Hydra-Ring 1.0 : probabilistics toolbox for the WTI2017 : validation document

The Dutch primary flood defences are periodically tested against statutory safety standards. Currently, policymakers are contemplating a move towards safety standards defined in terms of maximum allowable probabilities of flooding. To facilitate such a move, a new probabilistic framework for assessing the safety of flood defences is being developed within the project WTI2017 (Wettelijk ToetsInstrumentarium 2017). The new probabilistic framework is embedded in software that is currently being developed. The software consists of a user-interface (‘Ringtoets’) and a computational kernel (‘Hydra-Ring’). The computational kernel Hydra-Ring, the subject of this report, incorporates the probabilistic calculation schemes, the statistical treatment of hydraulic data and the failure mechanisms for flood defences. The functionality used in the project VNK (Veiligheid Nederland in Kaart) has been the basis for the implementation of the software components in Hydra-Ring version 1.0. The TMR2006 are used as hydraulic boundary conditions. The implemented failure mechanisms comprise overtopping (dykes and structures), piping (dykes and structures), macrostability (dykes), erosion (dunes), non-closure (structures) and constructive failure (structures). In later versions of Hydra-Ring, new modules for functional components are to be implemented. During the development of the Hydra-Ring software, tests have been carried out on multiple levels of sophistication: units tests (on the level of the separated subroutines), integration tests (on level of the aggregation of subroutines) and system tests (the functioning of the software as such). The results of the tests are gathered in falsifiable claims which are substantiated in separate chapters dedicated to specific functionalities of the Hydra-Ring software.