Wednesday 25 Jan 2017
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Bathymetric Modelling of the Yellow River Delta Estuary

In order to integrate data acquired during the 2013 field campaign into a numerical model, a bathymetry for the estuary part of the Yellow River has to be generated. In a first step a closed landboundary boundary for the model was defined along the present coastline, which was extracted form so-called water mask products provided by the German Aerospace Center (DLR) (see Fig. 1). Furthermore, two open flow boundaries were implemented at the pontoon bridge, respectively 5 km seawards of the mouth of the estuary.

 

Within those boundaries a computational grid for the numerical model was defined. Consequently bathymetry points measured in 2013 were interpolated onto the model grid. The bathymetry for shallow water parts, where no measurements were available, had to be extrapolated. At the transition to the Bohai Sea data from navigational charts was used for the bathymetry. Maximum water depths within the estuary part of the model reach up to 8 m within the main channel, with a mean water depth of 1 to 2 m, and decrease towards the shoreline. In the shelf part of the model the water depth increases up to 15 m (see Fig. 2). The width of the estuary is approximately 250 m at the pontoon bridge and increases up to 1 km at the mouth of the estuary (FKM 15). During tidal low waters large parts of the delta fall dry and a sand bar splits the estuary into a main channel discharging into the Bohai Sea in northward direction and a side channel flowing eastwards.

 

Fig. 1: Watermask products for October 2013 and August 2014 (provided by DLR) used for the definition of a coastline at different water elevations, Landsat image for October 2013 and implemented coastline and computational grid

 

Fig. 2: Generated bathymetry for the 3d delta model and corresponding coastline

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