Shoreline Analysis Research Articles

Assessing sandbar morphology in the Nakdong River Estuary using SPOT series satellite imagery

This study assessed sandbar-topography changes in Nakdong River Estuary. The island shorelines in the study area, including Jinwoo Island, Shinja Island, and Doyo Sandbar, were analyzed using SPOT satellite images from 2006 to 2022. Shoreline analysis via ArcGIS revealed that Jinwoo Island is expanding at 6.46 m/year towards Nulcha Island. Shinja Island’s western side is expanding at 4.76 m/year, while the eastern side is retreating at 24.41 m/year. Doyo Sandbar’s southern shoreline is retreating at 14.69 m/year, with a gradual decrease in speed. Significant topographical changes indicate that the interlinked barrier islands are undergoing deposition and erosion, altering the shoreline.

Assessing Satellite-Derived Shoreline Detection on a Mesotidal Dissipative Beach

The accuracy and robustness of the shoreline definition from satellite imagery on different coastal types are crucial to adequately characterising beach morphology and dynamics. However, the generic and widespread application of satellite-derived shoreline algorithms is limited by the lack of robust methods and parameter assessments. This work constitutes a quantitative and comprehensive assessment of the satellite-derived waterlines from Sentinel-2 by using the novel SAET tool (Shoreline Analysis and Extraction Tool) on the exposed and mesotidal beach of La Victoria (Cádiz, SW Spain). The diverse parameters available in SAET, such as water indexes, thresholding methods, morphological filters, and kernel sizes, were combined to define water/land interface positions that were compared against coincident video-derived waterlines. Satellite-derived waterline errors are found to be affected by extraction parameters, as well as by the oceanographic and morphological conditions at the time of the image acquisition. The application of a morphological erosion filter on the water mask, which tends to shift the extracted waterline seawards and reduce bias, is the best solution at the dissipative site of La Victoria Beach. Moreover, using a 3 × 3 kernel size consistently shows higher accuracies than a larger kernel. Although there was no parameter combination showing the best skill for all dates, the employment of the Automated Water Extraction Index for images with no shadows (AWEInsh) with a threshold = 0, erosion morphological filter, and 3 × 3 kernel was, overall, the best combination of extraction parameters for this beach (average waterline RMSE of 5.96 m). The combination of the Modified Normalised Difference Water Index (MDNWI) with the Otsu thresholding also led to similar positions of the resulting waterlines and offered good accuracies. In line with other recent research efforts, our work stresses the lack of generic shoreline extraction solutions that can be applied automatically at a global level and the necessity to adapt and validate the extraction methodologies to the different types of coastlines.

Analysis of Shoreline and Erosion Changes along the West African Coast from 1980 to 2020

The manifestations of climate change in coastal areas may represent a serious threat to livelihoods and lives. In West Africa, where many capital cities are located with a high concentration of people, shoreline changes have been studied in some port cities and beaches. This study investigates the changes along the coastline of West Africa from 1980 to 2020 at a regional scale including twelve countries. Spatial technique, remote sensing and GIS were employed in the assessment and analysis and monitoring of the shoreline changes from Mauritania to Nigeria. The findings revealed noticeable decadal changes with the most significant change evident from 1980 to 1990. The study further indicates that the coasts of Senegal and Guinea and Guinea Bissau experienced significant shift in the shoreline as it moved landward from 1980 to 1990. The results of the geospatial analysis indicates that erosion and accretion trends were dominated by loss of coastal land totaling 17372.45 km2 from 1980 to 1990 with erosion rates higher than areas gained through accretion. The difference between erosion and accretion rates between 1980-1990 period is 15,769.8 km2 with erosion rates on the increase. Study has provided to demonstrate decadal changes of coastal erosion and shoreline changes that characterize the West Africa coast from 1980-2020 highlighting its vulnerability. The study recommends concerted effort by relevant authorities in the region in mitigating against the adverse the consequences of sea level rise at a regional scale.

Assessment of satellite-derived shorelines automatically extracted from Sentinel-2 imagery using SAET

The definition of the shoreline position from satellite imagery is of great interest among coastal monitoring techniques. Understanding the reality mapped by the resulting shorelines and defining their accuracy is of paramount importance. The assessment described in this paper constitutes a validation of the shorelines obtained by using the novel tool SAET (Shoreline Analysis and Extraction Tool) for automatic shoreline extraction. The resulting shorelines applying the different parameters available in SAET are assessed in 9 test sites with diverse morphology and oceanographic conditions along the Atlantic European and Western Mediterranean coasts. The reference data is obtained along large coastal segments (covering up to about 240 km) from nearly coincident very high-resolution satellite images.Different image processing levels and extraction methods have been tested, showing their key role in the accuracy of shoreline position. When defining the approximate shoreline position the Automated Water Extraction Index for images without shadows (AWEInsh) with a 0 threshold generally constitutes the best segmentation method. In turn, the employment of the mathematical morphological operations of dilation or erosion considerably improves the results in certain coastal typologies. On the contrary, the employment of atmospherically-corrected images has a smaller influence on the accuracy of the SDSs.Results support the idea that the magnitude of the errors is strongly related to the specific coastal conditions- In general, the lowest errors appear in low-energetic microtidal sites, contrary to the energetic and mesotidal coasts with gentle slopes.The shoreline errors range between 3.7 m and 13.5 m RMSE (root-mean-square error) among the different coastal types when selecting the most appropriate extraction parameters. The shoreline position identified with SAET shows a similar or better accuracy to that obtained by other tools.

Natural opening of a new inlet in Chilika Lagoon: A cause and impact analysis

Natural opening of inlet(s) is very common along the shorefront of Chilika Lagoon. Inlet openings in most of the cases have been triggered due to the narrow spit width and cyclonic storm/ depression (CS/D). Wave height and energy get further enhanced when the CS/D occurs concurrently with a full moon/ new moon with a lag/lead of 2–3 days. This has happened many times in the past. Recently, a new inlet was opened on 13th July 2022 due to deep depression (DD) over the northwestern Bay of Bengal from 09th to 12th July 2022. A cyclonic circulation prevailed over the northwest and adjoining west-central Bay of Bengal off the south Odisha-north Andhra Pradesh coast in lower and mid-tropospheric levels tilting southwestwards with height. Wave heights during the pre and post-inlet opening period spanning over one month suggest the peak wave condition coinciding with the period of the inlet opening. Geomorphological conditions of the spit before and after the inlet opening were monitored. Results indicate fast expansion of inlet width due to erosion of the spit on both sides of the inlet and the tidal incursion into the lagoon predominantly during the full-moon day/new moon day. After the opening of a narrow inlet of width 246 m on 13 July 2022, it was doubled within a month. Shoreline analysis using Sentinel 2A imagery for pre- and post-inlet opening was carried out and validated with observations. Oceanographic conditions near the new inlet were simulated and monitored by deploying a Seaguard RCM current meter with a pressure and temperature sensor. This study assessed the reasons for the inlet opening and monitored the geomorphological changes after the inlet opening. More importantly, the impact of the new inlet on lagoon ecosystem was assessed, which has severe implications for the management of the lagoon ecosystem.

Assessing the impact factors and corresponding weights affecting the coastal morphology of Hsinchu Coast, Taiwan

This study investigates the long-term morphological pattern of the Hsinchu coast in northwestern Taiwan using three different methods: long-term isobath and shoreline change analysis, bathymetric volume change analysis, and the empirical orthogonal function (EOF) method. Our objectives include analyzing and understanding the effects of anthropogenic structures, natural processes, and their combined impacts on coastal morphological change. The shoreline analysis and bathymetric volume analysis briefly reveal that the morphological pattern of Hsinchu coast. Then, EOF analysis is applied to identify the dominant impact factors affecting the coastal morphology near the harbor, determine the weights of the impact factors, and infer the impact range of anthropogenic structures. Moreover, the EOF analysis is divided into two-time segments—namely, the periods 2005–2010 and 2017–2021—based on different bathymetric surveys and the corresponding values of impact factors. The primary and secondary EOF modes are strongly linked to the “interaction between wave and structure” and “interaction between river discharges and structure”, respectively. The spatial components of the EOF modes demonstrate that the impact range influenced by river discharges was mainly located in the northern part of the harbor, while the minimum impact range of the structures on coastal morphological interaction changes under natural factors was 3.5 km south of Hsinchu Fishing Harbor.

Sedimentary Facies and Morpho-dynamics of Sand Spit and Island Inference as Coastal River Process

Abstract This study aimed to characterize the sedimentary facies and understand the morphodynamics of the study area, and their results were correlated with various analytical methods. Different analyses such as depositional environmental, statistical, shoreline change, and grain size illustrated the temporal and spatial distribution of sediments. It has previously been claimed that current research locations are locii to fluvial landforms and are affected by fluvial processes. However, there are currently no rivers in the study region. This study was done to better understand the presence of fluvial landforms and to evaluate the previous findings. The dynamic behavior of the coast was revealed through shoreline analysis, which was done using satellite images from various years. Oceanographic parameters and longshore sediment transport play a vital role in geomorphological changes in coastal zones. According to the grain size analysis results, mean values showed that the deposits predominantlyare medium grained. The outcome discussed the spatiotemporal variations in geomorphology, sedimentation, and the function of coastal and fluvial processes on the beach of an island and a sand spit. Also highlighted was the role that wave action, fluvial currents, and tidal currents had in the long-term evolution of coastal geomorphological features such as spits, beaches, open coasts, and islands. The standard deviation signifies that the sediments are very well sorted to poorly sorted. Skewness ranges from fine skewed to strongly fine skewed and the kurtosis values show that the sediments are predominately very platykurtic which implies a low-energy environment of deposition. Four sedimentary facies (Facies A, B, C, D) have been found and facies A, B, and C may be wave-influenced deposits, but facies D may be formed by fluvial processes and contain medium to sand-sized particles. The direction of the tip area is also pointing to the south and this result concluded that the tip area is continuously growing. Thus, the results of this study revealed that sediment transport and coastal geomorphology evolution may be governed by two main processes such as the present ocean hydrodynamics and paleo fluvial processes of the study regions.

Shoreline Analysis and Extraction Tool (SAET): A New Tool for the Automatic Extraction of Satellite-Derived Shorelines with Subpixel Accuracy

SAET (Shoreline Analysis and Extraction Tool) is a novel open-source tool to enable the completely automatic detection of shoreline position changes using the optical imagery acquired by the Sentinel-2 and Landsat 8 and 9 satellites. SAET has been developed within the ECFAS (European Coastal Flood Awareness System) project, which is intended to be the first European service for coastal flood forecasting, management, and recovery analysis. The tool is developed to characterise the shoreline response associated with punctual events such as coastal storms as well as any other phenomenon. For a given beach segment, SAET facilitates the selection of the satellite images closest in time to the analysed events that offer an adequate cloud coverage level for analysing the shoreline change. Subsequently, the tool automatically downloads the images from their official repositories, pre-processes them and extracts the shoreline position with sub-pixel accuracy. In order to do so, an initial approximate definition of the shoreline is carried out at the pixel level using a water index thresholding, followed by an accurate extraction operating on the shortwave infrared bands to produce a sub-pixel line in vector formats (points and lines). The tool offers different settings to be adapted to the different coastal environments and beach typologies. Its main advantages refer to its autonomy, its efficiency in extracting complete satellite scenes, its flexibility in adapting to different environments and conditions, and its high subpixel accuracy. This work presents an accuracy assessment on a long Mediterranean sandy beach of SDSs extracted from L8 and S2 imagery against coincident alongshore reference lines, showing an accuracy of about 3 m RMSE. At the same time, the work shows an example of the usage of SAET for characterising the response to Storm Gloria (January 2020) on the beaches of Valencia (E Spain). SAET provides an efficient and completely automatic workflow that leads to accurate SDSs while only relying on publicly available information. The tool appears to be a useful extraction tool for beach monitoring, both for public administrations and individual users.

Effectiveness of grey and green engineered solutions for protecting the low-lying muddy coast of the Chao Phraya Delta, Thailand

Coastal protection measures can be categorized into grey and green solutions in terms of their ecosystem impacts. As the use of grey solutions has become a serious issue due to environmental consequences during the last few decades, green/nature-based solutions have become prioritized. This study evaluates the effectiveness of grey and green solutions applied along the eastern Chao Phraya Delta (ECPD) based on historical shoreline change analysis and coastal observations using Light Detection and Ranging technology. The results from shoreline analysis indicate that nearshore breakwaters installed 100–250 m from the shoreline have successfully reclaimed the coastline with a sedimentation rate of 17–23 cm/y. Meanwhile, sand-sausage-submerged breakwaters were ineffective at stabilizing the coastline during 2002–2010 due to land subsidence. With a low subsidence rate, the rubble-mound-submerged breakwaters can reduce the shoreline retreat rate with a vertical deposition rate of about 5 cm/y. In contrast, use of a bamboo fence, a green solution widely used along muddy coasts, traps sediment at a rate of less than 1.3 cm/y and typically lasts only for 2–3 years after installation. Decomposed bamboo causes environmental degradation so local communities disapprove of the approach. Results reveal that grey solutions are more effective for stabilizing the ECPD coastline and result in less coastal environmental impact than the nature-based solution using a bamboo fence.

Historical morphological changes (1956-2017) and future trends at the mouth of the Ebro River delta (NE Spain)

The present work focuses on the recent morphological changes recorded in the Ebro River delta, by using aerial photographs in the last six decades and by analyzing changes in the main constitutive features through geomorphological maps. Geomorphological maps of the years 1956 and 2017 are here presented. The results obtained give very valuable clues about the recent trends of the river delta mouth, which can be used to predict future coastal changes to be expected in the following decades. In this sense, by analysing changes in the surface by means of the geomorphological maps together with a shoreline analysis, a differential behavior has been described at both sides of the river mouth: the left side, El Garxal wetland, shows an accretionary trend with rates reaching +40 m/year, while the right side, San Antonio Island, shows erosive trends of more than -20 m/year. This last side also presents a surface reduction of more than 50 ha in the last 60 years. These results suggest that, approximately by the year 2050, the emerged San Antonio Island may disappear if shoreline retreat trends are maintained, making El Garxal exposed to easterly storms, the main erosive dynamic processes in this zone and, therefore changing the entire configuration of the Ebro River delta mouth in the upcoming years. Despite possible solutions have been described in recent works, they may not contribute to a total recovery of the most natural part of the Ebro Delta. Urgent management plans are required to attempting to slow or reverse these trends, otherwise one of the most valuable ecosystems of the delta could disappear.

Urban pocket-beach morphodynamics along the wave-dominated southwest coast of Lake Michigan: An analysis of shoreline and sand volumetric changes

Many of the world’s beaches are embayed, but while a large body of work addresses the geomorphology of pocket beaches in oceanic settings, little is known about urban analogs, especially within the Great Lakes of North America. Groins and jetties shelter these systems from direct interaction with littoral processes, which elsewhere can influence how changes in lake level, winter-ice cover, and wave climate impact beach evolution. We address the direct controls of these forcing parameters on beach morphodynamics over a 33-yr period at North Point Beach, which is confined to an engineered ‘container’ along Lake Michigan’s wave-dominated SW margin. Analysis of near-annual beach change suggests lake-level change is the dominant geomorphic driver over inter-annual to decadal timeframes, with winter ice playing a secondary role. Pocket-beach shoreline positions were found to be unreliable indicators of sand volumetric changes. Lake-level rise facilitated shoreline retreat and overwash-induced beach accretion while high lake levels created the accommodation for additional sands to enter the embayment. This is important for coastal managers to consider when developing mitigation strategies for ongoing lake-level fluctuations and anticipated regional climate impacts. This foundational assessment has implications for embayed beaches of the greater Chicago coastal margin (n > 20), where many other site-specific variables (e.g., groin orientations and shoreline aspect) may factor into nearshore and onshore beach morphodynamics. Continued research into urban pocket beaches of the Great Lakes stands to offer useful information on the impacts of littoral fragmentation on coastal sediment routing during different lake-level phases and degrees of littoral interconnectivity.

The Influence of Rock Resistance for Geomorphology of Krakatau Islands, South Lampung District, Lampung Province

Krakatoa Islands is one of the results of high activity volcanic islands located in the Sunda Strait, Indonesia. Volcanic activity of the research area is highly influential on the typical morphological conditions. Rocks produced from this volcano activity a role in the formation of geomorphology that is typical of areas with high volcanic activity. Rocks in the study area were the result of volcanic activity such as lava, pyroclastic alluvial. Geomorphology analysis was conducted by analyzing river flow pattern, slope criteria analysis and shoreline analysis since 1984. East Anak Krakatoa island which is dominated by lava, in contrast to the krakatoa west of which the rock formers are dominantly pyroclastic fall. Unconsolidated rocks form west Sertung island, east Panjang island and south Rakata island which the rock formers are dominantly pyroclastic flow. Evidence of 1883 catastrophic eruption is highly visible on the north Rakata island, east Sertung island and west Panjang island shown by vertical high cliff which is indicated as a caldera structure. The results of the geomorphological analysis are poured into geomorphological maps. Geomorphology unit in research area consist of 9 (nine) geomorphology units of Krakatoa Islands. Krakatoa Islands in this geomorphological case, is still controlled by climate change, erosional of sea water wave, 1883 catastrophic eruption which produces rock in the form of lava and pyroclastic and volcanic activity still continues to this day.

Volcanostratigraphy of Krakatoa Islands, South Lampung District, Lampung Province

The research area is within the territory of Nature Preserve and Marine Preserve region of Krakatoa Islands, South Lampung District, Lampung Province. The study aims to determine the surface geological, mapped on a scale of 1: 20,000, and to determine the geological history that forms the Krakatoa Islands. Volcanostratigraphy is made by combined from literature studied, shoreline analysis, petrographic analysis and field observation. From these results, it is poured into a map of geological outcrops, maps of volcanostratigraphy profiles, geological maps and geological sections. Volcanostratigraphy on the research area is divided into 30 rock units that consists of 22 lava, 8 pyroclastic and allvuial. Geological structure that developed in the research area in the form of secondary structure that is crater and caldera, and the primary structure that is sheeting joinnt, columnar joint, vesicular and autobreccia. New and detailed geological map of Krakatoa volcano is presented.

Coastal vulnerability assessment of Vedaranyam swamp coast based on land use and shoreline dynamics

In the recent decades, the 60-km coastal stretch of Vedaranyam swamp located in the southern coast of Tamil Nadu is identified as a major ‘Vulnerable Hotspot’, due to increased land-based infrastructures and associated episodic hazards including floods attributable to heavy rain, cyclones, storm surges, earthquakes and tsunami. In order to assess the impact of the land use/land cover changes (LULC) on the historical shoreline of this geographical area, vulnerability study between the periods 1978, 1998 and 2017 was attempted. The LULC change analysis from 1978 to 2017 indicated significant increase in aquaculture farms, salt pans and settlement areas upon conversion of crop lands, mudflats, coastal dunes and scrub lands especially along the coast. The end-point rate resulting from the shoreline analysis over the study period showed evidences of accretion and erosion ranging from 9.93 to − 2.28 m year−1 while the net shoreline movement transects about − 107.79 to 382.71 m, respectively. Changes in the land uses and shoreline dynamics of the study area were considered as key parameters for the vulnerability assessment of this coast. This analysis will help to create awareness among the people about impacts of land use changes and effects of natural hazards such as coastal erosion, inundation and their consequences which includes loss of life and properties. The stress driving vulnerability parameters, namely sea-level rise, relief, wave exposure, surge potential, were considered for calculating the vulnerability index of the 60-km coastline considered for the study. The outcome of the study indicates that about 6 km of the coast is very highly vulnerable, 45 km is highly vulnerable, and 9 km is moderate vulnerable to episodic natural hazards.

Unmanned aerial vehicle remotely sensed datasets, a reference dataset for coastal topography change and shoreline analysis

To analyze tendency of temporal and spatial change of coast using long-term topography and shoreline change data is important. In this study, high-resolution digital elevation model and orthorectified image data were generated using rotary-wing UAV(unmanned aerial vehicle) system for coastal topography and shoreline change analysis. The UAV system has advantage of low cost and high efficiency compared to satellite remote sensing platform so UAV system easily acquire time series image data. The spatial resolution of generated digital elevation model and orthorectified images are very high, in centimeter. Therefore, the above image data can be used in various fields of remote sensing and geography such as detailed coastal topography.

Rapid retreat of permafrost coastline observed with aerial drone photogrammetry

Abstract. Permafrost landscapes are changing around the Arctic in response to climate warming, with coastal erosion being one of the most prominent and hazardous features. Using drone platforms, satellite images, and historic aerial photographs, we observed the rapid retreat of a permafrost coastline on Qikiqtaruk – Herschel Island, Yukon Territory, in the Canadian Beaufort Sea. This coastline is adjacent to a gravel spit accommodating several culturally significant sites and is the logistical base for the Qikiqtaruk – Herschel Island Territorial Park operations. In this study we sought to (i) assess short-term coastal erosion dynamics over fine temporal resolution, (ii) evaluate short-term shoreline change in the context of long-term observations, and (iii) demonstrate the potential of low-cost lightweight unmanned aerial vehicles (“drones”) to inform coastline studies and management decisions. We resurveyed a 500 m permafrost coastal reach at high temporal frequency (seven surveys over 40 d in 2017). Intra-seasonal shoreline changes were related to meteorological and oceanographic variables to understand controls on intra-seasonal erosion patterns. To put our short-term observations into historical context, we combined our analysis of shoreline positions in 2016 and 2017 with historical observations from 1952, 1970, 2000, and 2011. In just the summer of 2017, we observed coastal retreat of 14.5 m, more than 6 times faster than the long-term average rate of 2.2±0.1 m a−1 (1952–2017). Coastline retreat rates exceeded 1.0±0.1 m d−1 over a single 4 d period. Over 40 d, we estimated removal of ca. 0.96 m3 m−1 d−1. These findings highlight the episodic nature of shoreline change and the important role of storm events, which are poorly understood along permafrost coastlines. We found drone surveys combined with image-based modelling yield fine spatial resolution and accurately geolocated observations that are highly suitable to observe intra-seasonal erosion dynamics in rapidly changing Arctic landscapes.

Sandbar Migration and Shoreline Change on the Chirihama Coast, Japan

Sandy beaches play a key role in regional tourism. It is important to understand the principal morphological processes behind preserving attractive beaches. In this study, morphological variation on the Chirihama Coast, Japan, an important local tourism resource, was investigated using two sets of field surveys. The objective was to analyze and document the multi-scale behaviors of the beach. First, long-term shoreline changes were examined based on shoreline surveys over the last two decades. Then, the middle-term behavior of multiple bar systems was analyzed based on the cross-shore profile surveys from 1998 to 2010. An empirical orthogonal function (EOF) analysis was conducted to capture the principal modes of the systematic bar migration. The shoreline analysis indicated a long-term eroding trend and showed that the seasonal variation has recently tended to increase. The profile analysis demonstrated that net offshore migrations of bars have been repeated with a return period of approximately four years. This general behavior of the bar system is similar to the net offshore migration phenomena observed at other sites in the world. EOF analysis revealed a relationship between bar configuration and middle-term variations in shoreline location; when a new bar is generated near the shoreline and a triple bar configuration is established, the shoreline tends to temporarily retreat, whereas the shoreline experiences an advance when the outer bar has most evolved.

Natural and Human-Induced Dynamics on Big Hickory Island, Florida

Big Hickory Island, located in Lee County along the mixed-energy west Florida coast, experiences high long-term rates of shoreline recession, with much of the erosion concentrated along the central and southern portions of the island. In 2013, approximately 86,300 cubic meters of sand from an adjacent tidal inlet to the north were placed along 457 m to restore the beach and dune system. In an effort to combat erosion, seven concrete king-pile groins with adjustable panels were constructed subsequent to the completion of the beach nourishment. Natural and human-induced dynamics of Big Hickory Island are discussed through analysis of shoreline and morphologic change using historic aerial photographs and topographic and bathymetric field surveys of the recent beach erosion mitigation project. Although much of the long-term anomalously high rates of erosion for the area are related to natural interchanges between the sand resources of the barrier islands and adjacent ebb tidal shoals, additional reduction in sand supply is a result of human-interventions updrift of Big Hickory over the last several decades. The coupled natural and anthropogenic influences are driving the coastal processes toward a different morphodynamic state than would have occurred under natural processes alone.

Shoreline Analysis and Barrier Island Dynamics: Decadal Scale Patterns from Cedar Island, Virginia

Abstract Nebel, S.H.; Trembanis, A.C., and Barber, D.C., 2012. Shoreline analysis and barrier island dynamics: Decadal scale patterns from Cedar Island, Virginia. Aerial photography, topographic maps, high-resolution satellite imagery, and global positioning system (GPS) data were compiled in ArcMAP™ and analyzed using the Digital Shoreline Analysis System (DSAS) to determine decadal trends of shoreline movement on Cedar Island, Virginia. Shoreline retreat rates for Cedar Island had an alongshore average of −4.1 m/y based on simple endpoint analysis (1852–2007), while the short-term (1994–2007) retreat rates increased to −12.6 m/y. Retreat statistics were further calculated for the time intervals 1852–1910 (−5.1 m/y), 1910–62 (−3.5 m/y), 1962–80 (−3.9 m/y), 1980–94 (−6.5 m/y), 1994–2002 (−12.4 m/y), and 2002–06 (−13.8 m/y). This analysis indicates that retreat of the Cedar Island shoreline has been accelerating with a notable increase in rate within the years 1980 to 1994. Additionally, the shoreline data...

AERIAL PHOTOGRAPH OF SENDAI COAST FOR SHORELINE BEHAVIOR ANALYSIS

The shoreline analysis around the Nanakita River mouth has been performed by utilizing aerial photographs to reveal the different behavior between left and right side of the river mouth. The shoreline on left side of river mouth has been moving more dynamically than the right side. The empirical orthogonal function (EOF) method is also applied on the shoreline data to reveal the behavior of shoreline change. The first mode of variability reflects the cross-shore movement which is shown by uniform advance and retreat movement along the beach. The shoreline change around the Nanakita River mouth is dominated by the cross-shore movement which is shown by around 80% contribution of first mode. The second mode of variability depicts the longshore sediment movement which is shown by different shoreline movement between left and right side of river mouth. The longshore movement only contributes around 10% to the shoreline change around the Nanakita River mouth. The second mode also reveals the influence of river mouth to the longshore sediment transport characterized by different shoreline response between left and right side.