Flood depth — 10-year return, present climate (GIRI)
This layer estimates how deep floodwater would stand at a given location during a flood of the kind expected roughly once a decade, under present-day climate.
Category: Physical risks · Mitigating services · Climate Acute Risks Coverage: Global Format: Raster grid (~1 km) Used in risk analysis: Yes — gates Mitigating services
What it shows
This layer estimates how deep floodwater would stand at a given location during a flood of the kind expected roughly once a decade, under present-day climate. By giving a site-level water depth rather than a broad category, it can tell apart floodable and non-floodable ground within river corridors, deltas and urban areas, making it well suited to screening flood exposure precisely.
How it is built
The layer is produced by UNEP-GRID for the Global Infrastructure Resilience Index (GIRI), developed with the Coalition for Disaster Resilient Infrastructure. It is based on a distributed hydrological model (Silvestro et al., 2013, 2015) driven by a global meteorological dataset for the present-climate run, coupled with a hydraulic model that converts simulated river discharge into flood depth. The output is a global grid of inundation depth at roughly 1 km, for a 10-year return period and a present-climate baseline (1979–2016). It represents both river and rainfall-driven flooding; coastal storm surge is not included and is covered by a separate coastal-flood layer. Forward-looking climate-scenario versions are available as separate layers.
How to read it
Higher values mean deeper projected floodwater at that location for a once-in-a-decade flood, indicating greater exposure. Locations with little or no depth are effectively outside the modelled flood footprint at this return period.
Source
GIRI — Global Infrastructure Resilience Index (UNEP-GRID / CDRI, 2023). Licensed under CC BY 3.0 IGO. https://giri.unepgrid.ch/.
Comparison with the WWF Risk Filter Suite
This maps to WWF Biodiversity Risk Filter indicator S3_7 Flooding (and the Water Risk Filter B3 Flood category). WWF expresses flooding as a basin-level composite of occurrence and hazard, whereas Darwin provides a fine-grained, site-level flood-depth surface for a defined return period. Darwin is more spatially detailed here.
Risk analysis
A site is flagged on a dimension by combining a proximity trigger (this layer) with an activity trigger (the entity's ENCORE pressure/service). Proximity only → Potentially material; proximity and the matching ENCORE pressure/service is material → Very material; neither → Not material.
| Dimension | ENCORE service / pressure | Proximity trigger (this layer) | Activity trigger (entity) |
|---|---|---|---|
| Mitigating services | Flood mitigation services | Layer value above 100 | “Flood mitigation services” pressure ≥ 4 |
Legend
Symbolised field: Flood depth (10-year return)
| Class | Colour |
|---|---|
| Very low (<0.5 m) | #fee08b |
| Low (0.5–1 m) | #fdae61 |
| Moderate (1–2 m) | #f46d43 |
| High (2–4 m) | #d73027 |
| Very high (>4 m) | #7b3294 |
Generated from darwin/layers/layer-flood-depth-giri-10yr-present.toml and risk_indicator_pairs.toml (develop).