Expert judgment-based reliability analysis of the Dutch flood defense system

Rongen, G.W.F.; Morales Napoles, O.; Kok, M.

doi:10.1016/j.ress.2022.108535

Expert judgment-based reliability analysis of the Dutch flood defense system

Title

Expert judgment-based reliability analysis of the Dutch flood defense system

Author

Rongen, G.W.F. (TU Delft Hydraulic Structures and Flood Risk; HKV Consultants)
Morales Napoles, O. (TU Delft Hydraulic Structures and Flood Risk)
Kok, M. (TU Delft Hydraulic Structures and Flood Risk; HKV Consultants)

Date

2022

Abstract

The Wettelijk Beoordelingsinstrumentarium (WBI) is the legal set of instruments for flood risk analysis in the Netherlands. Often, engineers have the impression that some failure probabilities of flood defenses resulting from these instruments are overestimated. In an effort to better estimate the failure probabilities of dikes along the Dutch river Rhine, this study sets out to assess them with experts and compare them to model results. We used Cooke's method for combining experts’ estimates in a structured way and follow two approaches to estimate a system failure probability. In the first approach, experts estimate discharges that lead to at least one dike failure. This gives plausible results; failure probabilities between 1/30 and 1/17.000 in a year. The second approach is based on adjusting existing model-based assessment results, by estimating the model-bias and incorporating additional dependencies. This mostly leads to large, implausible, failure probabilities: Experts tend to give more conservative answers as they are asked for detailed estimates without clear reference values. This results in large uncertainty and consequently (too) high failure probabilities. Our research shows that when applied in a clear frame of reference, structured expert judgments can be successfully used for estimating the reliability of Dutch flood defenses.

Subject

Cooke's method
Expert judgment
Flood risk
Reliability analysis

To reference this document use:

http://resolver.tudelft.nl/uuid:f6c4eec8-74f4-4a28-838b-05c1134dff31

DOI

https://doi.org/10.1016/j.ress.2022.108535

ISSN

0951-8320

Source

Reliability Engineering & System Safety, 224

Part of collection

Institutional Repository