Query: Structural design of an innovative multifunctional artificial reef

title: Structural design of an innovative multifunctional artificial reef
abstract: Marine resources are essential to support an ever growing world population and approaches that can foster the growth and survival rates of habitats and promote the sustainability of human activities are seen as urgent. Artificial reefs (AR) or multifunctional artificial reefs (MFAR) are considered promising and viable solutions to increase the number of marine populations, prevent erosion and produce energy. As a consequence, there have been several attempts to design these structures in recent years. Several challenges still exist, related to the design approaches, materials used, durability requirements, hydrodynamic behaviour and interaction with the environment (fluid) among others. Thereby, the aim of this research is to discuss the structural behaviour of a concrete and steel complex, modular, slender and reticulated MFAR and to develop its design, by using numerical analysis. In order to do that, computational fluid dynamics models (CFD) and fluid structure interaction (FSI) are considered. This analysis shows great complexity and the results show that the design of these innovative structures is both challenging and promising.

title: Innovative monitoring strategies for multifunctional artificial reefs
abstract: This paper is focused on topic of exploration structural health monitoring which serve for several purposes. However, optimization of design and construction of MFARs considering civil and environmental engineering means is poorly investigated. The aim of this paper is to describe define structural monitoring capabilities which were implemented to creation of Multifunctional artificial reefs (MFAR) Prospective reef will be capable to perform as a potential tool for marine biodiversity restoration and rehabilitation, coastal protection to prevent erosion of a shore line and a scientific platform with various sensors able to self monitoring and sensing ambient environment. Main efforts have been dedicated to review of existing state of the art on Structural Health Monitoring (SHM) methods for offshore systems and computations of fluid structure interaction to validate possible approaches. Suggestions in optimization of future sensors integration for monitoring structural health and environmental variables have been provided based on data from state of the art and simulation results. Delivered artificial reef design will serve as a base for future manufacturing of the artificial reef modules to help provide insight in how human made construction may affect marine and coastal ecosystems.

title: Experimental testing and CFD modelling for prototype design of innovative Artificial Reef structures
abstract: This research aims to provide insight on the experimental results obtained induring hydraulic flume channel testing of a multifunctional artificial reef (MFAR) prototype employing various turbulence models and discretization schemes for Computational Fluid Dynamics (CFD) numerical simulations. The recently developed Multifunctional Artificial Reef is believed to be an effective tool to support marine ecosystem regeneration. Innovative design of the reef structure involves reticulated unconventional geometry, which results in complex interactions with the surrounding environment. To evaluate the structures behavior in water flow, hydraulic water flume tests were performed, to obtain the horizontal and vertical mean water flow velocity profiles.Additionally, the experimental setup and conditions were replicated in numerical simulation models to obtain comparative results, using different turbulence models and solution controls. Finally, these physical experimental results could be compared against numerical models within the CFD. This proved that the second order discretization scheme, and particularly k o turbulence model, had the closest approximation to experimentally obtained data.

title: Biofilms: an emergent form of bacterial life
abstract: Bacterial biofilms are formed by communities that are embedded in a self produced matrix of extracellular polymeric substances (EPS) Importantly, bacteria in biofilms exhibit a set of 'emergent properties' that differ substantially from free living bacterial cells. In this Review, we consider the fundamental role of the biofilm matrix in establishing the emergent properties of biofilms, describing how the characteristic features of biofilms such as social cooperation, resource capture and enhanced survival of exposure to antimicrobials all rely on the structural and functional properties of the matrix. Finally, we highlight the value of an ecological perspective in the study of the emergent properties of biofilms, which enables an appreciation of the ecological success of biofilms as habitat formers and, more generally, as a bacterial lifestyle.

title: Morphological impact of a deep water reef
abstract: For local protection of coastal stretches where buildings are situated in or form part of the coastal defense line the deep water reef concept has been developed. Two reef concepts were designed; a shore parallel breakwater (of 3 km length) and a segmented breakwater (three blinds of 1 km length) both located in 10 m water depth at 1.5 km off the coast of Scheveningen. In the present research the hydrodynamics and long term morphodynamics of the two deep water reefs are analyzed with the physics based numerical model Delft3D. The two reef concepts are modeled in 2DH mode with the Parallel Online morphological approach. The hydrodynamic processes at submerged breakwaters are different from those operating at emerged breakwaters. Wave transmission by the submerged breakwater crest creates two additional effects; 1) a water level set up with a discharge over the reef and 2) reduced wave action at the landward area of the reef. The water level set up drives two large scale circulation cells off the reef tips, with velocities up to 1 m/s. In the surf zone the longshore currents are directed towards the shadow zone, where the second effect creates a sheltered area. The magnitude of these effects is for the parallel reef concept amongst other parameters dependent on the wave height and wave transmission, whereas for the blinds reef concept this is also dependent on the wave direction due to the orientation of the blinds. The longshore varying currents and reduced waves in the surf zone cause the coastline to development into a salient form. At the lee of the reef accretion occurs, whereas at the southward and northward sides of the sheltered area erosion occurs. The morphological development is similar for the two reef concepts and of the same order of magnitude. The blinds reef is the preferred alternative for construction, as less severe erosion is modeled to occur. Equilibrium will likely be attained in 15 to 25 years after construction.

title: Artificial Reefs as Recreational Scuba Diving Resources: A Critical Review of Research
abstract: This paper reports on the increasing practice of developing and promoting artificial reefs as sites for scuba diving tourism and recreation. A comprehensive definition of artificial reefs is presented that encapsulates the diversity of structures used by marine recreationists, particularly scuba divers, followed by a review of existing literature that specifically examines artificial reefs as a resource for the conduct of recreational scuba diving. Three main thematic areas were identified in the existing literature: social dimensions, socioeconomic impacts and environmental engineering. A typology of artificial reefs is offered to better describe and categorise artificial reef structures according to unit characteristics that may influence recreational use such as material used, appearance, complexity and cost. The paper presents a conceptual model that identifies the components of an artificial reef scuba diving experience and discusses the potential of artificial reefs to act as tourism resources and management tools to redistribute scuba diver numbers away from natural reefs. Directions for future research are suggested, emphasising collection of data on aspects of the artificial reef scuba diving experience to better inform marine resource management.

title: Experimental characterization of the scour of innovative artificial reef prototypes using hydraulic flume and photogrammetry
abstract: This paper describes an experimental study of an innovative Multifunctional Artificial Reef geometry, as part of the decision framework for its planning, design, construction, and installation. The aim is to experimentally assess the scour phenomenon and the hydrodynamic behaviour of a small scale multifunctional artificial reef prototype (PMFAR) in a non cohesive bed of sediment. Hydraulic flume tests and a photogrammetry survey were conducted. An Acoustic Doppler Velocimeter was used to measure flow velocities both upstream and downstream of the PMFAR to quantify the impact of the PMFAR on the hydrodynamic flow field. A non invasive experimental method was developed, allowing information to be obtained on the scour cavity located around the structure and thus to characterize this phenomenon. This proved to be interesting and an important approach in support of the decision framework for the development and design of these innovative structures.

title: The economic, social and conservation benefits of recreation orientated artificial reefs

title: Design catalogue for eco engineering of coastal artificial structures: a multifunctional approach for stakeholders and end users
abstract: Coastal urbanisation, energy extraction, food production, shipping and transportation have led to the global proliferation of artificial structures within the coastal and marine environments (sensu "ocean sprawl" with subsequent loss of natural habitats and biodiversity. To mitigate and compensate impacts of ocean sprawl, the practice of eco engineering of artificial structures has been developed over the past decade. Eco engineering aims to create sustainable ecosystems that integrate human society with the natural environment for the benefit of both. The science of eco engineering has grown markedly, yet synthesis of research into a user friendly and practitioner focused format is lacking. Feedback from stakeholders has repeatedly stated that a "photo user guide" or "manual" covering the range of eco engineering options available for artificial structures would be beneficial. However, a detailed and structured "user guide" for eco engineering in coastal and marine environments is not yet possible; therefore we present an accessible review and catalogue of trialled eco engineering options and a summary of guidance for a range of different structures tailored for stakeholders and end users as the first step towards a structured manual. This work can thus serve as a potential template for future eco engineering guides. Here we provide suggestions for potential eco engineering designs to enhance biodiversity and ecosystem functioning and services of coastal artificial structures with the following structures covered: (1) rock revetment, breakwaters and groynes composed of armour stones or concrete units; (2) vertical and sloping seawalls; (3) over water structures (i.e. piers) and associated support structures; and (4) tidal river walls.

title: Innovative Coastal Risk Reduction through Hybrid Design: Combining Sand Cover and Structural Defenses
abstract: Miller, J. and Verhagen, H.J. 2020. Innovative coastal risk reduction through hybrid design: Combining sand cover and structural defenses.  174 188. Coconut Creek (Florida) ISSN 0749 0208. Worldwide, sand dunes and hard coastal structures help to minimize loss of lives and property from storm impact and flooding along or behind coastlines. Both sand dunes and hard coastal structures have their benefits and shortfalls in terms of protective capacity, cost, flexibility, and impact to coastal systems. Combining these two inherently different coastal risk reduction measures into a single hybrid system can preserve some of the individual benefits of each while creating an Engineering with Nature(tm) system that fulfills the requirements of high levels of protection, adaptability to future challenges related to climate change, sustainability, and pleasing natural aesthetics. Although such hybrid systems have the potential to become viable alternatives to conventional coastal risk reduction schemes, there are still many unknowns related to the interaction between the soft and hard structural components and their effectiveness in storm surge mitigation and flood prevention that require targeted research efforts to create acceptable design guidelines. Specifically, the combination of hard and soft alternatives into a single structure has not been studied in detail. Here, hybrid coastal risk reduction systems consisting of traditional hard structures (levees, revetments, and sea walls) covered by sand layers attempting to mimic dunes are investigated. It is emphasized that these sand covers can look like natural dunes, but they cannot evolve like natural dunes in the long term due to spatial constrictions along developed coasts and lack of natural sediment supply in eroding coastal systems. Just like any engineered beach and dune system, these hybrid structures require episodic maintenance nourishment, particularly after storm impact. The present overview covers design advances and issues related to both hard structures and engineered sand dunes for coastal risk reduction and investigates existing hybrid approaches. Future research goals to better understand hybrid coastal risk reduction systems and to create applicable design guidelines are discussed.