1642 research outputs found
Sort by
Habitat suitability modelling for restoration of intertidal seagrass, Zostera noltei: A case study from The Greater Thames Estuary, UK
No full textSeagrasses are marine flowering plants that play crucial roles in blue carbon capture and coastal protection, providing a critical feeding and nursery habitat for several species. However, the extent of seagrass meadows has drastically decreased around the UK coastline since the 1930s. As such, restoration of Zostera spp. seagrasses is a growing field for academics and practitioners, yet for Zostera noltei (dwarf eelgrass) in particular, restoration is hampered by knowledge of current distributions and where to restore. Habitat suitability modelling is a valuable tool for mapping and can be applied by practitioners at a site-specific scale to identify potential areas for restoration. Here we have created a Maximum Entropy (maxent) habitat suitability model to predict Z. noltei suitability in the Greater Thames Estuary based on seven environmental variables at a ten-metre resolution within an intertidal boundary. Using areas of higher suitability to identify restoration potential, our results indicate 602.9 Ha of “good” suitable habitat for potential restoration around existing Z. noltei beds in the Thames, Medway and Swale Estuaries. Despite reasonable predictive accuracy, our model was limited by the availability, resolution and extent of important environmental variables such as sediment type. Nonetheless, we believe this is a valuable tool for practitioners in the initial stage of site selection at a local scale for Z. noltei restoration projects in the UK
Updating the UK Estuaries Database: Making key data and information readily available for everyone involved in estuarine management and monitoring.
No full textOver the last year, under the ReMeMaRe programme, the UK Estuaries Database and its online companion the Estuary Guide (http://www.estuary-guide.net) have been reviewed consulted upon and updated. This presentation describes these products and highlights the recent improvements made to them (including a new Estuaries Database Viewer hosted on ArcGIS Online).
The database and guide were first created over 20 years ago under the Estuary Research Programme (led and funded by the Environment Agency and Defra). They were developed by specialists to provide a central location where critical information about the characteristics, morphologies and dynamics of UK estuaries could be collated and readily accessed.
The information they contain has been valuable for managing and monitoring estuaries, but these products were getting old. The last update to the database was in 2015 while the online guide was created in 2004 and has only been supported, not improved, since then.
Following discussions with stakeholders during 2023, it was agreed that these tools should be reviewed and updated to support emerging uses for these information resources. This review was undertaken by ABPmer, HR Wallingford and Prof. Townend (the same core team that built and created the original products). It was informed by discussions with product users including those leading the Environment Agency’s Water Environment Regulations (WER) and Habitat Compensation and Restoration Programmes (HCRP).
In addition to describing the content, uses and new updates of these tools, this presentation considers how they can now be developed in the future
Hurricane surge and inundation in the Bahamas, part 2: Flood risk assessment
No full textA hurricane surge and inundation risk assessment has been carried out for Grand Bahama and Eleuthera in The Bahamas. 10,000 years of synthetic hurricane tracks were generated based on a statistical analysis of historical hurricanes from 1979 to 2020 inclusive. The surge and inundation were modelled using a hydrodynamic TELEMAC-2D model covering sea around The Bahamas and the land of the two islands. Predictions of flood extents and depths were mapped for return periods of up to 1000 years for present day conditions and three climate change scenarios to 2100. The flooding experienced over Grand Bahama during Hurricane Dorian in 2019, was estimated to have a return period of up to approximately 450 years. Under the climate change scenarios the likelihood of flooding similar to Hurricane Dorian was estimated to be approximately 1.7 times more likely in 2050 and up to 3.4 times as likely in 2100 under a high greenhouse gas emissions scenario. The storm surge maps can be used by the Bahamas Department of Meteorology and other government agencies for emergency management, planning of infrastructure and building resilience in response to climate change
Current uses and potential future needs for climate services in South Africa
No full textA central aim of climate services is the design and delivery of information that is tailored and targeted to different decision-making contexts. To assess whether climate services are meeting this aim, it is necessary to take stock of the progress that has been made while also identifying where the gaps and additional needs remain. This paper provides a summary of currently available climate services in South Africa, and details the needs for new climate services, informed by the 10 priority sectors identified as part of the National Framework for Climate Services South Africa (NFCS-SA). South African stakeholders’ needs were assessed via 1,032 responses to surveys and 27 interviews conducted between March 2020 and June 2023. The existing climate services landscape in South Africa is complex. Although a range of climate services have been produced, there remain gaps, as well as the need to improve the way in which climate information is communicated, especially for disadvantaged groups such as low-income farmers. The engagement of beneficiaries in the development of public climate services in South Africa has often been superficial and true co-production has yet to take place. However, meaningful co-production of climate services comes at a cost and it remains to be seen how this challenge can be addressed given that many South African stakeholders perceive weather information as a public good and their willingness to pay for climate services is low
Throw distribution across the Dabbahu−Manda Hararo dike-induced fault array: Implications for rifting and faulting
No full textDike intrusion and formation of overlying dike-induced normal faults facilitate plate extension. The kinematics of these dike-induced normal faults provide an accessible record of subsurface diking. Here, we use high-resolution light detection and ranging (LiDAR) and interferometric synthetic aperture radar (InSAR) data to explore how strain was distributed across a preexisting dike-induced fault array during diking events in the Dabbahu−Manda Hararo magmatic segment (Afar, Ethiopia) in 2008 and 2010. By analyzing throw of the dike-induced normal faults, we show that only a small number of faults were reactivated during each diking event; the distribution of this reactivation likely reflects dike depth, opening, and inclination, as well as fault orientation. We also show fault throw favorably accrued toward fault centers, away from areas of soft- or hard-linkage. Our high-resolution data sets demonstrate the importance of reactivation to rifting, as it means extension can occur at lower extensional forces, and that fault slip (and seismic hazard) may not localize at sites of fault linkage
Breakwater overtopping and transmission characteristics associated with living shoreline functional atributes
No full textThe twenty-first century has heralded a new direction and vision for the coastal engineering community. The goal is no longer to simply design solutions to resist the ravages of natural forces through brute force installation of hardened surfaces, but to instead work with nature and leverage natural processes to evolve solutions that are as effective in performing the primary role of defending the coast. Such an approach can bring added value to the solution by intrinsically integrating habitat and natural forms into the design.
At Illinois Beach State Park, some 20 miles north of Chicago Illinois, USA, the last vestiges of the natural Lake Michigan shoreline has been rapidly eroding away. In some areas, the losses reached tens of meters in annual retreat, permanently removing critical and unique habitat from the local ecosystem. The Illinois Department of Natural Resources sought to find a way to mitigate the losses in as natural and least intrusive means possible. In the ideal solution, the mitigation would be unseen by park visitors. Such a solution would incorporate designs assembling submerged reefs and the limited use of major offshore structures. The latter would be ideally configured as islands and disguised as geologic formations and embody significant habitat character
Force-chain finder: A software tool for the recursive detection of force-chains in granular materials via minor principal stress
No full textForce transmission in granular media occurs through an inhomogeneous network of inter-particle contacts referred to as force-chains. A thorough understanding of the structure of these chains is indispensable for a better comprehension of the macroscopic signatures they generate. This paper introduces Force-Chain Finder (FCF), an open-source software tool designed for detecting force-chains in granular materials. Leveraging the stress tensor computed for each particle based on its interactions with neighbouring particles, the tool effectively identifies the magnitude and direction of the most compressive principal stress. Through a recursive traversal of particles and their neighbours, force-chains are robustly detected based on the alignment of the principal stress directions, which is decided by a parameter α (an angle in radians). The software provides a comprehensive suite of post-processing features, including the exportation of results in different formats, enabling detailed analysis of specific regions and dynamic phenomena. Additionally, the software facilitates the computation of statistical measures pertaining to chain size and population. By streamlining the identification and characterization of force-chains within discrete element method (DEM) simulations, this tool significantly enhances the efficiency and accuracy of force-chain analysis. Thus, the software promotes deeper insights into the behaviour of granular materials by enabling researchers to effortlessly detect and analyse force-chains
Flocs as vectors for microplastics in the aquatic environment
No full textMicroplastics (MPs) are an important component of suspended particulate matter in aquatic environments with two main transport modes, that is, as individual entities or in flocs. Despite its importance to MP pollution management, understanding and predicting MP flocculation remains a challenge. In this Article, we combined a meta-analysis of published data (>2,000 measurements) with new experimental data (>4,000 measurements) to investigate which size fraction of MPs can be incorporated into and transported by flocs in the aquatic environment. The size relationship between MPs and flocs can be used to predict the flocculation of MPs in various aquatic environments, and we have proposed a mathematical model to show that small MPs (<162 µm) are predominantly transported as flocs, regardless of the physicochemical characteristics of the MPs or water body. This provides valuable information to predict the transport modes of MPs, presenting a critical insight for multiple environmental settings and future pollution control strategies
Wind, water level, and fluid mud thresholds in Lake Apopka, Florida
No full textA study was undertaken at Lake Apopka in Florida to assess the minimum water depth required to contain a wind-induced episodic rise of fluid mud. In a year-long investigation, measurements were made at the mean water depth of 1.3 m to record the variation of suspended sediment concentration due to bed erosion and settling of the flocculated matter. The height of rise is defined as the elevation above the bed at which the mud floc volume fraction is at the threshold between the so-called flocculation settling and hindered settling regimes. The rise, which is considered significant when fluid mud occupies the 0.2 m high benthic boundary layer (BBL), occurs when the threshold wind exceeds about 9 m s−1 corresponding to a 4% cumulative probability of occurrence. Predictive modeling suggests that in 2 m water depth the required wind would be about 14 m s−1 with a low probability of 2%. Moreover, a transition occurs from wave-dominant resuspension at low depths to current-dominance in deeper water, which likely influences BBL dynamics with potential effects on the benthic biota. Provided a higher than present depth can be sustained in the large lake, the deduced relationship between fluid mud rise, wind speed, and water depth makes it feasible to select the depth at which the frequency of fluid mud occupying the BBL remains acceptably low. The developed protocol is general enough to be applicable to other similar shallow lakes where fluid mud rise must be contained