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

Abstract

Human activities such as the rapid development of marine aquaculture in the central Jiangsu coast have had a marked impact on the tidal flat morphology. This research focuses on characterizing the spatial expansion of laver cultivation and its influence on the sedimentary evolution of tidal flats in the central Jiangsu coast. First, seasonal digital elevation models (DEMs) were established using 160 satellite images with medium resolution. Then, laver aquaculture regions were extracted from 50 time-series satellite images to calculate the area and analyze the spatial distribution and expansion of these areas. Finally, seasonal and intra-annual sedimentary evolution patterns of both aquaculture and non-aquaculture regions were determined using the constructed DEMs. Our results show that aquaculture regions have gradually expanded to the north and peripheral domains of the entire sand ridge since 1999 and by 2013, the seaward margins of each sandbank developed into dense cultivation regions. Additionally, the aquaculture regions increased from 11.99 km2 to 295.28 km2. The seasonal sedimentary evolution patterns indicate that deposition occurs during the winter and erosion during the summer. Thus, the aquaculture regions experience deposition in certain elevation intervals during the laver growing period and in the non-growing period, alluvial elevation intervals in the aquaculture regions are eroded and erosive ones are deposited in order to maintain the balance between scouring and silting. The sedimentary evolution of each sandbank is heterogeneous due to their different locations and the difference in sediment transport. The intra-annual evolution pattern is characterized by deposition in the high tidal flats and erosion in low ones. Hydrodynamic conditions and laver cultivation dominate partial sedimentary evolution, which gradually shapes the beach surface.

Anthropogenic Influences on the Hydrodynamic and Tidal Discharge in Tongzhou Bay, Nantong, China

“…the alongshore reclamation engineering areas and its influence degree is reduced with the increase of the offshore distance, most of affected area decreases on account of resistance effect of structures, few bank angle area increases on account of the shrink of water crossing. It also can be found that the scope of influence of velocity in the period of the flood tide is larger, which is in accordance with the fact of flood tide prevailing [12]. After the construction of the polder project, an artificial headland was formed in the original open water, so the tidal exchange of this sea area is inevitably affected.…”

Deriving Tidal Flat Topography Using ICESat‐2 Laser Altimetry and Sentinel‐2 Imagery

“…The temporal change in tidal flats depends on local conditions, such as coastal morphology, sediment, hydrodynamics, and human activities (X. Chen et al, 2020;Lu et al, 2019;Jeong et al, 2019 ). In addition, the elevation range of the satellite derived tidal flat topography can be smaller than that from airborne lidar data (Figure 4), which may be explained by the fact that the 10-m resolution Sentinel-2 imagery is unable to characterize some narrow tidal creeks with lower elevations.…”

“…In Figures 4f and 4g, a general consistency and some tiny differences between tidal creeks derived from our results and airborne lidar data can be observed, which may be caused by different acquisition dates of satellite data and airborne lidar data. The temporal change in tidal flats depends on local conditions, such as coastal morphology, sediment, hydrodynamics, and human activities (X. Chen et al., 2020; Lu et al., 2019; Jeong et al., 2019 ). In addition, the elevation range of the satellite derived tidal flat topography can be smaller than that from airborne lidar data (Figure 4), which may be explained by the fact that the 10‐m resolution Sentinel‐2 imagery is unable to characterize some narrow tidal creeks with lower elevations.…”

Morphological Characteristics of Tidal Creeks in the Central Coastal Region of Jiangsu, China, Using LiDAR

“…However, these approaches are restricted by the large scale of observation required, and by the difficulty in simulating tidal creek characteristics under complex natural conditions. Remote sensing has major advantages for tidal flat observation [31][32][33][34], and light detection and ranging (LiDAR), in particular, can generate three-dimensional terrain data, and has been widely applied in intertidal zones [35][36][37]. Previous efforts using remote sensing have focused mainly on the extraction of tidal creeks [4,16,38,39], the analysis of morphological characteristics [40,41], and the process of evolution of tidal creeks [21,29,42,43].…”