Construction of an inter‐tidal digital elevation model by the ‘Water‐Line’ Method

Abstract

Progress in the development of a method for constructing a Digital Elevation Model (DEM) of an inter‐tidal zone using remote sensing and hydrodynamic modelling is described. The method allows the construction of an inter‐tidal DEM over large areas relatively quickly as well as frequent subsequent monitoring of the DEM to detect changes, and is particularly suited to SAR satellite data because of the all‐weather day‐night capability of SAR. The resulting DEM may be used for the development of improved hydrodynamic models, and for studying sediment mass transport in the inter‐tidal zone.

Multiple Stable States and Catastrophic Shifts in Coastal Wetlands: Progress, Challenges, and Opportunities in Validating Theory Using Remote Sensing and Other Methods

“…This is perhaps due to development of the science partially out of earlier remote sensing of inland lacustrine freshwater wetlands, where water level changes are typically less significant. However, some studies have used a sequence of satellite images to build an elevation model based on tidal inundation, although this method depends on known water levels at the time of image acquisition [227][228][229]. One variation uses a large number of images to overcome this challenge and reconstruct estimated topography from historical imagery taken at different, unknown flood levels [188,189].…”

“…One approach to overcoming this challenge is to use information contained in other data sets to derive the sense of the topographic changes. The waterline method has been a useful way of doing so, using the extent of flooding seen in multiple optical images of a site taken at different water levels to effectively contour the topography [227][228][229]. This method relies upon knowing the water levels at the remote sensing imaging times, however, which is difficult for long or old imagery time series and in ungauged field locations.…”

An Improved Method for Mapping Tidal Flats Based on Remote Sensing Waterlines: A Case Study in the Bohai Rim, China

“…Current studies for mapping tidal flats, both when analyzing waterlines related to the low (high) tide time [8], [11]- [13] and when choosing the outmost boundary of multitemporal waterlines [10], [15]- [17], do not identify the supratidal zone, the intertidal zone and the subtidal zone, as was successfully done here. We used DSAS software and Jenks Natural Breaks to achieve zoning of tidal flats, which is meaningful for government planners, ecologists and geographers.…”

“…To map tidal flats, we selected the outermost boundaries of all waterlines as the total extent of tidal flats [10], [14]- [16]. This process consisted of merging multiple waterlines and transformations from lines to polygons, which were implemented in ArcGIS 10.0 software.…”

“…Remote sensing, which can observe a large area repeatedly, is an effective tool for overcoming these difficulties and monitoring tidal flats [9]. Previous studies have used multiple boundaries between a water body and an exposed land mass in a remotely sensed image, known as waterlines [10], to identify tidal flats. As the tide constantly moves in a horizontal direction, the waterline represents information on the location of the tide when the satellite transits.…”