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D4.4 - Model validation
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The transportation of hazardous and noxious substances (HNS) on ships has been on the rise in recent years, posing a significant threat to both human health and the environment. The spill of these chemicals can have far-reaching consequences, particularly when dealing with highly volatile substances that can spread rapidly and unpredictably. The MANIFESTS project has been established with the goal of better understanding the behaviour of these substances to improve response capabilities in the event of a spill. Through research and analysis, the project aims to improve already existing models for predicting the behaviour of HNS in various environments, and to validate these models through a series of experiments and real-world scenarios. Models are essential tools to understand and predict the behaviour of HNS in the event of a spill. However, they are not perfect and have limitations in terms of accuracy, which must be considered by the users. During the MANIFESTS project, the models CHEMMAP, OpenDrift, OSERIT, and MOHID, have been utilized and compared against separate sets of data. These models will be introduced briefly in the next section. This report consists of three validation sections. The first section compares a small-scale laboratory experiment that visualizes the competition between evaporation, dissolution, and volatilization, and assesses the model's ability to simulate these processes. The second section investigates the impact of wind on the evaporation rate and provides as much environmental data as possible to the model, using a wind tunnel. The two last section of this report compares the models' simulation with the sea trials that took place at the end of May 2022. These sections compare both the drift in the water and the air dispersion against field data. By analysing these different experiments, we can understand the capabilities and limitations of the models used in this project.
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RBINS Staff Publications 2023 OA
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D4.3 - Models intercomparison
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Maritime transport represents more than 80% of the international trade volume (UNCTAD, 2017). Apart from crude oil, tanker trades of refined petroleum products, chemicals and gas have increased by 4% over the 2019-2021 period, with a 5.6% growth in Liquefied Natural Gas (LNG) trade (UNCTAD, 2022). The volume of hazardous and noxious substances (HNS) is thus constantly rising with an increased risk of accidental spillages potentially associated with marine pollutions, whether in ports or in the open sea. In the event of an incident and a spill in the environment, information on the fate of the chemical(s) involved is essential to better anticipate the risks incurred by responders and populations, the impacts on the environment as well as the appropriate response techniques (Mamaca et al., 2009). Chemicals accidentally spilled into the marine or aquatic environment generally undergo physical-chemical modifications that will characterize their behaviour and fate. As observed by Mamaca et al. (2004) and Le Floch et al. (2011), these modifications are dependent on the intrinsic parameters of the product involved, the in situ environmental parameters (temperature, density and salinity of the water) and the met-ocean conditions (e.g. sea state, wind speed, marine currents). A few hours following the spill short-term effects may thus occur such as spreading, natural dispersion in the water column (dissolution, emulsification) and evaporation into the atmosphere. Longer term degradation (e.g. polymerisation, biodegradation) and sedimentation processes can then follow, depending on the persistence and the nature of the substance. One of the main concerns is that around 2,000 different types of HNS are regularly shipped in bulk or package forms (Purnell, 2009) which thus make difficult to capture their behaviour if accidentally released in the environment. Of the wide variety of HNS traded, volatile and gaseous substances are particularly problematic for marine pollution response authorities. The release of such substances at sea can indeed lead to the formation of toxic, flammable, or explosive gas plumes – sometimes invisible to the naked eye – that can travel large distances and pose risks over a wide area in relatively short timescales. Yet, key information on the risks that responders or rescue teams could take when intervening, or those that could impact coastal communities and the environment when allowing a shipping casualty to dock at a place of refuge remain poorly known. The MANIFESTS EU-project is part of this context.
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RBINS Staff Publications 2023 OA
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D4.2 Improving the prediction of HNS concentration in the atmosphere
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Responding to maritime accidents can be extremely challenging when involving HNS that behave as evaporators. Due to their potential to form toxic or combustible clouds, evidence-based decisions are needed to protect the crew, responders, the coastal population and the environment. However, when an emergency is declared, key information is not always available for all the needs of responders. A case in point is the lack of knowledge and data to assess the risks that responders or rescue teams could take when intervening, or those that could impact coastal communities when allowing a shipping casualty to dock at a place of refuge. The MANIFESTS project aims to address these uncertainties and improve response and training capacities through the development of an operational decision-support system (DSS) for volatile HNS spills. Besides management and communication, the project includes four other work packages: WP2 on collecting new data on evaporators, WP3 on table top exercises and field training, WP4 on improving modelling tools and WP5 on the development of the DSS. Key expected outcomes include: · Operational guidance; · Desktop and field exercises; · In situ training; · Experimental data on gas cloud fate; · A brand-new fire and explosion modelling module; · Improved HNS database with new experimental data on evaporation/dissolution kinetics. This report presents the developments realized in the framework of the task 4.2. This task gave the opportunity to the MANIFESTS consortium to improve one or several features of their models allowing to better simulate the HNS concentration in the atmosphere. Only RBINS seizes this opportunity and has implemented in OSERIT some improvements in order to better simulate the HNS concentration at the sea surface, evaporation processes and finally has implemented a new atmosphere transport and dispersion model. OSERIT (Oil Spill Evaluation and Response Integrated Tool) is a model which describes the drift of a pollutant at sea using Lagrangian particle. It can be used in case of an accident with release of oil or chemical, to obtain an estimation of the pollution trajectory as well as some basic information about its behavior and fate at sea. In the framework of the MANIFESTS project, a new atmospheric dispersion module fully coupled to OSERIT has been developed and several marine processes have been improved. In this report, the improved processes are described and their actual implementation in OSERIT is explained.
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RBINS Staff Publications 2022 OA
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Quantification of hydrodynamic changes induced by an offshore mussel aquaculture farm using COHERENS (Part 2)
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The goal of this numerical study is the quantification of hydrodynamic changes (especially sea currents) induced by an offshore aquaculture farm similar to that of the industrial project “Westdiep Sea Farm”. To do that, a parameterization of the impact of longlines and droppers on hydrodynamics has been included in the 3D COHERENS hydrodynamic model and the impact of several configurations of the aquaculture farm on currents and bottom shear stress has been estimated in a simplified test case. In this previous internship project, a numerical study to quantify the impacts of an offshore aquaculture farm on hydrodynamics processes has been performed. To do so, a new module has been developed in the COHERENS model to compute the drag forces exerted by the droppers and then this module has been applied on a simplified case study, i.e. a modest farm with up to 40 longlines of 104 droppers and located in a straight open channel of 500 m width and 2 km length. The simulations show that, in all configurations tested, the presence of droppers significantly changes the hydrodynamics of the channel. Particularly, analysis of the bottom shear stress variations allowed to conclude that the presence of a modest offshore aquaculture farm could modify the erosion/sedimentation pattern around the farm, leading, for example, to a risk of destabilization of the neighbouring sandbanks, which would justify the implementation of an environmental monitoring program. Nevertheless, this previous work remains a preliminary study and many simplifications have been applied in order to obtain results in the given time. This second work (Part 2) will allow to refine the physics of the test channel in order to make it more realistic and to obtain results more faithful to the hydrodynamic reality in the North Sea. In this report, different sensitivity studies will be carried out mainly for the first phase of the project. Several metrics will be illustrated. Then, comparisons between the different phases will be made.
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RBINS Staff Publications 2022 OA
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Quantification of hydrodynamic changes induced by an offshore mussel aquaculture farm (SYMAPA)
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The goal of this numerical study is the quantification of hydrodynamic changes (especially sea currents) induced by an offshore aquaculture farm similar to that of the industrial project “Westdiep Sea Farm”. To do that, a parameterization of the impact of longlines and droppers on hydrodynamics has been included in the 3D COHERENS hydrodynamic model and the impact of several configurations of the aquaculture farm on currents and bottom shear stress has been estimated in a simplified test case. The mussel aquaculture technique of longlines used in this project is known to disturb currents by, among other things, increasing the velocity of currents under the farm and significantly increasing the turbulence developing in the wake of the rigs. From an environmental point of view, an open question is whether or not these changes can modify the erosion/sedimentation pattern around the farm, leading, for example, to a risk of destabilization of the neighbouring sandbanks. As part of the SYMAPA (Synergy between Mariculture & Passive Fisheries) project, the goal is to link current variations in and around the farm to the amount of food available for mussels attached to droppers. At the seabed, a link between hydrodynamic processes and modification of the sedimentation scheme may be considered following this report. This preliminary study can help lead to the final goal of determining the scope of the impact that the aquaculture farm may have on the ecosystems in the farm and on the benthos. Three major effects will be studied for three different farm designs: the impact on surface currents, the sinking of currents under the farm and the impact on bottom shear stress.
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RBINS Staff Publications 2022 OA
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D4.1 Explosive risk and fire module
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Responding to maritime accidents can be extremely challenging when involving HNS that behave as evaporators. Due to their potential to form toxic or combustible clouds, evidence-based decisions are needed to protect the crew, responders, the coastal population and the environment. However, when an emergency is declared, key information is not always available for all the needs of responders. A case in point is the lack of knowledge and data to assess the risks that responders or rescue teams could take when intervening, or those that could impact coastal communities when allowing a shipping casualty to dock at a place of refuge. The MANIFESTS project aims to address these uncertainties and improve response and training capacities through the development of an operational decision-support system (DSS) for volatile HNS spills. Besides management and communication, the project includes four other work packages: WP2 on collecting new data on evaporators, WP3 on table top exercises and field training, WP4 on improving modelling tools and WP5 on the development of the DSS. Key expected outcomes include: · Operational guidance; · Desktop and field exercises; · In situ training; · Experimental data on gas cloud fate; · A brand-new fire and explosion modelling module; · Improved HNS database with new experimental data on evaporation/dissolution kinetics. This report presents the results obtained in the framework of the task 4.1 aiming at developing tools that would help responders to asses risks in case of explosion and of fire of volatile HNS. The fire module computes the energy flux as a function of the distance to the fire source. It is useful to assess the safety distance at which e.g. a boat can approach a fire while keeping the crew safe. The energy flux can cause burning to people, and start new fire. The burning rate is also estimated. The explosion module computes the overpressure of the shockwave caused by the combustion of a chemical. This overpressure can be very dangerous for people and structure, causing wounds from minor injury to death and destruction of building. The model could be used to predict what could happen in case of the explosion of a stored explosive for instance. The two models are simplifications of the reality and do not take everything into account. Their results can be useful to have a rough idea of what could happen in open sea but should always be interpreted keeping the model hypotheses and limitations in mind. Due to the sensitivity of the topic, the source code of both modules is not made available to public
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RBINS Staff Publications 2021
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D2.1 - Literature review on past accident
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Maritime transport of Hazardous and Noxious Substances (HNS) has increased for 20 years, involving the risk of major pollution accidents with potentially more hazardous than oil. Chemicals may involve long-term environmental effects and the risks for public safety can be more severe for chemical releases (European Maritime Safety Agency [EMSA], 2007). Approximately 2,000 chemicals are transported by sea and only a few hundred chemicals are transported in bulk, but it represents the main volume of the chemical trade (Purnell, 2009). Alongside the expansion of chemicals transported at sea, incidents involving chemical tankers increased accordingly. Still, information on past and more recent incidents is not easily available. Furthermore, in the case of marine accident involving HNS, spill response is difficult due to the chemicals spilled, particularly when gas or volatile substances are released. The vapour cloud created can be toxic, flammable or explosive and there is a necessity to protect the crew, the population nearby as well as the environment and the stakeholders involved in marine pollution response. As an example, Figure 1 shows a picture of the explosion which occurred in September 2019 in the Ulsan harbour, South Korea. This explosion is the consequence of a styrene monomer leak on the chemical tanker Stolt Groenland that led to a massive explosion with fireball and mushroom cloud. The present report is a literature review on past accidents that have induced the formation of a toxic, flammable or explosive gas cloud. The information gathered will allow better identification of 1) the categories of chemicals most involved; 2) the main risks generated by the gas cloud dispersion in the air and 3) the consequences of a chemical slick on fire at the water surface as well as the hazard due to a vapour cloud explosion. This work is part of WP2: Enhancing knowledge and data on gases and evaporators of the MANIFESTS program (Managing risks and impacts from evaporating and gaseous substances to population safety) that studies risks associated to accidental chemical spills in the marine environment. The aim of this WP is to contribute to a better prediction of the consequences of vapour clouds due to marine accidents. This would facilitate the intervention of marine pollution organisms and would also help to protect population nearby, as we would know precisely where the dangerous area is.
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RBINS Staff Publications 2021 OA
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Quantification of hydrodynamic changes induced by an offshore mussel aquaculture farm (Part 1)
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The goal of this end-of-studies internship proposed by the Royal Belgian Institute of Natural Sciences (RBINS) is the quantification of hydrodynamic changes (especially sea currents) induced by an offshore aquaculture farm similar to that of the industrial project “Westdiep Sea Farm”. The mussel aquaculture technique used in this project is known to disturb currents by, among other things, increasing the velocity of currents under the farm and significantly increasing the turbulence developing in the wake of the rigs. However, according to the knowledge of the RBINS, no study quantifies these disturbances. From an environmental point of view, an open question is whether or not these changes can modify the erosion/sedimentation pattern around the farm, leading, for example, to a risk of destabilization of the neighbouring sandbanks. First, the objective of this internship is to implement the parameterization of droppers impacts in the COHERENS hydrodynamic model. For this, a literature study will be carried out. Then, a sensitivity study will be conducted in order to use the implementation in a test case of a similar and simplified mussel farm. If time permits, the final objective would be to apply these different tests and simulations on the realistic case of the "Westdiep Sea Farm".
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RBINS Staff Publications 2022 OA
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Etude d'impact des changements hydrodynamiques induits par une ferme d'aquaculture de moules offshore
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About 30 years ago, researchers of RBINS developed COHERENS (coupled hydrodynamical-ecological model for regional and shelf seas), a three-dimensional hydrodynamic model designed for a wide range of applications in coastal and shelf seas, estuaries, lakes and reservoirs. The main goal of this internship is to quantify the hydrographic changes (especially marine currents) induced by an offshore mussel aquaculture farm similar to the industrial project "Wesdiep Sea Farm", using the COHERENS model. The mussel aquaculture technique used in this project is known to disturb currents and turbulence in the water column. The goal of this internship is to implement the parameterisation of the impacts of the mussel droppers in the COHERENS hydrodynamic model as well as the addition of a new source term for turbulent kinetic energy production. Then, a sensitivity study will be carried out using the implementation made in a test case of a simplified mussel aquaculture farm. Note that in parallel to this report, a more complete report was produced for RBINS within the framework of this internship and the student has already been offered a contract of employment.
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RBINS Staff Publications 2022 OA
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Etude archéo-anthropologique du site de Huy, rue Saint-Hilaire
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RBINS Staff Publications 2023
