Print Email Facebook Twitter Validity of method de Haan for wind speed and set-up Title Validity of method de Haan for wind speed and set-up Author van Haaren, H.D. Contributor Vrijling, J.K. (mentor) van Gelder, P.H.A.J.M. (mentor) Battjes, J.A. (mentor) Gerritsen, H. (mentor) den Heijer, F. (mentor) Faculty Civil Engineering and Geosciences Date 2005-01-01 Abstract Failure of coastal protection due to flooding is mainly caused by a combination of high water level and waves. If one considers these as independent variables, the probability of failure can be calculated easily, but this would be an incorrect assumption. These two variables are de-pendent, so a method suitable for multivariate statistics is to be applied, if one does not want to over- of underestimate the probability of failure. 'Method de Haan' is a method that is suit-able for extrapolation of dependent variables. In general this method shifts a cloud of observa-tions in exponential space into the area of failure or other relevant area. Because this method does not have a physical basis it is important that the relation between the variables that are used, holds in cases of extreme events if one wants to determine events with a very low fre-quency of occurrence. In this study the relation between (skewed) set-up and wind speed is examined. Most impor-tant reason to examine these variables is that at RIKZ (National Institute for Coastal and Ma-rine Management) these variables are used to determine the hydraulic variables in case of extreme events. A relation between water level and wave height is used to determine the cor-responding wave heights. Because the highest water levels are of importance skewed set-up is used as a variable instead of water level. By using this variable a more homogeneous data set is generated and the high-est water level can be constructed afterwards. Skewed set-up is the surge effect determined by the highest water level around during a tidal cycle, where this moment does not necessarily coincides with the moment the astronomical tide occurs. Data of four locations are used, covering a period of 23 years of simultaneous data. In order to use homogeneous data selections based on wind speed and set-up are carried out. Three dif-ferent thresholds are imposed for these selection procedures. The extrapolation path with method de Haan using these data sets is compared with a reference situation and results of hydrodynamic model runs where manipulated storm fields are used as input. In 'WAQUA', over 80 model runs are carried out, where a wind and atmospheric pressure field of the 1953 storm, is manipulated. The intensities, storm duration and phase of the storm relative to the astronomical tide are varied. Based on model runs with WAQUA the relation between skewed set-up and aver-age/maximum wind speed at a certain location appears to hold under extreme circumstances. However, only one wind drag relation (Charnock) is used in the model runs. The relation be-tween skewed set-up and average/maximum wind speed with method de Haan (extrapolation path) is physically more plausible if the asymptotic dependence is good, judged by the asymp-totic plots. The extrapolation path also is better if data are selected based on thresholds re-garding set-up. These paths lie closer to the reference situation, although strongly varying with different thresholds that were used. Subject de Haanwindspeedset-up To reference this document use: http://resolver.tudelft.nl/uuid:e8559350-d0e2-4da3-b5f0-612b1a59ff21 Publisher TU Delft, Faculty of Civil Engineering and Geosciences, Hydraulic Engineering Part of collection Student theses Document type master thesis Rights (c) 2005 D.H. van Haaren Files PDF 2005VanHaaren.pdf 5.75 MB Close viewer /islandora/object/uuid:e8559350-d0e2-4da3-b5f0-612b1a59ff21/datastream/OBJ/view