· · · Repository Hydraulic Engineering Reports

Experimental research to the influence of the air pressure on the impact pressure cause by breaking waves. The research shows that there are three factors which load the structure during the breaking of waves: the water layer over the structure, the shock due to the impact of the water jet from breaking and the air pocket entrapped in the water mass. The influence of all of the factors is determined.

Overview of available datasets in the Netherlands

This report describes the flood defence structures of the pilot site River Schelde Estuary and the overall probability of failure of all flood defences in the area. First, the flood prone area is briefly described as follows: ¾ the flood prone area ¾ the failures observed in the past ¾ an overview of all defence structures ¾ the flood defence structures in detail together with their potential failure modes The report then continues to describe the algorithm how the flood defences are split into various sections. For each section the probability of failure is then calculated using level II and III methods. From this, the overall failure probability Pf is calculated. The overall purpose of this report is to provide a first idea on the failure probability calculations of the flood defences in the pilot site. This information will identify the gaps in knowledge (e.g. failure modes) and incomplete procedures to calculate Pf. Results will be fed into Theme 1 to improve understanding and knowledge where identified necessary. Calculations have been made by DHV Consultancy and Engineering (Amersfoort, NL) and TU Delft with checks by VNK (Ministry of Water Management, Delft, NL) and assessments by WZE (Waterboard, Zeeland, NL).

Uncertainties are introduced in probabilistic risk analysis when we deal with parameters that are not deterministic (exactly known) but that are unknown instead, hence uncertain. This report describes how uncertainties influence the reliability of flood defence systems. The purpose of the study is to identify all uncertainties that influence the reliability of dike ring systems, to determine which uncertainties contribute most to the probability of failure and how can be dealt with uncertainties.

Risk identification consists of defining the hazard, loss causing event E, probability P(E) of that event, perception Pe(E,P(E)) and consequences C(Pe) of that perception. Risk identification is followed by risk management, whose purpose is to mitigate the risks, for example by reducing P(E) or C(Pe) and providing suitable risk communication to the population at risk. Task 7 has focused in this approach for the safety issues of flood defences on the failure probability P(E). It has been subdivided into 4 activities: preliminary probability analyses of flood defences uncertainty analyses of all issues which are related to flood defences review and development of software codes for reliability calculation applicability of improved methods.

Risk identification consists of defining the hazard, loss causing event E, probability P(E) of that event, perception Pe(E,P(E)) and consequences C(Pe) of that perception. Risk identification is followed by risk management, whose purpose is to mitigate the risks, for example by reducing P(E) or C(Pe) and providing suitable risk communication to the population at risk. Task 7 has focused in this approach for the safety issues of flood defences on the failure probability P(E). It has been subdivided into 4 activities: preliminary probability analyses of flood defences uncertainty analyses of all issues which are related to flood defences review and development of software codes for reliability calculation applicability of improved methods.

Risk identification consists of defining the hazard, loss causing event E, probability P(E) of that event, perception Pe(E,P(E)) and consequences C(Pe) of that perception. Risk identification is followed by risk management, whose purpose is to mitigate the risks, for example by reducing P(E) or C(Pe) and providing suitable risk communication to the population at risk. Task 7 has focused in this approach for the safety issues of flood defences on the failure probability P(E). It has been subdivided into 4 activities, which are: - preliminary probability analyses of flood defences - uncertainty analyses of all issues which are related to flood defences - review and development of software codes for reliability calculation - applicability of improved methods --- The defence reliability analysis has been developed in this task to support a range of decisions and adopt different levels of complexity (feasibility, preliminary and detailed design). Each tier in the analysis of the reliability of the defence and defence system demands different levels of data on the condition and form of the defence and its exposure to load, but also different types of models from simple to complex. As a result each level will be capable of resolving increasing complex limit state functions. During the project, these levels has been considered and complexity of models and amount of data has been adjusted accordingly.