Abstract
Abstract. Knowledge of the actual condition of hydrodynamics in the nearshore and coastal area is essential for coastal monitoring activities. To this end, a coastal operational model system can serve as a tool in providing recent and up-to-date, state-of-the-art hydrodynamics along the coast. In this paper, we apply CoSMoS (Coastal Storm Modeling System), a generic operational wave and tide-surge modelling system applied here to predict waves and water levels along the Dutch coast. The CoSMoS application is not limited to storm impact prediction on the Dutch coast, but can also be applied to other coastal hazards such as rip currents and coastal flooding, in other environments. In this paper, we present the set-up of the CoSMoS system and a validation of the wave and surge model, with deep-water wave buoy data and tidal gauge measurements as ground truth validation material. The evaluation is presented as monthly error measures between computed parameters and observed ones. Hindcast results over the whole year of 2009 show that the simulated wave parameters and surge elevation from the CoSMoS are in good agreement with data, with average root mean square (rms) error over the year of 0.14 m for the surge elevation and 0.24 m for the significant wave height. It is noted that there is a tendency of the wave model to underestimate the height of northerly waves with lower frequencies (swell). Additionally, when a wave separation algorithm is applied on the overall spectrum, results show consistent underestimation of the swell component by the model, which for the Dutch coast will mainly come from the north, where the North Sea is open to the Atlantic Ocean. In the proposed model system, the swell boundary can have a significant effect on the simulated wave results, suggesting room for improvement for the swell boundary conditions to the north and the swell propagation within the Dutch Continental Shelf Model. Finally, we show that in forecast mode, CoSMoS can provide reasonably good wave and surge prediction.
Highlights
Knowledge of the actual condition of nearshore and coastal hydrodynamics is an essential point in coastal risk management and monitoring activities
A hindcast was performed for the calendar year of 2009, where the forcing for the model system is provided by the analyzed wind fields
A simulation is performed where we ignore the swell boundary and use only wind forcing from HIRLAM as the main input into the wave model to see the effect of such a scenario
Summary
Knowledge of the actual condition of nearshore and coastal hydrodynamics is an essential point in coastal risk management and monitoring activities. For coastal forecasting, De Kleermaeker et al (2012) present an operational model system for the Dutch coast under the framework of the FEWS system, combining data from different sources to provide a reliable forecast They use the hydrodynamic model of Delft3D-FLOW to compute tides and surge and SWAN (Booij et al, 1999) for the waves. Using WAM as spectral wave model and the POLCOMS model (Proudman Oceanographic Laboratory Coastal-Ocean Modelling System) as tide-surge model, they show that the coupled scheme performs very well at predicting total water level and waves They make use of a statistical measure called percentage model bias (PBias) to evaluate the skill of the model, and found that model system gives PBias of 14 until 37 % for significant wave height (Brown et al (2010) classify the PBias as follows: less than 10 % excellent, 10– 20 % very good, 20–40 % good, and greater than 40 % poor). Cornillon et al, 2003)
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