AfA480: 2004 Climate Change Fluvial Flood Depth Grids for England

A 2004 generalised modelling project produced this 5x5m resolution flood depth data for England, simulating a 20% increase in peak river flows to assess climate change sensitivity. The dataset covers two flood probabilities: a 1% and a 0.1% annual chance event, but has not been updated since its creation. Its primary purpose was to fill national data gaps for spatial planning, though the Environment Agency warns it is unsuitable for site-specific property assessments.

Use Cases

• High-level sensitivity analysis of climate change impacts on fluvial flooding based on a 20% peak flow increase.
• Defining approximate flood zone extents for spatial planning where detailed local models were unavailable in 2004.
• Comparing legacy generalised model outputs with more recent, detailed local flood models for specific areas.

Strengths

• Provides national coverage for England, generated from a consistent two-dimensional hydrodynamic model (JFlow).
• Offers high spatial resolution data on a 5x5 meter grid.
• Represents a historically significant, standardized national modelling effort from 2004.

Limitations

• The dataset has not been updated since 2004, and climate change allowances used are now outdated.
• Metadata is incomplete, with no information on row counts, file size, specific columns, or license.
• Sources conflict on the annual chance of flooding, listing both 1% and 0.1% probabilities for seemingly similar records.

Provenance

Source

Environment Agency (UK)

Collection Method

Modelled using the JFlow two-dimensional hydrodynamic model as part of the 2004 generalised modelling project.

Time Range

2004

Freshness

Last updated metadata dates are from 2026, but the underlying data and model are from 2004.

Geography

England, specifically for the 100x100km Ordnance Survey National Grid reference SJ. Data for other grid squares is reportedly available.