GCRI · Oceans and Coasts
Sea level and coastal flood
Sea level is rising as oceans warm and land ice melts, and coastal floods that were once rare are becoming frequent. Extreme sea levels combine mean sea level, tides, storm surge and waves, and local land subsidence can add as much as the global rise. This page sets out how coastal flooding develops, how extreme sea levels and projections are estimated, and what evidence serves the authorities planning coasts for decades ahead.
Sea level and coastal flood on the record.
Sea level and coastal flood: how the risk develops.
Shoreline exposure and changing sea levels. The dossier below sets out how the risk develops, what is measured, where the data come from, how it is modelled and who decides.
Warming and melting raise the sea
Thermal expansion of seawater and melting glaciers and ice sheets raise global mean sea level. The rise continues for centuries after warming stops, and ice sheet loss is the largest uncertainty.
Land movement changes local rise
Subsidence from groundwater extraction, sediment compaction and tectonics makes the sea rise faster relative to the land in many deltas and coastal cities.
Extremes ride on the mean
Storm surge, high tides and waves come on top of mean sea level. A modest rise in the mean makes today’s rare extreme levels occur far more often.
Coastal systems respond
Beaches erode, wetlands may migrate or drown, and saltwater intrudes into aquifers and rivers. Defences shift flooding elsewhere and can fail when overtopped.
Water now in Pacific Island states.
Marine heat, rain and flood water over Pacific Island states, from NASA GIBS. Each layer carries its own date.
The interactive map needs JavaScript; the layer list and sources are below.
Layers 3
Water now, for this page
About this layer
- Evidence
- Observed
- Source
- GHRSST MUR25 (NASA JPL PO.DAAC)
- Provider
- NASA JPL PO.DAAC
- Licence
- NASA open data
- Vintage
- daily; Satellite analysis
- Newest at build
- 2026-10-12
- Resolution
- about 2 km grid
- Uncertainty
- Satellite analysis of how far sea temperature departs from its usual value for the date shown; a marine heat indicator, not a coral bleaching alert.
- Reached through
- gibs.earthdata.nasa.gov, only after you allow the live map
About this layer
- Evidence
- Estimated
- Source
- GPM IMERG (NASA GES DISC)
- Provider
- NASA GES DISC
- Licence
- NASA open data
- Vintage
- daily; Satellite estimate, near real time
- Newest at build
- 2026-10-12
- Resolution
- about 2 km grid
- Uncertainty
- Satellite estimate, near real time. Satellite or model raster as the provider publishes it. Clouds, swath gaps and retrieval error leave gaps and noise; values are indicators, not measurements at a place.
- Reached through
- gibs.earthdata.nasa.gov, only after you allow the live map
About this layer
- Evidence
- Observed (clouds leave gaps)
- Source
- VIIRS Global Flood Product (NASA LANCE)
- Provider
- NASA LANCE
- Licence
- NASA open data
- Vintage
- daily; Satellite detection; clouds leave gaps
- Newest at build
- 2026-10-14
- Resolution
- about 250 m grid
- Uncertainty
- Satellite detection; clouds leave gaps. Satellite or model raster as the provider publishes it. Clouds, swath gaps and retrieval error leave gaps and noise; values are indicators, not measurements at a place.
- Reached through
- gibs.earthdata.nasa.gov, only after you allow the live map
About this layer
- Evidence
- Observed
- Source
- VIIRS NOAA-20 corrected reflectance (NASA LANCE)
- Provider
- NASA LANCE
- Licence
- NASA open data
- Vintage
- daily; Satellite image
- Newest at build
- 2026-10-14
- Resolution
- about 250 m grid
- Uncertainty
- Satellite image. Satellite or model raster as the provider publishes it. Clouds, swath gaps and retrieval error leave gaps and noise; values are indicators, not measurements at a place.
- Reached through
- gibs.earthdata.nasa.gov, only after you allow the live map
About this layer
- Evidence
- Observed
- Source
- GHRSST MUR (NASA JPL PO.DAAC)
- Provider
- NASA JPL PO.DAAC
- Licence
- NASA open data
- Vintage
- daily; Satellite analysis
- Newest at build
- 2026-10-12
- Resolution
- about 1 km grid
- Uncertainty
- Gap-filled satellite analysis of sea surface temperature for the date shown; not a reef or species condition report.
- Reached through
- gibs.earthdata.nasa.gov, only after you allow the live map
About this layer
- Evidence
- Observed (clouds and sun glint leave gaps)
- Source
- MODIS Aqua ocean colour (NASA OB.DAAC)
- Provider
- NASA OB.DAAC
- Licence
- NASA open data
- Vintage
- daily; Satellite retrieval; clouds and sun glint leave gaps
- Newest at build
- 2026-10-13
- Resolution
- about 1 km grid
- Uncertainty
- Satellite estimate of chlorophyll-a near the sea surface on the day shown, an indicator of plankton and ocean productivity; not a measure of fish stocks or harmful blooms.
- Reached through
- gibs.earthdata.nasa.gov, only after you allow the live map
Keyboard, with the map focused
Hold Ctrl or ⌘ and scroll to zoom
Latest available
NASA GIBS / EOSDIS · ASTER GDEM (METI, NASA) · Blue Marble (NASA) · © OpenStreetMap contributors (ODbL) · Natural Earth
Loading the latest NASA imagery.
Drag to move. Ctrl or ⌘ and scroll, pinch or the buttons to zoom; hover for the values under the pointer; reset returns to the region.
Water now, framed on Pacific Island states.Satellite and model products as NASA publishes them, each with its own date. They are indicators, not assessments of any place.
Data: NASA GIBS · ASTER GDEM · Blue Marble · © OpenStreetMap contributors · Natural Earth · NASA EONET · NASA GPM IMERG Early · NASA JPL OPERA DIST-ALERTSources and licences
- We acknowledge the use of imagery provided by services from NASA’s Global Imagery Browse Services (GIBS), part of NASA’s Earth Science Data and Information System (ESDIS). Colours redrawn from the published colour map; values averaged into hexagonal cells where shown (modified). NASA open data
- We acknowledge the use of imagery provided by services from NASA’s Global Imagery Browse Services (GIBS), part of NASA’s Earth Science Data and Information System (ESDIS). Colours redrawn from the published colour map; values averaged into hexagonal cells where shown (modified). NASA open data
- GHRSST Level 4 MUR analyses, NASA Jet Propulsion Laboratory; distributed by the NASA Physical Oceanography DAAC (PO.DAAC); imagery via NASA GIBS. Colours redrawn from the published colour map; values averaged into hexagonal cells where shown (modified). NASA open data
- GPM IMERG precipitation, NASA Precipitation Processing System; distributed by the NASA Goddard Earth Sciences Data and Information Services Center (GES DISC); imagery via NASA GIBS. Colours redrawn from the published colour map; values averaged into hexagonal cells where shown (modified). NASA open data
- VIIRS near-real-time products (flood, land surface temperature, snow cover, corrected reflectance), NASA LANCE; imagery via NASA GIBS. Colours redrawn from the published colour map; values averaged into hexagonal cells where shown (modified). NASA open data
- MODIS Aqua ocean colour, NASA Ocean Biology Processing Group; distributed by the NASA Ocean Biology DAAC (OB.DAAC); imagery via NASA GIBS. Colours redrawn from the published colour map; values averaged into hexagonal cells where shown (modified). NASA open data
- ASTER GDEM is a product of METI and NASA (ASTER Global Digital Elevation Model V003, NASA LP DAAC); imagery via NASA GIBS. Colours redrawn from the published colour map; values averaged into hexagonal cells where shown (modified). Cite as: NASA/METI/AIST/Japan Spacesystems and U.S./Japan ASTER Science Team (2019). ASTER Global Digital Elevation Model V003. doi:10.5067/ASTER/ASTGTM.003. NASA open data
- Made with Natural Earth. Free vector and raster map data @ naturalearthdata.com. Public domain
- © OpenStreetMap contributors (ODbL), via NASA GIBS (coastlines, boundaries, roads and place names). Colours redrawn from the published colour map; values averaged into hexagonal cells where shown (modified). ODbL
- Blue Marble, NASA Earth Observatory; imagery via NASA GIBS. Colours redrawn from the published colour map; values averaged into hexagonal cells where shown (modified). NASA open data
- Context on the globe and flat map: coastlines, boundaries, roads and place names from NASA GIBS reference layers (OpenStreetMap data, ODbL, © OpenStreetMap contributors); Blue Marble imagery as an optional base; 3D terrain and the elevation read-out from the ASTER GDEM elevation colour index (5 m to 200 m classes, exaggerated for legibility). Boundaries are drawn as published and imply no position on any territory.
- Live events: NASA Earth Observatory Natural Event Tracker (EONET); events are indicative and keep their original source links.
- Live: NASA EONET Events are indicative, not authority warnings.
- Live: NASA GPM IMERG Early. We acknowledge the use of imagery provided by services from NASA’s Global Imagery Browse Services (GIBS), part of NASA’s Earth Science Data and Information System (ESDIS).
- Observed (EO): NASA JPL OPERA DIST-ALERT (contains modified Copernicus Sentinel data 2026). We acknowledge the use of imagery provided by services from NASA’s Global Imagery Browse Services (GIBS), part of NASA’s Earth Science Data and Information System (ESDIS).
- NASA GIBS: We acknowledge the use of imagery provided by services from NASA’s Global Imagery Browse Services (GIBS), part of NASA’s Earth Science Data and Information System (ESDIS).
- River discharge forecast, 30 days with range (GloFAS via Open-Meteo): Contains modified Copernicus Emergency Management Service information 2026; not a flood warning.
- Past year, daily temperature (ERA5 via Open-Meteo): Contains modified Copernicus Climate Change Service information 2026.
- Past year, daily temperature and sunshine (NASA POWER): These data were obtained from the NASA Langley Research Center (LaRC) POWER Project funded through the NASA Earth Science/Applied Science Program..
- Weather data by Open-Meteo.com (https://open-meteo.com/), licensed under CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/).
- Optional layers (14 sources in the layer list: live, forecast, observed and context) print their provider credit on the map and here when switched on; forecasts are model output and derived indices are estimates.
Layers and dates
- Sea surface temperature anomaly: GHRSST MUR25, NASA JPL PO.DAAC · 12 Oct 2026
- Precipitation rate, daily mean: GPM IMERG, NASA GES DISC · 12 Oct 2026
- Flood water, 3-day composite: VIIRS Global Flood Product, NASA LANCE · 14 Oct 2026
- True colour: VIIRS NOAA-20 corrected reflectance, NASA LANCE · 13 Oct 2026
- Sea surface temperature: GHRSST MUR, NASA JPL PO.DAAC · 12 Oct 2026
- Ocean chlorophyll-a concentration: MODIS Aqua ocean colour, NASA OB.DAAC · 12 Oct 2026
Sea-level rise reaches every coastal domain.
Coastal flood analyses are designed for the Regional Systems series. The IPCC’s ocean and cryosphere report (2019) and AR6 Working Group I (2021) give projected ranges; tide gauge records come from the Permanent Service for Mean Sea Level, and vertical datums are always stated.
- Tide gauge and land subsidence records.
- Surveyed coastal flood extents.
Coastal adaptation pathways.
The screen a team would use to follow this subject: its measures, states and decisions. Names are examples and values are illustrative.
Coastal adaptation pathways
Sea level and coastal flood · Coastal zone A · Sea level scenario set
Flood extent by scenario
illustrative coastline
Relative sea level
Adaptation pathways
| Dune nourishment | 0.4 | 2 | Raise seawall | Overtopping twice in 5 yr |
| Raise seawall | 0.5 | 10 | Managed realignment | Seawall at design limit |
| Managed realignment | 1.0 | 14 | Relocate assets | Community decision |
What is measured, and how well.
Each indicator carries its unit, its cadence, the kind of source behind it and the evidence label a value would carry. No values are shown: a programme supplies them under its own authority.
| Indicator | Unit | Cadence | Source type | Label |
|---|---|---|---|---|
| Relative sea-level trend | millimetres per year | annual | Tide gauges | OBSERVED |
| Global mean sea level | millimetres relative to a reference | monthly | Satellite altimetry | OBSERVED |
| Extreme sea level at a return period | metres above a datum | per analysis | Extreme value analysis of tide gauge records | ESTIMATED |
| High-tide flood days | days per year | annual | Tide gauges and flood thresholds | OBSERVED |
| Vertical land motion | millimetres per year | per analysis | GNSS and radar interferometry | OBSERVED |
| Projected sea-level rise | metres by a stated year and scenario | per assessment | IPCC AR6 projections | MODELLED |
| Population in the low-elevation coastal zone | people | per assessment | Elevation and population grids | ESTIMATED |
Route a storm through a river network.
Rain becomes runoff by the curve number method, drains each sub-catchment through a linear reservoir and travels down the main stem by Muskingum routing; play it to watch the flood wave move and flatten. Teaching model with stated illustrative values, not a prediction. The map on this page shows Pacific Island states; the model itself is not tied to a place.
Controls
- Storm rainfall depth
- 120 mm
- Storm duration
- 12 h
- Curve number (soil and land cover)
- 78
- Catchment area
- 800 km²
- Reaches on the main stem
- 5
- Travel time per reach (Muskingum K)
- 6.0 h
- Muskingum X (storage weighting)
- 0.20
- Channel capacity per unit area
- 300 L/s per km²
Readouts
- Peak discharge at the outlet
- 452 m³/s
- Time to peak
- 21.6 h
- Attenuation by the channel
- 61%
- Hours over capacity
- 26.4 h
- Runoff coefficient
- 52%
Numbers, methods and sources
| Hour | Outlet (m³/s) | Unrouted (m³/s) | Upper reach (m³/s) |
|---|---|---|---|
| 2.4 | 0.0 | 678.9 | 0.0 |
| 12.0 | 308.3 | 1,151.4 | 181.8 |
| 21.6 | 452.4 | 35.1 | 73.7 |
| 31.2 | 363.3 | 1.1 | 11.1 |
| 40.8 | 198.8 | 0.0 | 1.5 |
| 50.4 | 79.3 | 0.0 | 0.2 |
| 60.0 | 25.4 | 0.0 | 0.0 |
| 69.6 | 6.9 | 0.0 | 0.0 |
| 79.2 | 1.7 | 0.0 | 0.0 |
| 88.8 | 0.4 | 0.0 | 0.0 |
| 98.4 | 0.1 | 0.0 | 0.0 |
| 108.0 | 0.0 | 0.0 | 0.0 |
| 117.6 | 0.0 | 0.0 | 0.0 |
| 127.2 | 0.0 | 0.0 | 0.0 |
| 136.8 | 0.0 | 0.0 | 0.0 |
Methods
- Curve number runoff USDA Soil Conservation Service (1972), National Engineering Handbook, Section 4: Hydrology
- Linear reservoir Nash (1957), The form of the instantaneous unit hydrograph, IAHS 45
- Muskingum channel routing McCarthy (1938); Cunge (1969), Journal of Hydraulic Research 7
- Uncertainty fan (parameter Monte Carlo) Spiegelhalter, Pearson and Short (2011), Visualising uncertainty about the future, Science 333
- One-at-a-time sensitivity (tornado) Saltelli and others (2008), Global Sensitivity Analysis: The Primer, Wiley
Data
The model runs on the teaching values set by the controls. To calibrate it for a place, read it against these admitted layers and series, which this page’s map can draw:
- Rivers Natural Earth
- Lakes and reservoirs Natural Earth
- Cities Natural Earth
- Rain rate, last half hour (IMERG) NASA GPM IMERG Early · register nasa.gibs.context-live-layers
- River discharge forecast, 30 days with range (GloFAS via Open-Meteo) Open-Meteo.com (CC BY 4.0), Copernicus GloFAS · register open-meteo.public-pages
- Surface soil moisture (SMAP) NASA SMAP · register nasa.gibs.context-live-layers
- Surface water, 30 m (OPERA DSWx-HLS) NASA JPL OPERA DSWx-HLS (contains modified Copernicus Sentinel data 2026) · register nasa.gibs.context-live-layers
- Surface water through cloud, 30 m (OPERA DSWx-S1 radar) NASA JPL OPERA DSWx-S1 (contains modified Copernicus Sentinel-1 data 2026) · register nasa.gibs.context-live-layers
Across the six pillars, led by Nexus Consortium
- Experiments Labs
- Built in Oceans and Coasts in Foundry
- Tested at Oceans and Coasts in Universe
- Codified in Climate and Earth Systems in Standards
- Published in Oceans and Coasts in Reports
- Taught in Faculty of Earth and Environmental Sciences in Academy
Where the evidence comes from.
Named public datasets and institutional records, each with its licence class. Sources by agreement are used only under their terms and never republished.
| Source | What it gives | Licence class |
|---|---|---|
| Permanent Service for Mean Sea Level (PSMSL) | Monthly and annual mean sea level from tide gauges worldwide | Free with citation, PSMSL terms |
| GESLA global extreme sea level archive | High-frequency tide gauge records for extremes | Free with citation, licence per contributor (to check) |
| Copernicus Marine Service sea level products | Satellite altimetry sea level and anomalies | Free, Copernicus Marine licence |
| IPCC AR6 sea level projection tool (NASA) | Regional sea-level projections by scenario | Open, NASA data policy |
| NOAA tides and currents data | Water levels, high-tide flooding outlooks and datums for US stations | Public domain, US government data |
| Copernicus DEM and other global elevation models | Coastal elevation for exposure analysis | Free, licence per product (to check) |
Model Sea level and coastal flood as a system. Run the cascade.
Assembled from the Nexus Standards area profile Oceans and coasts risk standards: the hazards it names, the systems and sectors that carry the loss, the controls that dampen it and the data that observe it. Choose the components, pick an initiating hazard and step through the cascade. The Map view places the run on an example geography with open data. Every coupling weight is a stated assumption you can change. A teaching model, not a forecast, an assessment or a certification. To model a place of your own choosing, open the full System Builder.
Hazards
- Sea-level rise
- Storm surge
- Coastal erosion
- Heatwave
- Ocean acidification
- Harmful algal bloom
- Extreme fire weather (set off downstream)
- Wildfire (set off downstream)
- Heat-driven grid stress (set off downstream)
- Agricultural drought (set off downstream)
- Flash drought (set off downstream)
- Snow drought (set off downstream)
- Ground-level ozone episode (set off downstream)
- Meteorological drought (set off downstream)
- River flood (set off downstream)
- Coastal flood (set off downstream)
- Estuary flood (set off downstream)
- Mass displacement (set off downstream)
Systems and couplings
- Oceans and coasts risk standards
- Supply chain and trade risk Cascade
- Food and agriculture risk standards Cascade
- Climate risk standards Common driver and feedback
- Cities and urban systems risk standards Exposure
Controls
NS-0Constitution and principlesNS-1The UNI and the artefact catalogue (grammar v0.2: domain, sector, region and environment segments)NS-3Risk record UNIs (grammar, legacy crosswalk, allocation authority)NS-3bDataset and product metadata profile (STAC, DCAT, PROV-O)NS-5Figure, map and visualisation standard (with the UI/UX kit)NS-9Contextual UNIs (deployments, instances, programme instances)NS-11Verification and monitoring (evidence, attestations, zero-trust conformance observation)NRS-X3Oceans and coasts riskNRS-H11Hazard family: Coastal and sea-level hazards (NHS-1 water.coastal)NRS-H79Hazard family: Mental health crises (NHS-1 health.mental)NRS-H12Hazard family: Ocean-state extremes (NHS-1 water.ocean-state)NRS-H67Hazard family: Ocean circulation and marine tipping (NHS-1 planet.ocean-tipping)NRS-K18Domain pack profile: Oceans coastal (DOMAIN-018)
Observation
- Copernicus Marine Service ocean products (listed for reference)
- Coral Reef Watch daily 5 km heat stress products (listed for reference)
- PSMSL tide gauge mean sea level records (listed for reference)
- GEBCO global bathymetric grid (listed for reference)
- Argo float profiles (listed for reference)
- Average marine acidity (pH) measured at agreed suite of representative sampling stations
- Index of coastal eutrophication and floating plastic debris density
- Direct economic loss attributed to disasters in relation to GDP, including damage to critical infrastructure
Example geography
- Pacific Island states: 150 hexagonal cells
- Night lights tonight, outages (VIIRS Day/Night Band), NASA GIBS
- Surface water through cloud, 30 m (OPERA DSWx-S1 radar), NASA GIBS
- Rain rate, last half hour (IMERG), NASA GIBS
- Surface air temperature, daytime (AIRS), NASA GIBS
Who decides, and what the evidence serves.
Oceans and Coasts prepares evidence. The decisions below are taken by the authorities named, under their own rules, and never by the platform.
| Who decides | The question | Evidence this page serves |
|---|---|---|
| Coastal and flood defence authorities | What standard of protection to build and when to raise it | Extreme sea levels; projections; land motion |
| Spatial planning authorities | Where to restrict development or plan retreat | Exposure maps by scenario |
| Port and infrastructure owners | Which design sea levels to adopt for long-lived assets | Projections with ranges stated |
| Water utilities | How to protect aquifers and intakes from saltwater | Sea-level and intrusion evidence |
Outputs this topic produces
- Extreme sea-level analyses with record length and uncertainty stated
- Relative sea-level projections combining global projections and land motion
- Coastal flood exposure maps by return period and scenario
- Evidence notes for shoreline and adaptation planning
Coupled risk, applied response.
The sectors coastal storm surge touches and how strongly they depend on each other: what a study has to observe and model together.
Choose a context
Sectors · Coastal storm surgeStress
Pillars · Coastal storm surgeKPI
In this contextDependence or handoff, heavier is strongerOutside this context
Programme yearAll phases
Context
Coastal storm surge
Mangroves and dunes absorb the surge; where they are gone, ports, substations and water intakes take it.
W · E · I · F · H · B
Risk
- Sectors
- 5 of 6
- Relations
- 10 of 15
- Coupling
- 0.64 share of total
Hover a corner, a line or a row to trace it across both sides.
Route
Applied to coastal storm surge
L · F · U · S · R · A
Response
- Pillars
- 5 of 6
- Handoffs
- 12 of 18
- Loops
- 8 closed
Expected value
- What is at stake
- $390Ba year at least, in infrastructure disruption costs to households and firms in low- and middle-income countriesWorld Bank, Lifelines, 2019
- Return on resilience
- 4 : 1benefit to costWorld Bank, Lifelines, 2019
- Avoided loss
- $80Bflood losses avoided a yearGlobal Commission on Adaptation, Adapt Now, 2019
Hover a pillar, a line or a row to read how it is applied.
A: a teaching cascade (shock 0.6, gain 0.35, four rounds) over teaching values for a typical city-region, not measurements. B: illustrative applications and the KPI each pillar answers for; values are published benchmarks, cited, not forecasts. Open events: NASA EONET, live.
The questions experts ask.
- How much will relative sea level change at this location, including vertical land motion?
- How often will a given flood height be reached now and in future decades?
- How do surge, tide, waves and river flow combine during an event?
- Which assets, people and ecosystems are exposed, and how will exposure shift as the shoreline moves?
- How should the deep uncertainty in ice-sheet contributions be represented in planning?
How Sea level and coastal flood is modelled, measured and tested.
The model, its assumptions, its data and its uncertainty, in the form a scientist or engineer would check. Structures follow published methods. The values drawn are illustrative, not findings.
Earth observation chain
How a satellite or sensor record becomes evidence on sea level and coastal flood, and where each step adds uncertainty.
- 01 · Acquireorbit, sensor and revisitUncertainty: gaps from cloud and orbit
- 02 · Calibrateradiometric and geometricUncertainty: sensor drift
- 03 · Correctatmosphere and terrainUncertainty: aerosol and slope assumptions
- 04 · Retrieve or classifythe variable or the classUncertainty: model and training error
- 05 · Validateagainst ground truthUncertainty: sample design and size
- 06 · Publishwith error bars and lineageUncertainty: stated, never hidden
How seas rise and coasts flood.
Global mean sea level rises mainly through thermal expansion of warming water and through the loss of land ice from glaciers and the Greenland and Antarctic ice sheets. Regional sea level departs from the global mean because of ocean circulation, the gravitational and rotational effects of where ice is lost, and vertical land motion from tectonics, glacial rebound and subsidence. In many deltas and coastal cities, subsidence from groundwater and hydrocarbon extraction and sediment compaction is a large part of relative sea-level rise.
Extreme water levels arise when storm surge, driven by wind and low pressure, coincides with high tide and large waves, and when rivers carry high flows to the coast. As the baseline rises, a flood height that was once rare is reached more often, and the shoreline itself retreats where sediment supply cannot keep pace.
Observation, statistics and models.
Tide gauges and altimetry
Long tide-gauge records and satellite altimetry measure sea level; GNSS measures land motion. Gauges are sparse in many regions.
Extreme value analysis
Return levels are estimated from observed maxima; short records and changing baselines widen the uncertainty.
Hydrodynamic and inundation
Surge and wave models drive inundation maps; results depend strongly on the accuracy of coastal elevation data.
Limits: ice-sheet processes add deep uncertainty to late-century projections, and coastal elevation models can misstate flood extent where vegetation or buildings bias the terrain. Flood maps should state their scenario, time horizon, datum and resolution.
How it is studied, and what the methods cannot say.
- 01Ocean and coastal scienceRegional sea-level budgets · Marine heatwave analysis · Wave climate assessmentApplied here
- 02Extreme value theory and tail riskExtreme sea level return levels · Amplification factors · Extreme wave heightsApplied here
- 03Earth and geophysical scienceDelta subsidence · Sediment budgets · Tsunami source characterisationApplied here
- 04Geospatial information systemsCoastal exposure mapping · Marine spatial planning layers · Fishing effort mappingApplied here
- 05Earth observation and remote sensingOcean colour and blooms · Shoreline change mapping · Coastal habitat mappingApplied here
Where this page’s references lead.
The bodies and documents this page is read against. Status and editions change; each link goes to the issuing body.
Questions and answers.
Why does sea level rise differ from place to place?
What is an extreme sea level?
How much will sea level rise?
Is a flood map a prediction of where water will go next time?
Why do local projections differ from global ones?
Does the platform publish flood maps for specific places?
Contribute evidence from this page.
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