Shoreline Locations Research Articles

The use of unmanned aerial vehicles in flood hazard assessment

AbstractFlood inundation models are central components of any flood risk analysis system because they transform the bulk discharge outputs from flood‐frequency analyses or rainfall‐runoff models into distributed predictions of flood hazard in terms of water depth, inundation extent, and flow velocity. The accuracy of flood hazard maps depends on the availability of distributed observations of inundation outlines. Unfortunately, the acquisition of aerial photographs or satellite images is costly and in addition, their temporal resolution is strongly limited by weather conditions. Remote sensing based on unmanned aerial vehicles (UAV) is becoming increasingly popular due its flexibility and quickly decreasing costs. In particular, UAV can provide precise up to date georeferenced information about the location of a river shorelines, channel geometry, and vegetation. This information is particularly useful for the calibration and validation of distributed flood routing models. The application of cheap, well georeferenced UAV images of river shorelines is an unprecedented source of distributed observations. The aim of this article is to present a procedure for the updating of boundary conditions of the hydrodynamic model, based on UAV‐born data. The approach proposed is also a very effective means of on‐line updating of flood risk maps and their verification.

Deltaic response to climate change: The Holocene history of the Nueces Delta

Deltas host large urban centers and expanses of coastal wetlands worldwide. As such, their future will play an important role in the economic and ecological health of many coastal communities. Although threats to deltas from drowning due to subsidence and accelerating sea-level rise are well-studied, far less is known about the physical effects of climate change on deltas. Here we map the location of the Nueces Delta shoreline of the northwestern Gulf of Mexico over the last ~8.0 ky to show that the delta retreated and prograded at rates greater than 10 m/yr and over distances of up to 22 km in a few centuries at the same time as independent proxy records of Holocene climate change indicate decreased and increased effective precipitation, respectively. These periods of retreat occurred at 5.0 and 3.2 ka; an earlier, previously documented period of retreat at 8.2 ka was driven by a rapid increase in the rate of sea-level rise. The Nueces Delta experienced periods of progradation at 6.6 ka, 3.8 ka and 2.2 ka. As some of these changes may have been driven simply by avulsion or other autogenic processes, we test the role of climate in driving these changes by quantifying the amount of sand, thought to be a conservative proxy for sediment flux, within the delta through the Holocene. The amount of sand delivered to the delta increased during periods of progradation and decreased during periods of retreat. These changes occurred despite decreasing rates of sea-level rise through the middle Holocene. These results suggest that deltas are susceptible to not only increasing rates of sea-level rise, but also other climatic-related forcings, such as those that modulate sediment supply. These stresses will be amplified in the future by decreased sediment supply to deltas due to the damming of their rivers. • We reconstruct the Holocene history of the Nueces Delta. • The delta retreated in response to dryer climates at 5.0, and 3.2 ka. • The delta prograded in response to wetter climates at 6.6, 3.8, and 2.2 ka. • Deltas are susceptible to rapid retreat caused by climate changes.

The scale of the central beach change processes in the west coast of Nha Trang bay

The central beach in west coast of Nha Trang bay has experienced erosion in recent years. The determination of hydrodynamic regime and causes of this beach fluctuation is still an open problem and is concerned by scientists and managers. This study shows the causes and scales of the shoreline change processes based on the results of shoreline change model and the analysis of remote sensing images of shoreline location.

Erosion of Carbonate Beaches on the Northeastern Coast of Cuba

Rodriguez Paneque, R. and Finkl, C.W., 2020. Erosion of carbonate beaches on the northeastern coast of Cuba. Journal of Coastal Research, 36(2), 339–352. Coconut Creek (Florida), ISSN 0749-0208.Beaches on the northeastern coast of Cuba have made this area one of the most important tourist destinations in the Caribbean, despite the fact that many beaches are visibly eroded. In this study, the causes and magnitude of coastal erosion on the northeastern coast of Cuba were evaluated using the Digital Shoreline Analysis System (DSAS 4.3) application, satellite images, and beach profiles. Time frames between 7 and 14 years were considered from 2003 to 2017 using satellite images and between 11 and 18 years using beach profiles. Results of this investigation showed that 56% of northeastern coast beaches tend to erode at a rate of less than 1.2 m/y. An increase in the recurrence of extreme events (hurricanes and tropical storms) during the last 39 years induced more beach erosion. It was furthermore observed that El Nino–Southern Oscillation events enhanced the sedimentary balance of the beaches by returning sand volumes that were transported in a westerly direction to their original shoreline locations. Possibly due to sea-level rise, which may be occurring in response to global warming, beaches on the northeast coast will retreat on average about 0.17 m/y. At this rate of shoreline recession, by the end of the twenty-first century, 14% of the beaches on this littoral will be lost, and the width of 27% of the other beaches will be significantly reduced.

An Indicator and Min-Cost Approach for Shoreline Extraction From Satellite Imagery in Muddy Coasts

Shoreline location plays a key role in coastal research, management, and engineering. Remote sensing enables the quantification of shoreline information with the large spatial extent and high temporal frequency. Driven by river discharge and ocean dynamics, muddy coasts exhibit complicated spatiotemporal variations. It is essential, yet challenging to extract effective shoreline features from satellite images. Taking the Yellow River Delta coast in China as the study area, we present an indicator and min-cost approach to extract the shoreline in muddy coasts. The shoreline is represented as a set of linearly connected central points with high shoreline probabilities, and a set of image and spatial indicators are developed to assess these probabilities. The Salient Value indicator integrates the gradient magnitude and the edge intensity to detect the boundary strength; the Regional Difference indicator separates the water/land class from edge intensity to measure the possibility of being water or land; and the Seaward Distance indicator spatially distinguishes the true shoreline from other spectrally similar boundaries. A cost function combines these indicators to evaluate the local shoreline possibilities. A shoreline set is produced by an improved min-cost path method to evaluate the overall shoreline possibilities. The optimal shoreline paths are selected based on the parameter analyses of the shoreline set. The performance of the approach is confirmed by comparing with the ground truth and state-of-the-art methods. The effectiveness of the approach is tested for different spatial resolution data and coastal environments.

Full Polarimetric ALOS-2/PALSAR-2 Analysis for the Location of Shorelines with Varying Orientation and Coastal Characteristics

Full Polarimetric ALOS-2/PALSAR-2 Analysis for the Location of Shorelines with Varying Orientation and Coastal Characteristics

The thin blue line: A review of shoreline dynamics across time scales and environments

AbstractA major thread of theoretical research on the response of shorelines to changing boundary conditions has adapted the moving‐boundary approach from heat transfer and solidification/melting. On sufficiently short time scales, shorelines respond to changes in relative sea level in a simple, geometrically predictable way. On longer time scales, their behaviour becomes far more complex and interesting, because the surface over which the shoreline moves is itself continually modified by morphodynamics that depend sensitively on shoreline location. This makes the shoreline the archetype of moving‐boundary problems in morphodynamics, and subject to potentially counterintuitive behaviours over time scales on which the sediment surface modifies itself as relative sea level changes. We review existing moving‐boundary theories and propose two significant extensions to allow inclusion of first‐order effects of waves and tides. First, we show how wave effects can be included via planform diffusion linked to river‐mouth location, which results in shoreline smoothing during delta‐lobe growth and localized transgression after channel abandonment. Tides produce a low‐gradient region in which the sea and land overlap; we show how this can be treated in a moving‐boundary framework by replacing the shoreline with a ‘mushy region' so that the handoff from land to water occurs over a zone rather than a line. We also propose that the moving‐boundary approach can be readily generalized to other dynamic moving boundaries, such as those separating different regimes of river transport. The shoreline thus serves as a prototype for modelling dynamic facies boundaries along the whole source–sink system. © 2019 The Authors. Earth Surface Processes and Landforms published by John Wiley & Sons Ltd.

Morphodynamics of sandy beaches under the influence of storm sequences: Current research status and future needs

This paper reviews and discusses the current research status, trends, and future needs in the field of beach morphodynamics under the influence of storm sequences. The paper reviews how the three main research methods, field investigations, numerical modelling, and physical modelling, have been used to study beach morphodynamics during storm sequences. Available quantitative definitions of storm sequences at different sites are presented and discussed. It is shown that the definition of storm sequences is site-specific and requires knowledge of the storm climate, beach characteristics, and the temporal scale of beach recovery. Subsequently, the paper brings together currently available approaches aimed at describing the effect of storm sequences on beach erosion in a general way. The importance of storm chronology and the effects of an extreme storm within a sequence of storms are highlighted. Following that, the more poorly studied aspect of beach recovery in between storms within a sequence is discussed. Three indicators for defining beach recovery, namely the shoreline location, sediment volumes, and the beach state, are identified and compared. Finally, important research needs, including the need for detailed physical modelling, are identified.

Identifying Salt Marsh Shorelines from Remotely Sensed Elevation Data and Imagery

Salt marshes are valuable ecosystems that are vulnerable to lateral erosion, submergence, and internal disintegration due to sea level rise, storms, and sediment deficits. Because many salt marshes are losing area in response to these factors, it is important to monitor their lateral extent at high resolution over multiple timescales. In this study we describe two methods to calculate the location of the salt marsh shoreline. The marsh edge from elevation data (MEED) method uses remotely sensed elevation data to calculate an objective proxy for the shoreline of a salt marsh. This proxy is the abrupt change in elevation that usually characterizes the seaward edge of a salt marsh, designated the “marsh scarp.” It is detected as the maximum slope along a cross-shore transect between mean high water and mean tide level. The method was tested using lidar topobathymetric and photogrammetric elevation data from Massachusetts, USA. The other method to calculate the salt marsh shoreline is the marsh edge by image processing (MEIP) method which finds the unvegetated/vegetated line. This method applies image classification techniques to multispectral imagery and elevation datasets for edge detection. The method was tested using aerial imagery and coastal elevation data from the Plum Island Estuary in Massachusetts, USA. Both methods calculate a line that closely follows the edge of vegetation seen in imagery. The two methods were compared to each other using high resolution unmanned aircraft systems (UAS) data, and to a heads-up digitized shoreline. The root-mean-square deviation was 0.6 meters between the two methods, and less than 0.43 meters from the digitized shoreline. The MEIP method was also applied to a lower resolution dataset to investigate the effect of horizontal resolution on the results. Both methods provide an accurate, efficient, and objective way to track salt marsh shorelines with spatially intensive data over large spatial scales, which is necessary to evaluate geomorphic change and wetland vulnerability.

Automatic determination of shoreline at maximum retreating

Coastal zones are the most influenced areas by global sea level rising. One of the important coastal zones in Egypt is the Red Sea. Red Sea coastal area is an attractive touristic area, which still under development. For the high value of such areas, the position of the set-back construction line is required for well planning and development. This position influenced greatly by the position of the shoreline at the maximum retreating. This paper introduces an automatic approach for determining the shoreline at the maximum retreating. This approach depends on three types of information; 1) the location of the current shoreline, 2) the mean higher high-water level (MHHWL), and 3) the topography of the coastal area.A study area North of Hurghada, is selected to apply the introduced approach. The shoreline is extracted out of Landsat-8 images based on a combination of three factors; a modified normal difference water index, the reflectance values of the water bodies in specific bands within the shortwave infra-red spectrum, and the relation of the reflectance values of water bodies in the Green, Red, NIR, and SWIR bands. The higher high-water level is determined from near tidal gauge station that has collected data each 30 min since 2008, and the topography of the coastal area is determined by the Kinematic GPS technique. The extracted shoreline was assessed by comparing it to actual shoreline traced on the ground. The results show that the accuracy of the extracted shoreline is within 15 m of the actual shoreline.

ĐẶC ĐIỂM ĐỊA MẠO VÀ TAI BIẾN TỰ NHIÊN LIẾN QUAN Ở VÙNG CỬA SÔNG VEN BIỂN SÔNG HƯƠNG

The geomorphological features and related geological hazards of the estuarine and coastal area of the Huong river are concluded from latest synthetic data. The estuarine terrain of Huong river was the result of interaction amongst neo and modern tectonic activities with exogenic dynamic factors as marine, marine - fluvial and fluvial. The estuary of Huong river is placed on the northwest - southeast neo - modern tectonic Quang Dien - Phu Vang depressed plate which has 3 local depressed blocks where then were filled by marine, marine - fluvial and fluvial sediment. The marine sediment was mostly distributed on the northwestern and southeastern blocks while the central block was mostly filled by marine - fluvial sediment. The terrain of coastal and estuarine area of Huong river had 18 types, they have changed dramatically within spatial and sequential dimension for those periods: Pliocene - early Pleistocene, middle - late Pleistocene, early - middle Holocene and late - modern Holocene. During Pliocene - early Pleistocene and middle-late Pleistocene, weak uplifting movement to the north of the area had created the denudation surfaces, erosion and abrasion terraces with heights over 20 m, whereas the depressed area to the east had been filled by several hundred meters of fluvial and fluvial - marine sediment. In the early - middle Holocene, depressing movement and retrogradation caused the marine and fluvial - marine sediment accumulated rapidly up to tens of meters. In the last phase of late-modern Holocene, weak depressing combined with moderate uplifting movement happenned, hence the accumulation of fluvial, fluvial - marine - marsh sediments. The shoreline of studied area had changed dramatically in the modern Holocene. In the early-middle Holocene, the shoreline was about 20 km inland of Quang Dien - Inner Citadel area and about 15 km of Phu Vang area. The strong morphodynamic process occured and caused erosion - accretion of the coastal estuarine of Huong river, and changed the modern shoreline locations. At Thuan An inlet, erosion happened by the foot of coastal dunes at the rate of 6.4 m annually; but there was only accretion in Hai Duong coast. The bank of Huong river was also eroded, especially from Tuan junction to Tam Giang lagoon, and the most seriously erosion locations area La Khe commune, Bang Lang - Thuy Bang, Long Ho - Xuoc Du, Thien Mu pagoda and Dia Linh - Huong Vinh.

Study on shoreline monitoring system based on satellite SAR imagery

ABSTRACTThe present study develops a SAR-based shoreline monitoring system which consists of: (i) selection of SAR scenes suitable for shoreline detection; (ii) extraction of shoreline from the selected scenes; and (iii) estimation of the shoreline at arbitrary water level. The first model focused on ALOS-2 SAR scenes and determined fitting formulae for estimation of the backscattering coefficients at a sea and a beach surfaces. To quantify the suitability of scenes for shoreline detection, a parameter, P, was newly introduced. The value of P represents a probability at which a backscattering coefficient at a beach becomes higher than the one at a sea and it was confirmed that P reasonably indicates suitability of scenes for shoreline detection. A shoreline extraction technique was then developed based on the edge detection technique. Bilateral filter was applied to reduce the speckle noise of SAR images and wavelet transform was applied to detect the edge location. Validity of the proposed technique was confirmed through application of the present technique to Shimizu and Shonan coasts. Finally, a simple polynomial function was introduced to represent the shoreline location at arbitrary water level. Applicability of the proposed technique was also tested and validated against the detailed data obtained by image analysis.

Lagrangian simulation of oil trajectories in the Florida Straits

A Lagrangian floating oil trajectory model is developed to simulate a continuous surface spill in the Florida Straits. The trajectories are initiated at locations representative of exploratory drilling sites around Cuba's Exclusive Economic Zone and integrated for ten days. The simulation is initialized for different seasons, using leeway-corrected observed winds, ocean currents, different climatologies, and a first-order Markov Lagrangian Stochastic Model. A Monte-Carlo scheme is used to parameterize oil weathering processes collectively. Overall, the simulations exhibit a strong seasonal dependence, where the Florida coast is most affected during the summer and the Cuban coast in the winter. Drilling sites at the center of the Straits show the largest impact on Florida. Cuba is most affected by shoreline locations. A significant amount of oil reaches the Florida coastline within two to ten days, and Cuba is potentially affected within hours. Many simulations project impacts for the Florida Keys, South Florida, and the north shore of Cuba.

The Estimation and Evaluation of Shoreline Locations, Shoreline-Change Rates, and Coastal Volume Changes Derived from Landsat Images

ABSTRACT Do, A.T.K.; de Vries, S., and Stive, M.J.F., 2019. The estimation and evaluation of shoreline locations, shoreline-change rates, and coastal volume changes derived from Landsat images. Journal of Coastal Research, 35(1), 56–71. Coconut Creek (Florida), ISSN 0749-0208. Shoreline-change data are of primary importance for understanding coastal erosion and deposition as well as for studying coastal morphodynamics. Shoreline extraction from satellite images has been used as a low-cost alternative and as an addition to traditional methods. In this work, satellite-derived shorelines and corresponding shoreline-change rates and changes in volumes of coastal sediments have been estimated and evaluated for the case of the data-rich North-Holland coast. This coast is globally unique for its long in situ monitoring record and provides a perfect case to evaluate the potential of shoreline mapping techniques. A total of 13 Landsat images and 233 observed cross-shore profiles (from the JAaRlijkse KUStmeting [JA...

Shoreline mapping: how do Fuzzy Sigmoidal, Bayesian, and Demspter-Shafer classifications perform for different types of coasts?

ABSTRACTThis study examined Fuzzy Sigmoidal, Bayesian, and Demspter-Shafer classifications to map shorelines in Kuala Terengganu, Malaysia for different types of coasts (CT). These three soft classification methods were applied to simulated Satellite Pour l’Observation de la Terre-5 (SPOT-5 with 10 and 20 m spatial resolutions) images covering the three shoreline locations which were typically different in shape and orientation: (a) rocky breakwater coasts (CT-1), (b) rocky and sandy airport coasts (CT-2), and (c) sandy beach coasts (CT-3) for predicting shorelines. Visual inspection and statistical measures showed that variations in accuracies were evident, predominantly due to differences in CTs; mapping accuracy decreased with an increase of spatial resolution, but accuracy increased if shorelines were aligned exact parallel to the column of pixel grid. Sigmoidal can predict shoreline over the CT-3 areas with greater accuracy than the other two methods and has less dependence on spatial resolutions for across the CTs. But effective use of Bayesian membership function for mapping shoreline over certain small and narrow jetty-like structures makes this classifier also efficient. The soft classifier assessed in this study produced reliable shoreline maps and should help shoreline change detection and monitoring from coarser spatial resolution imagery.

Reducing the impacts of intra-class spectral variability on the accuracy of soft classification and super-resolution mapping of shoreline

ABSTRACTThe main objective of this research is to assess the impact of intra-class spectral variation on the accuracy of soft classification and super-resolution mapping. The accuracy of both analyses was negatively related to the degree of intra-class spectral variation, but the effect could be reduced through the use of spectral sub-classes. The latter is illustrated in mapping the shoreline at a sub-pixel scale from Landsat ETM+ data. Reducing the degree of intra-class spectral variation increased the accuracy of soft classification, with the correlation between predicted and actual class coverage rising from 0.87 to 0.94, and super-resolution mapping, with the RMSE in shoreline location decreasing from 41.13 m to 35.22 m.

Shoreline mapping: how do Fuzzy Sigmoidal, Bayesian, and Demspter-Shafer classifications perform for different types of coasts?

ABSTRACTThis study examined Fuzzy Sigmoidal, Bayesian, and Demspter-Shafer classifications to map shorelines in Kuala Terengganu, Malaysia for different types of coasts. These three soft classification methods were applied to simulated Satellite Pour l’Observation de la Terre-5 (SPOT-5 with 10 and 20 m spatial resolutions) images covering the three shoreline locations which were typically different in shape and orientation: (a) rocky breakwater coasts (CT-1), (b) rocky and sandy airport coasts (CT-2), and (c) sandy beach coasts (CT-3) for predicting shorelines. Visual inspection and statistical measures showed that variations in accuracies were evident, predominantly due to differences in CTs; mapping accuracy decreased with an increase of spatial resolution, but accuracy increased if shorelines were aligned exact parallel to the column of pixel grid. Sigmoidal can predict shoreline over the CT-3 areas with greater accuracy than the other two methods and has less dependence on spatial resolutions for across the CTs. But effective use of Bayesian membership function for mapping shoreline over certain small and narrow jetty-like structures makes this classifier also efficient. The soft classifier assessed in this study produced reliable shoreline maps and should help shoreline change detection and monitoring from coarser spatial resolution imagery.

Shoreline and Beach Cusps Dynamics at the Low Tide Terraced Grand Popo Beach, Bénin (West Africa): A Statistical Approach

Bonou, F.; Angnuureng, D.B.; Sohou, Z.; Almar, R.; Alory, G., and du Penhoat, Y., 2018. Shoreline and beach cuspsdynamics at the low tide terraced Grand Popo beach, Benin (West Africa): A statistical approach. In: Almar, R.; Almeida, L.P.; Trung Viet, N., and Sall, M. (eds.), Tropical Coastal and Estuarine Dynamics. Journal of Coastal Research, Special Issue No. 81, pp. 138–144. Coconut Creek (Florida), ISSN 0749-0208.This paper presents the description of a 2-dimensional shoreline and 3-dimensional shoreline behaviour around a ‘storm free’ microtidal beach from a 3-year video observation using empirical orthogonal function (EOF) analysis. The EOF method is applied successfully to delineate 2D and 3D developments that show the beach evolution influenced by the action of waves and tides. The EOF model results are in agreement with measurements that reflect the morphological concepts for the 2D and 3D cases: the first temporal EOF mode which accounts for an overwhelming 80% of shoreline variation reflects the alongshore-averaged cross-shore migration (2D) largely influenced by waves while the higher eigenfunctions with 20% shoreline variation reflect beach deformation/irregularities (3D). Shoreline location is correlated to cross-shore energy flow from waves, while 3D is associated to the longshore energy flow. The influence of wave height increases cross-shore uniform migration and beach seasonality. The results show that with EOF method, beach cusps are clearly identified for 3D developments to be evaluated. Beach cusps are well observed at low tides on video images. Tide and cusps increase the importance of short term events and deformation; at the lowest high tide mark, beach cusps were observed on higher spatial functions of EOF. This indicates that a study of these morphological features as a coupled system, promotes their contribution in predicting 2D and 3D shoreline changes.

Kelp Gull (Larus dominicanus) Use of Alternative Feeding Habitats at the Bahía San Blas Protected Area, Argentina

Kelp Gull (Larus dominicanus) foraging patterns were studied by deploying GPS loggers on 20 incubating individuals at their colony in the Bahia San Blas protected area, Argentina. Mean number of trips per day was 1.5 ± 0.5, and mean trip duration was 272.6 ± 165.2 min. Mean maximum distance from the colony was 19.6 ± 24.4 km. Incubating Kelp Gulls visited natural and anthropogenic environments. Individuals switched between two or three different habitat types 47% of the time during a given foraging trip. Kelp Gulls showed a differential use of feeding areas, with a significantly higher use of refuse dumps (75%; n = 151 trips) than coastal (47%), terrestrial (10%) and offshore (10%) habitats. In 72% of the recorded trips, Kelp Gulls targeted the dump located in the small town of Bahia San Blas, where waste generated by recreational fishing is regularly disposed. Moreover, most visited shoreline locations were those regularly used by recreational fishers. Despite showing plasticity in foraging habitat use, the local refuse dump and nearby shoreline sites where fish waste is regularly disposed were the main feeding habitats for incubating Kelp Gulls.

Environmental Determinants of Malaria Transmission Around the Koka Reservoir in Ethiopia.

New dam construction is known to exacerbate malaria transmission in Africa as the vectors of malaria—Anopheles mosquitoes—use bodies of water as breeding sites. Precise environmental mechanisms of how reservoirs exacerbate malaria transmission are yet to be identified. Understanding of these mechanisms should lead to a better assessment of the impacts of dam construction and to new prevention strategies. Combining extensive multiyear field surveys around the Koka Reservoir in Ethiopia and rigorous model development and simulation studies, environmental mechanisms of malaria transmission around the reservoir were examined. Most comprehensive and detailed malaria transmission model, Hydrology, Entomology, and Malaria Transmission Simulator, was applied to a village adjacent to the reservoir. Significant contributions to the dynamics of malaria transmission are shaped by wind profile, marginal pools, temperature, and shoreline locations. Wind speed and wind direction influence Anopheles populations and malaria transmission during the major and secondary mosquito seasons. During the secondary mosquito season, a noticeable influence was also attributed to marginal pools. Temperature was found to play an important role, not so much in Anopheles population dynamics, but in malaria transmission dynamics. Change in shoreline locations drives malaria transmission dynamics, with closer shoreline locations to the village making malaria transmission more likely. Identified environmental mechanisms help in predicting malaria transmission seasons and in developing village relocation strategies upon dam construction to minimize the risk of malaria.