Flood inundation prediction and risk assessmentsDecision-makers in both public and private arenas need accurate information on fluvial flood risks to assess strategic decision-making on risk reduction and climate adaptation in the short-term (e.g. efficient warning and decision-making, evacuation planning, financial liquidity to cover losses) as well as long-term.

In particular, flood risk assessments are relevant for civil protection and the private insurance sector for household and business policies. Also, new approaches are needed for assessing correlated risks related to flood occurrence and impacts at local and European scales.

In this sectoral survey, we developed short-to-medium, seasonal and long-term improved flood risk assessments for fluvial flooding, in close consultation with stakeholders who needed flood risk and damage information.

The case studies for this sectoral survey included the lowland stretches of the Rhine River (in the Netherlands and Germany, downstream from Bonn), the Elbe River (Germany), Somerset (UK), the Bisagno catchment (Italy) and several water board areas in the Netherlands. In addition, an EU-wide analysis was performed.

Partners: Deltares, KNMI, UREAD, IVM, HKV, CIMA, GFZ

Reports

Correlated flood risk and finance

This report presents the relationship between climate indices (such as ENSO and NAO) and flood impacts. To achieve this, the report looks into two papers:

  • one where the correlation between three indices (ENSO, NAO, EA) and rainfall and flood damage is investigated for the whole of Europe using statistical analyses.
  • the other is based on recent literature and takes a more global view.

In this deliverable, both studies are reported and implications for the management of flooding and finance are discussed. We show that for various regions/seasons there are (strong) links between climate indices and flood impacts. When such a climate index can be forecasted for that region and season, this opens doors to prepare for flood events (and similarly for drought events) by flood managers and multi-national businesses. Moreover, the correlated nature of such extreme events is also of importance for (re-)insurance and supra-national funds (such as the EU solidarity fund).

Read the full report on correlated flood risk and finance.

Compound flood risk events

In December 2017, a focus group was held at the University of Reading in collaboration with the UK Environment Agency. It included a decision-making activity designed to capture how different water sector users currently interpret and act on SHFs to inform decisions in the West Thames. Participants were shown progressively confident and locally tailored SHF out to four months to focus on a period of extreme stormy weather and flooding.

To avoid participant bias through prior knowledge, they were not told which time period was covered by the SHFs.

Most West Thames local stakeholders present at the focus group reported using seasonal hydrological forecasts in their everyday job and believed that they could possibly forecast flood and drought risk. The stakeholders also indicated that the forecasts could be used to support decision-making and to increase preparedness. Still, many noted that the forecasts cannot yet be used in this way as the products that are available in the UK show too much uncertainty and have a coarse spatiotemporal resolution.

Read the full report on compound flood risk events.

Flood damage risk assessment

The report describes the potential economic benefit of improved forecasts for waterway transport on the River Rhine. A detailed cost structure model was applied to a large set of different water level conditions to estimate the transport costs in dependence of the ship’s payload and the available water depth at the relevant bottleneck.

Transport costs of 7 commonly used ship types for the transport between the ports of Amsterdam/ Rotterdam/ Antwerp and the Rhine-Neckar region have been analyzed. Based on these transport cost-relationships different forecast information was used to determine the payload of the different vessel types: deterministic water level forecasts, raw ensemble water level forecasts and post-processed probabilistic water level forecasts.

Read the full report on compound flood risk events.