Flood hazard mapping methods: A review Mudashiru, Rofiat Bunmi; Sabtu, Nuridah; Abustan, Ismail ...
Journal of hydrology (Amsterdam),
December 2021, 2021-12-00, Letnik:
603
Journal Article
Recenzirano
•State-of-the-art review of related publications from 2000 to 2021 for the three discussed methods in FHM.•The review study gave a comprehensive overview of the methodologies in flood hazard ...mapping.•Explained the strengths and limitations of the physically-based, physical, and empirical modeling methods in flood hazard modeling.•Presented case studies of the methods, uncertainties, recent trends, and future directions associated with the methods in the review study.
Flood hazard mapping (FHM) has undergone significant development in terms of approach and capacity of the result to meet the target of policymakers for accurate prediction and identification of flood-prone or affected regions. FHM is a vital tool in flood hazard and risk management analysis. Previous review studies have focused on flood inundation modelling methods. This present study presents a thorough and current review of the physically-based, empirical, and physical modelling methods in FHM. The study gives insight into strengths, limitations, case studies, and uncertainties associated with the methods. It further discusses the approaches in handling uncertainties related to each method, and its recent development. The review study is targeted at enlightening researchers and decision-makers with an extensive understanding of the methods and of the recent improvements in FHM thereby empowering flood management agencies, decision-makers, design engineers, early warning system agencies, and responders in addressing and making accurate decisions in flood-related problems, employing best management practices in flood management, and adaption of climate decision-making towards building resilient infrastructures.
•Optimal design for epoxy-based polymer concrete.•Investigation of the resin-to-filler ratio and matrix-to-aggregate ratio.•Mechanical and durability properties of epoxy-based polymer ...concrete.•Empirical models for mechanical properties of epoxy-based polymer concrete.
Polymer concrete has shown a number of promising applications in building and construction, but its mix design process remains arbitrary due to lack of understanding of how constituent materials influence performance. This paper investigated the effect of resin-to-filler ratio and matrix-to-aggregate ratio on mechanical and durability properties of epoxy-based polymer concrete in order to optimise its mix design. A novel combination of fire-retardant, hollow microsphere and fly ash fillers were used and specimens were prepared using resin-to-filler ratios by volume from 100:0 to 40:60 at 10% increment. Another group of specimens were prepared using matrix-to-aggregate ratios from 1:0 decreasing to 1:0.45, 1:0.90 and 1:1.35 by weight at constant resin-to-filler ratio. The specimens were inspected and tested under compressive, tensile and flexural loading conditions. The epoxy polymer matrix shows excellent durability in air, water, saline solution, and hygrothermal environments. Results show that the resin-to-filler ratio has significant influence on the spatial distribution of aggregates. Severe segregation occurred when the matrix contained less than 40% filler while a uniform aggregate distribution was obtained when the matrix had at least 40% filler. Moreover, the tensile strength, flexural strength and ductility decreased with decrease in matrix-to-aggregate ratio. Empirical models for polymer concrete were proposed based on the experimental results. The optimal resin-to-filler ratio was 70:30 and 60:40 for non-uniform and uniform distribution of aggregates, respectively, while a matrix-to-aggregate ratio of 1:1.35 was optimal in terms of achieving a good balance between performance and cost.
Supercritical fluids are increasingly utilized in various industrial applications due to their unique properties. Accurate prediction of heat transfer in supercritical fluids is crucial for the ...design and optimization of these systems. However, the existing empirical correlations for supercritical Nusselt number often exhibit large uncertainties and discrepancies. In this study, a comprehensive Systematic Empirical Modelling (SEM) and evaluation of supercritical Nusselt number correlations for carbon dioxide flow in bare tubes was conducted. A total of 42 dimensionless variables were investigated, generating over 6 million potential forms of empirical correlations. The most accurate correlations, involving three to six dimensionless variables, were identified based on the root mean square percentage error between experimental and recalculated or predicted values of the Nusselt number and wall temperature. The identified correlations exhibited good agreement with the experimental data, with root mean square percentage errors ranging from 4.949% to 5.759% for the wall temperature. This study underscores the substantial benefits of employing SEM and systematic evaluation in identifying the most accurate correlations, and facilitates the development of robust and dependable correlations for system-level thermal-hydraulic codes.
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•The SEM method is employed to fit approximately 6.2 million variations of correlations.•42 dimensionless variables are systematically tested to model the Nusselt number.•Identification of the best Nusselt number correlation with MPE of wall temperature at 0.129%.•Multi-range bisection method is adopted for comprehensive wall temperature approximation.•This work provides valuable insights into the conventional empirical modeling techniques.
•Peak forces of hail impact tests are provided for impact velocities up to 314 m/s.•Impact energies in the range of 2000–3000 J have been reached.•Peak forces for speeds above 200 m/s follow the ...trend reported at lower speeds.•The rigidity of the target is suspected to influence the measured peak force.
In the presented work, high velocity hail impact tests have been conducted on an instrumented rigid target. The synthetic hails, consisting of ice spheres with a nominal diameter of 48 mm and a mass between 50 and 55 g conditioned to temperatures in the range of -3, -20 and -50 °C were accelerated using a gas gun. The range of impact velocities was 46–314 m/s leading to maximal impact energies between 2000 and 3000 J which had not been investigated so far in the literature. Peak force and time to reach the peak force where extracted from the experimental tests. The obtained results were compared with results from the literature using empirical equations established in another publication from the literature. The obtained results confirm the trend reported in the literature in terms of dimensionless peak force versus dimensionless impact velocity. However, the dimensionless time to reach the peak force during the impact could not be compared successfully with previous results. The role of the target characteristics is estimated to be the reason for this difference.
Forests dominate carbon (C) exchanges between the terrestrial biosphere and the atmosphere on land. In the long term, the net carbon flux between forests and the atmosphere has been significantly ...impacted by changes in forest cover area and structure due to ecological disturbances and management activities. Current empirical approaches for estimating net ecosystem productivity (NEP) rarely consider forest age as a predictor, which represents variation in physiological processes that can respond differently to environmental drivers, and regrowth following disturbance. Here, we conduct an observational synthesis to empirically determine to what extent climate, soil properties, nitrogen deposition, forest age and management influence the spatial and interannual variability of forest NEP across 126 forest eddy-covariance flux sites worldwide. The empirical models explained up to 62% and 71% of spatio-temporal and across-site variability of annual NEP, respectively. An investigation of model structures revealed that forest age was a dominant factor of NEP spatio-temporal variability in both space and time at the global scale as compared to abiotic factors, such as nutrient availability, soil characteristics and climate. These findings emphasize the importance of forest age in quantifying spatio-temporal variation in NEP using empirical approaches.
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•CF energy and ZFSP of Ni2+ ions are calculated using the orbit-lattice interactions, lattice stress–strain and distortions of host/dopant structure in A2Ti2O7 (A = Y, Gd)•Overlap ...integrals for π-bond between Ni2+ and O2− ions increase with increasing doping concentration.•The calculated ZFS magnitude Δ and CF strength parameter (S) versus nephelauxetic ratio is proposed as general descriptor for dopant ions in different hosts.
Effects of orbit-lattice interaction (OLI), structural distortions, and lattice strain on energy levels, crystal-field parameters (CFPs) and zero-field splitting parameter (ZFSPs) for metal ions in ligands polyhedra are largely unexplored. This study examines Ni2+ doped pyrochlores: Y2Ti2O7 and Gd2Ti2O7 involving static and dynamic structural distortions causing stress–strain effects in Ti/Ni-O6 polyhedra. Incorporation of OLI enables correlating lattice strains with changes in CFPs. Utilizing exchange charge model (ECM) and superposition model (SPM) for CFP modelling, OLI and stress–strain effects are investigated. So-obtained CFPs serve as input for CFA/MSH program predicting CF energies, states, and ZFS magnitude (equal ZFSP |D|) of Ni2+ ions. Relation between ZFS magnitude (and CF strength) and nephelauxetic ratio is studied. Results obtained with and without OLI, while including or excluding distortions, reveal profoundly impact of OLI on CF energy levels and ZFSP of Ni2+ ions. The variations of SPM/CFPs due to OLI and/or distortions are analyzed in terms of directional strain components. This computational study offers insights into the structural, spectroscopic, and magnetic properties of Ni2+:Y2Ti2O7 and Ni2+:Gd2Ti2O7. Our combined modelling approach is useful for exploring other hosts doped with transition or rare-earth ions at arbitrary symmetry sites, which are of interest for computational materials science.
The use of alternative fuels, such as bio-alcohols, in advanced propulsion systems could a feasible strategy to address several of the current issues associated to the use of internal combustion ...engines fuelled by carbonaceous fossil fuels. Particularly, soot particles, are one of the key pollutants emitted from compression ignition engines. Therefore, the development of soot formation prediction models providing new understanding on the impact of alternative fuels combustion in compression ignition engines become essential for soot mitigation purposes.
This study proposes a new semi-empirical model that predicts in-cylinder soot primary particle growth from an engine fuelled with alcohol–diesel fuel blends. The model uses macroscopic experimental measurements of engine parameters such as instantaneous in-cylinder pressure. Furthermore, an empirical correlation is presented predicting the mean soot primary particle size as a function of alcohol–diesel fuel blend properties and fuel/air ratio. The experimental measurement of primary soot particle mean size are obtained from High Resolution Transmission Electron Microscope (HT-TEM) micrographs obtained from soot particles collected via thermophoresis. Overall, the research findings presented in this work contributes to propose environmentally friendly fuel candidates for transportation.
•Different alcohols blended with diesel were investigated as promising advanced fuels.•A model has been developed to predict the temporal growth of primary soot particles.•A model is generated using microscopic measurement and in-cylinder pressure.•This work enriches the advanced fuels for clean and efficient transportation.
•The common semi-empirical modelling for positive-displacement expanders is revised.•A more physically sound modelling is adopted for mechanical and ambient heat losses.•The proposed procedure is ...calibrated and validated for a single-screw expander.•Mass flow rate, electric power and exhaust fluid temperature are appreciably simulated.•The expander performance is analyzed based on variations of the operating conditions.
The common semi-empirical modelling adopted for positive-displacement rotary expanders is revised in this paper. Paying particular attention to the leakage flow rates, the mechanical losses at the shaft and the ambient heat losses by the proposal of a more physically sound modelling, this paper aims at improving the performance simulation of a single-screw expander for which there exists a wide experimental campaign in literature. In detail, the mechanical losses are modelled with an approach consistent with the Stribeck’s theory, whereas the contributions of both natural convection and radiation are taken into account for a proper modelling of the ambient heat losses.
After calibration and validation of the modelling procedure, based on experimental data of the expander operation with R245fa, mean absolute percentage errors of 0.69%, 1.77% and 0.33% as regards mass flow rate, electric power output and exhaust fluid temperature, respectively, are calculated. These errors are lower than the ones reported by other researchers, so the current simulations are more consistent with the experimental data.
Considering the higher reliability for a better performance simulation by the new modelling procedure, the model is finally used to study the behavior of the expander. In particular, attention is paid to the mass flow rate, the shaft and the electric power outputs, the expander efficiency, as well as the ambient heat losses, and to their relations with the operation parameters such as the degree of fluid superheat at the expander inlet, the fluid pressure at the expander inlet, the pressure ratio and the rotational speed.
•GB domestic heat pump electricity demand in 2050 is modelled.•Modelling is based on monitored data from heat pumps and gas boilers in homes.•Uptake of heat pumps in all homes more than doubles peak ...GB electricity demand.•Moderate improvements in HP performance and dwelling fabric reduce peak GB demand.•Flexibility in DHW and space heating provision also reduce peak GB demand.
To meet net zero carbon targets by 2050s, countries with cold winters, such as Great Britain (GB), will turn to low carbon domestic heating systems such as electric heat pumps.
In this paper, a statistical model is developed using measured performance data from over 550 heat pumps installed in GB homes in 2012. The model is used to predict the additional load on the GB electricity generation and distribution infrastructure for various current and future (2050) climates, dwelling energy efficiencies and heat pump deployment scenarios.
For a cold year in the 2020s, a 100% uptake of heat pumps in the existing GB dwelling stock gave a peak electricity demand for the heat pumps of 78 GW and an annual electricity demand of 189 TWh. When added to the other, existing electricity demand, this represents an increase in the GB peak electricity demand in excess of 100% and an annual electricity demand increase of around 60%. Making reasonable assumptions about heat pumps’ future efficiency and use, and the future climate and dwelling stock fabric efficiency, and assuming 80% heat pump uptake and no load shifting, the peak heat pump electricity demand for a cold year in the 2050s halved to 37 GW. By shifting demand for water and space heating the 2020s cold year peak demand reduced by 15%.
The work provides a more robust estimate of future GB heat pump electricity demands than any previously available. The predicted future ramp rates, peak and annual total electricity demands, are lower than predicted by previous analysts.
Streams and rivers are among the most threatened ecosystems in Europe due to the combined effects of multiple pressures related to anthropogenic activities. Particularly in the Mediterranean region, ...changes in hydromorphology along with increased nutrient loadings are known to affect the ecological functions and ecosystem services of streams and rivers with the anticipated climate change being likely to further impair their functionality and structure. In this study, we investigated the combined effects of agricultural driven stressors on the ecology and delivered services of the Pinios river basin in Greece under three future world scenarios developed within the EU funded MARS project. Scenarios are based on combinations of Representative Concentration Pathways and Shared Socioeconomic Pathways and refer to early century (2030) and mid-century (2060) representing future climate worlds with particular socioeconomic characteristics. To assess the responses of ecological and ecosystem service indicators to the scenarios we first simulated hydrology and water quality in Pinios with a process-based model. Simulated abiotic stressor parameters (predictors) were linked to two biotic indicators, the macroinvertebrate indicators ASPT and EPT, with empirical modelling based on boosted regression trees and general linear models. Our results showed that the techno world scenario driven by fast economic growth and intensive exploitation of energy resources had the largest impact on both the abiotic status (nutrient loads and concentrations in water) and the biotic indicators. In contrast, the predicted changes under the other two future worlds, consensus and fragmented, were more diverse and were mostly dictated by the projected climate. This work showed that the future scenarios, especially the mid-century ones, had significant impact on both abiotic status and biotic responses underpinning the need for implementing catchment management practices able to mitigate the ecological threat on waters in the long-term.
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•We examined the response of the Pinios river to future world scenarios.•Abiotic state was assessed with the Soil and Water Assessment Tool.•Macroinvertebrate metrics were assessed by employing empirical modelling.•Results predict degradation of biotic and abiotic state by 2060.•Climate effects prevail over future management in the basin.
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