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Based on multi-temporal topographic maps, remote sensing images and field surveys covering the entire coastal zone of mainland China, the coastlines of six periods since the early 1940s were extracted. Coastline changes over the last 70 years were then analyzed in terms of coastline structure, coastline fractals, coastline change rates, land-sea patterns, and bay areas. The results showed that mainland coastline structure changed dramatically, and due to the significant coastline artificialization mainly driven by sea reclamation and coastal engineering, the remaining natural coastline merely accounts for less than one third at present. Coastline fractal dimension represented an overall spatial pattern of ＂north 〈 entirety 〈 south＂; however, the discrepancy between the north and south coast was apparently narrowed due to dramatic coastline artificialization of northern China which in turn altered the whole pattern. Patterns and processes of land-sea interchange along the mainland coast were complex and varied spatially and temporally, with over 68% advancing toward sea and 22% retreating toward land. The net growth of land area was nearly 14.2 ×10^3 km2 with an average growth rate of 202.82 km2 al; and coast retreat was characterized by area decrease of 93 bays with a magnitude of 10.1 ×10^3 km2 and an average shrinking rate up to 18.19% or an average shrinking speed up to 144.20 km2 a-1, among which the total area of Bohai shrunk by 7.06%, with an average annual loss amounting to 82 km2. The dramatic coastline changes along mainland China have brought about kinds of challenges to the coastal environment, therefore the integrated management, effective environment protection and sustainable utilization of coastlines is urgent.

Sellanes, L.; Alonso, R., and Solari, S., 2024. Performance analysis of groyne fields on the Uruguayan coast. In: Phillips, M.R.; Al-Naemi, S., and Duarte, C.M. (eds.), Coastlines under Global Change: Proceedings from the International Coastal Symposium (ICS) 2024 (Doha, Qatar). Journal of Coastal Research, Special Issue No. 113, pp. 814-818. Charlotte (North Carolina), ISSN 0749-0208. Groyne fields are one of the most common coastal structures on the Uruguayan coast of the Rio de la Plata estuary. However, the performance of these structures has not been systematically evaluated since the late 1970s. Knowing and understanding the past performance of these structures is key to predict their future performance, and to plan the adaptation of these beaches to climate change. A background review of the performance of the groynes prior to the 1980s was carried out, as well as the analysis of aerial photos and historical plans prior to 1985. Then, satellite images from 1985-present, processed with CoastSat, were analysed to quantify the evolution of the coastline, with particular attention to the areas where new groynes were built, or existing ones were enlarged in the early 1980s. At the same time, the hydrodynamics of the groyne fields were analysed using XBeach to relate the observed behaviour to different geometric variables (e.g. spacing and length of the groynes). The results indicate that the groyne fields located on the Uruguayan coast have been successful in terms of their functional performance, managing to advance and maintain the position of the coastline, and that in general their hydrodynamic behaviour is that of short groynes. However, several groynes have presented poor structural performance, in some cases of such importance that their functional performance has been compromised. In addition, the rate of sediment accumulation in some groyne fields has allowed gaining insight into the sediment budget in the littoral cells in which they are installed.

The acquisition of dynamic coastline change at fine spatial and temporal resolution is essential for enhancing sustainable coastal economic development and coastal environmental conservation. Port construction, land reclamation, urban development, and sediment deposition have resulted in extensive coastline change. In this study, the coastlines along the 56 coastal countries in 1990, 2000, 2010, 2015, and 2020 were delineated and classified into six categories using Landsat time–series images. Five relevant indices, i.e., the length, length ratio, length change rate, index of coastline utilization degree (ICUD), and fractal dimension (FD), were calculated to analyze and explore the spatiotemporal pattern of the coastlines. The results indicate that: (1) The overall length of the coastlines has increased from 3.45 × 105 km to 3.48 × 105 km in the past 30 years, with a net increase of nearly 3904 km. Between 1990 and 2020, the length of the artificial coastline increased by about 13,835 km (4.9~8.8%), while the length of the natural coastline decreased by 9932 km (95.1~91.2%). The increase in artificial coastline is concentrated in Southeast Asia and South Asia. (2) The coastline fractal dimensions (FDs) of countries and continents show that the average FD values of countries in South Asia (1.3~1.4) and Southeast Asia (1.2~1.3) were higher than other countries in the study regions, meaning that the coastlines in South Asia and Southeast Asia are more complex and curved. (3) The value of the ICUD index increased consistently between 1990 and 2015 (177.7~186.6) but decreased sharply between 2015 and 2020 (186.6~162.4), implying that the impact of human activities on the coastline continued to increase until 2015 and began to decrease after 2015. Our study examined the changes in various types of coastlines, which could be significant for sustainable development and environmental protection in coastal areas.

The length of the mainland coastline in Guangdong Province ranks first in the country, and the rapid development of the marine economy have also supported Guangdong Province’s GDP to remain at the top of the country for 35 consecutive years. The coastline has extremely important ecological functions and resource values. Guangdong Province has always attached great importance to the renovation and restoration of its coastline, continuously strengthening the ecological, disaster reduction, and tourism functions of the coastal areas. This article analyzes the main measures, achievements, and main problems of coastal protection in Guangdong Province and selects typical areas for driving force analysis. Finally, some thoughts and targeted countermeasures on the protection of Guangdong Province’s coastline are proposed, which provide useful references for comprehensively strengthening coastline protection, scientifically carrying out coastline renovation and restoration, and improving the natural coastline retention rate in the future. This can also output wisdom and experience for the construction of a maritime power under the background of land–sea coordination.

The Indramayu Regency, located on the northern coast of West Java, has experienced mangrove loss and dynamic shoreline changes, largely due to the conversion of mangrove areas into aquaculture ponds. This study quantifies the changes in mangrove cover and shoreline position from 1991 to 2021 and assesses their relationship. Landsat imagery for 1991, 2001, 2011, and 2021 was classified in Google Earth Engine using a Random Forest algorithm, whereas shoreline change rates were derived in ArcGIS with the Digital Shoreline Analysis System (DSAS). Total mangrove extent declined from 1,443.74 to 833.07 ha between 1991 and 2001 (−610.67 ha) with an average shoreline retreat of −15.98 m/year. From 2001 to 2011, mangroves increased slightly to 844.24 ha (+11.17 ha) as the shoreline advanced at 13.69 m/year, and from 2011 to 2021, mangrove cover expanded to 1,521.27 ha (+677.03 ha), while the mean shoreline change reverted to retreat at −1.49 m/year. Linearity tests and the low coefficient of determination (R² = 0.191) indicated that there was no significant linear relationship between mangrove change and shoreline dynamics, suggesting that effective erosion mitigation requires an integrated coastal management approach that combines mangrove rehabilitation, coastal protection, and sediment management.

Arekmane’s coastline, located on the Oriental Mediterranean coast of Morocco, is undergoing changes (Erosion/Accretion). This study aims to examine the shoreline of Arekmane’s villa zone to understand these changes by using remote sensing and DSAS technique. Two Landsat images from 2004 and 2014 were used to evaluate shoreline evolution by calculating End Point Rate (EPR). The obtained results revealed important alterations, ranging from erosion to accretion. On average, the EPR is -0.07 m/year while the maximum erosion rate is -0,71 m/year and the maximum value of accretion is 0.71 m/year. The erosion processes dominated the study area’s shoreline between 2004 and 2014 with 74,56% of erosional transects, and 25,44% of accretional transects. The dominance of erosion can be explained by the sea level rise related to climate change, in addition to human interventions. This present research contributes to the sustainable coastal development by identifying high-risk erosion transects in villa zone of Arekmane and recommends a long-term monitoring of the entire Arekmane’s coastline over different periods to check the evolution of the coastline in order to propose appropriate adaptation measures and strategies.

BACKGROUND AND OBJECTIVES: Coastal zones represent dynamic interfaces where terrestrial and marine spaces meet, often creating challenges for governance, spatial planning, and cadastral clarity. In Bekasi Regency, the nonexistence of a unified reference line between land and sea has given rise to overlapping jurisdictions, ambiguous land tenure, and complications in carrying out integrated coastal management. The study aimed to define a legal coastline founded on the high-water spring datum, serving as a unified framework for land and marine cadastre, while ensuring conformity with the International Hydrographic Organization S-4 and C-13 standards and Indonesian Law Number: 32/2004 on coastal zone governance. METHODS: The research integrated extensive tidal data from Muara Bendera, orthophotos derived from unmanned aerial vehicles, the extraction, and global navigation satellite system surveys to delineate the High-Water Spring shoreline. Unmanned aerial vehicle images were collected at both high and low tide to capture the full range of shoreline positions, while real time kinematic measurements provided precise ground control for validation. The shoreline was subsequently modified to align with the high-water spring vertical datum as per the guidelines set forth by International Hydrographic Organization, and it was cross-validated across various coastal morphologies, including sandy beaches and mangrove-lined areas. FINDINGS: Unmanned aerial vehicle mapping achieved strong performance on sandy coasts (Muara Beting: mean positional error 2.06 meters, overall validation score 75.6/100) but struggled in mangrove-dominated areas (Muara Bendera: mean error 34.63 meters, score 37.7/100), demonstrating the importance of RTK ground validation in complex coastal environments. Despite these variations, the integrated workflow proficiently created a continuous high-water spring-based coastline for Bekasi Regency that aligns with both scientific and legal standards. CONCLUSION: The study concludes that adopting a high-water spring based legal coastline provides a stable and authoritative boundary to unify land and marine cadastre. It addresses spatial overlaps while simultaneously reinforcing the framework for administrative governance, spatial planning, and coastal zone management. While unmanned aerial vehicle photogrammetry offers a practical solution for sandy coast, mangrove habitats demand a combination of remote sensing techniques and ground-based surveys.

Gharnate, A.; Taouali, O., and Mhammdi, N., 2024. Shoreline change assessment of the Moroccan Atlantic coastline using DSAS techniques. Journal of Coastal Research, 40(2), 418–435. Charlotte (North Carolina), ISSN 0749-0208. Coastal zones are critical from a physical, social, and economic point of view; however, most of the world's coastal zones are highly vulnerable to coastal erosion because of high population density, tourist attractions, and developed economies. To support mitigation strategies, a coastal erosion vulnerability assessment is essential to generate accurate information on this significant phenomenon. This study presents an integrated approach to coastal erosion vulnerability using a geospatial assessment of coastal dynamics in the Moroccan Atlantic coastal region between Rabat and Casablanca. To contribute to current and future knowledge of the study area's coastline dynamics, a cartographical and statistical approach was used to calculate historical rates of coastline change using aerial photos and satellite images from 1969 to 2022. To accomplish this, the images have been followed by the digitalization of the coastlines, as contained in the images created by using software ArcGIS10.8. These digitalized shorelines were subsequently incorporated into the digital shoreline analysis system, which provided multidate maps with graphical end point–rate (EPR) values. The results for Oued Cherrat estuary and the adjacent sandy beach indicate a general phase of erosion, with the average overall EPR value having reached –2.00 m/y, with the notable exception of a small part of the sandy beach, where progradation manifested itself in the form of an EPR value of +0.10 m/y. The Oued Nfifikh estuary is showing more erosion than the Oued Cherrat estuary. The retreat has affected the greater part of the area, reaching a maximum EPR speed of –5.00 m/y, with the possible exception of a smaller portion that has seen the shoreline progress at an average speed equal to +0.75 m/y. The resulting data may be used by the appropriate authorities to help effectively protect coastlines from erosion and to mitigate its impact on the environment and coastal properties.

As the boundary between the sea and the land, information on the location and type of coastline constantly changes with environmental changes in coastal zones. Monitoring of coastline changes in long time series becomes important for the monitoring and assessment of the coastal zone environment. In this study, Landsat series images from five time periods (1990, 2000, 2010, 2015, and 2020) were selected for monitoring and analyzing the changes in coastline length, sea–land pattern, the index of coastline diversity, and fractal dimension characteristics. Our conclusions are as follows: (1) The lengths of the entire coastline and the artificial coastline of mainland China increased from 30,041.22 km and 10,022.49 km in 1990 to 32,977.34 km and 17,660.84 km in 2020, with annual change rates of 97.87 km/year and 254.61 km/year, respectively. From 1990 to 2020, the rate of natural coastline decreased from 66.68% to 42.29%, and the artificial coastline increased from 33.32% to 57.71%. (2) The length of natural coastline decreased from 20,018.73 km to 15,316.5 km; among the types of natural coastline, the length of sandy coastline and bedrock coastline decreased the most, at 2062.95 km and 1815.8 km, respectively. (3) The coastal zone of mainland China had a significant increase in land area, with a net increase of about 10,902.55 km2. (4) The index of coastline diversity continued to decrease, and the coastline structure tended to be simple. The fractal dimension of the mainland coastline was consistent with the trend of the length of the coastline, which basically shows an increasing trend. Therefore, the length of the mainland coastline and artificial coastline displayed an upward trend between 1990 and 2020, which also led to simpler coastline diversity and more complex coastline shapes. Since the first year of the SDGs (2015), the growth rate of the artificial coastline has decreased by 158.32 km/year compared with that between 2010 and 2015. In recent years, China has enacted a number of laws, regulations, and action plans to protect its coastline, and it has proposed that by 2020, the proportion of natural coastline will be no less than 35%. The rapid development of China’s coastal areas drives the construction of coastal zone cities but also creates a variety of challenges for the ecological environment of the coastal zone, and the management and sustainable use of the mainland coastline resources should be further strengthened.

Choung, Y.-J., 2023. Mapping coastlines in an estuary of the West Nakdong River using SAR satellite imagery. In: Lee, J.L.; Lee, H.; Min, B.I.; Chang, J.-I.; Cho, G.T.; Yoon, J.-S., and Lee, J. (eds.), Multidisciplinary Approaches to Coastal and Marine Management. Journal of Coastal Research, Special Issue No. 116, pp. 200-204. Charlotte (North Carolina), ISSN 0749-0208. A coastline is significant for describing the coastal shapes and preserving the coastal properties. Remote sensing datasets acquired by the satellite sensors are useful for mapping coastlines in the wide coastal zones without human access. In this research, the Sentinel-1 satellite image, a widely used SAR satellite imagery, was used for mapping the coastlines in an estuary of the West Nakdong River, as follows. First, the given Sentinel-1 satellite image was radiometrically calibrated to get the sigma nought image. Next, the speckle filter was employed to remove some radar backscatter noises in the sigma nought data. Then, the refined image was terrain corrected using the reference digital elevation model, and the binarized image was generated from the terrain corrected image to classify the water and non-water features. Finally, the boundary lines in the binarized image were selected as the coastlines. The statistical results showed that the accuracy of the generated coastlines was less than 10 m. In future research, the optical satellite imagery and the SAR satellite imagery would be compared for mapping the accurate coastlines in the various type of coasts.