Beachrock Formation Mechanism Using Multiproxy Experimental Data from Natural and Artificial Beachrocks: Insights for a Potential Soft Engineering Method

Beachrocks are a window to the past environmental, geological, sedimentological and morphological conditions that were dominant in the coastal zone during their formation. Furthermore, beachrocks have the ability to reduce coastal erosion impact on sandy beaches. This study focuses on the beachrock formation mechanism through the comparison of cement characteristics, mineral chemistry and sedimentology of beachrock occurrences from two different geological and geographical localities: Diolkos, Corinth, Greece and Sumuide, Okinawa, Japan. In addition, in order to investigate a potential soft engineering method to protect coasts from erosion, artificial beachrock samples were created in vitro using sand samples and ureolytic bacteria from both areas under accelerating conditions. For Okinawa artificial beachrock experiments, the bacteria Pararhodobacter sp. was used, and for Diolkos, it was the bacteria Micrococcus yunnainensis sp. For the natural beachrocks, a multi-analytical approach was accomplished with the use of microscopic investigation, a scanning electron microscope, energy-dispersive X-ray spectroscopy, X-ray diffraction and X-ray fluorescence. Correlations were made between natural and artificial beachrocks. Results have shown that Diolkos beachrock was formed in the upper part of the intertidal zone, consisting of detrital material originating from the local bedrock, while Sumuide beachrock formed in the low intertidal–upper subtidal zone, consisting of coral sand and foraminifera fragments. For the artificial beachrocks, three samples were created using the microbial-induced carbonate precipitation (MICP) method, one from Diolkos (Corinth, Greece) and two from Sumuide (Okinawa, Japan). Diolkos artificial beachrock was better consolidated in comparison to Sumuide. Our investigation has shown that bacterial density was the key factor for the creation of the artificial beachrocks, while the samples’ granulometry played a secondary role in the process. The laboratory artificial beachrocks show encouraging results for a new soft engineering method to encounter beach erosion while keeping an ecofriendly character by saving energy, material resources and gas emissions. Artificial beachrocks can share the same properties of a natural beachrock and can contribute positively to marine biodiversity as a natural rocky habitat.

Mediterranean developed coasts: what future for the foredune restoration?

The feasibility and efficacy of soft engineering foredune restoration approaches still lack insight from research and monitoring activities, especially in areas where dunes are under persisting human disturbance. We evaluated the efficacy of Mediterranean foredune restoration in dune areas freely accessible to tourists. Foredunes were reconstructed using only sand already available at nearby places and consolidated through the plantation of seedlings of native ecosystem engineer species and foredune focal species. We monitored transplanted and spontaneous seedlings for one year to assess their mortality and growth in relation to the distance from the closest beach access, either formal or informal, as proxy of human disturbance. We also tested whether species differing in their ecology (i.e., affinity to a given habitat) and growth form showed different response to human disturbance. The relationship between seedling mortality and growth and the distance from the closest beach access was tested through Generalized Linear Mixed Models. We found a clear spatial pattern of seedling survival and growth, which decreased as the proximity to the closest beach access increased. Only invasive alien plants and erect leafy species showed to better perform at lower distances from beach accesses. In dune areas with a strong tourist vocation, foredune restoration should be coupled with the implementation of integrated management plans aiming at optimising the relationship between protection and use. Management plans should not only rely on passive conservation measures; rather they should include educational activities to stimulate a pro-environmental behaviour, increase the acceptance of behaviour rules and no entry zones, and actively engage stakeholders in long-term conservation.

Short-term seasonal changes of the Dzita beach of Ghana using geographic information system and photogrammetry

Coastal erosion has become an issue globally. As the sea level continues to rise due to global warming, projections are that erosion would increase. To address the issue sustainably, relevant scientific information such as sediment transport and shoreline dynamics is required at local scales. Over the years, erosion at the eastern coast of Ghana has been mainly evaluated using low-resolution imagery due to the challenges in retrieving high-resolution data in the nearshore region. An unmanned aerial vehicle (UAV) approach was used to assess beach evolution on a seasonal and short-term basis between May 2018 and December 2019. Using the UAV approach, shoreline changes, sediment volume changes, and profile elevation parameters were extracted for the Dzita beach of Ghana. Shoreline changes indicated the dominance of erosion during the first and third phases (May 2018 to December 2018 and June 2019 to December 2019, respectively) at a rate of −7.23 ± 0.23 and −4.85 ± 0.23 m/yr, whereas the second phase showed accretion of +8.44 ± 0.23 m/yr. Beach profiles from the first, second, and third phases had steep and gentle slopes, respectively. From these observations, it was recommended that soft engineering approaches such as beach nourishment should be implemented to protect the shoreline and strict prevention of nearshore sand mining and gravel mining. It is also possible that the beach could go through a cycle of changes. Further studies using this same approach should be done as well as probing into other parameters such as nearshore bathymetry to have a better understanding of beach dynamics as envisaged.

The socio-ecologic aspects of nature-based solutions for coastal flooding mitigation

<p>Coastal flooding has been historically mitigated through engineered artificial (grey) infrastructures such as breakwaters, dikes, and sea walls. However, these structures have a pervasive long-term impact on coastal ecosystems (e.g. sediment transport disruption), and require constant maintenance, and have little resilience to climate change (e.g. hurricanes, sea-level rise) related events.  Grey infrastructures failed to mitigate the effects of coastal floods, and the damages were significantly less in areas where healthy coastal ecosystems were present. This highlighted the role and contribution of coastal habitats to mitigate coastal floods and adapt to new conditions. The inefficiency of grey infrastructure to mitigate the impact of extreme events and following ecosystem-based management led to the development of the Nature-Based Solutions (NBS) concept. In the context of coastal flooding mitigation, to reduce the effects of storm surges, wave action, and erosion, NSB can be designed using (1) natural solutions (e.g., the creation of marine protected areas), (2) soft engineering and ecological restoration practices (e.g., mangrove plantation), and (3) hybrid solutions, which integrates natural and grey infrastructures (e.g. artificial reefs). NBS integrate multiple international environmental agendas, for their capacity to provide multiple co-benefits (e.g. recreation, fisheries). NBS are also key for supporting other agendas and global objectives: the Sustainable Development Goals (e.g. SDG14), Green/Blue economy, coastal resilient and climate-adapted coastal communities, biodiversity targets of the Convention for Biological Diversity and Circular Economy.</p><p> </p><p><br>“Lithuanian National Ecosystem Services Assessment and Mapping (LINESAM)” No. 09.3.3-LMT-K-712-01-0104 is funded by the European Social Fund according to the activity “Improvement of researchers’ qualification by implementing world-class R&D projects” of Measure No. 09.3.3-LMT-K-712.</p>

Protecting Coastlines from Flooding in a Changing Climate: A Preliminary Experimental Study to Investigate a Sustainable Approach

Rising sea levels are causing more frequent flooding events in coastal areas and generate many issues for coastal communities such as loss of property or damages to infrastructures. To address this issue, this paper reviews measures currently in place and identifies possible control measures that can be implemented to aid preservation of coastlines in the future. Breakwaters present a unique opportunity to proactively address the impact of coastal flooding. However, there is currently a lack of research into combined hard and soft engineering techniques. To address the global need for developing sustainable solutions, three specific breakwater configurations were designed and experimentally compared in the hydraulic laboratory at Coventry University to assess their performance in reducing overtopping and the impact of waves, quantifying the effectiveness of each. The investigation confirmed that stepped configurations work effectively in high amplitudes waves, especially with the presence of a slope angle to aid wave reflection. These results provide a very valuable preliminary investigation into novel sustainable solutions incorporating both artificial and natural based strategies that could be considered by local and national authorities for the planning of future mitigation strategies to defend coastal areas from flooding and erosion.

Manejo sostenible de inundaciones, cuencas y riberas en la provincia de Manabí

Sustainable management of floods, catchments and river banks in Manabí province En Manabí las autoridades locales y nacionales han elaborado e implementando planes de gestión de inundaciones; sin embargo, las inundaciones aún causan grandes daños frecuentemente. El objetivo de la presente investigación es explorar técnicas que se podrían aplicar en Manabí para un manejo sostenible de inundaciones (SFM). Dos objetivos específicos son: explorar los enfoques y técnicas para i) SFM basado en manejo de cuencas hidrográficas, y ii) SFM basado en manejo de ríos y riberas. Se realiza un análisis desde un punto de vista técnico, económico, social y ambiental. La revisión y el análisis revelan que, en cuanto a manejo de inundaciones basado en manejo la cuenca, existen proyectos y planes hidráulicos que han sido efectivos en cierta medida. Específicamente represas, muros para retención de escorrentía y encauzamiento de quebradas. Sin embargo, se ha venido dando un manejo inadecuado a las riberas de varios ríos. Sus taludes se limpian y quedan desprotegidos contra la erosión con posibles implicaciones para la sedimentación y el riesgo de inundación aguas abajo de las zonas intervenidas. Enfoques sostenibles incluyen la bioingeniería y la ‘ingeniería suave’. El presente análisis puede contribuir al debate sobre el camino a seguir para la gestión de inundaciones en la provincia. Palabras clave: Agua Superficial; Desastre Natural; Erosión; Gestión; Uso de la Tierra. Abstract In Manabí local and national authorities have implemented flood management plans; however, floods still cause major damages frequently. The objective of this research is to explore techniques that could be applied in Manabí for sustainable flood management (SFM). Two specific objectives are to explore the methods and techniques for i) SFM based on management of catchments, and ii) SFM based on management of rivers and riverbanks. An analysis is undertaken from the technical, economic, social and environmental points of view. The review and analysis reveals that, regarding flood management based on catchment management, there are projects and hydraulic plans that have been effective to some extent. Namely: dams, runoff-retention walls and gully channelization and diversion works. However, an inadequate management has been given to the banks of many rivers. These river banks are cleaned and left unprotected against erosion, with possible implications for sedimentation and flood risk downstream of the intervened areas. Sustainable approaches include bioengineering and 'soft engineering'. The present analysis can contribute to the debate on the way forward for flood management in the province. Keywords: Surface Water; Natural Disasters; Erosion; Management; Land Use.

Dynamic metal-polymer interaction for the design of chemoselective and long-lived hydrogenation catalysts

Metal catalysts are generally supported on hard inorganic materials because of their high thermochemical stabilities. Here, we support Pd catalysts on a thermochemically stable but “soft” engineering plastic, polyphenylene sulfide (PPS), for acetylene partial hydrogenation. Near the glass transition temperature (~353 K), the mobile PPS chains cover the entire surface of Pd particles via strong metal-polymer interactions. The Pd-PPS interface enables H2 activation only in the presence of acetylene that has a strong binding affinity to Pd and thus can disturb the Pd-PPS interface. Once acetylene is hydrogenated to weakly binding ethylene, re-adsorption of PPS on the Pd surface repels ethylene before it is further hydrogenated to ethane. The Pd-PPS interaction enables selective partial hydrogenation of acetylene to ethylene even in an ethylene-rich stream and suppresses catalyst deactivation due to coke formation. The results manifest the unique possibility of harnessing dynamic metal-polymer interaction for designing chemoselective and long-lived catalysts.

Shoreline Response to a Sandy Nourishment in a Wave-Dominated Coast Using Video Monitoring

Beach nourishment is a soft engineering intervention that supplies sand to the shore, to increase the beach recreational area and to decrease coastal vulnerability to erosion. This study presents the preliminary evaluation of nourishment works performed at the high-energy wave-dominated Portuguese coast. The shoreline was adopted as a proxy to study beach evolution in response to nourishment and to wave forcing. To achieve this aim, images collected by a video monitoring system were used. A nourishment calendar was drawn up based on video screening, highlighting the different zones and phases where the works took place. Over the six-month monitoring period, a total amount of 25 video-derived shorelines were detected by both manual and automated procedures on video imagery. Nourishment works, realized in summer, enlarged the emerged beach extension by about 90 m on average. During winter, the shoreline retreated about 50 m due to wave forcing. Spatial analysis showed that the northern beach sector was more vulnerable and subject to erosion, as it is the downdrift side of the groin.