Interpolation of an intertidal digital elevation model from heighted shorelines: a case study in the Western Wash

Abstract A method of interpolating a spatiotemporal digital elevation model (DEM) of an intertidal zone from a set of heighted shorelines is described. The heighted shorelines are obtained by the ‘water-line’ method using remote sensing and hydrodynamic modelling. This enables an intertidal DEM to be constructed over a large area relatively quickly, as well as frequent subsequent updating of the DEM to detect changes. The DEM may be used for studying sediment transport in the intertidal zone, and for the development of improved hydrodynamic models. The spatiotemporal interpolator is based on universal block kriging, and its results are illustrated using data from the Wrangle Flats area of the western Wash, U.K. For a kriging block size of 50 m × 50 m × 1100 days, an average block height estimation standard deviation (σ) of 14.3 cm is achieved, using shorelines from 33 images collected over the period 1992–1994. This height accuracy is compared with those obtained from DEMs constructed from beach transect data, and is shown to be an improvement over the transect DEM accuracies away from transects. The construction of DEMs of improved accuracy (σ=13 cm) from combined shoreline and beach transect data using cokriging is discussed. Ways in which the shoreline accuracies may be improved are also considered.