Fault tree analysis for urban flooding

Fault tree analysis for urban flooding

Ten Veldhuis, J.A.E.
Clemens, F.H.L.R.
Van Gelder, P.H.A.J.M.

Civil Engineering and Geosciences

Water Management

2008-12-31

Traditional methods to evaluate flood risk mostly focus on storm events as the main cause of flooding. Fault tree analysis is a technique that is able to model all potential causes of flooding and to quantify both the overall probability of flooding and the contributions of all causes of flooding to the overall flood probability. This paper gives the results of a fault tree analysis for urban flooding for the case of Haarlem, a city of 105.000 inhabitants. Data from a complaint register, rainfall data and hydrodynamic model calculations are used to quantify the probabilities of the basic events in the fault tree. The flood probability that is calculated for Haarlem is 0.78/week. Gully pot blockages make the main contribution to flood probability: 79%, storm events contribute only 5%. This implies that in this case an increased efficiency of gully pot cleaning is a more effective strategy to reduce flood probability than to increase the drainage system capacity. Whether this is also the most cost-effective measure can only be decided if the risk calculation is completed with a quantification of the consequences of both types of events. To do this will be the next step in this study.

fault tree
risk analysis
uncertainty
urban flooding

http://resolver.tudelft.nl/uuid:39bc815d-99d6-4099-a7d7-7abdf64a7f15

11 ICUD: 11th International Conference on Urban Drainage, Edinburgh, Scotland, UK, 31 August-5 September 2008

Institutional Repository

conference paper

(c) 2008 The Author(s)