Tidal flat digital elevation model generation by the ”„water-line”¦ method
Chin-Yi Yang
Abstract
Tidal flat is an active zone between land mass and ocean. This zone is temporarily flooded and is separated into tidal flats that fall dry and tidal channels that remain filled with water during a tidal circle. The topography over this area is usually flat over many kilometers. Due to currents and wave action, the topography of these areas is highly dynamic.
Surveying the topography in the tidal flat zone is a difficult task. The water depth of inter-tidal zone is too shallow to use the traditional method ”V sonar sounding system . Therefore, combination of remote sensing and hydrodynamic modeling techniques allow to construct the high precision terrain height over wide areas in a convenient time period.
The main method to obtain a digital elevation model of an inter-tidal zone is called ”„water-line”¦ method. The waterline method is to stack the extracted boundaries between seawater and exposed bottom surface (or ”„waterline”¦) in images acquired under different tidal conditions, then superimposing the heights of the relative to mean sea level on the corresponding positions. And these heights of tidal position are predicted using a hydrodynamic tide-surge model run for this area with the atmospheric conditions pertaining at the time of image acquisition. From multiple images obtained over a range of tide and surge elevation, it is possible to build up a set of heighted shorelines within the inter-tidal zone, and from this a gridded DEM may be interpolated.
References
Mason, D. C., Davenport. I., Flather, R. A., McCartney, B. S., and Robinson, G. J., 1995, Construction of an inter-tidal digital elevation model by the ”„water-line”¦ method. Geophysical Research Letters, 22, 3187-3190.
(Abstract)(Full text)
Mason, D. C., Davenport. I., Flather, R. A., and Gurney C., 1998, A digital elevation model of the inter-tidal areas of the Wash, England, produced by the waterline method. INT. J. REMOTE SENSING, 19, 8, 1455-1460