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Abstract: Singapore Strait located between the South China Sea and Andaman Sea is driven by tides coming from both sides and the hydrodynamics in this area is complex. From the viewpoint of long term forecasting, however, models developed for this area suffer from limitations introduced by parametric uncertainty, absence of data for appropriate specification of forcing and lateral boundary conditions. For improving the model forecasts, a data assimilation technique based on ensemble Kalman filter is implemented and applied. Based on the latter, an ensemble based steady state Kalman filter is derived to address the computational limitation for daily operational forecasting. Via a twin experiment on a simulation period that includes a significant storm surge event (sea level anomaly) the skills of both data assimilation schemes are assessed and compared. [Copyright &y& Elsevier]

Abstract: This paper describes the generic data assimilation software tool DATools. DATools can be used as standalone or within Delft-FEWS. DATools is completely configurable via XML configuration. DATools is built up of three components: a Filter, a Stochastic Modeler, and a Stochastic Observer. Configuration of all these three parts is explained in detail. At the moment two data assimilation filters are available within DATools: (1) ensemble Kalman Filter and (2) the residual resampling filter. Results of a twin experiment with both filters with DATtools show similar results as a previous study performed with custom implementations. It is also shown that DATools can function inside Delft-FEWS software used for operational flood forecasting. Applying EnKF to a 1D hydrodynamic SOBEK-RE model of the river Rhine within the operational system FEWS-NL Rhine and Meuse improves the forecasts at the Lobith gaugin station and downstream of Lobith. DATools has been coupled with the HBV-96, SOBEK, and REW models and will be coupled to MODFLOW, Delft-3D, and the geotechnical model MSetlle in the near future. Uncertainty analysis with this tool is also possible and calibration will be added later this year. [Copyright &y& Elsevier]