Digital Shoreline Analysis System Research Articles

Long‐term and short‐term analysis of shoreline change and cliff retreat on Brazilian equatorial coast

AbstractAssessing historical changes in the shoreline and retreat of cliffs is essential for understanding the evolution and behaviour of specific coastal systems. The present study focused on shoreline changes and cliff base retreat trends at different time scales (annual/decadal) along a 680‐m stretch of Pacheco Beach (Caucaia, Northeast Brazil), which are characterized by coastal erosion and mass movements that have posed risks to residents and visitors to this beach. Shoreline position data were obtained through images collected by satellites and field campaigns for precision mapping through unmanned aerial vehicle (UAV) photogrammetry. The spatiotemporal variations of the shoreline were acquired through an extension of the ArcGIS Digital Shoreline Analysis System (DSAS) and the linear regression rate (LRR) statistical method that reflects the variations that have occurred in the coastal segment. The long‐term results show constant erosion patterns in the study area, with a shoreline retreat of −31 m in the last 17 years at an average rate of −1.8 m/year. In the short term, the average rate of retreat between May 2021 and Jan 2022 was −2.9 m, indicating that 88.78% of the evaluated section was in a continuous process of erosion. Several factors and processes cause the short‐term rates to be more severe than historical rates, demonstrating the stochastic nature of the Pacheco Beach cliff system. This research provides essential data for understanding and predicting shoreline changes on different time scales, thereby contributing to the identification and zoning of unstable cliffs and allowing for the mapping of risk areas to direct coastal management strategies.

Spatio-Temporal Shoreline Movement of the Afram River in Ghana: The Application of Endpoint Rate and Net Shoreline Movement

Shoreline change is a severe threat to life and property in wetland regions. Shoreline change analysis is critical for integrated wetland zone management and is accomplished through the field and aerial surveys. The Afram River is a significant source of water, food, and economic activity for Kwahu and its neighbouring communities and a form of funds for the residents. The shoreline, nevertheless, has been transforming because of erosion and accretion. This study examined a low-cost innovative approach using space-based peripheral visuals and metrics. Transects and data analysis for the riverbank were created using the Digital Shoreline Analysis System (DSAS) in the Spatial database. The study employed Landsat images from three historical years (2001, 2015 and 2022) across 22 years. End Point Rate (EPR) and Net Shoreline Movement (NSM) statistics in DSAS were used to determine the extent of change. Questionnaires and key informant interviews were administered to farmers, boat operators, fishermen, and older residents to learn more about the factors responsible for changes in shoreline position. According to the study, 24% of the shoreline erodes at a section, while 86% is stable. The survey's mean erosion rate is -0.24 m/yr, whereas the average accretion proportion is 27 m/yr. The ramifications of the Afram River channel change have affected the socio-economic livelihoods, including out-migration, farm loss and displacement of settlement. As a result, all organisations and participants responsible for these riverbanks should work together to prevent further damage and erosion of the shoreline line and its marine life and resources.

Shoreline change rate detection applying the DSAS technique on low and medium resolution data: Case study along Ash Shu’aybah-Al Mujayrimah coastal Area of the Eastern Red Sea, Saudi Arabia

The Ash Shu’aybah and Al Mujayrimah coast area in Saudi Arabia is threatened by constantly changing shoreline dynamics. This work explains how to appropriately quantify shoreline change rates using the Landsat and Sentinel-2 datasets, predict the coastline after twenty years (2022–2042) and compare the results from both satellite data. The technique used depends on the integration of remote sensing data and Geographic Information Systems (GIS) with a Digital Shoreline Analysis System tool (DSAS). For calculating shoreline change rates and predicting future shoreline positions in 2042, eight Landsat satellite images over 36 years from 1986 to 2022 were analysed along with four Sentinel-2 satellite images from 2015 to 2022. Based on the LRR models’ data, the shoreline is exposed to erosion with average values of −3.25 and −2.12 m/yr for the Sentinel-2 and the Landsat datasets, respectively. Segment 2 in the central part of the coastline is the area most affected by the dynamics of the shoreline. To assess the accuracy of the obtained results, the root mean square error (RMSE), the mean annual error (MAE) and coefficient of determination (R2) were used. The results indicated that both the Sentinel-2 and the Landsat datasets can reliably calculate the shoreline change rate of the study area based on the similar patterns of their data, although the Sentinel-2 had a somewhat better ability in calculating the change of the shoreline.

The assessment of shoreline changes along the Johor Strait using Sentinel-1 synthetic aperture radar imagery and GIS

ABSTRACT This paper presents a robust approach for shoreline detection using the K-Means clustering and the Digital Shoreline Analysis System developed by the United States Geological Survey. The shoreline changes along the Johor Straits of Malaysia are assessed by using the multi-temporal Sentinel-1 Synthetic Aperture Radar images from 2018 to 2022. This area is known to be important for both socioeconomic activities. The retrieved shorelines are found reliable with a good accuracy of 1.4 m when validating against the Global Positioning System rapid static survey. This merits finding a robust approach that goes beyond the normal practice in Malaysia where manual digitization is usually exercised. The rate of change is calculated by using the end point rate (EPR) for providing a short-term (annual) rate of change while using the linear regression rate (LRR) for providing a long-term (5 year) rate of change. Based on the EPR, the mean annual changes are approximately 10 m/yr for erosion and up to 9.83 m/yr for accretion; meanwhile, the mean of 5-year changes based on the LRR is 62% and 37% for erosion and accretion, respectively. This study reveals that 10 out of 12 sites along Johor Strait are categorized as ‘high’ erosion, two locations are categorized as ‘medium’ erosion and none are as ‘low’ erosion.

Assessment of human interventions presence and their impact on shoreline changes along Nile delta, Egypt

Coastal erosion is a natural process, that contributed to shaping the Nile Delta shoreline in Egypt over history. The objective of this research is to investigate shoreline changes, accretion, and erosion and to detect particularly vulnerable locations that require immediate attention. Another goal is to assess the efficiency of coastal installations that have been recently implemented along the study area and determine whether they have performed their role to the fullest or need additional modifications. Several Landsat images (TM, ETM+, and OLI) were utilized over 37 years to track the shoreline changes and were analysed using remote sensing (RS) and Geographic Information System (GIS). The digital shoreline analysis system (DSAS) was integrated with the LRR model for assessing historical changes for shorelines from 1985 to 2022 and forecasting future shoreline positions in 2030, 2050, and 2100. Most of the eight zones that make up the Delta region have lately seen the establishment of coastal projects, such as the development of the Abu Qir port's breakwater in 2021. From the results, it was found that the areas around Rosetta promontory, Burullus headland, and Damietta promontory experienced a significant and rapid retreat and with large rates over the study period, with average values of –15.7, –3.25, and –16.8 m/y, respectively. However, both the coast of Alexandria, and Gamasa embayment were subjected to accretion as a prevailing case, with average rates of 2.85, and 4.03 m/y, respectively. Many groins were installed in the east of the Rosetta promontory (zone 3) in 2016 to decrease the erosion process; however, it didn't pay off and could not solve the problem. In contrast, the groins system, which was implemented at the East Kitchener Drain (zone 5) in the same year, lowered erosion rates from 17.6 m/y from 2000 to 2010 to 7 m/y from 2010 to 2022. In 2019, Y-groins built in zone 7, east of Damietta Port, succeeded in slowing rates of erosion. Finally, inlet jetties at El-Gamil (zone 8) were constructed in 2016, resulting in the coastline advancing at 14.7 m/y on average in the period of 2010–2022. The findings of this study confirmed that hard structures are dangerous because they exacerbate the problem of shoreline erosion by disseminating it to the neighbouring beaches and acting as an impediment to the movement of longshore sediments. According to the expected future shoreline patterns, it is necessary for authorities to implement both short-term and long-term protective measures to stop the erosion of several areas of the beach.

Long-term mapping of land use and cover changes using Landsat images on the Google Earth Engine Cloud Platform in bay area - A case study of Hangzhou Bay, China

Large-scale, long-term series, and high-precision land use and cover change (LUCC) mapping is the basic support for territorial spatial planning and sustainable development in the Bay Area. In response to the sustainable development agenda, for characteristics of high landscape fragmentation, strong surface heterogeneity and frequent land use type conversion in the Bay Area, this study developed a random forest (RF) algorithm that considers spectral bands, remote sensing indices and components of a principal component analysis, and the mapping and monitoring of LUCC in Hangzhou Bay from 1985 to 2020 based on Google Earth Engine (GEE) and Digital Shoreline Analysis System (DSAS) were carried out. The results are as follows. (1) The overall accuracy (OA) and kappa coefficient were 92.83% and 0.91, respectively. (2) During the study period, the areas of the construction land, water area, and bare land increased, while the areas of the wood land, cultivated fields, and tidal flats decreased. (3) During the study period, the total area of the tidal flats decreased from 181.65 km2 to 161.50 km2, with an average annual decrease of 0.58 km2, and the tidal flats were primarily concentrated on the south shore of Hangzhou Bay. (4) During the study period, the transfer of cultivated fields to construction land was the most significant (2268.05 km2). (5) During the study period, the length of the coastline decreased from 383.73 km to 362.80 km, with an average annual decrease of 0.60 km. According to the DSAS statistics, the net shoreline movement (NSM) of the coastline on the north shore of Hangzhou Bay was 773.58 m, the end point rate (EPR) and the linear regression rate (LRR) were 22.10 m/a and 27.00 m/a, respectively. The NSM of the south shore was 4109.57 m, and the EPR and LRR were 117.42 m/a and 132.22 m/a, respectively. The proposed methods improve the accuracy of land use classification of the RF algorithm in the complex environment of the Bay Area, and it can provide technical support for natural resource survey and regional sustainable development in the Bay Area.

Unravelling Spatial-temporal Evolution of Shoreline Changes in Pantai Mek Mas – Pantai Cahaya Bulan, Kelantan, Malaysia

Kelantan is a state on Peninsular Malaysia’s East Coast famed for its tropical jungle and seaside areas. Kelantan is a “flood-state” that encounters monsoons and tidal currents. Kelantan was devastated by tsunami-like floods in 2014 where it brought changes on its coastal geomorphology. Using a universal Digital Shoreline Analysis System (DSAS) technique, this study assesses shoreline changes along Kelantan’s coastline between 2013 (before the catastrophic flood) and 2021. A multipronged approach incorporating DSAS via GIS and satellite imagery were used to explore the coastline changes in Kelantan. This study found that Pantai Mek Mas and Pantai Kundur were the most sedimented and the most eroded area were around Pantai Cahaya Bulan, Kota Bharu respectively. The Shoreline Change Envelope (SCE) and Net Shoreline Movement (NSM) analysis concluded that the coastal area has the highest accretion rate of 177.07m/year and the greatest negative distance via NSM of -171.53m/year. The sedimentation along Pantai Mek Mas may happen due to the transportation of sedimentation via river flows from Kelantan River estuary and the degradation of shoreline along Pantai Cahaya Bulan may cause by the concentration of anthropogenic interventions. In conclusion, can be seen that the Kelantan’s coastal area shoreline does progressively proliferate over the past decade and the community vulnerability on the shoreline changes are at risk which comprehensive mitigation is needed to improve its resilience.

Changes in the normal baseline due to changes in the Coast's dynamics and Their effects on the sea boundary in Weh Island, Nanggroe Aceh Darussalam, Indonesia

The United Nations Convention on the Law of the Sea (UNCLOS) 1982 gave archipelagic states the authority to set maritime boundaries based on such baselines. The basepoint is any point on the usual normal baseline. The base point must be established where the beach's sea level and lowest tide coincide. The location of the base point will change if the coastline's terrain or sea level changes due to physical land- and water-based causes. The reference to establish marine limits will change if the base point changes.It is possible to discover deviations from the average baseline by combining multitemporal satellite imagery with remote sensing techniques. Using satellite images, the position of the shoreline is established according to the time of image acquisition. Utilizing tidal analysis data on changes in vertical position and the slope of the coastal topography, the position of the immediate coastline is then restored to the low water line/normal baseline. Using normal baseline data, the Digital Shoreline Analysis System (DSAS) method is utilized to calculate the rate and rate of temporal changes.According to calculations of the usual baseline's speed and acceleration on the eastern portion of Weh Island, which has a Base Point (TD) of 178, the baseline has drifted 21 m seaward between 2017 and 2022, growing on average approximately 5 m per year. Consequently, coastal dynamics must be taken into account when calculating the base point if the location of TD 178 is updated in accordance with UNCLOS 1982 standards.

Shoreline change dynamics along the Augusta coast, eastern Sicily, South Italy

AbstractThe coastal region of Augusta, eastern Sicily, Italy, is a densely populated zone, where human pressures profoundly shaped the coastal and land dynamics. So far, understanding the interaction between natural and human processes in modelling coastal geomorphology is still quite challenging. However, coastal and environmental monitoring poses the bases for managing coastal areas properly. Therefore, the aim of this research was first to understand the medium‐term shoreline changes along Augusta Bay between 1972 and 2021, and then assess the main local coastal modifications determined by the increasing coastal armouring. To do so, the shorelines dataset was extracted from Landsat and Sentinel‐2 satellite imageries using the NDWI and mNDWI methods and then statistical parameters were computed using Digital Shoreline Analysis System (DSAS). Results show that this coastal fringe experienced significant shoreline recession over the studied time interval. Negative shoreline shifts are higher in correspondence with torrent deltas, as a result of the increasing human and natural forces insisting on the land and coastal environments. Since 1970s, Augusta Bay registered a significant increase in artificial coastal length and a coastal armouring index of Maximal level was reached today.

Analisis Perubahan Garis Pantai Di Pantai Matras Kabupaten Bangka Kepulauan Bangka Belitung

Matras Beach is one of the beach in the Bangka Belitung Archipelago used as a tourist destination. The coastline is the line that separates land and sea which can change every year. The aims of this study are to determine the change and rate of shoreline change before (2000-2010) and after the breakwater (2010-2020), and its impact on beach tourism at Matras Beach. The method used in this research is the digitization method and the Digital Shoreline Analysis System. The results showed that from 2000 to 2010, before the Matras Beach breakwater, there was a maximum increase of 34.23 m at a rate of 3.42 m/year and a maximum reduction of -35.10 m at a rate of -3.51 m/year, while after the breakwater in 2010-2020 Matras Beach experienced a maximum increase of 72.79 m at a rate of 7.28 m/year and a maximum reduction of -81.72 m at a rate of -8.17 m/year. This change resulted in 3.64 ha of abrasion and 1.50 ha of accretion before the breakwater and 8.48 ha of abrasion and 4.20 ha of accretion after the breakwater. This abrasion has a negative impact on beach tourism on Matras Beach because it will damage vegetation and buildings on the coast.

Evaluating the long-term geomorphic process in-relation to hydrodynamics in the central coastal zone of Bangladesh

The central coast of Bangladesh is dynamic for its geographical location, hydrodynamic characteristics and residual flow. The research employed the Digital Shoreline Analysis System (DSAS), an ArcGIS extension tool, to conduct a historical trend analysis of shoreline. The study demonstrates that the central coast is eroding to the north and accreting to the south. The highest accretion value was found as 195.42 m/year, whereas the maximum value of erosion was estimated as −185.83 m/year, according to End Point Rate (EPR). The Linear Regression Rate (LRR) indicates that the average rate of erosion and accretion are −17.77 m/year and 17.88 m/year, respectively. Meanwhile, using Weighted Linear Regression (WLR), 0.48% of all transects demonstrated statistically significant erosion, while 0.43% showed statistically significant accretion. During the wet season, heavy river discharge leads to a low salt level in the ocean. Ocean currents hit central coast of Bangladesh from east to west, affecting the majority of the islands in the Meghna Estuary in the dry season. Changes in current directions can be seen during the wet seasons. Southern central coast areas are hit by south-east currents that split in two directions. The Sandwip Channel has a flow of 10,000 to 15,000 m³ s−1 northward. The Tetulia River, Shahbazpur Channel, and Hatia-Sandwip flow southward at rates ranging from 3000 to 17,000 m³ s−1, 14,000 to 60,000 m³ s−1, and 7000 to 39,000 m³ s−1, respectively. In the Meghna Estuary, the combined forces result in a counter-clockwise residual circulation, with the northward flow in the Sandwip channel and southbound flow in the Hatia and Shahbazpur channels. As a result of hydrodynamic, ocean currents, and residual flow, the Central Coast of Bangladesh is continually changing in appearance.

Assessing the Impact of the 2004 Indian Ocean Tsunami on South Andaman’s Coastal Shoreline: A Geospatial Analysis of Erosion and Accretion Patterns

The 2004 Indian Ocean earthquake and tsunami significantly impacted the coastal shoreline of the Andaman and Nicobar Islands, causing widespread destruction of infrastructure and ecological damage. This study aims to analyze the short- and long-term shoreline changes in South Andaman, focusing on 2004–2005 (pre- and post-tsunami) and 1990–2023 (to assess periodic changes). Using remote sensing techniques and geospatial tools such as the Digital Shoreline Analysis System (DSAS), shoreline change rates were calculated in four zones, revealing the extent of the tsunami’s impact. During the pre- and post-tsunami periods, the maximum coastal erosion rate was −410.55 m/year, while the maximum accretion was 359.07 m/year in zone A, the island’s east side. For the 1990–2023 period, the most significant coastal shoreline erosion rate was also recorded in zone A, which was recorded at −2.3 m/year. After analyzing the result, it can be seen that the tsunami severely affected the island’s east side. To validate the coastal shoreline measurements, the root mean square error (RMSE) of Landsat-7 and Google Earth was 18.53 m, enabling comparisons of the accuracy of different models on the same dataset. The results demonstrate the extensive impact of the 2004 Indian Ocean Tsunami on South Andaman’s coastal shoreline and the value of analyzing shoreline changes to understand the short- and long-term consequences of such events on coastal ecosystems. This information can inform conservation efforts, management strategies, and disaster response plans to mitigate future damage and allocate resources more efficiently. By better understanding the impact of tsunamis on coastal shorelines, emergency responders, government agencies, and conservationists can develop more effective strategies to protect these fragile ecosystems and the communities that rely on them.

Understanding the landscape evolution of El Mogote barrier spit, Baja California Sur, Mexico, using OSL dating, satellite images and a multivariate analysis

Barrier spits are natural archives that provide information about coastal evolution and prevailing environmental conditions of the mainland. In this study, we analyze one of the largest barrier spits in Baja California Sur, Mexico, known as El Mogote bar, using a multi-method approach to unravel the coastal landscape evolution. We used (1) OSL dating to provide a robust geochronology and depositional rates of the emerged beach-dune ridges, (2) satellite imagery interpretation using the Digital Shoreline Analysis System (DSAS) software to assess shoreline changes on Landsat images from 1986 to 2014, and (3) the Principal Component Analysis (PCA) with climatic and geomorphologic parameters to elucidate the environmental conditions of the beach-dune ridges for the period comprised in the DSAS analysis. OSL results indicate that the emerged bars started to form ∼2 ka and were developed in three main building phases: (1) the Medieval Warm Period (MWP) and part of the Little Ice Age (LIA) with accretional rates of 1.13 m yr −1, (2) the ending of the LIA with 7.03 m yr −1 and (3) the post-LIA with 3.98 m yr −1. In this paper, we hypothesize two probable causes that led to the destruction of the former beach-dune ridges: (1) tsunami waves triggered by seismic events and (2) local sea level rise associated with local tectonic subsidence. Satellite images and DSAS analysis show that, in the barrier spit, accretion and erosion have been in dynamic equilibrium for at least three decades. PCA results indicate that dry and cold weather conditions, El Niño modes, and tropical cyclone occurrence with high accretional rates on the barrier spit are the main controls on the beach-dune ridges. We conclude that the multi-method approach used in this research is suitable to tease out the landscape evolution of a barrier spit from a climatic and geomorphological perspective, as we were able to identify that the accretional episodes of El Mogote bar are mainly related to rainfall during the coldest and driest environmental conditions that enhance sediment supply from continental areas to the coast.

Decoding Chambal River Shoreline Transformations: A Comprehensive Analysis Using Remote Sensing, GIS, and DSAS

Illegal sand mining has been identified as a significant cause of harm to riverbanks, as it leads to excessive removal of sand from rivers and negatively impacts river shorelines. This investigation aimed to identify instances of shoreline erosion and accretion at illegal sand mining sites along the Chambal River. These sites were selected based on a report submitted by the Director of the National Chambal Sanctuary (NCS) to the National Green Tribunal (NGT) of India. The digital shoreline analysis system (DSAS v5.1) was used during the elapsed period from 1990 to 2020. Three statistical parameters used in DSAS—the shoreline change envelope (SCE), endpoint rate (EPR), and net shoreline movement (NSM)—quantify the rates of shoreline changes in the form of erosion and accretion patterns. To carry out this study, Landsat imagery data (T.M., ETM+, and OLI) and Sentinel-2A/MSI from 1990 to 2020 were used to analyze river shoreline erosion and accretion. The normalized difference water index (NDWI) and modified normalized difference water index (MNDWI) were used to detect riverbanks in satellite images. The investigation results indicated that erosion was observed at all illegal mining sites, with the highest erosion rate of 1.26 m/year at the Sewarpali site. On the other hand, the highest accretion was identified at the Chandilpura site, with a rate of 0.63 m/year. We observed significant changes in river shorelines at illegal mining and unmined sites. Erosion and accretion at unmined sites are recorded at −0.18 m/year and 0.19 m/year, respectively, which are minor compared to mining sites. This study’s findings on the effects of illegal sand mining on river shorelines will be helpful in the sustainable management and conservation of river ecosystems. These results can also help to develop and implement river sand mining policies that protect river ecosystems from the long-term effects of illegal sand mining.

Analysis of Multi-Temporal Shoreline Changes Due to a Harbor Using Remote Sensing Data and GIS Techniques

Coastal landforms are continuously shaped by natural and human-induced forces, exacerbating the associated coastal hazards and risks. Changes in the shoreline are a critical concern for sustainable coastal zone management. However, a limited amount of research has been carried out on the coastal belt of Sri Lanka. Thus, this study investigates the spatiotemporal evolution of the shoreline dynamics on the Oluvil coastline in the Ampara district in Sri Lanka for a two-decade period from 1991 to 2021, where the economically significant Oluvil Harbor exists by utilizing remote sensing and geographic information system (GIS) techniques. Shorelines for each year were delineated using Landsat 5 Thematic Mapper (TM), Landsat 7 Enhanced Thematic Mapper Plus (ETM+), and Landsat 8 Operational Land Imager images. The Normalized Difference Water Index (NDWI) was applied as a spectral value index approach to differentiate land masses from water bodies. Subsequently, the Digital Shoreline Analysis System (DSAS) tool was used to assess shoreline changes, including Shoreline Change Envelope (SCE), Net Shoreline Movement (NSM), End Point Rate (EPR), and Linear Regression Rate (LRR). The results reveal that the Oluvil coast has undergone both accretion and erosion over the years, primarily due to harbor construction. The highest SCE values were calculated within the Oluvil harbor region, reaching 523.8 m. The highest NSM ranges were recorded as −317.1 to −81.3 m in the Oluvil area and 156.3–317.5 m in the harbor and its closest point in the southern direction. The maximum rate of EPR was observed to range from 3 m/year to 10.7 m/year towards the south of the harbor, and from −10.7 m/year to −3.0 m/year towards the north of the harbor. The results of the LRR analysis revealed that the rates of erosion anomaly range from −3 m/year to −10 m/year towards the north of the harbor, while the beach advances at a rate of 3 m/year to 14.3 m/year towards the south of the harbor. The study area has undergone erosion of 40 ha and accretion of 84.44 ha. These findings can serve as valuable input data for sustainable coastal zone management along the Oluvil coast in Sri Lanka, safeguarding the coastal habitats by mitigating further anthropogenic vulnerabilities.

Coastal erosion and accretion on the Caribbean coastline of Costa Rica long-term observations

Several studies show erosive processes on the Caribbean coastline of Costa Rica. These processes may be accelerated as a result of an increase in the sea level. This study covered the entire Caribbean coastline of Costa Rica between 1986 and 2019. This allowed reporting new sites with accelerated coastal accretion and erosion processes, as well as confirming other processes that have already been identified. The methodology was based on shoreline rising images obtained from Landsat and on their processing in a Geographical Information System supported with the “Digital Shoreline Analysis System” (DSAS) tool. The presence of important accretion areas related to the mouth of significant fluvial systems, such as Colorado, Parismina, Matina, Estrella, and Sixaola rivers is highlighted. Moreover, eight beach sectors showing erosion problems have been analyzed. The beach located to the south of Isla Portillos and beaches located on Cahuita Point stand out due to their intensity. Additionally, an intense beach erosion process has been detected at Soropta in Panamá. It should be highlighted that six of the eight sites showing erosion are located within protected zones. This confirms the little anthropic interference on these processes. It was not possible to find a difference between the north and the south of the Caribbean Coast in terms of the magnitude of coastal erosion. The contribution of the rivers is a key factor in the North Caribbean while the responses to the 1991 earthquake conditioned the behavior on the South coast. The results may serve as a basis for management plans or adaptation to climate change proposals.

Influence of a fishing harbour on coastal geomorphology of the southwest coast of India and predictions of its future trends

In the present study, we estimated the shoreline change along Ponnani Fishing Harbour (PFH), the coastal part of Malappuram, India, using the Digital Shoreline Analysis System (DSAS) version 5.0. We also assessed the land use and land cover (LULC) changes in the gateway of Ponnani Fishing Harbour (PFH) and its surrounds using Geographical Information System (GIS) and Remote Sensing (RS) techniques. LULC estimated that vegetation cover was more in 2004 than in 2020, supported by the values shown by VSB (Vegetation with Scattered Built-up) and BSV (Built-up with Scattered Vegetation) show a significant areal change in the study area. On the comparison of erosion and accretion in the two zones of the study area, erosional activities are dominant in Ponnani, which is in the southern part. Based on the Linear Regression Rate (LRR) values, the maximum erosion rate was -7.41 m/year at Ponnani. The southern sector is also undergoing a maximum accretion rate of 8.11 m/year in the Ponnani Harbour region. The End Point Rate (EPR) estimated similar trends of the highest erosion -43.24 m/year and highest accretion, 37.34 m/year rates in the southern sector. The Net Shoreline Movement (NSM) values demonstrate that the shoreline retreated by -285.9 m, and the shoreline accreted by 132.32 m at the Ponnani Harbour area over the last three decades. The Kalman filter model predicted that the shoreline at Ponnani and Puthuponnani beaches might experience further erosion of approximately a 100-metre shift by 2030. An increase in the erosion rate could erode another 140 m from the shoreline by 2040. The Ponnani and Puthuponnani beach extents must be considered high erosion risk zones in the perspective of the estimated results. This assessment indicates that the southern stretch of the area under the study of the PFH coastline is eroding. The significant changes in land use and land cover that have been seen over the past few years following the construction of PFH are expected to be the main cause of the severe loss of the coast in the southern part. The main reason for erosion in PFH would be construction operations that put pressure on the coastline side. The limited supply of sand used to replenish the coast naturally causes shoreline change due to the large drop in sediment load from the river, which is evident by the shrinking of the braided island size. The methods employed in this study and the results might help manage the PFH coast sustainably. The outcomes of this assessment suggest that similar studies should be conducted in other regions of India's western coastline to understand the shoreline evolution and develop a better coastal management strategy.

The impact of coastal erosion on the archaeology of the Cyrenaican coast of Eastern Libya.

Coastal erosion in Cyrenaica (Eastern Libya) represents a major problem for archaeology and heritage management. The area is rich in archaeological sites, often understudied or not fully documented, but also has extensive stretches of vulnerable eroding coastline. This study demonstrates the extent and impact of erosion via shoreline change assessment at two spatial scales. Firstly, wide area assessment using shorelines extracted from a time-series of medium-resolution Landsat imagery. Secondly, site-specific assessment using recent and historic Very High Resolution (VHR) satellite imagery. In both cases, extracted shorelines at different timesteps were compared using the Digital Shoreline Analysis System (DSAS) tool to quantify rates and magnitudes of shoreline movement. The results show extensive zones of erosion at and around the key ancient harbour sites of Apollonia, Ptolemais and Tocra. They also suggest increased rates of coastal retreat in recent years, which is likely linked to anthropogenic actions such as sand mining and urbanization. Forecasts based on present-day shoreline change rates, coupled with ground-level documentation of the vulnerable shorelines is used to identify archaeological features and structures which will likely be progressively damaged or destroyed over the next 20 years. The ability to actively protect archaeological sites is unclear, but there is a clear need for mitigation in the form of enhanced awareness of environmental problems (e.g. caused by sand mining) and more intensive survey/documentation of sites and areas which will be lost in the coming years.

Assessing the influence of transect interval in monitoring and analysis of shoreline change

Shoreline analysis helps to understand the coastal dynamism for decision-making in coastal management. As there are still doubts in transect-based analysis, this study attempts to understand the influence of transect intervals in shoreline analysis. Shorelines were delineated on high-resolution satellite images in Google Earth Pro for twelve beaches in Sri Lanka under different spatial and temporal scales. Shoreline change statistics were calculated using Digital Shoreline Analysis System in the ArcGIS 10.5.1 software under 50 transect interval scenarios, and influence of the transect interval for shoreline change statistics were interpreted using standard statistical methods. Transect interval error was calculated with respect to the 1m scenario as this has the best beach representation. Results revealed that there is no any significant difference (p > 0.05) of shoreline change statistics between 1 and 50m scenarios in each beach. Furthermore, it was found that the error was extremely low up to 10m scenario and then after it was subject to fluctuate in an unpredictable manner (R2 < 0.5). Overall, the study concludes that the influence of the transect interval is negligible and 10-m transect interval is ideal in shoreline analysis for the highest efficacy in small sandy beaches.

Assessment and Forecast of Shoreline Change Using Geo-Spatial Techniques in the Gulf of California

In coastal regions, the combined effects of natural processes, human activity, and climate change have caused shoreline changes that may increase in the future. The assessment of these changes is essential for forecasting their future position for proper management. In this context, shoreline changes in the Gulf of California (GC), Mexico, have received little attention and no previous studies have addressed future forecasting. In this study, the researchers assessed the historical shoreline changes to forecast the long-term shoreline positions. To address this, shoreline data were obtained from Landsat satellite images for the years 1981, 1993, 2004, 2010, and 2020. The Net Shoreline Movement (NSM), Linear Regression Rate (LRR), End Point Rate (EPR), and Weighted Linear Regression (WLR) geo-spatial techniques were applied to estimate the shoreline change rate by using a Digital Shoreline Analysis System (DSAS) in the GIS environment. A Kalman filter model was used to forecast the position of the shoreline for the years 2030 and 2050. The results show that approximately 72% of the GC shoreline is undergoing steady erosion, and this trend is continuing in the future. This study has provided valuable and comprehensive baseline information on the state of the shoreline in the GC that can guide coastal engineers, coastal managers, and policymakers in Mexico to manage the risk. It also provides both long-term and large-scale continuous datasets that are essential for future studies focused on improving the shoreline forecast models.