Beach wizard : A data model assimilation method for nearshore bathymetry and coastal state indicator estimation

The objective of this study is to derive a robust assimilation model with which accurate estimates of the seasonal variation are possible, apply this model to two field cases and calculate the coastal state indicators on an intra-annual time scale. Specifically, the following objectives are defined (based on the RFP by Rijkswaterstaat): 1. Continue to develop the model such that an analysis of the seasonal variability is possible, including improvement in the nearshore and trough areas. 2. Define uncertainty estimates of the bathymetry. 3. Validate with data from Egmond and Duck. 4. Make predictions with a high resolution in time (on the order of 40 estimated per year) of the Momentary Coast Line, bar positions and bar elevations. 5. Determine the seasonal variation of the MCL, including a comparison with MCL estimates from ground-truth JARKUS measurements. 6. Discuss the added value of the Beach Wizard for Rijkswaterstaat purposes. Concretely, we will present an improved 2DH method assimilation method based on the derivatives of the observed properties with respect to depth (a ?gradient-descent? method). We will extend Aarninkhof?s method from one source to multiple (currently three) sources, while reducing the number of free parameters that need to be set from two per source to nil per source, and only one overall parameter. The sources that are added are video-observed intertidal bathymetry and radar-derived wave celerities. The uncertainties in the bathymetric estimates are quantified and presented with the bathymetric estimates.