Muddy Coasts Research Articles

Shoreline Planform Stability of Embayed Beaches Along the Malaysian Peninsular Coast

Ab Razak, M.S.; Suryadi, F.X.; Jamaluddin, N., and Mohd Noor, N.A.Z., 2018. Shoreline Planform Stability of Embayed Beaches Along the Malaysian Peninsular Coast. In: Shim, J.-S.; Chun, I., and Lim, H.S. (eds.), Proceedings from the International Coastal Symposium (ICS) 2018 (Busan, Republic of Korea). Journal of Coastal Research, Special Issue No. 85, pp. 631–635. Coconut Creek (Florida), ISSN 0749-0208.The existence of embayed beaches is pronounced along the coast of Peninsular Malaysia. The stability of such beaches is yet to be confirmed. The present study aims at investigating the shoreline planform stability on the east and west coasts of Peninsular Malaysia. 190 embayed beaches were found along the Malaysian Peninsular coast, including natural beaches and man-made beaches. Of these, 139 beaches were on the west coast while 51 beaches were on the east coast. Results of the MEPBAY model show along the east coast, 45%, 51% and 4% were classified as the static, dynamic, and natural beach reshaping, respectively. Beaches on the west Peninsular coast that is mainly characterised by the muddy coast were more pronounced to be in the static state which comprised of 85% compared to the beaches on the east coast, that are mostly sandy. While, another 15 % were fall under dynamic equilibrium state. Sediment supply from the river, improper placement of coastal structures, sediment bypassing at headland are some possible factors that may cause the dynamic and instability of the embayed beaches studied.

Melaleuca entrapping microsites as a nature based solution to coastal erosion: A pilot study in Kien Giang, Vietnam

Accumulation of fine grained sediment and natural regeneration of mangrove species are normally prioritized to control erosion on mangrove dominated muddy coasts. Current solutions to manage eroded mangrove dominated muddy coasts have been not as cost-effective as expected. Entrapping microsites, although mainly used for restoring eroded terrestrial resources, were first tested for restoring an eroded mangrove dominated muddy coast of Vam Ray, Hon Dat, Kien Giang, Vietnam. Entrapping microsites, constructed with a 50 cm layer of discarded Melaleuca small sticks that were overlain on the surface of the site, accumulated a high level of fine grained sediment and promoted robust natural regeneration or regrowth of local mangrove species after approximately two years. The effectiveness and efficiency of the Vam Ray Melaleuca entrapping microsites provide a good basis on which further research and ground works can proceed.

Piedras viajeras. De las misiones a Buenos Aires

El estudio de las piedras y escombro de una pequeña sección de la costa ya totalmente artificial de la ciudad de Buenos Aires, mostró la presencia de dos piedras recién llegadas y muy desgastadas. Por su coloración rojiza, su composición geológica y con la evidencia de tallado manual era de suponer que provenían de la zona de Misiones y que debieron formar parte de uno o dos edificios. Desconocemos de dónde vienen, cómo se hizo ese viaje enorme en distancia y en siglos, pero llegaron en fecha reciente y quedaron sobre la tierra de la costa. Finalmente es solo una curiosidad, deben ser cientos los edificios jesuíticos destruidos en el tiempo y cuyas piedras cayeron al agua; estas dos curiosamente quedaron a la vista a una enorme distancia, y poco antes de salir al océano y perderse para siempre.

沧州泥质海岸土壤含盐量与电导率关系

沧州泥质海岸土壤含盐量与电导率关系

Gradual expansion of mangrove areas as an ecological solution for stabilizing a severely eroded mangrove dominated muddy coast

While current coastal erosion solutions have had limited success in controlling coastal erosion, the gradual expansion of mangrove areas was effective in stabilizing an actively eroded mangrove dominated muddy coast in Vam Ray, Kien Giang, Vietnam for a short time period. The gradual expansion method was developed as a result of local comprehensive involvement and capacity, and the integration of different knowledge systems. However, the method was not sufficiently reported. Local involvement and capacity were not adequately emphasized during the reporting process. Insufficient reporting caused the failure in replicating the method elsewhere in Kien Giang. Inadequate emphasis of local involvement and capacity probably breached moral rights for the Vam Ray community. This manuscript documented the gradual expansion method using different sources of data and information and inputs from the key Vam Ray community members. The gradual expansion method involved closure of current mangrove gaps by transplanting mangroves protected by appropriate fences as the first stage, and gradual expansion of the mangrove belt seawards in the second stage. The method has a potential replication elsewhere in Vietnam and in Southeast Asia.

A STUDY ON WAVE-INDUCED PARTICLE VELOCITIES IN FLUID MUD LAYER

Cohesive sediments can be found in many coastal zones all over the world. The upper layer of these muddy coasts may be fluidized under the wave action. Fluid mud is also formed by settlement of fine particles when the waves and currents exert a small shearing stress on the bed. When the waves pass over the fluid mud layer, it absorbs wave energy and, in turn, moves due to the wave action. The present study offers a numerical and experimental study of wave-mud interaction on a horizontal bed. A number of wave flume laboratory tests are presented to investigate wave attenuation, particle velocities in fluid mud layer and mud mass transport under different wave characteristics. The laboratory results are also compared with a developed semi-analytical model.

Developing a framework for integrating local and scientific knowledge in internationally funded environment management projects: case studies from Kien Giang Province, Vietnam

ABSTRACTLocal and scientific knowledge, when adequately and properly integrated, produces enormous benefits for natural resource management in comparison to a single knowledge system being used. Adequate and proper integration has major constraints that include ineffective use of the integrated knowledge, thoroughly inclusive processes, and true public participation. A six-stage framework is developed using the results and conclusions of two case studies regarding sustainable management of eroding mangrove-dominated muddy coasts in Vam Ray, Hon Dat district, Kien Giang Province, Vietnam. The framework does not stop with the creation of integrated knowledge, but should undergo a longer process. The new knowledge developed in this framework is the understanding gained and lessons learnt during the testing of products of multiple knowledge systems in a local context rather than products of integrated knowledge systems themselves. The Vam Ray framework promotes a high level of participation, effective use of products of multiple knowledge systems, maximum integration of local and scientific knowledge, local ownership, and sustainability. Therefore, the Vam Ray framework adds a new dimension to the literature in relation to integration of local and scientific knowledge in natural resource management.

Realistic representation of grain shapes in CFD–DEM simulations of sediment transport with a bonded-sphere approach

Development of algorithms and growth of computational resources in the past decades have enabled simulations of sediment transport processes with unprecedented fidelities. The Computational Fluid Dynamics–Discrete Element Method (CFD–DEM) is one of the high-fidelity approaches, where the motions of and collisions among the sediment grains as well as their interactions with surrounding fluids are resolved. In most DEM solvers the particles are modeled as soft spheres due to computational efficiency and implementation complexity considerations, although natural sediments are usually a mixture of non-spherical (e.g., disk-, blade-, and rod-shaped) particles. Previous attempts to extend sphere-based DEM to treat irregular particles neglected fluid-induced torques on particles, and the method lacked flexibility to handle sediments with an arbitrary mixture of particle shapes. In this contribution we proposed a simple, efficient approach to representing common sediment grain shapes with bonded spheres, where the fluid forces are computed and applied on each sphere. The proposed approach overcomes the aforementioned limitations of existing methods and has improved efficiency and flexibility over existing approaches. We use numerical simulations to demonstrate the merits and capability of the proposed method in predicting the falling characteristics, terminal velocity, threshold of incipient motion, and transport rate of natural sediments. The simulations show that the proposed method is a promising approach for faithful representation of natural sediment, which leads to accurate simulations of their transport dynamics. While this work focuses on non-cohesive sediments, the proposed method also opens the possibility for first-principle-based simulations of the flocculation and sedimentation dynamics of cohesive sediments. Elucidation of these physical mechanisms can provide much needed improvement on the prediction capability and physical understanding of muddy coast dynamics.

A behavior-oriented formula to predict coastal bathymetry evolution caused by coastal engineering

The two common expressions of near-bed sediment flux (also called erosion and deposition flux) in terms of sediment carrying capacity and bed shear stress are unified in this study. A behavior-oriented formula to calculate coastal bathymetry evolution caused by coastal engineering on a muddy coast is also developed based on the unified expression. Compared with the other common behavior-oriented formulas on a muddy coast, the vertical suspended sediment distribution and near-bed sediment exchange mechanism are considered, and the formula has the advantage of calculating both bed siltation and erosion distribution. The formula is applied to simulate the local morphology change resulting from the siltation-promoting works at the mouth of the Yangtze River estuary of China. A comparison between the measurement and the calculated results of other common formulas shows that the morphology change caused by the project is well reproduced, and the behavior-oriented formula can be used to predict the coastal bathymetry evolution caused by coastal engineering on muddy coast.

The Shoreline Retreat and Spatial Analysis over the Coastal Water of Belawan

Abstract – An examination of shoreline retreat is conducted over the muddy coast in the vicinities of the port of Belawan. The related sea level rise is estimated using the well-known Bruun Rule based on the characteristics of mud profile prevalent along the eastern coast of North Sumatera Province. The spatial analysis involved is done utilizing the concept and procedure of GIS. The averaged shoreline retreat over the hot spot area of erosion, i.e. 18 m per year, implies that the relative rate of sea level rise is in the range of 14 to 18 mm per year, indicating an extremely severe rate. In addition, three other cases of simple GIS applications related to coastal water of the port are spatially demonstrated. Keywords – coastal water, coastal erosion, sea level rise, and GIS

Continuous monitoring of coastline dynamics in western Florida with a 30-year time series of Landsat imagery

Abstract Continuous monitoring of coastline dynamics is of crucial importance to the understanding of relative contributions of various potential driving factors behind the long-term coastline change. While a large number of efforts have been made to extract coastline and detect coastline change with remotely sensed data, the temporal frequency and spatial resolution of coastline datasets obtained are generally not fine enough to reflect the detailed process of coastline retreat and/or advance, particularly in coastlines with subtle variability. To overcome these limitations, we developed a method to continuously monitor the dynamics of a muddy coastline with subtle variability in western Florida at annual and subpixel scales using time-series Landsat data (1984–2013). First, robust indicators were used to indicate the annual “average” location of the dynamic coastline. Due to the complexity of muddy-coast morphology, the annual average location is represented not by the coast “line”, but by the fractional inundated “area” of coastline pixels (pixels where the coastline is located), namely annually inundated area. Second, the annually inundated area of coastline pixels was estimated with a model proposed in this study, and the uncertainty was estimated with the Monte Carlo method. The retrievals were validated at 10 sites with aerial imagery, and the overall RMSE (root mean square error) is 11.48%. Third, the long-term trend for the time series of annually inundated area was derived with a statistical model. The results indicate that the muddy coast in western Florida continues to shrink with an average rate of 0.42 ± 0.05 km2/year during the three decades. This study demonstrates the feasibility of time-series Landsat data in continuous monitoring of coastline dynamics.

International scientists discuss impact on China’s estuarine and coastal environment by intensive anthropogenic activities – The 2nd workshop on sediment dynamics of muddy coasts and estuaries: Physics, biology and their interactions, Zhoushan, China, 23–26 October, 2015

International scientists discuss impact on China’s estuarine and coastal environment by intensive anthropogenic activities – The 2nd workshop on sediment dynamics of muddy coasts and estuaries: Physics, biology and their interactions, Zhoushan, China, 23–26 October, 2015

Community perspectives on an internationally funded mangrove restoration project: Kien Giang province, Vietnam

It is common for environmental restoration projects to be reviewed by the administering organizations but it is much less common for the communities that the projects are meant to serve to detail their experiences and perceptions of the outcomes. We evaluate an internationally funded mangrove restoration project and reflect upon the lessons learned in regard to the project strategies and interventions, particularly from the perspective of the local community.The Vam Ray coast, Kien Giang Province, Vietnam, was seriously eroded by 2008. In May 2009, a demonstration project was established which achieved a high survival rate of transplanted mangroves and sea mud accumulation. This study used participatory action research methods (literature review, semi-structured interviews, field visits, and peer debriefing) to evaluate the project outcomes. Despite the project being generally very successful, its implementation and results were inadequately documented by agencies involved due in large part to insufficient local involvement during the reporting process, even though the local community was fully involved in the project planning and implementation. Inadequate documentation has led to mistakes being made when attempts have been made to replicate the project elsewhere, and incomplete findings have been incorporated into mangrove management plans at the provincial and regional levels. Using the community knowledge from the time of the project implementation and since, we detail the successes and problems encountered to provide more complete reporting, to assist transferability of the methods to other eroding muddy coasts in Vietnam and potentially elsewhere.

Future vegetation patterns and primary production in the coastal wetlands of East China under sea level rise, sediment reduction, and saltwater intrusion

AbstractTo explore the effects of sea level rise (SLR), sediment reduction (SR), and saltwater intrusion (SWI) on the vegetation patterns and primary production of one exotic (Spartina alterniflora) and two native dominant (Scirpus mariqueter and Phragmites australis) species in the coastal wetlands of East China, range expansion monitoring and stress experiments were conducted, followed by model prediction. After a rapid invasion period, the expansion rate of S. alterniflora slowed down due to the decreasing availability of suitable habitat under prolonged inundation. SLR was shown to decrease the colonization of S. alterniflora and the native P. australis up to 2100. In contrast, the native S. mariqueter that has a high tolerance of inundation increased in area following SLR, due to a reduction in competition from S. alterniflora in low‐lying habitats and even recolonized areas previously invaded by the exotic species. The combination of SLR and SR resulted in further degradation of S. alterniflora and P. australis, while the area of S. mariqueter was not reduced significantly. The decrease in the area of vegetation would reduce the gross primary production under SLR and SR. SWI exacerbates the impacts, especially for P. australis, because S. alterniflora and S. mariqueter have a higher tolerance of salinity. Thus, the coastal vegetation pattern was predicted to be modified due to species‐specific adaption to changed geophysical features. This study indicated that the native species better adapted to prolonged inundation and increased salinity might once again become key contributors to primary production on the muddy coasts of East China.

The 7th International Conference on Coastal Dynamics, Arcachon, France, 24–28 June 2013

The international Coastal Dynamics conference has rapidlybecome one of the most important meetings for scientists ac-tive in the field of nearshore sciences and coastal evolution.The first event took place in 1994, and since 2001, the con-ference is held every 4 years, typically in Europe althoughonce in Japan in 2009. The Coastal Dynamics conferenceseries advances the community’s understanding of recent ap-plied and basic research concerning coastal waves and cur-rents, interactions between wind, water and sediments, andmorphology changes in the coastal zone. A wide range ofenvironments (with and without structures) are consideredsuch as sandy, rocky, and muddy coasts, inlets, and estuaries.The conference documents research and applications treatingthese coastal dynamics at the short, medium, and large/longspatial and temporal scales.The 7th International Conference on Coastal DynamicswasheldinJune23–26,2013,inthecityofArcachon,France.ItwasjointlyhostedbytheUniversityofBordeaux,theCentreNationaldelaRechercheScientifique(CNRS)andtheServiceHydrographique et Oceanographique de la Marine (SHOM),chaired by Dr. Philippe Bonneton and Dr. Thierry Garlan.Approximately 270 researchers from 27 countries attendedthe conference. At the conference, we had 137 oral and 51poster presentations, each associated with a full paper in theconference proceedings volume. The contributions were se-lected among more than 300 submitted abstracts, peerreviewed by an international technical abstract review com-mittee. During the conference, three keynote lectures weregiven by Gerben Ruessik, Huib de Swart and FabriceArdhuin. The conference also comprised two short coursesand two field trips in the Arcachon lagoon and adjacentbeaches. A gala dinner took place at the prestigious ChateauSmith-Haut-Lafitte. During the dinner, the organizing com-mittee honoured Prof. Peter Nielsen as theCoastalDynamics’13 coastal award winner, for his significant contri-bution in the field of coastal sediment transport. The organiz-ing committee also announced the Coastal Dynamics’13 beststudent presentation winners, Anouk de Bakker, MelissaMoulton and Gerad Dam and the Coastal Dynamics’13 beststudent poster winner Thibaud Revil-Baudard.For this Topical Collection, we had thus invited 15 papersthat were presented at the conference based on (1) the overallimpressionduringthepresentationattheconferenceincludingcommentsfromtheaudience,(2)ourownadditionalreviewofthe candidate papers and (3) scores and comments from thefirst abstract review round. The authors of these 15 paperswere further invited to submit a full scientific paper to meetthe Ocean Dynamics guidelines and to be evaluated throughits regular peer-review process. All 15 papers did pass thereviewround,asanticipated,giventhecriteriaoftheinvitationprocess.Roland and Ardhuin (2014) review the recent improve-ments in forcing fields, physical parametrizations andnumerical techniques of spectral wave models, which cannow provide highly accurate wave hindcasts and forecasts.Arns et al. (2015) propose a methodology to estimate region-alized return water levels at ungauged sites, illustrated by anapplicationtothenortherncoastofGermany.Twopapersdealwith modelling of interactions between hydrodynamics and

GIS-based methodology for erosion risk assessment of the muddy coast in the Yangtze Delta

Muddy coasts are widely distributed around the world, especially adjacent to large estuaries. These regions are highly susceptible to coastal erosion with its dense population, developed economy and low-lying land. Due to immense natural and human pressures, there is an urgent need for a more comprehensive understanding of coastal erosion risk in such areas. Various models have been established, but most of them focused on sandy coasts and physical factors that influence coastal erosion while socioeconomic factors were usually ignored. Accordingly, this study presents a GIS-based risk assessment of coastal erosion for muddy coasts by combining both the physical and socioeconomic aspects of erosion. The method is used to assess coastal erosion risk in the Yangtze Delta. Based on the DPSIR (Driving forces, Pressure, State, Impact, and Response) framework, 10 vulnerability indicators and 3 impact indicators corresponding to physical and socioeconomic aspects, respectively, are identified to constitute an indicator system. These indicators are weighted using the Analytic Hierarchy Process (AHP) technique, and then are combined into a Vulnerability Index and a Hazard Index, which then are merged into a Risk Index. Then, these indexes are normalized to 0%–100%. Finally, the normalized values are ranked into 5 levels: very low (<20%), low (20% ≤ Is<40%), moderate (40% ≤ Is<60%), high (60% ≤ Is<80%) or very high (≥80%). This study is the first to comprehensively assess coastal erosion risk in the Yangtze Delta by integrating physical and socioeconomic factors at a detailed spatial scale. The results provide a clear picture of the current coastal erosion risk in the study area, despite of some limitations. The study also reveals key gaps in data gathering and coastal management practices that need to be addressed in order to develop more effective long-term coastal management.

STUDY ON SEDIMENT CONCENTRATION DISTRIBUTION UNDER BREAKING WAVES OF MUDDY COAST

Muddy coast is an important part of China's coast,Wave lifting sand and tide transporting sand are the main form of sediment movement on muddy coast. The sediment concentration becomes high during heavy storm wave. The high sediment concentration can produce serious effect on port and channel siltation. In the past, the experimental study is more on sand and silt concentration under breaking waves. In this paper, flume tests study the distribution characteristics of muddy concentration and mechanism of lifting sand under spilling waves, the gentle slope(1:200) is built in wave-current flume. The mud density is 1.35kg/L、1.40kg/L and 1.45kg/L respectively. The mud is from the trial tunnel of Xuwei channel. Research results show that the capacity of the breaking wave lifting sand and the mud density has strong nonlinear, and the sediment high concentration has been produced before wave breaking point,the maximum concentration near wave breaking point, Water stratification in the certain distance after wave breaking point, when muddy density is less than 1.45kg/L, and the characteristics of vertical distribution of muddy and silt concentration are non-uniform under breaking waves when the concentration is high near the bottom.

Shoreline mapping with cellular automata and the shoreline progradation analysis in Shanghai, China from 1979 to 2008

This paper presents a cellular automata (CA) algorithm to extract shorelines from remote sensing images by analysing the edge directional information of the images. Using this algorithm, the tide-coordinated shorelines along the entire coast in Shanghai Municipality of China were extracted and analysed using the multi-temporal Landsat TM images from 1979 to 2008. The shorelines of four sub-regions, including the mainland and three islands (Changxing, Hengsha and Chongming) were analysed along with six areas experiencing drastic shoreline changes. The results show a total progradation of 551.7 km2 along the coastal area of Shanghai over the past 30 years, due to both long-term sediment deposition and short-term land reclamation. Furthermore, both horizontal and vertical displacements along the shorelines were identified. Fractal analyses between the length of the shorelines and the spatial resolution of the images achieved goodness-of-fit (R2) values above 0.6 for the shorelines of the entire Shanghai as well as for each of the four subregions, indicating that the relationship between the length of the shorelines and the spatial resolution of the images accord with the power laws. The fractal dimension values indicate that the shorelines of both Changxing and Chongming Islands were getting regular. The paper also demonstrates that the CA-based shoreline extractor can detect shoreline information of both artificial and muddy coasts from remote sensing images. The shoreline extraction and change analysis tool is valuable not only for shoreline mapping but also for comprehensive coastal management.

Evolution Characteristic and Reclamation Potentiality of the Muddy Coast in Jiangsu Province, China

The study area was located in central coast of Jiangsu Province, China. The coast between Wanggang estuary and Chuandonggang estuary belonged to a typical accumulation muddy coast. When the Yellow River flowed into the Yellow Sea using the Huai River course, the coast deposited rapidly and the coastline advanced to the sea about 60 km. The deposition source stopped after the Yellow River returned to the north and flowed into the Bohai Sea. The entral coast of Jiangsu still maintained a high deposition rate in the supratidal zone because of the erosion supply of the abandoned Yellow River delta. But the subtidal zone was in the erosion state. The coast entered into the adjustment period in the 21st century and showed the equilibrium of the erosion and deposition. In recent years, the supratidal area decreased because of the reclaimation. The living space of the salt marshes was limited. The reclamation potentiality will be limited too in the future.

Field observation and analysis of wave-current-sediment movement in Caofeidian Sea area in the Bohai Bay, China

In order to study the mechanism of flow-sediment movement, it is essential to obtain measured data of water hydrodynamic and sediment concentration process with high spatial and temporal resolution in the bottom boundary layer (BBL). Field observations were carried out in the northwest Caofeidian sea area in the Bohai Bay. Near 2 m isobath (under the lowest tidal level), a tripod system was installed with AWAC (Acoustic Wave And Current), ADCP (Acoustic Doppler Current Profilers), OBS-3A (Optical Backscatter Point Sensor), ADV (Acoustic Doppler Velocimeters), etc. The accurate measurement of the bottom boundary layer during a single tidal period was carried out, together with a long-term sediment concentration measurement under different hydrological conditions. All the measured data were used to analyze the characteristics of wave-current-sediment movement and the BBL. Analysis was performed on flow structure, shear stress, roughness, eddy viscosity and other parameters of the BBL. Two major findings were made. Firstly, from the measured data, the three-layer distribution model of the velocity profiles and eddy viscosities in the wave-current BBL are proposed in the observed sea area; secondly, the sediment movement is related closely to wind-waves in the muddy coast area where sediment is clayey silt: 1) The observed suspended sediment concentration under light wind conditions is very low, with the peak value generally smaller than 0.1 kg/m3 and the average value being 0.03 kg/m3; 2) The sediment concentration increases continuously under the gales over 6–7 in Beaufort scale, under a sustained wind action. The measured peak sediment concentration at 0.4 m above the seabed is 0.15–0.32 kg/m3, and the average sediment concentration during wind-wave action is 0.08–0.18 kg/m3, which is about 3–6 times the value under light wind conditions. The critical wave height signaling remarkable changes of sediment concentration is 0.5 m. The results show that the suspended load sediment concentration is mainly influenced by wave-induced sediment suspension.