Coastal Erosion Management Research Articles

Doing nothing is no solution: Coastal erosion management in Guardamar del Segura (Spain)

Human activities like dam construction in rivers and urban development in coastal areas, combined with climate change, are degrading coastal systems. As a result, many European countries have implemented laws and strategies to protect their shorelines. This research focuses on Guardamar del Segura in Spain, where human actions in the Segura River basin and changes in wave patterns have significantly damaged the beach-dune system, with erosion rates reaching −0.71 m/year. If these rates and extreme climate events continue to rise, the shoreline will keep retreating, leading to the destruction of beachfront houses and parts of the dune surface by 2050. This will cause changes in land ownership and irreversible ecological damage to the natural ecosystem. The Spanish Public Administration's inaction on coastal protection is due to a lack of coordination between government levels, insufficient technical tools to combat erosion, and inadequate legal mechanisms to fund protective measures. In contrast, countries like Germany, the Netherlands, and the United Kingdom have effective models in place. Potential solutions for Guardamar del Segura include beach and dune restoration or adding sand through revetments. Another option is a managed retreat of the most vulnerable buildings to avoid continuous repair and maintenance costs. Coastal erosion is a growing issue, and preserving our coastal ecosystems requires proactive measures, so doing nothing is no solution.

Geohazard features of the Eastern Sardinia

ABSTRACT The MaGIC project (Marine Geohazard along the Italian Coasts) had the aim of mapping the geohazard in the Italian seas and resulted in numerous maps. In this paper, we present the maps: ‘Maps of Geohazard features of the eastern Sardinian Margin’. The Eastern Sardinia margin has mainly a narrow shelf, which reaches a width of 20 km only to the north. At the base-of-slope, a series of intra-slope basins sits in the structural depressions formed during the opening of the Tyrrhenian back-arc system. Submerged, coastal depositional bodies are present in the Olbia area where the continental shelf is large. They most likely represent the remnants of coastal environments formed during the last rise in sea level. They can represent important geo-resources for application in the issue of coastal erosion management. They are also the site of ecosystems hosting a specific biodiversity, which need to be preserved. In the central and southern part of the mapped area, the shelf is very narrow with an average width of about 4 km. Here, many canyon heads are very close to the coastline. They develop through retrogadational processes. Particularly in those canyons, where the canyon heads reach the coast, sediment instability represents an important source of geohazards to the coastal regions.

Multi-scenario analysis in the Apulia shoreline: A multi-tiers analytical framework for the combined evaluation and management of coastal erosion and water quality risks

Ongoing climate change is causing threats to coastal areas, according to scenarios of Intergovernmental Panel on Climate Change (IPCC). The coastal areas are becoming highly exposed to erosion as a direct consequence of natural and anthropogenic processes that occur at different spatial-temporal scales. Against this interplay, coastal managers are calling for integrated tools supporting a multi-scenario evaluation of risks arising from natural and anthropogenic stress. A multi-tier analytical framework, exploiting the openly available Earth Observation databases, was developed, allowing the combination of remote sensing, GIS and Bayesian Network to evaluate the probability and uncertainty of coastal erosion risks and connected water quality variation, against ‘what-if’ scenarios, representing different management measures (i.e., Nature-Based Solution) and climate change impacts (e.g., higher incident waves due to increased storminess). Based on the available data for the Municipality of Ugento (Italy), the designed framework was applied over the 2009–2018 timeframe, allowing to capture local-scale shoreline erosion dynamics and driving forces. Results from scenario analysis revealed, to a minor extent, a nexus between oceanographic drivers, shoreline evolution, and water quality changes, with increasing probability of high erosion/accretion and higher turbidity under the simulated rising maximum significant wave height. However, the implementation of Nature-Based Solutions (i.e., circular approach exploiting beached Posidonia oceanica leaves) resulted in significant positive effects, stabilizing the shoreline by reducing high erosion and accretion rates. Despite data constraints, outcomes of the performed assessment could represent valuable information to drive adaptive policy pathways in the context of coastal management along the Ugento shoreline.

연안침식 관리책임에 관한 법적 고찰

Today, the coast is recognized as an essential space for national welfare. That's because the coast provides important ecological habitats and natural resources, and at the same time half of the population provides ports, harbors and bases for several industries. Recently, the coastal erosion is becoming national issue nationwide.
 Coastal erosion can be caused by both natural and artificial causes. The main natural causes of coastal erosion were the influence of waves, currents, wind etc., and in recent years, erosion has been intensified due to sea level rise and wave changes caused by climate change. On the other hand, artificial causes include coastal drift blocking, wave shielding area, revetment, windbreak forest, and sea sand collection etc.
 Coastal erosion management is based on Article 23, Paragraph 1, Article 34, Paragraph 6, Article 35, Paragraph 1, and Article 120, Paragraph 2 of the Constitution. The legal grounds for coastal erosion management include the Coastal Management Act, the National Land Planning and Utilization Act, the Countermeasures Against Natural Disasters Act, Public Waters Management And Reclamation Act, the Building Act, the Erosion Control Work Act, and the Island Development Promotion Act etc.
 Measures to fulfill administrative responsibility (legal relief) for coastal erosion under the current law are based on the Article 2(State’s negligence liability) of the State Compensation Act , Article 5(liability for structures) of State Compensation Act, compensation for losses, Article 758(Responsibility for installation or maintenance of structures) of Civil Act.
 In order to make administrative responsibility for coastal erosion more practical, it is necessary to legislate no-fault liability for those who cause coastal erosion, legalize responsibility for preventing coastal erosion in advance, and legislate compensation for losses caused by acts that cause coastal erosion in managed areas.
 First, it is necessary to legislate no-fault liability for those responsible for coastal erosion. In order to prevent environmental harm by realizing no-fault liability for coastal erosion damage and promptly healing coastal erosion, it is necessary to identify the person responsible for coastal erosion and secure the fulfillment of responsibility.
 Second, it is necessary to legislate the responsibility for preventing coastal erosion in advance. Risks from coastal erosion include both identified and potential risks. Even if the risk of coastal erosion is uncertain, it needs to be understood as a concept that includes the principle of forethought, which states that if the damage caused by the hazard is serious and irreversible, precautionary measures can be taken to prevent or reduce the hazard even before the hazard becomes certain.
 Third, it is necessary to legalize compensation for losses caused by acts that cause coastal erosion in managed areas. The loss compensation provisions of the current Coastal Management Act mean compensation for loss due to access to land, etc. This is not directly related to damage caused by coastal erosion. It is necessary to establish a legal basis for receiving compensation for losses caused by acts causing coastal erosion in the management area under Article 20-2, paragraphs 1 and 2.

Assessment and management of coastal erosion in the marine protected area of the Rosario Island archipelago (Colombian Caribbean)

By utilizing historical satellite image databases, it was possible to assess the rates of coastal retreat in the Grande, Rosario, and Tesoro Islands from 2010 to 2021, due to the influence of climatic variables. It was discovered that the three islands have lost 0.4%, 1.6%, and 9.3% of their landmass, respectively. The notable increase in sea level rise, which has risen 6.2 mm/year since 2010, has emerged as the primary driving factor in the magnitude of erosion by altering the wave transformation patterns in shallow waters. This enables the wave trains to maintain more energy and intensify their height in surf zones, particularly during the dry season, where the wave height has increased by 12%. At the same time, the intensity of longitudinal currents has increased due to the new wave dynamics, leading to changes in the coastlines. Areas characterized by a coastal geomorphology of terraces and beaches, such as Tesoro Island, were found to be the most affected, unlike the cliffs of Grande and Rosario Islands. The study also revealed a lack of policies and concrete actions aimed at mitigating erosion in the coral islands of the Colombian Caribbean. Thus, a set of guidelines is proposed as a starting point to address this issue.

Eruditing from indigenous adaptation strategies for resilient and sustainable coastal erosion management in southeastern Ghana

Ghana is witnessing an increase in the construction of coastal flood defence walls on its coast but the effects of the coastal defence on people have not been well documented. This paper explores two issues: (1) indigenous strategies for preventing sea erosion and (2) the effects the modern coastal flood defence structures constructed along the southeastern coast of Ghana are having on the people. This study provides new insights into the understanding of indigenous methods that were used to address coastal flooding in the eastern section of Ghana and the effects the modern coastal defence structures are having on the people. Through multiphase sampling, a sample of 282 residents living in 17 communities affected by sea erosion in the Keta, Anloga, and Ada East District Assemblies where coastal defence structures were constructed were selected. Questionnaires were administered to these 282 respondents. Focus Group Discussions (FGDs) were also held in three communities, namely Keta, Atorkor and Totepe where coastal defence structures were constructed. The planning officers of the 3 district assemblies, the chief fishermen in the 3 communities where the FGDs were held, leaders of salt winners and 3 elders in each community were the key informants. Using descriptive statistics, the study revealed that, indigenous strategies like filling the beach with sand, building away from the seashore, and raising the foundations of buildings were used to protect the houses and communities from sea erosion but these strategies are no longer working thereby forcing the government to construct ‘modern’ coastal flood defence wallson the coast. The ‘modern’ coastal defence structures are in some places protecting the people and the land since they no longer experience sea erosion on a large scale. However, in places where armour rocks are used to protect the land, people now see them as preventing them from enjoying the natural beach as they used to and as a hindrance to their livelihoods of fishing. It is recommended that, as far as possible, soft engineering strategies like beach nourishment or sand dunes which are in line with the indigenous methods be used since they can lead to easy adaptation for sustainability.

Adaptation of coastal defence structure as a mechanism to alleviate coastal erosion in monsoon dominated coast of Peninsular Malaysia

The complexity of the coastal environment and the advent of climate change cause coastal erosion, which is incontrovertibly a significant concern worldwide, including Peninsular Malaysia, where, the coast is threatened by severe erosion linked to anthropogenic factors and monsoonal wind-driven waves. Consequently, the Malaysian government implemented a mitigation plan using several coastal defence systems to overcome the coastal erosion problem. This study assesses coastal erosion management strategies along a monsoon-dominated coasts by evaluating the efficacy of coastal protection structures against the coast. To this end, we analysed 244 km of the coastline of Terengganu, a federal state located on the east coast of Peninsular Malaysia. Due to a higher frequency of storms and the ensuing inception of high wave energy environments during the northeast monsoon (relative to southwest monsoon), the study area is the most impacted region in Malaysia with regard to coastal erosion. Fifty-five (55) coastal defence structures were detected along the Terengganu coastline. The Digital Shoreline Analysis System (DSAS) was utilised to compute changes in the rate statistics for various historical shoreline positions along the Terengganu coast to assess the efficacy of the defence structures. Additionally, this study acquired the perception of the existing coastal management strategies through an interview session with the concerned stakeholders. The rate statistics revealed the effectiveness and impact of the coastal defence structure on the coastline. Assessing the functionality of the coastal defence structures shed light on the present scenario of coastal erosion management. Greater efficacy and lower impact of coastal defence structures are prescribed for coastal erosion management strategies across the monsoon-dominated coast.

Natural and anthropogenic effects on spatio-temporal variation in sediment load and yield in the Godavari basin, India

River sediment, the most crucial component of the land-ocean interaction, is enduring substantial changes worldwide because of anthropogenic alterations and climate change. Our study assesses the interaction of sediment load variability and yield to the rainfall, land-use, and dam constructions at both spatial and temporal scales in the Godavari and its major tributaries. The most important river basin in Peninsular India, the Godavari, has witnessed a dramatic decline (p-value <0.001) in sediment load over the past five decades, with average annual rates of 2 million tonnes (Mt) yr−1. Sediment load in the Godavari reduced from 150 Mt between 1970 and 1979, to 115 Mt in 1980–1989, 98 Mt in 1990–1999, 48 Mt in 2000–2009, and 47 Mt in 2010–2019, respectively. While sediment load in the Godavari and its major tributaries is declining significantly, the rainfall showed an overall insignificant increasing trend barring the Sabari sub-catchment, where the rainfall is increasing at a significant rate of 7 mm yr−1 (p-value = 0.001). Twenty-five sub-basins in the Godavari showed a large variation in sediment yield (28 to 3404 t km−2 yr−1). Our results revealed that spatial variability in sediment yield is primarily associated with both rainfall and land-use pattern. The temporal variation in sediment load in the Godavari and Pranhita is associated with intensified human activities during the most recent decades, while climate is the primary controlling factor in Indravati and Sabari sub-catchments. Sediment entrapment under a high rate of siltation by reservoirs in the Godavari has sharply reduced the sediment flux to the Bay of Bengal, causing aggravated delta erosion by wave actions. The findings of this study have significant implications for understanding the complex interrelationship between the management of reservoirs, land use, sediment loads, denudation, and coastal erosion in the Godavari catchment.

A new shoreline change assessment approach for erosion management strategies

Shoreline evolution studies are fundamental to assess the rate of beach accretion or retreatment. In the last years, researchers developed many methods with several techniques belonging to different disciplines and backgrounds. Nowadays, the Shoreline Change Analysis (SCA) is the most widespread method to assess shoreline evolution. In fact, the SCA is needed to perform management strategies able to respond to current erosion or potential future erosion problems. This paper presents a new approach using an automatic method for SCA with accuracy and speed improvements. Indeed, in the framework of the management of coastal erosion and to develop an adaptation plan to coastal hazards it is necessary to study the links existing between coastal and marine morphological transformations. A new tool was written in Matlab, the input files were built using a GIS environment and the results were arranged in a GIS project. The present tool adopts two approaches: the Transect Based Analysis (TBA) and the Area Based Analysis (ABA). New roughness and irregularity indexes were defined to calculate the transects’ spacing. Moreover, a piecewise polynomial baseline was defined to improve accuracy in shoreline position assessment. The approaches TBA and ABA were validated both by synthetic benchmarks and by a study case. The adopted synthetic benchmarks represent very common types of beaches: with one or more salients, with cusps and groynes. The case study was a logarithmic spiral Mediterranean beach on the southwestern coast of Sicily. All the studied test cases provided good results in terms of accuracy and easiness of use. The new tool and methodology, with TBA and ABA coupling, encloses many practical aspects. Indeed, ABA allows the general assessment of advancing/retreating beach areas, whereas TBA is needed to study very short stretches of beach. The proposed SCA analysis is useful for the requirements of a complete coastal management plan and to evaluate erosion management options. Moreover, the SCA gives a sound technical understanding of the physical coastal processes and should engage the community, the stakeholders and the agencies responsible for development application decisions. The new approach gives high-quality results achieved with significant speediness making it suitable for regional studies and directly providing parameters needed for erosion managing strategies.

Numerical modelling of sediment transport in southwest coast of Nigeria: Implications for sustainable management of coastal erosion in the Bight of Benin

Coastal erosion is widespread across the Bight of Benin owing to the perturbation of the sediment transport by the installation of the major ports of Lomé (Togo), Cotonou (Benin), and Lagos (Nigeria), among other factors. While different coastal management measures have been put in place to mitigate the effects of this hazard, they have seldom lessened the damage caused by it. To this end, this study examined the coastal processes in Southwest Nigeria (Barrier-Lagoon and Mud coast sections) through the numerical modelling of the hydrodynamic, spectral-wave, and sediment transport for three months to apprehend the poor performance of the management measures. Model results reveal that the nearshore current is mainly directed eastward with the persistent exposure of the area to wave-action. Two major sediment transports; the eastward/south-eastward and westward/north-westward sediment transports, were also identified. The predominance of these sediment transport patterns implies that the continuous adoption of reactive, site-specific hard-engineering coastal management approaches will give counter-productive results. Thus, to sustainably manage the coastal erosion problem across the Bight of Benin, there is the need to adopt a long-term, regional perspective with a cascade of coastal management measures covering all areas under the influence of the predominant sediment transports.

Coastal Erosion Vulnerability in Mainland China Based on Fuzzy Evaluation of Cloud Models

Global climate change-induced sea-level rise and storm wave intensification, along with the large population densities and high-intensity human development activities in coastal areas, have caused serious burden and damage to China’s coasts, led to the rapid growth of artificial shorelines development, and formed a “new Great Wall” of reinforced concrete against the laws of nature. After the last ice age, transgression formed the different features of China’s coast. Depending on the types of geological and landform features, coasts are divided into 36 evaluation units, and 10 indicators are selected from natural aspects (including tectonics, geomorphology, sediment, and storms) and aspects of social economy (population, GDP, Gross Domestic Product), and cloud model theory is used to build a coastal erosion vulnerability evaluation index system in China. The results show that high grade (V), high-middle grade (IV), middle grade (III), low-middle grade (II), and low grade (I) coastal erosion vulnerability degrees account for 5.56, 13.89, 41.67, 33.33, and 5.56% of the Chinese coastlines, respectively. The coastal erosion vulnerability of the subsidence zone is significantly higher than that of the uplift zone. Reverse cloud model and analytic hierarchy process calculation show that the main factors that control coastal erosion vulnerability since the transgression after the last ice age are geological structure, topography and lithological features, and in recent years, the decrease in sea sediment loads and increase in reclamation engineering. Mainland China must live with the basic situation of coastal erosion, and this study shows that the index system and method of cloud modeling are suitable for the evaluation of the coastal erosion vulnerability of the Chinese mainland. This study provides a scientific basis for the adaptive management of coastal erosion, coastal disaster assessment and the overall planning of land and sea.

Investigating the physical and chemical characteristics of construction and demolition wastes as filler to regenerate beaches

Currently, many countries around the world face serious problems related to coastal erosion. The use of natural fillers extracted from shallow areas as well as from rivers for coastal regeneration and beach nourishment generates additional environmental impacts that affect plants and animal communities, water circulation and coastal dynamics, amongst others. On the other hand, construction and demolition wastes (CDW) are becoming more abundant worldwide, generating additional environmental impacts related to water pollution due to leaching of contaminants, as well as loss of landscape quality. In this work it is proposed that CDW can be better suited to replace natural gravel for coastal erosion management. In addition, the use of CDW for beach regeneration will help to reduce the use of natural sources and thus to reduce the environmental impacts produced by extraction. This study investigates the physical characteristics of some fractions of construction and demolition wastes (CDW), particularly concrete, ceramics, asphaltic, and mixture material, to be used as filler to regenerate beaches, replacing the traditional filler generally used elsewhere. A wet ball milling method was used to adequate the physical characteristics (i.e. such as sphericity, roundness, and roughness) of the aggregates of CDW to be used for beach regeneration. The effects of the water mass to solid mass ratio (W/S), mass of sample to the mass of the balls (S/B), as well as ball milling time on the shape of CDW aggregates were studied. The optimum conditions to generate the required aggregates were W/S = 1, S/B = 0.5 and 1 h of ball milling. As particle size is considered an important parameter to avoid water turbidity, it is recommended to use particles with size greater than 2 mm, and the shape of the generated aggregates was calculated and compared to natural beach gravel. Wet ball milling significantly increased their roundness and contributed to a decrease of surface roughness, thus the final material presented high similarity with standard beach gravel aggregates. The durability of the material was also studied and compared to commercial gravel and beach gravel. The results show that weight loss during durability tests mainly depends on chemical composition of the CDW aggregates assayed. The chemical composition and mineralogical phase identification of CDW show the absence of hazardous elements and the presence of dolomite, quartz and calcite as principal phases. Inorganic composition of the CDW was also determined in order to comply with the Spanish Technical Instruction for the Environmental Management of Marine Extractions to obtain sand. Additionally, leaching tests of organic and inorganic substances were carried out according the European Standard EN12457/4 which specifies a compliance test providing information on leaching of granular wastes and sludges under specified experimental conditions, particularly a liquid to solid ratio of 10 L/kg dry matter for materials with a particle size below 10 mm (without or with limited size reduction). All generated aggregates complied with standard requirements, thus based on the satisfactory results produced by wet ball milling treatment on the physicals characteristics of CDW aggregates as well as on their chemical composition and results of the leaching tests, it is proposed the use of CDW as filler in beach and coastal regeneration.

Shoreline Change Prediction for Integrated Coastal Erosion Management

Kim, Y.-J.; Kim, T.-W.; Yoon, J.-S.; Hur, D.-S, and Kim, M.-K., 2021. Shoreline change prediction for integrated coastal erosion management. In: Lee, J.L.; Suh, K.-S.; Lee, B.; Shin, S., and Lee, J. (eds.), Crisis and Integrated Management for Coastal and Marine Safety. Journal of Coastal Research, Special Issue No. 114, pp. 121–125. Coconut Creek (Florida), ISSN 0749-0208. The mechanism of sediment transport occurring in littoral zone shows complex patterns. Establishing an accurate longshore sediment budget prediction is difficult. Littoral drift flowing into and out of the coast shows sensitive responses to natural and anthropogenic changes in the surrounding area. In particular, at the coast where rivers are located, the littoral drift is significantly affected by the inflow of sediment from the upstream. However, the sediment management at the coast has been conducted by respective measures established in different areas, such as mountains in the upstream region, dams, rivers, and coasts, and thus, measures are established without an appropriate feedback between these different areas. Therefore, determining the exact causes of erosion occurring in the coastal zone is challenging. In addition, for accurate prediction of sediment budget in coastal areas, it is necessary to construct a model with mixed particle size distribution that can consider the properties of sediment inflow from the river and the sediment constituting the sea area. Thus, for integrated coastal erosion management, based on the determination of sediment transport mechanism flowing into the coastal zone, accurate estimation of sediment transport rate and sediment budget prediction according to the shoreline changes affected by waves play an important role. In this study, a series of mechanism of sediment transport flowing into the sea area through the river was analyzed, and the sediment budget according to the shoreline change occurring in the sea area was estimated. The sediment load flowing into the sea area and the representative wave acting on the sea area were calculated to construct the IN-MPS (INje-Mixture Particle Shoreline) model considering the sediment particle size distribution in mixed condition. The accuracy of the model was evaluated by comparing the results obtained from the model with those of long-term observations by calculating the exact sediment budget in the coastal zone, and when the inflow from the river and the mixed particle size distribution of sediment were considered, the accuracy in the shoreline change prediction was improved.

Not just an engineering problem: The role of knowledge and understanding of ecosystem services for adaptive management of coastal erosion

Coastal ecosystems are recognized as important providers of ecosystem services such as carbon storage, increased fish productivity, and wave energy reduction. In a context of climate change, coastal ecosystems are exposed to erosion and subject to coastal squeeze, even as they provide natural coastal protection against extreme weather. While civil engineering solutions often take centre stage in mitigating coastal erosion and protecting infrastructure from storms and sea level rise, we seek to explore the social dimension of adaptive management of socio-ecological systems and more specifically the role of knowledge and learning. Using an ecosystem services (ES) framework, we provide a first evaluation of local stakeholders’ perceptions of coastal habitats in maritime Quebec. The findings demonstrate the importance of a social approach for coastal ES valuation, in particular in addressing the complex question of cultural ES. A better understanding of the links between coastal stakeholders and their natural environment can help decision-makers and practitioners design conservation management and coastal adaptation measures mainstreaming the role of coastal habitats. Nevertheless, a change towards a socio-ecological perspective will require long-lasting processes that build on social capacities, such as flexible institutions and multilevel governance systems.

Assessment and management of coastal erosion: Insights from two tropical sandy shores in Mauritius Island

Rising sea level and increasing tropical storm frequency caused by the changing climate are threatening small Island economies which depend on their coastal environments and resources. Owing to the high socio-economic and environmental values of tropical sandy beaches, monitoring the evolution trends of shorelines are regarded as an essential strategy to improve the resilience of Island states. The present study conducted in Mauritius, indicates a net erosional effect at Le Morne amounting to 8049.7 ± 5% m2 which is attributed to the hydrodynamics of the lagoon, whilst a net accretional effect has been observed at Flic-en-Flac, equivalent to 6571.3 ± 5% m2 and attributed to periodic beach nourishments. The shoreline evolution at Le Morne is predominantly influenced by Passe de la Prairie where an average energy of 0.162 m2/Hz, corresponding to an average wave height of 1.16 m, carries enough energy and momentum to influence the sediment transport near the peninsula. At Flic-en-Flac, longshore currents propagating on either sides of the central region and directed northwards and southwards influence the shoreline, resulting in an accretion zone extending 62.5 ± 15 m near Villa Caroline over the 2009–2018 period. To dampen this problem, a beach management strategy is proposed which revolves around the restoration of corals in front of eroded shores, replacement of casuarina trees, and enforcement of regulatory laws.

Economic analysis of choices among differing measures to manage coastal erosion in Hoi An (a UNESCO World Heritage Site)

The paper presents one of the first economic analyses of residents’ choice of different coastal erosion control measures in a developing country — Vietnam. Hoi An, a UNESCO World Heritage Site, was selected given the frequency of coastal erosion events which have caused increasing damages to property, tourism activities and the livelihood of local people in an iconic tourist destination. We designed a discrete choice experiment based on responses from 399 households in order to estimate the willingness to pay (WTP) for differing coastal erosion control measures. Using the generalized multinomial logit model, empirical results yield five important findings. First, residents prefer wider, more public beaches having both trees and restaurants and are willing to accept visible structures such as groynes and stair revetment to prevent further erosion. Second, residents place a higher value on a beach that is protected by robust permanent structures. In particular, residents have the highest WTP for groynes. Third, there exists preference and scale heterogeneity across respondents which are driven by level of education, knowledge of the problem, and the stated level of choice certainty. Fourth, knowledge and experience of coastal erosion are shown to have a strong influence on the valuation residents place on the choice of protective structures. Finally, on average, a resident is willing to pay USD 1.7 per year for a coastal erosion management program that increases beach width by additional 50 meters, beach access by additional 25%, restaurants and trees on the beach and groynes as the erosion protection structure.

Coastal Erosion Management by Implementing Concept of Building with Nature (BwN) in Demak Regency, Central Java, Indonesia

Coastal erosion that occurring in the north coast of Java, led to significant coastline erosion. One of the areas that run into the coastline erosion is Demak Regency. To overcome the problem, the concept of Building with Nature (BwN) is proposed. This concept uses the media from nature to reduce the wave energy and being sediment trap. BwN has applied in Demak Regency, exactly in Sayung village since 2013. According to the evaluation, the BwN was able to capture sediment of 0.4 cm/year. The amount of sediment is expected to be increased by adding the number of BwN and change the pattern of BwN. To determine the amount of increased sediment, a model using the DELFT3D software is utilized. The data used in the model is based on field measurement data in 2016. BwN in the model is defined as thin dam. The results show that the average amount of sediment around BwN after adding two BwN in front of the existing BwN increase to 0,6 cm/year. This solution is expected to help the faster shoreline restoration in Demak coast.

Using quantitative dynamic adaptive policy pathways to manage climate change-induced coastal erosion

Adaptation requires planning strategies that consider the combined effect of climatic and non-climatic drivers, which are deeply uncertain. This uncertainty arises from many sources, cascades and accumulates in risk estimates. A prominent trend to incorporate this uncertainty in adaptation planning is through adaptive approaches such as the dynamic adaptive policy pathways (DAPP). We present a quantitative DAPP application for coastal erosion management to increase its utilisation in this field. We adopt an approach in which adaptation objectives and actions have continuous quantitative metrics that evolve over time as conditions change. The approach hinges on an adaptation information system that comprises hazard and impact modelling and systematic monitoring to assess changing risks and adaptation signals in the light of adaptation pathway choices. Using an elaborated case study, we force a shoreline evolution model with waves and storm surges generated by means of stochastic modelling from 2010 to 2100, considering uncertainty in extreme weather events, climate variability and mean sea-level rise. We produce a new type of adaptation pathways map showing a set of 90-year probabilistic trajectories that link changing objectives (e.g., no adaptation, limit risk increase, avoid risk increase) and nourishment placement over time. This DAPP approach could be applied to other domains of climate change adaptation bringing a new perspective in adaptive planning under deep uncertainty.

Economic Values of Coastal Erosion Management: Joint Estimation of Use and Existence Values with recreation demand and contingent valuation data

Revealed and stated preference survey data from North Carolina households are utilized to estimate structural micro-econometric models of recreation demand and willingness-to-pay (WTP) for coastal erosion management among beach visitors and non-visitors. We test for and reject weak complementarity, implying existence values associated with management of North Carolina’s beaches. We find stronger preferences for shoreline retreat (median WTP = $22.20 per household, per year) as a management strategy relative to beach nourishment (WTP = $7.91), and we find substantially weaker preferences for shoreline armoring (WTP = $0.09). Shoreline retreat exhibits much larger estimates of existence values, whereas existence values for shoreline armoring are negative. Our data permit estimates of marginal value of incremental beach width accruing to beach users and non-users (which range from $0.23 and $0.48 per meter).

Are We Managing in the Right Way the Coastal Erosion along the Caribbean Coast of Colombia?

Rangel-Buitrago, N., 2020. Are we managing in the right way the coastal erosion along the Caribbean coast of Colombia? In: Malvárez, G. and Navas, F. (eds.), Global Coastal Issues of 2020. Journal of Coastal Research, Special Issue No. 95, pp. 930–934. Coconut Creek (Florida), ISSN 0749-0208.Coastal erosion has become a severe problem, rising in magnitude, dominance, and extension along the Caribbean coast of Colombia. Circa 55% of this critical area for the country is undergoing severe erosion problems related to a multiplicity of factors contrasted by their degree of influence and magnitude. The management of the coastal erosion processes has been implemented via traditional hard defense options. During the last 30 years, the necessity to protect the coast with hard structures has been driven by the growing coastal zone population and political - economic pressures. At the beginning of 2019, at least 15000 both cross and hard longshore structures have been built along the coastline. These hard structures have altered the natural conditions of the study area, producing impacts such as (i) coastal hardening, (ii) reduced sediment supplies to downdrift areas, (iii) intensification of erosion processes, (iv) generation of nearby new erosion hot spots, (v) deterioration of coastal scenery quality, among others. Direct and indirect experience indicates that optimal results, on money and a time basis, can be achieved using a combination of other coastal erosion management options, such as, “accommodation,” "planned retreat," or “do nothing” solutions delivered through legally adopted coastal management plans, coordinated by one government department is urgently required. This work describes and evaluates the functionality of current coastal erosion management strategies used up to the present. It also indicates the current and future coastal erosion management scene for the region and highlights major trends and challenges faced by users, landowners, and coastal managers.