the high zone is close to where the flat land begins, and very little of the town is in between.
Surface water from heavy rain isn't measured separately for Belvedere. It's counted in the postcode-level measure further down, alongside rivers and the sea, so it can't be read off these zone figures.
Once the Environment Agency adds its allowance for a changing climate, about 14% of the area's postcodes fall inside the adjusted flood zone. That's a modelled projection of where the water could reach, and it doesn't put a date on anything.
Insurers have their own maps, and a house on the old marsh will be priced very differently from one on the slope a few streets away. Get a real quote on the specific address, and ask what's excluded, as early as possible. A purchase with no affordable insurance can quickly become a purchase with no mortgage.
Counting every measure together, rivers, the sea and surface water, about 12% of Belvedere's postcodes rate high on at least one of them, about 20% medium and about 41% low. A postcode counts as soon as any one measure flags it, which is why these shares don't match the zone figures above.
In terms of homes, the Environment Agency's rivers-and-sea mapping lists 3,203 properties in the postcodes that carry some risk, and only those postcodes are counted. Of them, 235 are rated high risk, 162 medium, 73 low and 2,009 very low. Of the 235 high-risk properties, 226 are homes. That's a specific, finite number, and the question that matters is whether the house you're viewing is one of them.
The defences make a real difference to the map. Leave them out and about 27% of Belvedere's postcodes are inside the high-risk flood extent. Put them in and the figure is about 6%. "Defended" only means a defence appears in the model, and it says nothing about how well it would hold. The Environment Agency has 43 recorded flood events for the area, and the most recent, in 1953, came from the sea when a defence failed. That was the North Sea Flood, which wrecked homes on Belvedere Marshes. The name always told you which part of town was at risk.
At Dover, the nearest tide gauge with a long record, sea level rose by about 2.2 millimetres a year between 1961 and 2010. That's what the gauge measured over those years, and nobody should treat it as a speed limit for the future.
Flood risk is one of Belvedere's weaker points. It's serious on the old marsh by the river, and much easier to live with the further up the slope you buy.