River (fluvial) flooding
Where rivers overtop their banks, and how that exposure shifts as the climate warms.
The question it answers
Which of our assets sit where rivers are most likely to flood, and does that exposure get worse under higher-emissions scenarios?
Screening river (fluvial) flooding across a portfolio
- Screens every asset for fluvial flood exposure using global hydrodynamic flooded-fraction data.
- Reads exposure at the asset location, then projects how it trends across SSP scenarios and horizons.
- Returns a banded result on the same axis used by every other physical hazard, so results compare cleanly.
Inputs in, banded result out
The governed model combines the inputs below into a single banded, scenario-aware result, under formal version and change control.
Inputs
- Flooded fraction (~2-year return period)
- Asset coordinates
- Scenario / horizon projections
Governed model
River (fluvial) flooding
Anchored to public, peer-reviewed climate science.
Version and change controlledOutputs
- Asset risk band
- Scenario–horizon trajectory
- Portfolio roll-up
What goes in, and where it comes from
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Flooded fraction (~2-year return period)
Global river-flood hydrodynamic modelling (~1 km, 30 arc-second), 1985–2014 baseline
Primary signal — the share of a grid cell expected to inundate at a frequent return period.
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Asset coordinates
Client asset register
Located against the ~1 km flood grid by nearest-cell snapping.
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Scenario / horizon projections
CMIP6 multi-model ensemble
Drives the forward trajectory across SSP1-2.6 to SSP5-8.5.
The futures we test
- Baseline reflects the 1985–2014 climatology, treated as present-day exposure.
- Forward horizons read flooded-fraction change under SSP1-2.6, SSP2-4.5, SSP3-7.0 and SSP5-8.5.
- The hazard is screened at a frequent return period, so the band reflects routine flood exposure rather than rare extremes.
How the result is built
- Snap each asset to its nearest ~1 km flood-grid cell and read the baseline flooded fraction.
- Read the projected flooded fraction for each scenario and horizon at the same cell.
- Combine baseline level and forward trajectory into a single composite score.
- Translate the composite score into a Low / Medium / High band on the shared physical-risk axis.
What you get back
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Asset risk band
Low / Medium / High exposure at screening resolution.
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Scenario–horizon trajectory
How the band moves from baseline through 2030, 2040 and 2050.
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Portfolio roll-up
Share of assets in each band, aggregated by group, country or region.
- Low
- Medium
- High
Exposure trajectory for a single asset
Read the band first, then the trajectory. A High band at baseline means present-day exposure, not a future risk.
Portfolio band migration across scenarios
How the mix of Low / Medium / High assets shifts as the scenario hardens.
How to read the band
- Read the band first. A High band at baseline means the asset is exposed today — not at some future date.
- Then read the trajectory. A Medium band that climbs under SSP5-8.5 flags an asset to plan around even if it looks comfortable now.
- Screening High means "investigate with site hydraulics", not "this asset will flood". It prioritises where detailed engineering study earns its keep.
Disclosure relevance
- IFRS S2 Identification of climate-related physical risks across the asset base.
- IFRS S2 Resilience of strategy under multiple climate scenarios.
- TCFD Risk management — process for identifying and assessing physical risk.
Limitations
- Screening scope: this prioritises assets for further work; it is not a hydraulic flood model or a cat-loss estimate.
- ~1 km resolution smooths local relief — flood defences, channels and small watercourses are not resolved.
- Flooded fraction describes a grid cell, not a building footprint; nearest-cell snapping can place a coastal or upstream asset in a neighbouring cell.
Screening-level analysis; not investment or engineering advice.
Bring river (fluvial) flooding screening to your portfolio
Screened, banded and framed for IFRS S2 and TCFD disclosure.