River flood

River flood

A river overflows its banks and water enters the site. The water damages the building and its contents, and the site stops until it is cleaned and repaired. A site that stays dry can still stop when the roads, power and drainage around it flood. River flood prices both Property damage (% of asset value) and Business interruption (% of annual revenue).

What the map shows

• Today: the GIRI river flood depth for the 100-year flood, on a ~90 m grid (sheet), and the FLOPROS river flood protection standard per administrative unit.
• Projected: GIRI publishes one present climate, so the depth map does not move. A separate raster, the Aqueduct Floods river depth for the 100-year flood on a 2 km grid, shows where flooding gets worse at 2035, 2050 and 2080. Aqueduct publishes RCP4.5 and RCP8.5 only: the low and intermediate emissions settings read RCP4.5, the high emissions setting reads RCP8.5. The engine uses Aqueduct only as a ratio that scales the GIRI depth, never as a depth.

How the loss is computed

The engine reads the flood depth at each return period over the site's footprint, keeping the depth reached by the wettest 20 % of the site. A depth-damage curve turns each depth into a share of asset value lost, and a restoration-time relation turns it into days out of operation. The site also reads the depth in a 500 m ring around it, priced as days of disruption; business interruption keeps the longer of the two. Losses are integrated over all return periods into an annual loss, cut at the FLOPROS design standard where a river defence exists. River flood is tagged Built, except the surroundings disruption, which is a proposal. See Damage functions: Flood and the shared chain in Climate risks.

Sources

• GIRI, Global Infrastructure Resilience Index riverine flood hazard (UNEP-GRID / CDRI, 2023), Continuum hydrological model forced with W5E5, present-climate run. Licence not confirmed.
• WRI Aqueduct Floods v2 (inunriver), 5-GCM median, resampled to 2 km. CC BY 4.0.
• FLOPROS (Scussolini et al. 2016, NHESS), global database of flood protection standards, merged riverine layer. CC BY 3.0.
• JRC depth-damage curves: Huizinga, de Moel & Szewczyk (2017), EUR 28552.
• HAZUS Flood Model depth-band loss-of-use (business interruption).

Limits

• The surroundings disruption table is a first-cut Darwin proposal, uncalibrated and deliberately generous.
• GIRI encodes 0 for both "dry" and "no data", so a site outside its coverage reads as no risk.
• FLOPROS standards are taken at face value until calibrated.
• At 2035 the river arm reads its present depth, because Aqueduct's 2035 band is the anchor its change is measured from.