Coastal flooding
Compound coastal water levels: sea-level rise, tides and storm surge read together at the shoreline.
The question it answers
Which coastal assets could be reached by the combination of rising seas, high tides and storm surge — now and under higher-emissions futures?
Screening coastal flooding across a portfolio
- Builds a compound coastal water-level picture from sea-level rise, tides and storm surge for each coastal asset.
- Weighs that water level against the asset’s elevation and distance from the coast.
- Bands the result and projects it forward across SSP scenarios and horizons.
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
- Mean sea-level rise
- Mean higher-high-water tide
- 100-year storm surge + wave setup
- Tropical-cyclone modifiers
- Asset elevation & distance to coast
Governed model
Coastal 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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Mean sea-level rise
NASA MSL projections; World Bank CCKP
The slow-moving baseline shift the whole water column rides on.
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Mean higher-high-water tide
JRC LISCoAsT
The routine high-tide datum the surge builds on top of.
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100-year storm surge + wave setup
JRC MeteoTide / LISCoAsT
The extreme-event contribution to total water level.
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Tropical-cyclone modifiers
Historical TC tracks (AEP & rainfall)
Adjusts exposure where cyclone-driven surge and rainfall are credible.
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Asset elevation & distance to coast
Global DEM; coastline geometry
Determines whether a given water level can actually reach the asset.
The futures we test
- Sea-level rise is read per scenario, so the baseline water level itself differs between SSP1-2.6 and SSP5-8.5.
- Tide and surge components are combined into a compound water level rather than treated in isolation.
- Tropical-cyclone modifiers apply only where historical track evidence supports them.
How the result is built
- Assemble a compound water-level signal from sea-level rise, high tide and storm surge plus wave setup.
- Apply tropical-cyclone modifiers where the historical track record warrants it.
- Compare the compound water level against asset elevation and distance to coast.
- Resolve to a Low / Medium / High band on the shared physical-risk axis, per scenario and horizon.
What you get back
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Asset risk band
Compound coastal exposure at screening resolution.
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Scenario–horizon trajectory
How exposure rises with sea level through 2030, 2040 and 2050.
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Portfolio roll-up
Coastal exposure aggregated by group, country or region.
- Low
- Medium
- High
Compound exposure trajectory
Coastal trajectories tend to steepen later in the century as sea-level rise accumulates.
Coastal exposure by region
Where compound coastal exposure concentrates across a portfolio.
- South-East Asia High 24 assets
- East Asia Medium 31 assets
- South Asia High 18 assets
- Western Europe Low 27 assets
- North America Medium 22 assets
- Middle East Medium 9 assets
- Sub-Saharan Africa Medium 12 assets
- Oceania Low 8 assets
How to read the band
- A High band means the modelled compound water level can plausibly reach the asset at screening resolution — confirm with site survey and local defences.
- Coastal trajectories often look flat near-term then steepen, because sea-level rise compounds over decades. Read the 2040 and 2050 points, not just baseline.
- Distance-to-coast and elevation do a lot of the work: two neighbouring assets can band very differently.
Disclosure relevance
- IFRS S2 Physical risk identification for coastal and waterfront assets.
- IFRS S2 Strategy resilience under multiple sea-level-rise pathways.
- TCFD Metrics for assets exposed to acute coastal hazards.
Limitations
- Screening scope: not a coastal inundation model and not a flood-defence assessment.
- Local defences, sea walls and drainage are not represented — a defended asset may screen High.
- 0.25° climate inputs and DEM resolution limit precision close to complex shorelines.
Services
Screening-level analysis; not investment or engineering advice.
Bring coastal flooding screening to your portfolio
Screened, banded and framed for IFRS S2 and TCFD disclosure.