Editing Coastal flood inundation extent

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|+ SIGNAL Earth Structured Data
|-
! Object type
| Damage Signal
|-
! SIGNAL Earth ID
| DS-00703
|-
! Observable type
| Flooded area extent
|-
! Unit
| km2 (km2 (square kilometers of area))
|-
! Temporal structure
| Event-based
|-
! Monitoring backbone
| —
|}
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refers to the spatial area of land that becomes submerged due to elevated coastal water levels. This phenomenon encompasses flooding caused by high tides, storm surges, and long-term sea-level rise. Understanding the extent of coastal flooding is critical for assessing risks to coastal ecosystems, infrastructure, and communities.

Coastal flooding results from a combination of natural and anthropogenic factors influencing sea levels and coastal dynamics. It can vary widely in scale and duration, affecting localized areas during storm events or more extensive regions over longer periods due to gradual sea-level rise. Monitoring and quantifying this inundation extent supports hazard assessment and informs coastal management strategies.

Within the broader context of global climate change and increasing coastal development, coastal flood inundation extent remains a key environmental indicator. It integrates hydrodynamic processes and topographic features that determine how and where floodwaters encroach onto land.

== Geographic / System Context ==
Coastal flood inundation extent is relevant to all coastal zones worldwide, spanning diverse geographic settings from low-lying deltas and estuaries to rocky shorelines and barrier islands. The spatial variability of coastal topography, tidal regimes, and storm patterns influences the extent and frequency of inundation.

While this signal is not restricted to a specific geographic area, it inherently relates to the interface between marine and terrestrial environments where global mean sea level interacts with local landforms. Coastal areas subject to tropical cyclones, extratropical storms, and seasonal tidal cycles are particularly susceptible to episodic flooding events.

== Monitoring and Measurement ==
Scientists monitor coastal flood inundation extent using a combination of remote sensing, in situ observations, and hydrodynamic modeling. Satellite imagery, including synthetic aperture radar and optical sensors, enables mapping of flooded areas during and after flood events. Airborne lidar and digital elevation models (DEMs) provide high-resolution topographic data critical for floodplain delineation.

Hydrodynamic models simulate coastal water levels and inundation patterns by integrating tides, storm surges, river inflows, and sea-level rise projections. Observations from tide gauges and wave buoys contribute to validating model outputs. Institutions such as the National Oceanic and Atmospheric Administration ([https://en.wikipedia.org/wiki/National_Oceanic_and_Atmospheric_Administration NOAA]) and university research programs develop and maintain datasets and methodologies for assessing coastal flooding.

Within the SIGNAL system, this phenomenon is treated as a defined environmental signal whose boundaries and measurement conventions are described below.

== Signal Definition ==
The {{SignalTerm|type=DS|id=DS-00703|label=Coastal flood inundation extent}} measures the spatial extent of land area subject to inundation from elevated coastal water levels. This includes flooding induced by high tides, storm surges, and sea-level rise influences. The observable type associated with this signal is flooded area extent, quantified in square kilometers (km²). The temporal structure is event-based, capturing discrete flooding occurrences.

== Boundary Conditions ==
Boundary inclusions encompass all coastal inundation driven by sea-level rise, storm surge, and related elevated coastal water-level conditions. This includes temporary and permanent flooding of land areas contiguous to the ocean or estuaries.

Boundary exclusions specify that this signal does not encode information about threshold exceedance duration, return-period shifts, or changes in event frequency. It focuses solely on the spatial extent of inundation without detailing temporal persistence or probabilistic risk metrics.

== Aggregation Semantics ==
Geographic aggregation aggregates flooded area extents over defined coastal regions, which may range from local shorelines to broader coastal zones depending on data resolution and analysis scope. Temporal aggregation is event-based, meaning each flooding incident is considered individually rather than as a continuous time series.

Cross-signal aggregation involves integrating this extent data with related environmental signals such as coastal storm surge height and global mean sea level to provide comprehensive assessments of coastal flood risk. Aggregations must account for spatial heterogeneity and temporal variability inherent in coastal flooding phenomena.

== Observational Status ==
Monitoring of coastal flood inundation extent is ongoing, supported by advances in remote sensing technologies and hydrodynamic modeling approaches. Current datasets provide snapshots of flood extents during major storm events and contribute to understanding long-term trends influenced by sea-level rise.

Future SIGNAL releases may incorporate enhanced temporal resolution, improved integration with related coastal hazard signals, and expanded geographic coverage. Continued refinement of digital elevation models and flood mapping methodologies will improve accuracy and utility for risk assessment.

== Related Signals ==
* Coastal salinity intrusion extent
* Coastal storm surge height
* Flooded area extent
* Global mean sea level
* Return period contraction of coastal storm surge height extremes (declared percentile threshold regime)
* Significant wave height

== Key People ==
* National Oceanic and Atmospheric Administration (NOAA)
* University of Florida Coastal and Oceanographic Engineering Program
* University of the Sunshine Coast, Queensland

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== Key Associated People ==
* '''Amit Misra''' — University of California, Berkeley [Researcher; High]
* '''Brandon Victor''' — University of California, Berkeley [Researcher; High]

Inclusion reflects material contribution to the scientific understanding of this damage signal; it does not imply review, endorsement, or affiliation with SIGNAL Earth.
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== Sources ==
* [https://arxiv.org/abs/2411.01411 Mapping Global Floods with 10 Years of Satellite Radar Data] — arXiv, 2024. DOI: 10.48550/arXiv.2411.01411. [Paper; Supporting; High]
* [https://arxiv.org/abs/2409.18591 Off to new Shores: A Dataset & Benchmark for (near-)coastal Flood Inundation Forecasting] — arXiv, 2024. DOI: 10.48550/arXiv.2409.18591. [Paper; Supporting; High]
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