Shoreline Management Plans Research Articles

One hundred years of inlet processes and barrier adjustments at North Inlet, SC

Debidue Beach and North Inlet are a coupled mixed-energy inlet-barrier system along the South Atlantic Bight in South Carolina, USA. Long-term chronic erosion along much of Debidue throughout the 20th century is the result of a shoreline adjustment triggered by an avulsion in the main channel of North Inlet occurring between 1926 and 1934. We use a historical database of shoreline positions compiled by the United States Geological Survey (USGS) and the Analysis of Moving Boundaries Using R (AMBUR) package to quantify changes in the Debidue Beach shoreline over nearly 150 years from 1872 to 2011. This analysis documents relatively large-scale shoreline changes (and equivalent volumetric changes above local depth of closure “DOC”) following the shift in channel position, and a logarithmic decrease in erosion rates over the following decades. Mixed-energy ebb-dominant inlets have considerable effects on adjacent beaches due to their ability to retain and shed large quantities of sand relatively quickly. This study demonstrates that even systems exhibiting long-term stability — like North Inlet — are indeed migrational landforms and should be considered as such when formulating shoreline management plans along adjacent beaches.

Managing a potential conflict between the protection of geological sites and the need to safeguard essential road infrastructure: the Coverack North Coast Protection Scheme and palaeo-Moho in Cornwall, UK

In alignment with the Cornwall & Isles of Scilly Shoreline Management Plan (SMP2), adopted by Cornwall Council, the Coverack North Coast Protection Scheme comprised the construction of a circa 125m long rock armour revetment, and 55m long retaining wall, at Coverack Cove on the Lizard peninsula in Cornwall, UK. This was to prevent sea erosion impacting vehicle access via the B3294, the main public highway into Coverack. The site of the proposed works on Coverack Beach is part of a Natural England designated Site of Special Scientific Interest (SSSI) for its geology, specifically the exposure on the foreshore of an almost continuous cross section of a palaeo-Moho, the former boundary between the earth's crust and underlying mantle. Following a period of consultation, a set of management proposals and mitigation measures were agreed with Natural England and Cornwall Council to protect and offset the impact of the proposed works on the SSSI asset. It is sometimes difficult to reconcile the issue of protecting communities from coastal erosion and ensuring the protection of geological assets. This can be mitigated if a balanced approach is adopted, and the work is sensitively managed to offset the impact of coastal protection schemes such of this.

Wave climate analysis for shoreline management plan in Kelantan, Malaysia

Wave climate analysis for shoreline management plan in Kelantan, Malaysia

Nation-scale multidecadal shoreline extraction and coastal spatio-temporal change monitoring using cross-mission remote sensing data

Mapping shorelines is critical for coastal management and conservation, as shorelines are essential indicators for understanding coastal geomorphology and dynamics. Nonetheless, as shorelines are often lengthy and rugged, in-situ surveys are labor-intensive and costly. Oppositely, spaceborne remote sensing data provide cost-efficient alternatives, yet, most earlier studies rely on manual digitization or thresholding band ratio-based water indices to delineate instantaneous shorelines, which locations are affected by varying water color and tides. Consequently, cross-temporal assessments of environmental and anthropogenic impacts on coastal stability remain challenging. The present study develops an edge detection-based, dual-temporal, nationwide, tide-coordinated, and sediment cell-based shoreline dataset in Japan, i.e., the TSSD-JP. Both 1980s and 2020s shorelines along the Japanese coasts are extracted using cross-mission multispectral data and an automated shoreline extraction method. The results are validated with national coast surveys and global shoreline databases, confirming a positional accuracy better than 80% at 50 m. Moreover, founded on the extracted dual-temporal shorelines, 30+ year coastal changes are measured. An increased land area of 293.21 km2 at a rate of 8.50 km2/yr is estimated. Evident accretions in bay regions of southern Honshu due to extensive land reclamation and engineering constructions are observed. Since the analysis is conducted on natural management units with a physical basis, potential biases caused by jurisdictional boundaries are overcome. Practically, because TSSD-JP is derived from freely accessible data and tools, its universal applicability is guaranteed. Thence, the proposed approach can be applied to different nations' intertidal zones to assess the coastal vulnerability and resilience as well as support local governments’ shoreline management plans (SMPs).

Transitions in modes of coastal adaptation: addressing blight, engagement and sustainability

Coastal defences have long provided protection from erosion and flooding to cities, towns and villages. In many parts of the world, continued defence is being questioned due to both environmental, sustainability and economic considerations. This is exemplified in England and Wales, where strategic Shoreline Management Plans envisage realignment of many protected coasts, often with low population densities, over the coming decades. The policy transition from protection to realignment is often resisted by affected communities and can have high political costs. Whilst some preparations for such transitions have been made, the communities affected are often not fully aware of the implications of policy change, and this brings the potential for blight. In this paper, we investigate the challenges of implementing transitions in coastal policy within England and Wales. The analysis is based on data obtained from three workshops held in 2019 that were attended by council members, engineers, planners, scientists and other relevant professionals. Five conditions are found to promote contention: (i) policy actors with competing priorities and different decision making time frames (immediate to decadal to a century); (ii) divergence between regulations and ad hoc political decisions (e.g. in relation to the demand for new housing); (iii) limited or non-existent funding to support policy transition; (iv) community expectation that protection is forever; and (v) a disconnection between people and ongoing coastal change. Our research indicates that transitions can be better supported through: (1) integrated multi-scalar preparedness for coastal change; (2) an accessible evidence base and future vision to nurture political confidence in adaptation; and (3) defined, time-bound and accessible diverse funding streams to achieve transitions. Critically, these generic actions need to be embedded within the local political and planning system to facilitate transition to more sustainable coasts and their communities.

Unmanaged realignment: Recent examples and the morphological evolution of naturally breached flood defences

Managed realignment describes the breaching of coastal flood defence such as sea walls, embankments, and barrier beaches for habitat restoration and flood defence purposes. These sites are deliberately breached at pre-determined locations, often with extensive engineering works carried out to encourage a mosaic of habitat types. However, landscaping and engineering works typically alter the site's morphology, resulting in a more simplified creek and drainage network with lower topographic variability than natural saltmarshes. As a result, drainage might be restricted, impacting the plant communities that can colonise and preventing widespread sedimentation and seed dispersal. In contrast, unmanaged realignment (uMR) is the natural breaching of flood defences without any of these costly engineering or landscaping works performed prior to site breaching. uMR sites provide an opportunity to assess the ‘natural’ morphological evolution of realignment sites without the influence of extensive site design, engineering, or landscaping features, yet there remains little analysis of the evolution of ‘recent’ uMR sites. To address this gap in knowledge, this paper describes ten recent occurrences of uMR on the coast of England since 1996. From these sites, five were selected for analysis of the pre-breach morphology in comparison to areas of natural saltmarsh and the subsequent morphological evolution. In general, lower topographic variability, although a higher density of creeks, was found within the sites before breaching in comparison to the adjacent areas of natural marsh. Following site breaching, results suggest that uMR sites become less topographically diverse, with some evidence of subsequent increases in topographic variability at the two oldest uMR sites. Findings are discussed in terms of the potential benefits of uMR for shoreline management planning. It is recommended that further consideration of the wider impact of uMR on coastal and estuarine systems is required within the shoreline management process to ensure uMR sites have a positive impact on the strategic delivery of shoreline management planning.

Mapping and assessment of coastal infrastructure for adaptation to coastal erosion along the coast of Ghana

Globally, coastal managers are challenged to make informed decisions when selecting coastal infrastructure to respond to climate-induced sea-level rise and associated coastal hazards like coastal erosion and flooding. Classifying the types of coastal infrastructure permits the comparison of their potential efficiency, environmental and socioeconomic impacts, and long-term response to sea-level rise. At present, information on coastal infrastructure implemented along the coastal area of Ghana is not known thus creating a research gap to catalog this information. To achieve this, we combined satellite images from Google Earth Pro and the use of ArcGIS capabilities to conduct a national assessment of coastal infrastructure and its distribution along the coast of Ghana. Even though similar approaches have been applied in different geographic contexts, this article focuses on evaluating coastal infrastructure in Ghana. Results show that between 2004 and 2022, at least 110 km or approximately 20% of the coast of Ghana has been protected using grey infrastructure, distributed as groins 35.9 km (6.5%), revetments and seawalls 50 km (9%), and jetties and port breakwaters 25 km (4.5%) of the 550 Km coastline. These do not include the numerous private recreational infrastructure that could increase coastal vulnerability. The increasing use of grey infrastructure, particularly seawalls, and revetments along the coast has adverse impacts on overall coastal evolution and causes socioeconomic challenges. This study supports coastal managers to review coastal adaptation policy and develop shoreline management plans for the coast of Ghana.

A system for in-situ, wave-by-wave measurements of the speed and volume of coastal overtopping

Wave overtopping of sea defences poses a hazard to people and infrastructure. Rising sea levels and limited resources mean accurate prediction tools are needed to deliver cost-effective shoreline management plans. A dearth of in-situ data means that the numerical tools used for flood forecasting and coastal scheme design are based largely on data from idealised flume studies, and the resulting overtopping predictions may have orders of magnitude uncertainty for complicated structures and some environmental conditions. Furthermore, such studies usually only provide data on the total volume of overtopping water, and no data on the speed of the water. Here we present WireWall, an array of capacitance-based sensors which measure the speed and volume of overtopping water on a wave-by-wave basis. We describe the successful validation of WireWall against traditional flume methods and present results from the first trial deployments at a sea wall in the UK. WireWall results are also compared with numerical predictions based on EurOtop guidance. WireWall technology offers an approach for reliable acquisition of the data needed to develop resilient coastal protections schemes.

Spatio-Temporal Assessment of Shoreline Changes and Management of the Transgressive Mud Coast, Nigeria

This study investigated changes due to erosion and the consequences of rising sea levels on the Transgressive mud coast of Nigeria using multispectral Landsat images and ALOS PALSAR (AW3D30) elevation models with the view of proffering a management strategy for a sustainable coast. Endpoint Rate (EPR) and Linear Regression Rate (LRR) techniques within the Digital Shoreline Analysis System (DSAS) were used to assess the rates of changes along the shoreline between 1986 and 2021. Inundation models were developed in line with sea-level rise scenarios of the Green House Gas emissions (SSP5-8.5) with GIS to assess sea-level rise’s impact on land and structures. Likewise, spatially disaggregated population and economic activity datasets projected to the year 2100 were overlaid on the inundation models to generate exposure indices for the coast. The study revealed that 49.8 km (64.67%) of the shoreline experienced retreat over the entire study period. This rapid rate of shoreline retreat has caused a land loss of 15.1 sq. km to the Atlantic over the last 35 years, which could trigger an additional 1.26 sq. km by the year 2032. Furthermore, the impact of sea-level rise is severe on the transgressive coast triggering submergence of the mud coast by inundation to the extent of 201 sq. km which will increase to 551 sq. km by 2100. Losses in terms of structures, population, and economic activity are recorded. To curtail the ongoing coastal changes, the study recommends the full adoption of the shoreline management plan (SMP) for sustainable shoreline management.

Responding to climate change around England's coast - The scale of the transformational challenge

Around the world coastal communities face an unprecedented challenge in responding to sea level rise and associated changes. For many responding through incremental adaptation may be appropriate (although not without limits). This may include progressively raising defences, nourishing beaches, and other conventional management measures. Such actions are well supported by existing governance structures and investment vehicles. For others however, continuing to provide protection from flooding may not be technically feasible or financially viable. For these communities, transformational adaptation will be needed (including realignment or relocation). Implementing transformational change, however, is difficult and requires a clarity of long-term planning and a means of supporting communities to take early action in making this transition.This paper explores the scale of the transformational challenge in England through to 2100. The combined influences of relative Sea Level Rise and the local lowering of the foreshore platform due to increased wave-driven surface erosion are considered. The realism of published shoreline policies (set out within England's Shoreline Management Plans) are assessed based on projected changes in flood risk and benefit-cost considerations. The assessment suggests 1,600–1,900 km (∼30%) of England's shoreline currently designated as a ‘Hold-the-Line’ policy is likely to see increasing pressure to realign (assuming a rise in Global Mean Surface Temperature of between 2 and 4 °C by 2100) with implications for ∼120,000–160,000 residential and non-residential properties by the 2050s. It is likely that a proportion of these properties will require relocation. It is not possible to say how many this will be. This will be a matter for government and the associated policy and funding priorities that will influence local outcomes.

Do habitat compensation schemes to offset losses from sea level rise and coastal squeeze represent a robust climate change adaptation response?

Habitat compensation schemes aim to offset unavoidable development-related losses at one site with replacement habitat elsewhere. They have become prominent policy tools used to address coastal squeeze of intertidal habitats occurring from sea-level rise and ‘hold-the-line’ management approaches. This policy development is evaluated against scientific evidence and its broader ethical dimensions regarding conservation of the natural environment. A case study is provided from the UK (England) where the National Habitat Compensation Programme aims to continue conservation obligations consistent with the EU Habitats Directive and Natura 2000. Progress is also referenced against Shoreline Management Plans and aspirations for a greater proportion of the coast to shift to managed realignment in response to sea level rise. Important barriers are identified, and issues of monitoring, transparency, and robustness are highlighted regarding habitat compensation and general coastal policy. At present, habitat compensation is based upon a simple area-based balance sheet approach which overlooks key uncertainties and gives a misleading indication of progress. Climate change adaptation planning needs to include more flexibility based upon alternative scenarios and response pathways, especially regarding recent evidence for higher future sea-level rises. Robust responses also require more emphasis on improved interpretation of ecological functioning, integrity, and coherence, as essential concepts to facilitate ecosystem-based adaptation consistent with international conventions and application of the precautionary principle.

Sediment cells and their dynamics along the coasts of India – A review

Coastal zone is dynamic in nature and is subjected to multiple interactions from marine, terrestrial, atmosphere, biosphere, fluvial systems and tectonic processes besides human interventions. Each coast is unique to its geographical location and set of physical interactions between land and oceanic parameters. Understanding these interactions are challenging and complicated in perception of its sustainability. A central concept in developing such a holistic approach is to view the coast as discrete functional units termed as ‘Sediment Cells’ rather than viewing it as a single continuous stretch of land surface. Sediment cell approach will provide a better understanding of the interrelation between the functions of the short term coastal processes and long term response and recovery of the coast. Based on sediment cell approach, a study was undertaken to delineate discrete functional units along the west and east coasts of varying spatial scales with confined sediment movement. Long term morphological changes, short term coastal processes and sediment dynamics were considered for the delineation. A total of 26 primary cells with 10 on the west and 16 on the east were identified from the study. These primary cells were further sub divided into 58 sub cells with 21 on the west and 37 on the east based on the sediment interruption factors either natural or manmade. The identified coastal sediment cells can be used in Integrated Coastal Zone Management (ICZM) especially to deal with shoreline changes and in the preparation of Shoreline Management Plans (SMP). To be specific, the delineated coastal sediment cells from the study are being used for the preparation of ICZM plans for Odisha and West Bengal.

25 Years of Beach Carrying Capacity in Portugal: A Place for Everything and Everything in Its Place?

Pereira da Silva, C.; Fonseca, C., and Nogueira Mendes, R., 2020. 25 years of beach carrying capacity in Portugal: A place for everything and everything in its place? In: Malvarez, G. and Navas, F. (eds.), Global Coastal Issues of 2020. Journal of Coastal Research, Special Issue No. 95, pp. 920–924. Coconut Creek (Florida), ISSN 0749-0208.In Portugal, the concept of beach carrying capacity was introduced in 1993, with the Shoreline Management Plans. From the Portuguese experience of the last 25 years, a review of the concept is discussed; it's evolution and implementation, the challenges drawn from the practice, highlighting recommendations for future use. Despite some methodological weaknesses, the application of the carrying capacity concept contributed significantly to the better quality that most of the Portuguese beaches have nowadays, particularly to the improvement of a range of aspects like safety, infrastructures, accessibility, parking facilities. However, there are still a few issues that can be developed to make this concept more effective, like replacing the idea of a precise number by a threshold that should be used in a flexible way, adapted to any specific site conditions.

Future challenges of coastal landfills exacerbated by sea level rise

In England and Wales, there are at least 1700 coastal landfills in the coastal flood plain and at least 60 threatened by erosion, illustrating a global problem. These landfills are a major issue in shoreline management planning (SMP) which aims to manage the risks associated with flooding and coastal erosion. Where landfills exist, “hold the line” (requiring the building or upgrading of artificial defences to maintain the current shoreline) is often selected as the preferred SMP option, although government funding is not available at present. To investigate these issues in detail, three case-study landfills are used to examine the risks of future flooding and erosion together with potential mitigation options. These cases represent a contrasting range of coastal landfill settings. The study includes consideration of sea-level rise and climate change which exacerbates risks of erosion and flooding of landfills. It is fundamental to recognise that the release of solid waste in coastal zones is a problem with a geological timescale and these problems will not go away if ignored. Future erosion and release of solid waste is found to be more of a threat than flooding and leachate release from landfills. However, while leachate release can be assessed, there is presently a lack of methods to assess the risks from the release of solid waste. Hence, a lack of science constrains the design of remediation options.

Coastal Adaptation Planning in Fairbourne, Wales: lessons for Climate Change Adaptation

ABSTRACTAdaptation to climate change is emerging as a central objective and policy frame for coastal communities. This paper examines recent climate change adaptation efforts in the UK, centring on the case of Fairbourne, Wales. The village is facing the long-term prospect of flooding and inundation due to the impacts of sea level rise. The recent Shoreline Management Plan for the area has recommended realignment of the coast and eventual decommissioning of Fairbourne. The paper draws on a qualitative research methodology of interviews, policy review and observation to narrate the case and provide key insights and lessons for planners working in environmentally vulnerable coastal settings and managing climate adaptation processes.

A new perspective on meso-scale shoreline dynamics through data-driven analysis

The twin ambits of climate change and coastal development have raised public awareness of shoreline management. Simultaneously, they have highlighted a gap in our understanding of sediment transport and morphodynamic processes at time and space scales appropriate for shoreline management purposes. Here, we analyse an exceptional set of beach surveys gathered over a period of twenty-two years along the Suffolk coast, eastern UK, that extends over approximately 80 km to investigate the meso-scale shoreline variations. The surveys have been made biannually along fixed transects spaced at approximately 1 km intervals as part of a strategic monitoring exercise undertaken by the coastal authorities to assist in shoreline management planning. Changes in beach volume, foreshore slope and shoreline position have been computed to investigate both spatial and temporal changes. The analysis reveals some distinct responses to the physical processes of tides and waves, anthropogenic interventions and geological controls. Neither a clear relationship between the presence of sea defences and beach response nor an ordered regional-scale shoreline movement are evident. Temporal variations in beach volumes and position provide a similarly complex picture with recessionary, accretionary and stable behaviour all apparent within the study site. There is evidence of quasi-cyclic behaviour at some locations as well as a reduction in variability over time-scales beyond approximately five years.

Shoreline management plan for embayed beaches: A case study at Vengurla, west coast of India

Embayed beaches play an important role in ensuring the environmental and morphological sustenance of coastal areas. Coastal processes along embayed beaches are different from that of open beaches. Shoreline management along embayed beaches is a major concern for engineers and policy makers worldwide, which requires a clear understanding of shoreline evolution. As shoreline evolution is the combined effect of natural and human activities, which vary over space and time, numerical models are vital to understanding shoreline change behaviour. The present study was carried out at Vengurla, an embayed beach along the west coast of India, using a well established numerical model. Wave climate, bathymetry, sediment characteristics and initial coastline were the primary inputs for the model. Nearshore wave climate at a depth of 15 m was collected using a wave rider buoy for the year 2015. Bathymetry and nearshore sediments were also collected during the same year. The initial coastline was extracted from satellite imagery of the year 2015. Shoreline change was studied over the preceding 26 years (1990–2016) using nine different satellite images. The model was then run for the following 26 years (2015–40), with present wave climate and future expected increase in wave heights. The results indicate that Vengurla embayed beach is not only affected by various anthropogenic modifications including the destruction of sand dunes, but also by future climate-change projections. We propose the implementation of a dune based shoreline management plan with strict regulations and awareness program. The findings of this study will interest policy makers and environmental managers, guiding them in developing management strategies for protection of this embayed beach. Overall, this paper demonstrates how numerical modelling can help in designing the shoreline management plan for an embayed beach, which can lead to save costs and to prevent further destruction of the beach.

An assessment of areal and transect-based historic shoreline changes in the context of coastal planning

With increasing sea levels and anthropogenic coastal pressure, it is more important than ever to develop coastal zone management techniques that are based on sound scientific methodologies. In this paper shoreline change rates were calculated for Port Eynon Bay, Gower, Wales, UK, using a two-step approach (areal and transect-based), to predict future shoreline position and propose management strategies. A Geographical Information System (Qgis) was utilised to calculate shoreline position from historical aerial photographic evidence covering a 60-year period (1944–2014). Results highlighted an increase in the vegetation of 0.41 km2 and a seaward migration of the shoreline (0.3 m/yr.−1); temporal linear regression models constructed around the cumulative data confirmed a consistent trend of areal increase and shoreline migration. Wind components were qualitatively linked to shoreline changes. Models created to predict shoreline position at 10-year and 50-year epochs can be aligned with shoreline management plans and inform embayed beach shoreline assessments at all scales. A management process model was developed based upon the application of transect and areal assessments that can be utilised to inform CZM by identifying locations of vulnerability, enabling management strategy development, that improves resilience under scenarios of sea level rise and climate change.

Shoreline Change Analysis at Chilika Lagoon Coast, India Using Digital Shoreline Analysis System

Shoreline is the dynamic interfaces of both terrestrial and marine environment, which constantly affected by natural coastal processes includes wave, tide, littoral drift and cyclonic storms as well as coastal development. Wave induced littoral drift and fluvial discharge causing the gradual inlet migration and has the concurrent impact on shoreline of Chilika lagoon. This study is to determine the long-term shoreline changes along the coast of Chilika lagoon. Historical satellite images were used to analyse the shoreline erosion and accretion based on statistical approach. The satellite data from 1975 to 2015 were processed by using ERDAS Imagine and the shorelines are extracted. The shoreline oscillation was analysed at an interval of 100 m along the coast of Chilika lagoon using DSAS software. Most commonly used statistical methods such as end point rate and linear regression rate are used. The shoreline change analysis for entire coast of the lagoon since 40 years (1975–2015) indicates that 62% is of accretion, 25% is under stable coast and erosion is 13%. The result reveals that the lagoon coast shows high accretion of 9.12 m/year at updrift side of the lagoon inlet whereas the downdrift side shows high erosion of − 10.73 m/year due to the wave induced northeasterly longshore sediment transport round the year and riverine discharge. This study would provide the potential erosion and accretion area at Chilika lagoon coast and would help in adaptive shoreline management plan.

Adaptive management and community reaction: The activities of Coastal Action Groups (CAGs) within the shoreline management process in England

Changes in UK government coastal and flooding policies in the last twenty-five years, have resulted in a reappraisal of all coastal defence schemes with a focus on a strategic analysis to ensure that all schemes provided the greatest net benefit. This strategy and the emphasis on adaptive management, particularly in the second wave of shoreline management plans (SMPs), provoked a reaction from local communities who felt their voice was largely being ignored as they became aware of SMP policies that increased their perceived risks but did not offer appropriate compensation. The formation of Coastal Action Groups (CAGs), has been a key community response and enabled diverse communities to feel that they can collectively participate in the ongoing planning process. Using a combination of questionnaire surveys and semi-structured interviews, this paper analyses the nature and effectiveness of CAGs. Although initially formed as opposition groups, the shared ideology of CAG members has resulted in the character of these groups evolving to units that embrace a broader range of social justice issues. It is argued that well led, well-supported, well-resourced and tactically astute CAGs have tended to be the most effective pressure groups. In reality however, CAGs have had relatively limited effects in changing the decisions of local SMPs, but have had great impacts in challenging the concept of meaningful public engagement in the coastal planning process, ultimately leading to more participatory approaches.