Cumulative Exceedance Duration of Coastal Flood Inundation Extent (Above Declared Threshold)
| Object type | Damage Signal |
|---|---|
| SIGNAL Earth ID | DS-00378 |
| Observable type | Top-of-atmosphere radiative imbalance |
| Unit | W/m2 (W/m2 (square meters of area)) |
| Temporal structure | Monthly |
| Monitoring backbone | — |
The
Cumulative Exceedance Duration of Coastal Flood Inundation Extent (Above Declared Threshold) is an environmental signal representing the total time during which coastal flood waters surpass a predefined inundation threshold. This phenomenon is critical for understanding the persistence and severity of coastal flooding events, which can have significant impacts on coastal ecosystems, infrastructure, and human communities. The signal integrates temporal exceedance information to provide a comprehensive measure of flood duration beyond critical levels.
Coastal flooding is influenced by a variety of factors including sea level rise, storm surges, tidal cycles, and atmospheric conditions. Monitoring the duration of exceedance above flood thresholds helps characterize flood risk and informs scientific assessment of coastal vulnerability. This signal is derived from measurements of top-of-atmosphere radiative imbalance, linking atmospheric state changes to coastal flood dynamics.
Within the broader context of environmental monitoring, this signal supports the assessment of coastal flood impacts on a global scale, contributing to improved understanding of flood persistence and its relationship to climate and atmospheric processes.
Geographic / System Context
[edit]This signal applies globally, encompassing coastal regions around the world where flood inundation events occur. Coastal zones are dynamic interfaces between terrestrial and marine environments, subject to complex interactions among oceanographic, atmospheric, and geological processes. The geographic scope includes low-lying coastal plains, estuaries, deltas, and island shorelines vulnerable to flooding. Variability in flood extent and duration is influenced by regional factors such as tidal regimes, storm frequency, and local topography.
Monitoring and Measurement
[edit]Monitoring of coastal flood inundation duration traditionally involves a combination of remote sensing, tide gauge observations, and hydrodynamic modeling. Satellite-based remote sensing techniques, including synthetic aperture radar and optical imagery, are used to map flood extent and temporal changes. The referenced method, FLDPLN, is a remote sensing flood inundation mapping approach that enhances detection of flood duration and extent. Atmospheric and oceanographic data from global observing systems contribute to understanding the drivers of flood events. The signal is linked to measurements of top-of-atmosphere radiative imbalance, which reflect changes in Earth's energy budget related to atmospheric state changes that can influence 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
[edit]This damage signal quantifies the cumulative duration, on a monthly timescale, during which the spatial extent of coastal flood inundation exceeds a declared threshold. It is derived from the observable type 'Top-of-atmosphere radiative imbalance' and represents a state change within the atmospheric domain that correlates with coastal flood persistence. The canonical unit of measurement is watts per square meter (W/m²), reflecting the radiative energy imbalance associated with the flood state.
Boundary Conditions
[edit]Boundary inclusions encompass all coastal flood inundation events where the spatial extent surpasses the predefined threshold level for inundation, capturing the full duration of exceedance within the monthly aggregation period. Exclusions include flood events below the threshold, inland flooding unrelated to coastal processes, and transient or minor inundations that do not meet the spatial or temporal criteria for inclusion. The signal focuses on atmospheric state changes influencing coastal flood duration and does not incorporate direct hydrological or groundwater flooding unrelated to coastal inundation.
Aggregation Semantics
[edit]Geographic aggregation is performed globally, integrating flood exceedance durations across all coastal regions within the defined spatial extent. Temporal aggregation is monthly, summarizing cumulative exceedance durations for each calendar month to capture seasonal and interannual variability. Cross-signal aggregation considers relationships with related signals such as coastal flood inundation extent, enabling combined assessments of flood severity and duration. Aggregation methods ensure that overlapping exceedance periods are accounted for without duplication, providing coherent temporal and spatial summaries.
Observational Status
[edit]Current monitoring capabilities rely on a combination of remote sensing flood mapping and atmospheric radiative measurements, with ongoing developments to refine threshold definitions and improve temporal resolution. The monitoring backbone is under development (TBD), indicating that future SIGNAL releases may incorporate enhanced datasets and more comprehensive spatial coverage. Continued integration of atmospheric and coastal flood data will improve the reliability and applicability of this damage signal for environmental assessment and research.
Related Signals
[edit]- Coastal flood inundation extent
Key Associated People
[edit]- J. Edwards (-) [Lead author]