Quantitative Analysis of the Waterline Method for Topographical Mapping of Tidal Flats: A Case Study in the Dongsha Sandbank, China

Abstract

Abstract:Although the topography of tidal flats is important for understanding their evolution, the spatial and temporal sampling frequency of such data remains limited. The waterline method has the potential to retrieve past tidal flat topography by utilizing large archives of satellite images. This study performs a quantitative analysis of the relationship between the accuracy of tidal flat digital elevation models (DEMs) that are based on the waterline method and the factors that influence the DEMs. The three major conclusions of the study are as follows: (1) the coverage rate of the waterline points and the number of satellite images used to create the DEM are highly linearly correlated with the error of the resultant DEMs, and the former is more significant in indicating the accuracy of the resultant DEMs than the latter; (2) both the area and the slope of the tidal flats are linearly correlated with the error of the resultant DEMs; and (3) the availability analysis of the archived satellite images indicates that the waterline method can retrieve tidal flat terrains from the past forty years. The upper limit of the temporal resolution of the tidal flat DEM can be refined to within one year since 1993, to half a year since 2004 and to three months since 2009.

Seasonal and Intra-Annual Patterns of Sedimentary Evolution in Tidal Flats Impacted by Laver Cultivation along the Central Jiangsu Coast, China

“…The accuracy of DEMs has been validated in a previous study and the mean error is 45.13 cm [50]. The main error sources in building tidal flat DEMs are from water level heighted process and interpolating process [51]. These DEMs provide the foundation for seasonal and intra-annual pattern analysis of the impact of laver cultivation on tidal flat sediment.…”

A New Methodology to Analysis and Predict Shoreline Changes Due to Human Interventions (Case Study: Javad Al-Aemmeh port, Iran)

“…Through the years, several systems have been established to provide the dataset of shoreline analyzing via the historical trend method. Beside the well-known systems, the LiDAR surveying, video images [61], infrared camera based imaging [62], UAV and drone system [63], synthetic aperture radar [64][65][66] and marine navigation radar [67] are some of these systems [12, 68,69]. The investigation of selecting the proper system usually is done by considering the time efficiency, area coverage, economic priority and availability of historical images for a specific region.…”

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

“…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.…”

“…Although the second method uses multitemporal remote-sensing images, they have limited precision due to the resolution of the available data. For example, high-spatial resolution imagery, such as SPOT [14] and the Landsat Archive (MSS, TM, ETM+, or Landsat8) [15], [16], have a low temporal resolution, while images with a higher temporal resolution, such as those derived from the MODIS, have a coarse spatial resolution (250 m) [16]. More importantly, these methods can only extract the extent of tidal flats but cannot determine the three functionally different zones within 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. Approaches to extract the extent of tidal flats using waterlines fall mostly within two categories: 1) waterlines are calculated from imagery taken as close as possible to the estimated time of high or low tide based on tide models [11] or tide gauge data [12], [13], and 2) the outermost waterline is selected from a series of waterlines extracted from multitemporal remote-sensing images [14]- [16]. For the first category, methods only apply waterlines at one moment to delineate tidal flats.…”