The typical approach for generating nonlinear waves in physical models involves employing first- or second-order wave theory, requiring a large water depth at the wavemaker. When the prototype bathymetry shows a gentle slope, a large facility is required. However, practical constraints often make this unfeasible, leading to the use of steep transition slopes to obtain sufficient water depth at the generator. Incorporating a transition slope may generate unwanted free waves beyond the transition point, significantly impacting the wave parameters. The presence of these free waves causes the response of the tested structure to deviate from that found in the prototype. This paper offers guidelines for using transition slopes effectively while avoiding the generation of unwanted free waves after the transition point.
Numerical tests are performed to investigate wave transformations of nonlinear nonbreaking regular waves with normal incidence to the shore in decreasing and increasing water depth. The wave height transformation (shoaling) of nonlinear waves can, just as for linear waves, be described by conservation of the mechanical energy flux. The numerical tests show that the mechanical energy flux for nonlinear waves on sloping foreshores is well described by stream function wave theory for horizontal foreshore. Thus, this theory can be used to estimate the shoaled wave height. Furthermore, the amplitude and the celerity of the wave components of nonlinear waves on mildly sloping foreshores can also be predicted with the stream function wave theory. The tests also show that waves propagating to deeper water (de-shoaling) on a very gentle foreshore with a slope of cot(β) = 1200 can be described in the same way as shoaling waves. For de-shoaling on steeper foreshores, free waves are released leading to waves that are not of constant form and thus cannot be modelled by the proposed approach.
Marine Spatial Planning (MSP) requires the analysis of the spatial distribution of marine uses and environmental conditions. Such analyzes can be carried out with GIS, but standard GIS programs do not feature a toolbox that combines the most needed functionalities for such analyses. The SPACEA toolbox presented here was created to bundle and adapt existing functionalities in one toolbox. SPACEA consists of several script tools that have been designed to be user-friendly and applicable to different analyzes for MSP. This includes the processing of different input layers with regard to marine uses and environmental conditions. The main functionalities of SPACEA are exemplified in a fictional case study in the Baltic Sea, where the tools are applied to find potentially suitable areas for mussel farming. The tools feature a user-friendly interface and more experienced users may also use the provided sample codes to run it from the python window or as a stand-alone script. As such, the tools can be applied by users with different levels of GIS knowledge and experience.
A new proposed framework to assess sustainability impacts of maritime spatial plans (MSP-SA) utilizes the ecosystem service (ES) concept to address the often-lacking social sustainability of the plans. This study departs from the MSP-SA framework and applies it to the (emerging) sea use of mussel farming. Informed by a literature review and two surveys, it is investigated whether the benefits and impacts of mussel farming can be related to underlying ES and relevant planning questions. The results show that most benefits and impacts of mussel farming can be connected to ES and reveal different user-environment-beneficiary interactions, ranging from conflicts to synergies. The marine planning framework is structured into different planning phases and it is shown that the ES concept can contribute to a normative vision, strategic objectives, and site-specific operational questions. Studying the different user-environment-beneficiary interactions can reveal who benefits and who loses from planning decisions. While the marine planning framework developed in this study is targeted at mussel farming, the approach can be adapted to other uses and planning areas and can contribute to social and equity aspects in MSP by considering the receivers of (dis)benefits.
There is growing evidence that the ecosystem service (ES) concept can provide valuable input to marine spatial planning (MSP), by highlighting which ecosystem goods and services can be produced from a planning area. ES link the underlying ecosystem processes and functions to the benefits humans can receive from ecosystems (the ecosystem cascade). In this study, we argue that the ecosystem cascade can be used to structure the stock-taking and future scenario analysis in MSP. However, indicators, which are needed for measuring ES, have often been applied in various ways to the different steps of the cascade. Here, we apply a consistent approach to sorting indicators into the cascade. The indicators are presented in an indicator pool that can be used to filter them based on the cascade steps, several quality criteria, and themes. The pool consists of 772 indicators, of which 735 were analyzed. In total, 252 analyzed indicators belong to the provisioning services, 314 indicators to the regulating services and 169 to the cultural services. The indicator pool offers a suitable starting point to select indicators for ES assessments within MSP. Using indicators at the different cascade steps allows the assessment of i) the ecosystem components generating the services and ii) the impacts on ES and their beneficiaries when changes occur in the provision of the services due to planning or management decisions.
Tropical marine ecosystems provide a wide range of provisioning, regulating, supporting and cultural services to millions of people. They also largely contribute to blue carbon sequestration. Mangroves, seaweeds, and seagrass habitats are important because they store large amounts of organic carbon while fish play a fundamental role in the carbon transport to deep waters. Protecting and restoring tropical marine ecosystems is of great value to society because their decline impairs the vital services they provide, such as coastal protection and seafood supplies. In this marine policy paper, we present options for enhancing blue carbon sequestration in tropical coastal areas. In addition, we outline the economic value of four components of coastal ecosystems (mangroves, seagrass beds, seaweed forests and fish) and discuss the economic levers society can apply to ensure the end of the current gross mismanagement of tropical blue carbon ecosystems. Market-based solutions, such as carbon taxes or fines for violations that use the ‘polluter pays' principle, can be very effective in achieving national or international climate agreements. Private investment can also finance the preservation of blue carbon ecosystems. One widely known financing method for blue carbon conservation, particularly of mangroves, is the use of municipal bonds, which can be issued like traditional bonds to finance the day-to-day obligations of cities, states and counties. Non-philanthropic investments can also be used in order to protect these ecosystems, such as debt-for-nature swaps and the improved application of regulatory frameworks. Overall, the protection of tropical marine ecosystems is an ecological imperative and should also be seen as an opportunity for new revenue streams and debt reduction for countries worldwide.
The offshore oilfields in the North Sea area are increasingly employed for projects beyond oil production, like carbon capture and storage (CCS). Still, the fossil fuel production from mature fields is significant. It has raised environmental concerns associated with discharging produced waters (PW) and drilling mud into the sea. These discharges, which may be highly saline and contain production chemicals, vary significantly in metals and particulate content. Due to density and release depth, the plume is assumed to sink towards the seafloor. Also, a single oilfield can input up to 7.5 tons of Ba, 675 kg of Fe, and 619 kg of P into the water column through PW. Therefore, this study investigates the impact of these discharges on seafloor sediments around two Danish oilfields, assesses the mobility of metals within these sediments, and evaluates the environmental status. PW samples were collected at the discharge outlets from the platforms. Sediment cores were taken near the two oil platforms and from control sites. Using Inductively Coupled Plasma Mass Spectrometry (ICP-MS) and an optimized BCR sequential extraction, we analyzed the composition and distribution of 24 elements in sediment samples. The results revealed significant differences in total extracted concentrations between sediments near the platforms and those from distant locations and stratigraphically older samples, with relevant levels of Br, Ba, and Sn near the platforms (averaged 14, 27, and 0.1 ppb, respectively). Sediment quality indices showed considerable enrichment and geo-accumulation of toxic metals, particularly at one of the platform sites. However, cumulative indices did not display significant pollution anomalies. Therefore, our findings suggest that oil extraction activities may increase the availability of toxic metals in nearby sediments, potentially impacting marine ecosystems.
A new motivation for marine restoration has been observed, associated with the dissatisfaction with current marine restoration governance arrangements (MRGAs). An MRGA consists of alliances of public and private actors (coalitions) who, through their common conceptualisation of the problem (discourses), try to influence and design marine restoration activities while considering the rules of decision-making, and the management of limited resources. Emerging MRGAs rise in parallel to existing ones and aim to contribute to the same goals or show another way of reaching those goals. This phenomenon raises questions of legitimacy both for the emerging and the existing arrangement. Building on existing literature, this paper proposes an analytical framework to simultaneously explore input, throughput and output legitimacy as three essential pre-conditions of legitimacy for MRGAs. The framework is tested in three European cases of MRGAs that were part of the European Union MERCES project (http://www.merces-project.eu/). Analysis showed that actors who are influential in achieving restoration goals, and also those who are impacted by restoration actions, should be involved in the MRGAs (input legitimacy); actors within MRGAs should establish and follow procedures for decision-making that are both transparent and clear (throughput legitimacy); and actors within MRGAs need to establish a common understanding of restoration, of the goal to reach and of the related uncertainties (output legitimacy). Awareness of these pre-conditions allows actors internal and external to MRGAs to address aspects that give legitimacy to restoration actions. It also creates a language that allows actors to engage in discussion on legitimacy that goes beyond the mere application of the rule of law.
This article contributes to the accelerating development of methods for sustainability assessment (SA) to support maritime spatial planning (MSP), by proposing an ecosystem services based framework for SA. MSP is generally seen as an important approach to promote a more sustainable use of sea space. However, so far all sustainability concerns are not equally well represented in planning practice; in particular, social sustainability aspects such as social justice and sociocultural values related to human-nature connectedness receive less attention. We first explored concepts and principles related to sustainability assessment and social sustainability in the scientific literature. Based on this, we analyzed how far the present approaches to assessments in Baltic Sea EU Member States have been extended from environmental concerns to towards broader sustainability concerns so far. Using current best practice in two pioneering countries (UK and Sweden), we illustrated how social sustainability principles could match with applied social impact criteria, and further, how such criteria can inform an ecosystem services-based impact assessment framework. Based on existing frameworks, including the DPSIR (driving forces, pressures, state, impact, response) environmental assessment framework and the ecosystem service cascade, we propose a sustainability impact assessment framework for MSP (MSP-SA) integrating across sustainability dimensions and including assessment of distributional aspects of marine ecosystem service benefits. Finally, we discuss the applicability and further development of the framework in relation to present day sustainability assessment practice in MSP.
The main objective of this research is to present an improved and more accurate formula to estimate the reflection coefficient (K R ) for rubble mound breakwaters. Physical model tests were performed for this purpose and existing data was also considered. The evaluation of existing prediction formulas for K R based on the Iribarren number (ξ) shows that the scatter in the experimental results increases with increasing ξ. This is caused by the wavelength having greater influence on the reflection than the wave height and thus the use of the wave steepness is inappropriate. The influence of potentially dimensionless parameters on the wave reflection from literature was analyzed. The major dimensionless parameters were found to be the relative water depth (h/L) and the structure front slope angle (α). Hence, a formula to estimate wave reflection for rubble mound breakwaters based on these two parameters is proposed.