Geomorphic Evolution of Radial Sand Ridges in the South Yellow Sea Observed from Satellites

The radial sand ridges consist of more than 70 sand ridges that are spread out radially on the continental shelf of the South Yellow Sea. As a unique geomorphological feature in the world, its evolution process and characteristics are crucial to marine resource management and ecological protection. Based on the multi-source remote sensing image data from 1979 to 2019, three types of geomorphic feature lines, artificial coastlines, waterlines, and sand ridge lines were extracted. Using the GIS sequence analysis method (Digital Shoreline Analysis System (DSAS), spatial overlay analysis, standard deviational ellipse method), the evolution characteristics of the shoreline, exposed tidal flats, and underwater sand ridges from land to sea were interpreted. The results demonstrate that: (1) The coastline has been advancing towards the sea with a maximum advance rate of 348.76 m/a from Wanggang estuary to Xiaoyangkou Port. (2) The exposed tidal flats have decreased by 1484 km2 including the reclaimed area of 1414 km2 and showed a trend of erosion in the north around Xiyang channel and deposition in the southeast around the Gaoni and Jiangjiasha areas. (3) The overall sand ridge lines showed a trend of gradually moving southeast (135°), and the moving distance is nearly 4 km in the past 40 years. In particular, the sand ridge of Tiaozini has moved 11 km southward, while distances of 8 km for Liangyuesha and 5 km for Lengjiasha were also observed. For the first time, this study quantified the overall migration trend of the RSRs. The imbalance of the regional tidal wave system may be one of the main factors leading to the overall southeastward shift of the radiation sandbanks.

Evaluating spatial variability of subsurface carbon stock and free-phase gas using ground-penetrating radar and direct measurements in coastal landforms of South-West Indian peatlands

Organic rich soils (peat) store significant amount of global soil carbon (C) in the form of methane (CH4) and carbon dioxide (CO2). Peat soils act as sinks and are a source of greenhouse gases (GHG) which occur in the form of Free Phase Gas in coastal landforms. South-West India has an extensive wetland system and is the primary source of GHG emissions, and CH4, in particular, has high potential to contribute to global climate change. In this scenario, this study sheds light on how SW Indian peatlands contribute to the global carbon cycle. The soil C stock and GHG spatial distribution in three distinct topographic coastal landforms within the peatland region were investigated: site 1, Muthukulam in the wetland boundary; site 2, Ramapuram in the paleo-sand ridge, and site 3, Eruva in the paleo-drainage channel. The combination of non-destructive Ground Penetrating Radar (GPR) and direct measurement (coring) in conjunction with the C core analysis helped in building the relationship between the GHG storage in the landforms of varying C stocks. Moreover, Common offset GPR has the ability to image subsurface features, lithological boundaries, coastal landforms, and peat-forming environments. The result from this study depicts the importance of different landforms in the storage of C and GHG in SW Indian peatlands.

A closer look at an eroded dune landscape: first functional insights into the Federmessergruppen site of Lommel-Maatheide

The vast Federmessergruppen site of Lommel-Maatheide, which is located in the Campine region (Northern Belgium), revealed the presence of numerous Final Palaeolithic concentrations situated on a large Late Glacial sand ridge on the northern edge of a contemporary lake. This situation offers a unique possibility for a large-scale functional analysis in order to understand the occupation of such a Late Glacial dune landscape. The variable preservation state of the lithic artefacts permitted to evaluate in detail the impact of post-depositional processes on the potential of functional studies. Also, the impact of excavation protocols on the preservation of wear traces and residues was evaluated, in particular the impact of mechanical sieving. The integrated functional research that included the microscopic examination of wear traces, fractures and residues, next to experimentation, permitted the identification of a range of crafting and hunting activities, thereby demonstrating the potential of such assemblages for obtaining innovative insights into Late Glacial site dynamics in spite of a varying preservation state.

A closer look at an eroded dune landscape: first functional insights into the Federmessergruppen site of Lommel-Maatheide

The vast Federmessergruppen site of Lommel-Maatheide, which is located in the Campine region (Northern Belgium), revealed the presence of numerous Final Palaeolithic concentrations situated on a large Late Glacial sand ridge on the northern edge of a contemporary lake. This situation offers a unique possibility for a large-scale functional analysis in order to understand the occupation of such a Late Glacial dune landscape. The variable preservation state of the lithic artefacts permitted to evaluate in detail the impact of post-depositional processes on the potential of functional studies. Also, the impact of excavation protocols on the preservation of wear traces and residues was evaluated, in particular the impact of mechanical sieving. The integrated functional research that included the microscopic examination of wear traces, fractures and residues, next to experimentation, permitted the identification of a range of crafting and hunting activities, thereby demonstrating the potential of such assemblages for obtaining innovative insights into Late Glacial site dynamics in spite of a varying preservation state.

Drymaeus virgulatus, an extirpated land snail species on Saint Kitts and Tintamarre islands

The land snail species Drymaeus virgulatus (Férussac, 1821) is recorded in St. Kitts in the form of 21 complete or fragmented shells collected on the island in November 2019. The complete shells were collected on the backshores of South Frigate Bay and Majors Bay, while shell fragments come from naturally exposed sections of the North Frigate Bay sand ridge, where they date to the pre-Columbian period. This evidence therefore attests to the past presence of this species on the island. The absence of this taxon from recent malacological surveys points to it having been extirpated from St. Kitts. Apertural fragments of a large bulimulidae collected in the caves of Tintamarre Island, near St. Martin, are also related to this taxon, adding a second West Indian island from which this species apparently disappeared in recent centuries.

Recent Evolution of the Intertidal Sand Ridge Lines of the Dongsha Shoal in the Modern Radial Sand Ridges, East China

The Dongsha Shoal is one of the largest shoals in the South Yellow Sea and has important marine ecological value. The shoal extends in a south–north direction and is controlled by the regional dominating tidal currents. Recently, due to human activities and some natural factors, the geomorphic dynamics of the Dongsha Shoal has undergone drastic changes. However, few people have proposed quantitative research on the changes of tidal flat morphology, let alone the long-term sequence analysis of sand ridge lines. Hence, we attempt to take the Dongsha Shoal in the Radial Sand Ridges as the research area, and analyze the trends of the long-term morphological evolution of the sand ridge lines over the period 1973–2016 based on a high-density time series of medium-resolution satellite images. The sand ridge line generally moves from southeast to northwest, and the position distribution of the sand ridge line from north to south has gradually changed from compact to scattered. We also found that the geomorphological dynamics at different positions of the sand ridge line are inconsistent. The north and south wings are eroded on the west side, while the central area is eroded on the east side. Most of the sand ridge line is moving eastward. In addition, the change of sand ridge line is affected by multiple factors such as sediment supply, typhoon, reclamation and laver cultivation.

A DSAS-based study of central shoreline change in Jiangsu over 45 years

A large-scale sand ridge group is distributed in the central Jiangsu coastal area, and a deposition muddy sea bank was developed in the nearshore area. Quantitative monitoring of coastline changes is of great significance for tidal beach development and protection. The shorelines of the central coast of Jiangsu within six periods (1973–2018) were extracted in this study, and their length changes over the years were analyzed. The Digital Shoreline Analysis System (DSAS) was employed to generate a cross section perpendicular to the baseline and calculate the linear regression rate (LRR) of the shoreline, changes in end point rate (EPR), and net shoreline movement (NSM), based on which the shoreline change features were analyzed. The DSAS results indicated that the shorelines in the study area maintained fluctuating growth and presented a continuous advancing trend towards the sea. From the changes in shoreline evolution distance during 1973–2018, the advancing shorelines in the study area accounted for over 50% of the total shorelines and presented first rising and then declining trends with the period of 2003–2013 taken as the time boundary. The average shoreline change rate was 207 m/year, and the periods with the highest change degrees were 1983–1993 and 1993–2013. The shoreline change tended to be stable during 2013–2018, and only a few estuaries and ports underwent obvious erosion and sedimentation.