Assessment of Hydraulic Loads and Derivation of Failure Probabilities as a Basis for the Deermination of Fragility Curves for Flood Defence Dunes

Abstract

Low lying coastal areas have always been preferred settlement areas as well as trading and industrial areas. Unfortunately, those areas are strongly endangered by extreme storm surges. In the event of a flood defence failure, protected areas are flooded and damages have to be expected. For the assessment and management of flood risk, the European Union approved the "Directive of the European Parliament and the Council on the assessment and management of flood risk".As one part of a risk and damage analysis the risk of flooding -being the product of failure probability of a certain flood defence and the damages resulting from a failure of this flood defence -has to be determined. One possibility for the assessment of the failure probability is provided by fragility curves. A method for the derivation of fragility curves for flood defence dunes is described. Hence, the applied dune erosion model as well as the method for the derivation of the required input data is explained. Furthermore, first results of the calculation of failure probabilities and fragility curves are presented.

Fragility Analysis of Dunes Reinforced With Geosynthetic Sand Containers

“…2 since infrastructure at this site encroaches on the dune and limits the potential effective flood protection crosssectional area of an unreinforced dune to approximately 25 m 2 . When compared to the minimum 40 m 2 crosssectional area recommended to withstand storm surges with a return period of 50 years, this reduced capacity would lead to an increased probability of failure during more frequent storm events (Gruhn et al 2012).…”

“…natural dune, reinforced dune, seawall, etc.) as a function of a certain stress acting on the structure (typically water level, wave height/period; Gruhn et al 2012). The main advantage of a fragility curve, compared to a damage function that quantifies a deterministic degree of damage directly to a stress, is that it can account for uncertainties in both the structural resistance (i.e.…”