Real-time monitoring and forecasting provides useful information in early warning situations for emergency response as part of a modern (flood) risk management. This paper presents a case study of a coastal dike line, where multiple sensors are installed to measure in real-time the water level outside and inside the dike. The dike stability is calculated based on the inputs of the phreatic line and on the schematization of the subsoil. The resulting safety factor is a direct assessment of the dike strength in real-time. For a prediction of the dike performance, fragility curves are derived within a model-based probabilistic analysis for different failure mechanisms: overflow, wave overtopping, wave impact, wave erosion, piping, micro- and macro-stability are considered. They are combined in one overall fragility curve that represents the total probability of failure per dike cross-section as a function of the water level. By combining forecasted water levels and fragility curves, it is possible to get a prediction of the dike reliability. The two workflows of real-time monitoring and forecasting of dike strength are being integrated into the FEWS-DAM Live software system. This allows for the visualization of real-time and historical data of dike stability and probability of failures based on the forecasted water levels. The generated results provide precise information for the emergency response, such as location, timing and probability of failure of specific sections of the flood defense line. With the help of this information, emergency measures that apply to the flood defense line (e.g. starting from increased inspection intervals up to temporally dike enforcement) can be operationally planned, adapted to the situation and triggered
dike strength, failure probability, forecasting, fragility curve, monitoring
 Melnikova, N.B., Jordan, D. & Krzhizhanovskaya, V.V., Experience of using FEM for real-time flood early warning systems: monitoring and modeling Boston levee instability. Journal of Computational Science, 10, pp. 13–25, 2015. http://dx.doi.org/10.1016/j.jocs.2015.04.033
 Melnikova, N.B., Jordan, D., Krzhizhanovskaya, V.V. & Sloot, P., Numerical prediction of the IJkDijk trial embankment failure. Geotechnical Engineering, 168(2), pp. 158– 171, 2015. http://dx.doi.org/10.1680/geng.14.00040
 Pyayt, A.L., Kozionov, A.P., Mokhov, I.I., Lang, B., Krzhizhanovskaya, V.V. & Sloot, P.M.A., An approach for real-time levee health monitoring using signal processing methods. Procedia Computer Science, 18, pp. 2357–2366, 2013. http://dx.doi.org/10.1016/j.procs.2013.05.407
 Thielen, J., Bartholmes, J., Ramos, M.-H. & de Roo, A., The european flood alert system – part 1: concept and development. Hydrology and Earth System Science, 13, pp. 125–140, 2009. http://dx.doi.org/10.5194/hess-13-125-2009
 Werner, M., Cranston, M., Harrison, T., Whitfield, D. & Schellekens, J., Recent developments in operational flood forecasting in England, Wales and Scotland. Meteorological Applications, 16, pp. 13–22, 2009. http://dx.doi.org/10.1002/met.124
 Roelevink, A., Udo, J., Koshinchanov, G. & Balabanova, S., Flood forecasting system for the Maritsa and Tundzha Rivers. Conference Water Observation and Information System for Decision Support, Balwois 25-29 May 2010.
 Flood Control 2015, available at www.floodcontrol2015.com
 Dike Data Service Centre, available at www.openddsc.nl
 Bishop, A.W., The use of the slip circle in the stability analysis of slopes. Geotechnique, 5(1), pp. 7–17, 1955. http://dx.doi.org/10.1680/geot.1922.214.171.124
 USACE, Benefit determination involving existing levees. Memorandum for Major Subordinate Commands and District Commands, Policy Guidance Letter 26, Washington DC, 1991.
 Hall, J., Dawson, R., Sayers, P., Rosu, C., Chatterton, J.U. & Deakin, R., A methodology for national-scale flood risk assessment. Water & Maritime Engineering, 156(3), pp. 235–247, 2003. http://dx.doi.org/10.1680/wame.2003.156.3.235
 Apel, H., Thieken, A.H., Merz, B. & Bloschl, G., Flood risk assessment and associated uncertainty. Natural Hazards and Earth System Science, 4, pp. 295–308, 2004. http://dx.doi.org/10.5194/nhess-4-295-2004
 Dawson, R., Hall, J., Sayers, P., Bates, P.D. & Rosu, C., Sampling-based flood risk analysis for fluvial dike systems. Stochastic Environmental Research and Risk Assessment, 19, pp. 388–402, 2005. http://dx.doi.org/10.1007/s00477-005-0010-9
 Simm, J.D., Gouldby, B.P., Sayers, P.B., Flikweert, J., Wersching, S. & Bramley, M.E., Representing fragility of flood and coastal defences: getting into the detail. Flood Risk Management: Research and Practice, Taylor & Francis Group: London, pp. 621–631, 2009.
 Van der Meer, J.W., ter Horst, W.L.A. & van Velzen, E.H., Calculation of fragility curves for flood defence assets. Flood Risk Management: Research and Practice, Taylor & Francis Group: London, pp. 567–573, 2009.
 Vorogushyn, S., Merz, B., Lindenschmidt, K.-E. & Apel, H., A new methodology for flood hazard assessment considering dike breaches. Water Resources Research, 46, 2010. http://dx.doi.org/10.1029/2009wr008475
 Bachmann, D. & Schüttrumpf, H., Integration der Zuverlässigkeit von Hochwasserschutzbauwerken in die einzugsgebietsbasierte Hochwasserrisikoanalyse. Hydrology and Water Resources Management, 58(3), pp. 168–177, 2014.
 Diermanse, F.L.M., De Bruijn, K.M., Beckers, J.V.L. & Kramer, N.L., Importance sampling for efficient modelling of hydraulic loads in the rhine–meuse delta. Stochastic Environmental Research and Risk Assessment, 29(3), pp. 637–652, 2015. http://dx.doi.org/10.1007/s00477-014-0921-4
 Schultz, M., Gouldby, B., Simm, J. & Wibowo, J., Beyond the factor of safety: developing fragility curves to characterize system reliability. ERDC SR 10 1. G. a. S. Laboratory, USACE, 2010.
 Bachmann, D., Johann, G., Huber, N.P. & Schüttrumpf, H., Fragility curves in operational dike reliability assessment. Georisk: Assessment and Management of Risk for Engineered Systems and Geohazards, 7(1), pp. 49–60, 2013. http://dx.doi.org/10.1080/17499518.2013.767664
 Bachmann, D., Beitrag zur Entwicklung eines Entscheidungsunterstützungssystems zur Bewertung und Planung von Hochwasserschutzmaßnahmen (Development of a decision support system for the assessment and design of flood mitigation measures). PhD Thesis, Aachen: Institut für Wasserbau und Wasserwirtschaft, RWTH Aachen, http:// darwin.bth.rwth-aachen.de/opus3/volltexte/2012/4043/ [Accessed 31.01.2015], 2012.
 Merz, B., Hochwasserrisiken - Grenzen und Möglichkeiten der Risikoabschätzung, Schweizerbart‘sche Verlagsbuchhandlung: Stuttgart, 2006.
 Schweckendiek, T., Reassessing reliability based on survived loads. Proceedings of the Coastal Engineering Conference, 32, 2010.