Aston Clinton has a modest flood risk, and almost none of it comes from rivers. The river flood zones barely reach the village. Rain is the likelier nuisance. No flooding is on record. The village sits at the foot of the Chiltern Hills, and water running off hills has only one direction to go.
The Environment Agency's river-and-sea mapping puts under 1% of postcodes across the Aston Clinton area in flood zone 2, the medium-probability band, and none in flood zone 3, the highest. Those two zones are separate bands, so the zone 2 share is the fringe on its own, with no high-probability core inside it to add.
That leaves surface water as the risk worth thinking about. With the river zones close to empty, the higher ratings on the wider postcode measure further down mostly point to rain with nowhere to go, and that is decided by slopes, drains and dips in the road more than by any river.
The Environment Agency's climate-adjusted mapping, which allows for heavier future rainfall and higher river flows, puts about 1% of the area's postcodes in the flood zones. That is a small increase on today's map.
For insurance, a risk this light should keep most homes in the ordinary market at ordinary premiums. The houses that do come up on the surface-water map can be treated differently, and insurers check the exact property, so the village-wide picture only goes so far.
On the broader postcode measure, which counts a postcode if it rates on any one of several flood indicators, surface water included, about 8% of postcodes in the area rate high on at least one, 9% medium and 28% low. A postcode only has to fail one test to count, so these shares run well ahead of the river zones above.
Counting homes is more useful. The Environment Agency's rivers-and-sea assessment lists 370 properties in the area's postcodes that carry some risk, and only postcodes with some risk appear at all. Of those, 19 are rated high, 5 medium, 38 low and 1 very low, and 3 of the high-rated properties are homes. Anyone looking at a house near either arm of the Grand Union Canal should enter the exact address into the Environment Agency's long-term flood risk service and read the surface-water results as well as the river ones.
Defences hardly come into it. The modelled flood extents put no postcodes in the high-risk extent, defended or undefended, and about 1% inside the low-risk undefended extent. A defence appearing in a model would only mean something is drawn on the map, and here there is barely anything for one to protect.
The nearest tide gauge is at Portsmouth, where sea level rose by about 2 millimetres a year between 1962 and 2023. That is the rate measured at that gauge over those years. If a nearest tide gauge at Portsmouth matters to a house in Aston Clinton, something has gone badly wrong elsewhere first.
The Environment Agency has no record of historic flooding in the area. That is reassuring, but it only covers floods that were recorded, and a blocked drain on a wet night rarely makes it into the archive.
Flood risk in Aston Clinton is middling and very local. The rivers leave it alone, and the few problem spots are wherever the rain from the hills collects.