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Publication Materials and service lives alterations impacts on reducing the whole life embodied carbon of buildings: A case study of a student accommodation development in Ireland(Elsevier, 2025-03-13) Moran, Paul; Flynn, Jack; Larkin, Conor; Goggins, Jamie; Elkhayat, YoussefTo meet the growing demand for student accommodations and fulfil climate change targets, it is essential to establish a methodology for evaluating and reducing their whole-life embodied carbon (WLEC) emissions. The study aims to develop a robust methodology for assessing and reducing the WLEC emissions of a new student accommodation development in Ireland as a replicable case study for other countries. The developed method is based on EN 15978 building whole life cycle standard and EU Level(s) framework. The reduction methodology based on hotspot analysis identifies the most impactful life cycle modules and materials. WLEC assessments were performed on an actual project with two base case scenarios: blockwork (BW) walls for the tender stage and precast walls (PC) for the as-built stage. The WLEC emissions were 749 kgCO2e/m2 for the BW and 838 kgCO2e/m2 for the PC. The production stage modules (A1-A3) and the replacement module (B4) were the primary contributors, with 56 % and 34 %, respectively. The proposed WLEC reduction methodology altered the concrete and the rebar with lower EC alternatives available in the Irish market. It modified the service life of seven building elements to align with the manufacturer's standards. Consequently, the WBEC emissions were reduced by 27 % and 33 % for the BW and PC scenarios. This methodology promotes low-EC and durable alternatives to replace conventional materials for the upcoming student accommodation projects in Ireland to achieve the Climate Action Plan EC reduction target by 2030.Publication Field monitoring and instrumentation in microtunnelling/pipe jacking: A review and future directions(KeAi Publishing Communications Ltd., 2025-03-19) Wadood, Asad; McCabe, Bryan; Sheil, Brian B.; Science Foundation IrelandThe popularity of trenchless techniques as a means of utility pipeline installation in urban environments, specifically microtunnelling/pipe-jacking, has increased in recent years due to its minimally-disruptive nature and reduced carbon footprint in comparison to conventional open-cut excavation methods. The response of pipes during the jacking process is complex and is governed by several factors, including ground conditions, the amount and distribution of lubrication, pipe and annulus size, pipeline misalignments and jacking force eccentricity, among others. Design practice remains based on empirical equations and previous drives through similar geology, resulting in uncertainty in jacking force estimates, thereby restricting adoption of the technique. In order to improve our understanding of the pipe-jacking process, pipes incorporating sensors providing real-time measurements of earth pressures, pore water pressures, axial strains and hoop strains can be used; but the number of such studies reported in the literature is small and the potential of instrumentation on routine projects is largely untapped. Moreover, jacking pipe monitoring practice lags behind the state-of-the-art instrumentation techniques used for monitoring other geotechnical infrastructure. The purpose of this paper is to provide a thorough review of learnings from instrumented pipe-jacking case studies and other supporting research, as well as to propose potential solutions to research gaps in the current state of design practice and field monitoring of pipe jacking projects.Publication Geotechnical characteristics of Belfast's estuarine clayey silt (sleech)(AIMS Press, 2025-03-10) McCabe, Bryan A.; Lehane, Barry M.Belfast, the capital city of Northern Ireland and the second largest city on the island of Ireland, has experienced significant construction activity in recent years, yet relatively little has been published on the problematic soft estuarine deposits known locally as sleech which underlie the city and its hinterland. Results of a detailed characterization of the sleech at a site near Holywood, Co. Down, 8 km northeast of the city centre, are presented in this paper. This characterization was carried out in conjunction with a unique suite of full-scale foundation load tests at the site, commencing in the late 1990s. In situ tests clearly identified distinct sandy and silty horizons within the deposit, the bulk of which is a high-plasticity lightly-overconsolidated organic clayey silt, with clay content increasing with depth and clay fraction dominated by illite and chlorite. Both the moderate organic content and presence of diatom microfossils explain the relatively high Atterberg limits, the high compression index and the high friction angle of this material. Undrained shear strengths in triaxial compression fall at the upper end of the expected range based on a widely-used correlation with overconsolidation ratio, but are broadly compatible with in situ shear vane strengths corrected for plasticity index. The constant volume friction angle is remarkably insensitive to the specimen's stress history and the particle size distribution. Despite the high silt content, permeabilities and coefficients of consolidation are more typical of a clay than a silt. While the sleech behaviour is shown to be broadly similar to the estuarine deposits at the well-characterised geotechnical test bed at Bothkennar in Scotland, the paper illustrates that low OCR clays can have their own distinguishing characteristics.Publication Composite upcycling: An experimental study on mechanical behaviour of injection moulded parts prepared from recycled material extrusion printed parts, previously prepared using glass fibre polypropylene composite industry waste(Elsevier, 2025-03-12) Sam-Daliri, Omid; Flanagan, Tomas; Modi, Vedant; Finnegan, William; Harrison, Noel; Ghabezi, Pouyan; Department of Business, Enterprise and Innovation; Taighde Éireann – Research Ireland; Horizon EuropeUpcycling pre-existing material extrusion (MEX) fabricated products is nascent as the industry's broader adaptation of MEX printers can be observed. This manuscript elucidates the post-process injection moulding manufacturing technique applied to MEX-printed thermoplastic composite waste materials composed of industrial glass fibre-reinforced polypropylene (GFRPP) composite. It evaluates the impact of glass fibre weight fractions (15 %, 30 %, and 40 %) on the injection moulded specimens' flexural and ultimate tensile strength. The mechanical performance of the injection moulded parts was compared with MEX additive manufactured parts derived from identical material. Homogeneous glass fibre distribution within the thermoplastic matrix was discerned in the injection moulded components utilising an optical light microscope. The mean ultimate tensile strength of the injection moulded parts was 29 MPa for the samples exhibiting a 40 % fibre weight fraction. It was demonstrated that the increase in glass fibre content from 15 % to 40 % improved the tensile strength, flexural strength, and elastic modulus of injection moulded specimens by 52 %, 135 %, and 52 %, respectively. Scanning electron microscopy (SEM) of the fracture surface of the injection moulded specimens revealed that the glass fibres predominantly displayed fibre pull-out rather than fibre breakage. Subsequent SEM imaging indicated that in contrast to the MEX printing manufacturing technique, the injection moulding fabrication process of GFRPP generally reduced porosity and minimised internal defects. The findings indicated that injection moulding post-process manufacturing possesses superior mechanical attributes compared to specimens fabricated through MEX printing. The results have substantiated the successful transformation of waste industrial GFRPP material into standardised specimens through the injection moulding fabrication technique. This study shows the potential of upcycling printed engineering-grade components via injection moulding, thereby converting them into functional composites within a circular economy framework.Publication Investigation and validation of numerical models for composite wind turbine blades(Finnegan, William, Jiang, Yadong, Dumergue, Nicolas, Davies, Peter, & Goggins, Jamie. (2021). Investigation and Validation of Numerical Models for Composite Wind Turbine Blades. Journal of Marine Science and Engineering, 9(5), 525. https://doi.org/10.3390/jmse9050525, 2021-05-12) Finnegan, William; Jiang, Yadong; Dumergue, Nicolas; Davies, Peter; Goggins, Jamie; European Commission H2020; Science Foundation IrelandAs the world shifts to using renewable sources of energy, wind energy has been established as one of the leading forms of renewable energy. As the requirement for wind energy increases, so too does the size of the turbines themselves, where the latest turbines are 10 MW with a turbine diameter in excess of 190 m. The design and manufacture of the blades for these turbines will be critical if they are to last for the design life, where the accuracy of the numerical models used in the design process is paramount. Therefore, in this paper, three independent numerical models have been created using three available finite element method packages—ABAQUS, ANSYS, and CalculiX—and the results were compiled. Following this, the accuracy of the models has been evaluated and validated against the results from an experimental testing campaign. In order to complete the study, a 13 m full-scale wind turbine blade has been used, which has been subjected to static testing in both the edgewise and flapwise directions. The results from this testing campaign, along with the blade mass and natural frequencies, have been compared to the results from the independent numerical models. The differences in the models, along with other sources of error, have been discussed, which includes recommendations on the development of accurate numerical models.Publication Tidal stream to mainstream: Mechanical testing of composite tidal stream blades to de-risk operational design life(Springer, 2022-02-28) Glennon, Conor; Finnegan, William; Kaufmann, Nicholas; Meier, Patrick; Jiang, Yadong; Starzmann, Ralf; Goggins, JamieTidal energy has seen a surge of interest in recent years with several companies developing technology to harness the power of the world’s oceans where the operational capacity in Europe was over 11 MW in 2020. One such developer is the partnership of SCHOTTEL Hydro (Germany) and Sustainable Marine (UK) who have developed a scalable multi-turbine device equipped with 70 kW turbines and capable of operating in arrays at sites around the world. The technology to harness tidal energy is still at a relatively early stage of development; hence, de-risking of component parts plays a vital role on the road to commercialisation. Despite this, the number of tidal energy blades undergoing test programmes remains small. Two different rotor diameters have been developed for the aforementioned device such that it can be optimised for sites of varying potential. In this paper, a blade from each of the 4.0 m and 6.3 m diameter devices was tested for their responses in natural frequency, static loading and fatigue loading under test standards IEC 62600-3:2020 and DNVGL-ST-0164. Testing saw the survival of a blade in fatigue at a lifetime-equivalent load and the generation of natural frequency, strain and displacement results for both blades. Data generated from the testing as a whole will contribute to the modelling and validation of future tidal blades.Publication Optimisation of highly efficient composite blades for retrofitting existing wind turbines(MDPI, 2022-12-22) Jiang, Yadong; Finnegan, William; Flanagan, Tomas; Goggins, Jamie; Sustainable Energy Authority of Ireland; Science Foundation Ireland; MaREI Research Centre for Energy, Climate, and Marine; Marine InstituteCurrently, wind energy, a reliable, affordable, and clean energy source, contributes to 16% of Europe’s electricity. A typical modern wind turbine design lifespan is 20 years. In European Union countries, the number of wind turbines reaching 20 years or older will become significant beyond 2025. This research study presents a methodology aiming to upgrade rotor blades for existing wind turbines to extend the turbine life. This methodology employs blade element momentum theory, finite element analysis, genetic algorithm, and direct screen methods to optimise the blade external geometry and structural design, with the main objective to increase the blade power capture efficiency and enhance its structural performance. Meanwhile, the compatibility between the blade and the existing rotor of the wind turbine is considered during the optimisation. By applying this methodology to a 225 kW wind turbine, an optimal blade, which is compatible with the turbine hub, is proposed with the assistance of physical testing data. The optimised blade, which benefits from high-performance carbon-fibre composite material and layup optimisation, has a reduced tip deflection and self-weight of 48% and 31%, respectively, resulting in a significant reduction in resources, while improving its structural performance. In addition, for the optimised blade, there is an improvement in the power production of approximately 10.5% at a wind speed of 11 m/s, which results in an increase of over 4.2% in average annual power production compared to the existing turbine, without changing the blade length. Furthermore, an advanced aero-elastic-based simulation is conducted to ensure the changes made to the blade can guarantee an operation life of at least 20 years, which is equivalent to that of the reference blade.Publication Numerical modelling, manufacture and structural testing of a full-scale 1 MW tidal turbine blade(Elsevier, 2022-12-01) Finnegan, William; Jiang, Yadong; Meier, Patrick; Hung, Le Chi; Fagan, Edward; Wallace, Finlay; Glennon, Conor; Flanagan, Michael; Flanagan, Tomas; Goggins, Jamie; European Commission, H2020; Sustainable Energy Authority of Ireland (SEAI); Science Foundation Ireland; MaREI Research Centre for Energy, Climate and MarineRenewable energy is now accepted as the preferred alternative for electricity generation and as the replacement for fossil fuels. In recent years, tidal energy has shown promise as it is a more reliable source of renewable energy, compared to wind and solar, and 12 GWh of electricity from tidal energy was generated in 2020. As tidal technologies move closer to commercial viability, key components need to be optimised, tested and certified. Among the key components that need to be type-certified for tidal energy are the turbine blades. In this study, a full-scale fibre-reinforced composite blade for use on 1 MW power generating nacelles of a tidal turbine was developed through numerical modelling, advanced manufacture technologies and state-of-the-art structural testing techniques. As a result of the high loads and harsh environment that a tidal turbine operates in, the blades have been manufactured using glass fibre reinforced powder epoxy and underwent an advanced structural testing programme that proved its structural integrity, where the results were used to validate the outputs from the numerical model of the blade. The load of 1,008 kN applied to the blade during the static testing was the highest load ever reported on a tidal turbine blade and this is the first time a large composite tidal blade has its equivalent design life of 20+ years through structural fatigue testing at full-scale.Publication Mechanical performance of 3D-printed continuous fibre Onyx composites for drone applications: An experimental and numerical analysis(Elsevier, 2023-11-01) Vedrtnam, Ajitanshu; Ghabezi, Pouyan; Gunwant, Dheeraj; Jiang, Yadong; Sam-Daliri, Omid; Harrison, Noel; Goggins, Jamie; Finnegan, William; Enterprise Ireland; Science Foundation Ireland; MaREI Research Centre; European Regional Development Fund.As drone technology grows in popularity, its application to automate aspects of society is increasing at a similar rate, where drones are now being trialled for delivering payloads over short distances. In order to progress the technology, 3D composite printing is being used to develop complicated parts for improved aerodynamic design that can be produced efficiently, where the resultant composite part has high specific strength and rigidity. This article reports 3D printing of high specific strength, high-temperature Polyamide 6 (Onyx), continuous glass-fibre reinforced Onyx, and carbon-fibre reinforced Onyx composites and characterising their mechanical and fracture behaviour. The Onyx + CF composites displayed up to 1243 % and 1344 % improvement in Young's modulus and tensile strength over neat Onyx samples. The flexural strength of Onyx + CF samples was up to 316.6 % higher than the flexural strength of the neat Onyx sample. SEM micrographs showed a strong bond between the hydration products and the carbon fibres, increasing their tensile and flexural strengths by preventing micro-crack propagation through fibre pull-out and breaking. The statistical analysis was conducted to ensure the validity of the results for the population and establish stress-strain relations, along with estimating errors. In addition, the carbon-fibre-reinforced Onyx composite was compared with commercially used alternatives for producing drone components. Finally, a finite element model was developed using a numerical homogenisation approach and validated to predict the tensile and flexural behaviour of Onyx and carbon-fibre reinforced Onyx samples. This study provides a direction for the next generation of drone manufacturers.Publication Structural analysis of a fibre-reinforced composite blade for a 1 MW tidal turbine rotor under degradation of seawater.(Springer, 2023-03-16) Jiang, Yadong; Finnegan, William; Wallace, Finlay; Flanagan, Michael; Flanagan, Tomas; Goggins, JamieThis paper presents a structural performance study of a fibre-reinforced composite blade for a 1 MW tidal turbine rotor blade that was designed for a floating tidal turbine device. The 8-m long blade was manufactured by ÉireComposites Teo and its structural performance was experimentally evaluated under mechanical loading in the Large Structures Research Laboratory at the University of Galway. Composite coupons, applied with an accelerated ageing process, were tested to evaluate the influence of seawater ageing effects on the performance of the materials. The material strength of the composites was found to have a considerable degradation under the seawater ingress. As part of the design stage, a digital twin of the rotor blade was developed, which was a finite-element model based on layered shell elements. The finite-element model was verified to have good accuracy, with a difference of 4% found in the blade tip deflection between the physically measured test results in the laboratory and numerical prediction from the model. By updating the numerical results with the material properties under seawater ageing effects, the structural performance of the tidal turbine blade under the working environment was studied. A negative impact from seawater ingress was found on the blade stiffness, strength and fatigue life. However, the results show that the blade can withstand the maximum design load and guarantee the safe operation of the tidal turbine within its design life under the seawater ingress.Publication Theoretical and experimental transverse vibration analysis of a non-uniform composite helical tidal turbine foil(Elsevier, 2024-06-08) Fakhari, Vahid; Munaweera Thanthirige, Tenis Ranjan; Flanagan, Michael; Kennedy, Ciaran; Jiang, Yadong; O'Conghaile, Micheal; Flanagan, Tomas; Courade, Clement; Cronin, Patrick; Dillon, Conor; Goggins, Jamie; Finnegan, William; Horizon 2020, European Commission; Enterprise Ireland; Science Foundation Ireland; Sustainable Energy Authority of IrelandRecently, tidal energy has gained attention as an attractive renewable source of power generation. In this context, tidal turbine foils must operate in harsh conditions and extremely variable dynamic loads. Considering the expensive dynamic tests required for these large structures, developing validated dynamic models could be valuable for failure prediction and design purposes. In this paper, the free and forced vibration behaviour of the cantilevered part of a non-uniform helical tidal turbine foil made from the composite material is investigated theoretically and experimentally. In this regard, governing vibration equations of the foil with related boundary conditions are presented. The free vibration analysis of the foil is performed by solving a boundary-value problem, where a closed-form solution, based on the mode summation method, for the forced vibration of the foil is employed. Finally, the obtained numerical results (natural frequency and dynamic displacements) are compared with the corresponding results from experiments to validate the vibration equations and the employed solution. Acceptable agreement between numerical and experimental data confirms that the vibration model presented in this study can be employed to predict the dynamic response, parametric study, optimization, and design of the tidal foil without performing costly experiments.Publication Advanced structural testing and modelling of a novel full-scale helical shape tidal turbine foil(Elsevier, 2025-02-13) Munaweera Thanthirige, Tenis Ranjan; Flanagan, Michael; Kennedy, Ciaran; Jiang, Yadong; O’Conghaile, Micheal; Courade, Clement; Cronin, Patrick; Dillon, Conor; Fakhari, Vahid; Ó Cadhain, Cormac; Walls, Michael; Bachour, Carlos; Flanagan, Tomas; Cahill, Brendan; McEntee, Jarlath; Goggins, Jamie; Finnegan, William; Horizon 2020, European Commission; Research Ireland; Sustainable Energy Authority of Ireland; Marine InstituteThe utilisation of tidal energy holds significant promise for sustainable power generation, particularly in regions with tidal resources. In this context, tidal energy sector is targeting to develop innovative tidal energy systems for tidal potential sites and rivers to enhance the green power generation and achieve United Nation’s sustainable development goals. However, ensuring the structural integrity of tidal turbine components, particularly the blades, is key for their effective operation, as blades play a pivotal role in determining the system's performance, lifetime, reliability, and efficiency. Therefore, the research aims to assess the structural integrity of a 5 m long crossflow helical tidal turbine foil, featuring a 1.8 m rotor and three foils designed to generate 40 kW, through structural testing and numerical modelling. The testing procedures adhere to DNVGL-ST-0164 and IEC DTS 62600–3:2020 standards, encompassing dynamic, static, fatigue, and residual strength assessments. A unique testing set up and testing protocol were followed to undertake the structural testing program for this innovative tidal foil compared to the commonly used horizontal axis tidal turbine blades. During the testing programme, the foil underwent 1,300,000 fatigue cycles, which is the highest number of fatigue cycles recorded on a tidal turbine blade in dry laboratory conditions, and, in the final static testing stage, the foil sustained damage at 110 % of the idealised full loading condition. A numerical model, based on the finite element method, of the foil has been initially developed using material properties from test coupons and datasheets. This model was then improved by using the mechanical properties obtained from coupons extracted from the foil after testing, however only a slight difference in the two models was observed. A comprehensive assessment of all the test results and selected numerical studies validated the novel design of the tidal foil, while developing a knowledge base to accelerate the structural testing programs of tidal turbine blades, has been presented. This paper also highlights the utilisation of modern tools and adaptations in testing methodologies to accommodate diverse design variations, thus mitigating industry risks for potential low tide and river deployments in the future.Publication A state-of-the-art review of structural testing of tidal turbine blades(MDPI, 2023-05-12) Munaweera Thanthirige, Tenis Ranjan; Goggins, Jamie; Flanagan, Michael; Finnegan, William; Science Foundation Ireland; Sustainable Energy Authority of IrelandOver the last two decades, the tidal energy industry has laid the groundwork for creating commercially viable tidal power generation projects to strengthen sustainable energy policies around the world. At the end of 2021, the cumulative installation of tidal stream technology that has been deployed in Europe reached 30.2 MW, where the majority of the installations are by small and medium-sized companies. Due to a growing demand among investors related to the global tidal energy industry, the reliability and safety of operational-stage tidal energy systems’ components are becoming increasingly important. In this context, companies, universities and research institutes are focusing on conducting large- and small-scale tests of tidal turbine elements to validate their projected design life, and major attention is being given to assessing the structural integrity of turbine blades. This review paper focuses on structural tests that have been reported for axial flow tidal turbine blades manufactured using composite materials around the world, highlighting the testing standards, equipment and instrumentation required. Overall, this review article discusses the state of the art in the structural testing of tidal turbine blades. In addition, it highlights the global concerns and research gaps to ensure the long-term sustainability of axial flow tidal turbine blades. In addition, the information contained in this article will be useful for formulating a smooth and reliable mechanism to enhance the evaluation process of the structural properties of tidal turbine blades in the future.Publication Financial assessment of integrating anaerobic digestion with cattle farming for biomethane production – Implications for farm economics and the supply chain(Elsevier, 2025-02-13) Tisocco, Sofia; Lenehan, James J.; Zhan, Xinmin; Crosson, Paul; Teagasc Walsh ScholarshipIntegrating anaerobic digestion (AD) into agriculture can support carbon neutrality and circular bioeconomy. However, economic benefits for stakeholders are crucial for implementing full-scale AD. This study assessed the financial implications of producing grass silage for AD on beef farms. It also assessed the financial viability of full-scale AD plants co-digesting grass silage and cattle slurry for biomethane, focusing on competitive grass silage pricing and support schemes. Results indicate that a grass silage price of €245/t dry matter (DM) is needed for competitiveness with beef production; this requires a biomethane certificate price of €0.12/kWh for the AD plant. At current prices (€0.098/kWh), the AD plant could afford €164/t DM for silage, requiring farm subsidies of €893/ha to cover price gaps. Methane yield of AD silage, along with biomethane certificate and silage prices, are key variables affecting the 20-year net present value of the AD plant. This study underscores the government's critical role in fostering a low-carbon livestock sector.Publication A review of best international life cycle assessment (LCA) practices in wood construction: Challenges for Ireland(Elsevier, 2025-01-30) Ge, Song; O'Ceallaigh, Conan; McGetrick, Patrick; Department of Agriculture, Food and the MarineUnder the dual pressure of carbon-neutral commitments by 2050 and increasing housing demands, the Irish construction industry is responsible for a 50% reduction in carbon emissions relative to 2018 levels. Timber has been identified as an excellent material choice for embodied carbon reduction. However, the widespread adoption of timber in construction is limited by several factors, including established practices and supply chains, and lack of public policy and incentives to quantify and reduce embodied carbon. The latter needs to be supported by accurate quantitative life cycle assessment (LCA). To identify gaps and challenges faced by LCA development for timber construction, this paper reviews various up-to-date Irish and international LCA practices. At the product level, 26 environmental product declaration (EPD) databases and 35 EPDs covering five wood product types are analysed. At the building level, 29 national and international building LCA methodologies worldwide are compared. Due to varying availability of Irish-customised data, disparities exist between the lifecycle inventory data used in current Irish timber product EPDs and other Irish-focused statistics. The challenges identified include a lack of mandatory regulations on embodied carbon disclosure and thresholds, a limited number of wood product EPDs in Ireland, and incomplete lifecycle inventory data.Publication Green public procurement in construction: A systematic review(Elsevier, 2024-12-01) Ahmed, Mohammed Zajeer; O'Donoghue, Cathal; McGetrick, Patrick; epartment of Agriculture, Food, and the Marine; Department of the Environment, Climate and Communications.Green Public Procurement (GPP) is an increasingly important environmental policy being incorporated with national action plans (NAP) across the European Union (EU). The aim of this paper is to look at related literature in the construction industry with a goal of identifying any gaps in literature. In addition, the review defines different facilitator and barriers to implementing GPP in the construction field. The paper employs a relatively unique approach using a theoretical framework to explore a wider set of variables within the GPP field. All papers from year 2000 onwards in English were considered for the review. The review finds a lack of emphasis on systems modelling within the reviewed paper set and a need for more diverse economic evaluation metrics that incorporate social and environmental costs. Furthermore, the paper discusses broad range of subjects varying from behaviour to tendering procedure, highlighting potential avenues of future research.Publication Integrated multi-index drought monitoring and projection under climate change(Elsevier, 2025-02-01) Moradian, Sogol; Gharbia, Salem; AghaKouchak, Amir; Haghighi, Ali Torabi; Olbert, Agnieszka Indiana; Irish Research CouncilUnderstanding drought trends under climate change is critical for effective water resources management. Given the complex nature of droughts, relying solely on a single variable for drought analysis might not be adequate for promptly and reliably detecting drought conditions. This study introduces a comprehensive approach to drought monitoring and projection under climate change. The methodology assesses drought conditions by considering different key factors such as soil moisture, precipitation, runoff, relative humidity and (unmet) water demands. By considering these variables, the study aims to provide a more holistic understanding of drought dynamics. To achieve this, a range of indices are used including the Standardised Precipitation Index (SPI), the Standardised Soil Moisture Index (SSI), the Standardised Relative Humidity Index (SRHI), the Standardised Runoff Index (SRI), the Multivariate Standardised Drought Index (MSDI), the Inflow-Demand Reliability Indicator (IDRI), the Water Storage Resilience Indicator (WSRI) and the Multivariate Standardised Reliability and Resilience Index (MSRRI). Furthermore, the study employs a (non-)parametric set of copula functions to analyze compound drought events, which consider the interconnected nature of different drought characteristics. These indicators detect drought onset, persistence, and spatial extent over Europe for different future climate scenarios, using data from the Coupled Model Intercomparison Project Phase 6 (CMIP6). The study explores future climatic changes and their potential impact on drought patterns, comparing them with historical data. Results indicate that drought estimates vary significantly across different locations, time periods, and types of drought. The study captures this complexity and provides a more nuanced and resilient framework for understanding drought risks across different contexts. For example, results show that in Dublin, Ireland, the used climate scenarios project general wet meteorological conditions until 2050 (SPI > 0). However, extreme hydrological droughts are anticipated during the time based on SRI (SRI = -1.8). In addition, considering MSRRI, more socio-economic droughts are expected for Dublin by 2050. This study serves as a valuable resource for hydrologists, policymakers, and risk managers, offering guidance on understanding drought dynamics and informing decision-making processes related to drought prevention and mitigation strategies.Publication On the patterns and mechanisms of residual currents and suspended sediment transport in the Lingdingyang of the Pearl River Delta(Elsevier, 2024-09-21) Ren, Lei; Ji, Jincai; Yang, Haokai; Wang, Hexu; Wang, Yaqi; Zhu, Qin; Guo, Leicheng; Lou, Xiaofan; Yao, Peng; Zhu, Zhenchang; Hartnett, MichaelTide-averaged current, i.e., Eulerian residual current (ERC), indicates net transport of sediment and pollutants in coastal and estuarine regions. In this paper, we examine the dynamics of tidal currents and associate residual currents (RCs), suspended sediment transport and its governing mechanisms in the Lingdingyang (LDY) of the Pearl River Delta based on field data and numerical modeling. Results indicate that seaward ERCs dominate throughout the LDY. The ERCs are greater in the wet seasons than that in the dry seasons. The ERCs are smaller in the middle layer of the water column over the shoals, whereas they ware are larger in the middle layers in deep channels. The ERCs mainly discharge into the sea through the deep channel and west shoal, forming a slack water zone in the middle shoal. Vertical circulation structures of ERCs are controlled by the channel-shoal structure. A dual ERC circulation structure was observed between the channels, which is characterized with seaward and landward ERCs at the surface and bottom layers, respectively. As a result, the residual sediment transports are seaward, with large rates at the shoal than in the channel. Seaward ERCs explain residual sediment transport in the deep channel. Both ERCs and Stokes RCs (SRCs) are important over the shoal. Tidal pumping is of secondary importance and its direction varies over time and in space. These findings provide a scientific basis for understanding the channel-shoal evolution and maintenance of the navigational waterway in the LDY.Publication Hindcasting and forecasting of surface flow fields through assimilating high frequency remotely sensing radar data(MDPI, 2017-09-08) Ren, Lei; Hartnett, MichaelIn order to improve the forecasting ability of numerical models, a sequential data assimilation scheme, nudging, was applied to blend remotely sensing high-frequency (HF) radar surface currents with results from a three-dimensional numerical, EFDC (Environmental Fluid Dynamics Code) model. For the first time, this research presents the most appropriate nudging parameters, which were determined from sensitivity experiments. To examine the influence of data assimilation cycle lengths on forecasts and to extend forecasting improvements, the duration of data assimilation cycles was studied through assimilating linearly interpolated temporal radar data. Data assimilation nudging parameters have not been previously analyzed. Assimilation of HF radar measurements at each model computational timestep outperformed those assimilation models using longer data assimilation cycle lengths; root-mean-square error (RMSE) values of both surface velocity components during a 12 h model forecasting period indicated that surface flow fields were significantly improved when implementing nudging assimilation at each model computational timestep. The Data Assimilation Skill Score (DASS) technique was used to quantitatively evaluate forecast improvements. The averaged values of DASS over the data assimilation domain were 26% and 33% for east–west and north–south velocity components, respectively, over the half-day forecasting period. Correlation of Averaged Kinetic Energy (AKE) was improved by more than 10% in the best data assimilation model. Time series of velocity components and surface flow fields were presented to illustrate the improvement resulting from data assimilation application over time.Publication Characterizing residual current circulation and its response mechanism to wind at a seasonal scale based on high-frequency radar data(MDPI, 2022-09-09) Ren, Lei; Yang, Lingna; Pan, Guangwei; Zheng, Gang; Zhu, Qin; Wang, Yaqi; Zhu, Zhenchang; Hartnett, MichaelResidual current characteristics are indicators for the net transports of sediments, nutrients, and pollutants, and for the dilution and diffusion of soluble substances in coastal areas, yet their driving mechanisms remain poorly understood. Here, we studied the characteristics of surface residual currents along the west coast of the island of Ireland, as well as the response mechanisms to wind at a seasonal scale based on the continuous observation data of high-frequency radar (HFR) for one year. Our analyses indicate that wind has a significant effect on generating surface residual currents, with correlation coefficients of 0.6–0.8 between wind speeds and residual current speeds at both annual and seasonal scales. However, the correlation between the directions of residual currents and the wind was not as significant as speed, likely because the directions of residual currents were not only affected by sea surface wind, but also by land boundary conditions in the research area. Moreover, the residual currents had a significant eastward flow trend identical to the wind direction at the maximum wind speed time, during which the effect of the tide on residual currents was relatively weak. Additionally, when compared with wind fields, HFR surface flow fields and surface residual current fields show that wind is the dominant driver of the variations of surface and residual flow fields. These findings shed light on coastal ecological and environmental management and can assist in the prevention and mitigation of marine disasters, by providing helpful information for improving the ability and accuracy of forecasting coastal currents.