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Numerical hydrodynamic models enable the simulation of hydraulic conditions under various scenarios and are thus suitable tools for hydropeaking related assessments. However, the choice of the necessary model complexity and the consequences of modelling choices are not trivial and only few guidelines exist. In this study, we systematically evaluate numerical one-dimensional (1D) and two-dimensional (2D) hydrodynamic models with varying spatial resolution regarding their suitability as input for hydropeaking-sensitive, ecologically relevant hydraulic parameters (ERHPs), and their computational efficiency. The considered ERHPs include the vertical dewatering velocity, the wetted area variation between base and peak flow and the bed shear stress as a proxy for macroinvertebrate drift. Furthermore, we quantified the habitat suitability of brown trout for different life stages. The evaluation is conducted for three channel planforms with morphological characteristics representative for regulated Alpine Rivers, ranging from alternating bars to a braiding river morphology. For the prediction of habitat suitability and bed shear stress, a 1D model appears to be always insufficient, and a highly resolved 2D model is suggested. Reducing the spatial resolution of 2D models leads to computational efficiency similar to 1D, while providing more accurate results. Thus, our results suggest, that while a highly resolved 1D model is sufficient for accurate predictions of the dewatering velocity and wetted area in the less complex alternating bar morphology, a 2D model is recommended for more complex wandering or braiding morphologies. This study can serve as guideline for researchers and practitioners in the selection and setup of hydrodynamic models for hydropeaking., River Research and Applications, 39 (3), ISSN:1535-1459, ISSN:1535-1467

Determining the residuary resistance per unit weight of displacement is one of the key factors in the design of vessels. In this paper, the authors utilize two novel methods – Symbolic Regression (SR) and Gradient Boosted Trees (GBT) to achieve a model which can be used to calculate the value of residuary resistance per unit weight, of displacement from the longitudinal position of the center of buoyancy, prismatic coefficient, length-displacement ratio, beam-draught ratio, length-beam ratio, and Froude number. This data is given as results of 308 experiments provided as a part of a publicly available dataset. The results are evaluated using the coefficient of determination (R2) and Mean Absolute Percentage Error (MAPE). Pre-processing, in the shape of correlation analysis combined with variable elimination and variable scaling, is applied to the dataset. The results show that while both methods achieve regression results, the result of regression of SR is relatively poor in comparison to GBT. Both methods provide slightly poorer, but comparable results to previous research focussing on the use of “black-box” methods, such as neural networks. The elimination of variables does not show a high influence on the modeling performance in the presented case, while variable scaling does achieve better results compared to the models trained with the non-scaled dataset.

The ability of reefs to protect coastlines from storm-driven flooding hinges on their capacity to keep pace with sea-level rise. Here, we show how and whether coral restoration could achieve the often-cited goal of reversing the impacts of coral-reef degradation to preserve this essential function. We combined coral-growth measurements and carbonate-budget assessments of reef-accretion potential at Buck Island Reef, U.S. Virgin Islands, with hydrodynamic modeling to quantify future coastal flooding under various coral-restoration, sea-level rise, and storm scenarios. Our results provide guidance on how restoration of Acropora palmata, if successful, could mitigate the most extreme impacts of coastal flooding by reversing projected trajectories of reef erosion and allowing reefs to keep pace with the ~0.5 m of sea-level rise expected by 2100 with moderate carbon-emissions reductions. This highlights the potential long-term benefits of pursuing coral-reef restoration alongside climate-change mitigation to support the persistence of essential coral-reef ecosystem services.

In this approach we will summarise the the last three publications highlighting the key mathematical approach like Exponential F ( x ) to further exponential –Gaussian F ( x ) and finally the Linear Combination of Atomic Orbital ( LCAO ) ie a hybridised Sp orbital overlapping to Remdesivir ( Drug ) –Covid19 approach.In this combinatorial study let us try to simulate the four cases starting from viral spreading kinetics ,Gaussian distribution of the infectious disease , modelling of remdesivir on the basis of molecular bonding approach and finally the most important mortality statistics like infection fatality ratio ( IFR ) with the distribution of age of the patient through sigmoid regression method . Keywords – Covid19 ,SARS-COV-2 , Simulation , Exponential , Gaussiun , Drug intermediate , Drug modelling , Quantum Chemistry , LCAO , Infection fatalality rate , Logistic regression , Sigmoid model , Hydrodynamic modelling , Bio-polymer , First order kinetics .

The mathematical modelling equations are developed to combine the mathematical model for a Pseudo – Gaussian distribution curve – for Growth of Covid19 . The superimposition of Gaussiun curve with Microbial growth curve can be fitted for the resulant model equation considering the sharp Exponential spreading of the Virus .https://data.mendeley.com/datasets/5cbs2c35ps/draft?a=5a5c488e-cd86-457c-8504-ea332132134f . Datta, Jaydip (2020), “Covid19 – A Mathematical modelling of a PSEUDO-GAUSSIUN Contour”, Mendeley Data, V3, doi: 10.17632/5cbs2c35ps.3

Whilst energy can be efficiently extracted from waves by a device exhibiting sloped motion, sustaining that performance in a deep water environment would conventionally rely on a costly support structure. Introduced herein, the WaveTrain device provides an alternative approach to retain the benefits of sloped motion, using a series of joints and struts to mechanically interconnect a series of sloped modules, each of which houses an internal water column to allow reaction against the surrounding water inertia. With a view to maximal power extraction in a real wave climate, this paper presents an optimisation of key parameters associated with the geometry and mass distribution. This relies upon an efficient hydrodynamic model, whose development is presented, particularly with respect to the use of ‘generalised’ modes to model hinges, for which a somewhat didactic treatment is given. A genetic algorithm, tailored specifically to handle the discontinuous parameter space and the numerical hydrodynamic model, is then used to identify design criteria that are essential for optimal power extraction. Five necessary but not sufficient criteria are presented, in addition to guidance regarding the remaining parameters, which is used to briefly highlight the potential benefits for the practical engineering design.

Understanding the spatiotemporal dynamics of surface water in varied, remote and inaccessible isolated floodplain lakes is difficult. Seasonal inundation patterns of these isolated lakes can be misestimated in a hydrodynamic model due to the short time of connectivity. The seasonal and annual variability of the Dinder River flow has great impact on what is so called Mayas wetlands, and hence, on the habitats and the ecological status of the Dinder National Park. This variability produces large morphological changes due to sediment transported within the river or from the upper catchment, which affects inflows to Mayas wetlands and floodplain inundation in general. In this paper, we investigated the morphological dimension using a quasi-3D modelling approach to support the management of the valuable Mayas wetlands ecosystems, and in particular, assessment of hydrological and morphological regime of the Dinder River as well as the Musa Maya. Six scenarios were developed and tested. The first three scenarios consider three different hydrologic conditions of average, wet and dry years under the existing system with the constructed connection canal. While the other three scenarios consider the same hydrologic conditions but under the natural system without an artificial connection canal. The modelling helps to understand the effect of human intervention (connection canal) on the Musa Maya. The comparison between the simulated scenarios concludes that the hydrodynamics and sedimentology of the Maya are driven by the two main factors: a) the hydrological variability of Dinder River; and b) deposited sediment plugs in the connection canal.

Flooding events can produce significant disturbances in underground transport systems within urban areas and lead to economic and socioenvironmental well-known consequences, which can be worsened by variations in the occurrence of weather and climate extremes. A better comprehension of these impacts and their conditions is consequently needed. Hence, this paper presents a state-of-the-art literature review on flood impact assessment in “metro” systems, analysing their purposes and their shortcomings. This document shows the adaptation measures dealing with specific classes of pluvial flood damages, besides identifying prospective paths towards the application of suitable actions facing actual and projected hazards in metro systems worldwide. This research was funded by the RESCCUE project, which is sponsored by the European Union’s Horizon 2020 research and innovation programme under grant agreement No. 700174, whose support is gratefully recognised.

The primary objective of this research is to demonstrate advanced surveying methods and techniques for coastal erosion identification and monitoring in a densely human-populated coastline, the southern coastline of the Gulf of Patras (Greece), which diachronically suffers erosion problems expected to become worse in the forthcoming years due to climate change and human intervention. Its importance lies in the fact that it presents a robust methodology on how all modern scientific knowledge and techniques should be used in coastal erosion problems. The presented methods include the use of satellite and aerial photo imaging, shallow seabed bathymetry and morphology, sediment sampling, geotechnical investigations, as well as hydrodynamic modelling. The results are extensively analyzed in terms of their importance in coastal erosion studies and are cross-validated to define those areas most vulnerable to erosion. Towards this scope, the seabed erosion rate produced by hydrodynamic modelling is compared with the coastal vulnerability index (CVI) calculations performed in the examined area to identify which coastal zones are under a regime of intensive erosion. The results between the CVI and the seabed erosion rate appear to coincide in terms of the erosion potential, especially in zones where the vulnerability regime has been calculated as being high or very high, with the P. oceanica meadows playing an important role in reducing erosion.

The Delft3D hydrodynamic and wave model is used to hindcast the storm surge and waves that impacted La Rochelle, France, and the surrounding area (Aytré, Châtelaillon-Plage, Yves, Fouras, and Île de Ré) during storm Xynthia. These models are validated against tide and wave measurements. The models then estimate the footprint of flow depth, speed, unit discharge, flow momentum flux, significant wave height, wave energy flux, total water depth (flow depth plus wave height), and total (flow plus wave) force at the locations of damaged buildings for which insurance claims data are available. Correlation of the hydrodynamic and wave results with the claims data generates building damage functions. These damage functions are shown to be sensitive to the topography data used in the simulation, as well as the hydrodynamic or wave forcing parameter chosen for the correlation. The most robust damage functions result from highly accurate topographic data and are correlated with water depth or total (flow plus wave) force.

Establishing a relationship between tidal current conditions and tidal turbine performance and loads is a criti-cally important consideration for turbine reliability. Nonetheless, obtaining in-situ information is often chal-lenging, and as a result both environmental and load data may be more sparse than desired. This study presents a method to make use of limited data sets by establishing a relationship between measurements of hydrodynamic variability and turbine power or blade strain variability, even when these measurements are not taken simul-taneously. The method is tested on data from the deployment of a full-scale pilot tidal turbine: in situ velocity measurements and turbulence characteristics taken at times when the turbine was not installed were associated with power and strain measurements during the turbine's deployment via a Delft3D proxy. The data show that the variability of active power correlates well with larger turbulence kinetic energy (TICE) when comparing similar populations via the proxy. Examination of blade strain variance against TICE shows a weaker correlation, with fat-tailed distributions and extremely high strain values prominent across all flow speeds. Acceleration or deceleration of the flow influenced the power variability of the turbine, with larger standard deviations recorded across accelerating flows. No significant difference was found when comparing blade strain variance in accel-erating and decelerating flows. We conclude that the proxy method studied can establish a population-level relationship between non-simultaneous environmental and load data, but that the accuracy and precision of this relationship depends on the amount of data available: this method is therefore only suitable where there is a sufficiently rich dataset. EAPA_333/2016 UID/MAR/00350/2020 info:eu-repo/semantics/publishedVersion

Wetlands are sensitive to hydrological conditions and human influence. The Abras de Mantequilla wetland (AdM) located at the centre of the Guayas River Basin (Western Ecuador), was declared a Ramsar site (2000) due to its important role in the conservation of bird fauna diversity. The wetland also supports significant populations of fish, including endemic species. The area exhibits two seasons: (i) a wet season (January–May); and (ii) a dry season (June–December). For the area of interest data is scarce, and a hydrodynamic model did not exist. In order to evaluate the interannual hydrodynamics and inundation patterns variability of this wetland system, a 2D hydrodynamic model was developed using the Delft3D software suite. Local knowledge was combined with field observations and expert elicitation to construct an appropriate model for the area. Results show that the Abras de Mantequilla is a river-wetland system that experiences extreme variations in hydrodynamic conditions from low water depths and almost stagnant conditions during the dry season, to a very dynamic behaviour during the rainy season. The inundation area ranges between 5 to 27 km2, water depths vary from 0.4 to 9 m and flow velocities from 0.0 up to 0.9 m/s. The “Nuevo River” is the main inflow to the wetland, with an overall contribution of about 85–90%, with peak discharges during February and March. A numerical tracer analysis indicated that the wetland can be divided into three main areas (upper, middle and low), with higher residence times found in the middle area. Overall, based on numerical hydrodynamic simulations it was possible to obtain adequate indications of the relative importance of the different river inflow conditions, as well as spatial and temporal inundation patterns, velocities and residence times under hydrological conditions varying from dry to extremely wet years. Furthermore, the hydrodynamic model provides a basis for other studies such as water quality assessment and primary production dynamics, as well as for determining the habitat suitability for fish.

Mapping flood risk areas is important for disaster management at the local, regional, and national scales. The aim of this study was to evaluate the ability of large-scale models to obtain flood hazard maps. The models were compared to the estimates developed by the Brazilian Geological Survey (CPRM) for different return periods (RP). The floods were evaluated for the municipalities of Uruguaiana, Montenegro and São Sebastião do Caí in the Rio Grande do Sul state. It was shown that the flood mapping generated by MGB covers larger areas (greater than 1000 km2; Siqueira et al. 2018), with a lower cost of obtaining for large scales. The - Hit Rate of the regional and continental MGB model versions with the CPRM maps ranged from about 40% to 90% in different cities, and the Hit Rate between the regional model and the CPRM map increased with the increased return period floods. The continental model compatibility was similar for all analyzed RPs. Our results suggest the agreement in terms of Hit Rate of current large-scale hydrological-hydrodynamic models to assess flood hazard. RESUMO Mapear áreas com risco de cheias é importante para o gerenciamento de desastres em nível local, regional e nacional. O objetivo deste estudo foi avaliar a capacidade de modelos de grande escala na obtenção de áreas inundadas com tempos de retorno específicos, em comparação com a mancha de inundação desenvolvida pelo Serviço Geológico do Brasil (CPRM). Foram avaliadas as manchas para os municípios de Uruguaiana, Montenegro e São Sebastião do Caí, no Rio Grande do Sul. Observou-se que os resultados gerados pelo MGB são mais abrangentes espacialmente (áreas maiores que 50km2), com um custo de obtenção menor para grandes escalas. A taxa de acerto das versões do modelo MGB regional e continental com os mapas da CPRM variaram desde cerca de 40% até 90% nas diferentes cidades, sendo que a taxa de acerto, entre o modelo regional e o mapa da CPRM aumentou com o aumento do TR. Já a compatibilidade do modelo continental foi similar para todos os TRs analisados. Os resultados sugerem a capacidade, em termos de taxa de acerto, dos modelos hidrológico-hidrodinâmicos de larga escala para avaliar o risco de inundação.

The Delft3D hydrodynamic and wave model is used to hindcast the storm surge and waves that impacted La Rochelle, France, and the surrounding area (Aytré, Châtelaillon-Plage, Yves, Fouras, and Île de Ré) during storm Xynthia. These models are validated against tide and wave measurements. The models then estimate the footprint of flow depth, speed, unit discharge, flow momentum flux, significant wave height, wave energy flux, total water depth (flow depth plus wave height), and total (flow plus wave) force at the locations of damaged buildings for which insurance claims data are available. Correlation of the hydrodynamic and wave results with the claims data generates building damage functions. These damage functions are shown to be sensitive to the topography data used in the simulation, as well as the hydrodynamic or wave forcing parameter chosen for the correlation. The most robust damage functions result from highly accurate topographic data and are correlated with water depth or total (flow plus wave) force.

The increasing demand for sustainable energy generation brings a need for tidal current energy resource exploration around the globe. Hydrodynamic modelling is an essential aspect to explore macro tidal sites. In the current research paper, a 2D hydrodynamic model is set up by utilizing the numerical application of Delft3D. The model is validated against the database results and the two macro tidal sites are identified along the coastline of Sarawak, Malaysia. The maximum available kinetic energy flux at the identified location is 0.6 kW/m2, during peak neap tide hours. This stands as a sound justification to have a detailed tidal energy assessment study in this area in future research.

In this paper we seek to understand the nature of flood spatial dependence over the conterminous United States. We extend an existing conditional multivariate statistical model to enable its application to this large and heterogenous region and apply it to a 40-year data set of ~2,400 U.S. Geological Survey gauge series records to simulate 1,000 years of U.S. flooding comprising more than 63,000 individual events with realistic spatial dependence. A continental-scale hydrodynamic model at 30 m resolution is then used to calculate the economic loss arising from each of these events. From this we are able to compute the probability that different values of U.S. annual total economic loss due to flooding are exceeded (i.e., a loss-exceedance curve). Comparing these data to an observed flood loss-exceedance curve for the period 1988–2017 shows a reasonable match for annual losses with probability below 10% (e.g., >1 in 10-year return period). This analysis suggests that there is a 1% chance of U.S. annual fluvial flood losses exceeding $78Bn in any given year, and a 0.1% chance of them exceeding $136Bn. Analysis of the set of stochastic events and losses yields new insights into the nature of flooding and flood risk in the United States. In particular, we confirm the strong relationship between flood affected area and event peak magnitude, but show considerable variability in this relationship between adjacent U.S. regions. The analysis provides a significant advance over previous national flood risk analyses as it gives the full loss-exceedance curve instead of simply the average annual loss.

Hanauma Bay is a 101-acre bay created by the partial collapse of a volcanic cone and once supported a vibrant coral reef system. It is the most popular swimming area in the Hawaiian Islands and has been reported to have averaged between 2.8 and 3.5 million visitors a year between the 1980s and the 2010s, with visitors averaging between 3000-4000 a day and peaking around 10,000-13,000 per day. Concentrations of oxybenzone and other common UV filters were measured in subsurface water samples and in sands from the beach-shower areas in Hanauma Bay. Results demonstrate that beach showers also can be a source of sunscreen environmental contamination. Hydrodynamic modeling indicates that oxybenzone contamination within Hanauma Bay's waters could be retained between 14 and 50 h from a single release event period. Focusing on only oxybenzone, two different Hazard and Risk Assessment analyses were conducted to determine the danger of oxybenzone to Hanauma Bay's coral reef system. Results indicate that oxybenzone contamination poses a significant threat to the wildlife of Hanauma Bay. To recover Hanauma Bay's natural resources to a healthy condition and to satisfactorily conserve its coral reef and sea grass habitats, effective tourism management policies need to be implemented that mitigate the threat of sunscreen pollution., Water and beach sand samples were collected under permit and permission from both the City and County of Honolulu's Department of Parks and Recreation and State of Hawaii's Department of Land and Natural Resources. We thank the BIO2MAR platform (http://bio2mar.obs-banyuls.fr) for providing technical support and access to instrumentation. We thank Wendy Wiltse and her associates for assistance in sample collection. We also greatly appreciate and profusely thank the three anonymous reviewers who improved the quality of this manuscript.

This thesis studies the numerical modelling of a range of hydrodynamic, solute transport and biochemical reaction processes in shallow water environment, combining both Euler and Lagrangian techniques. The research consists of two parts: the rapid flow modelling and the solute transport modelling. In the rapid flow modelling, the research is focused on demonstrating the impact of modifying the Boussinesq coefficient when simulating rapid flows in various situations. The traditional Alternating Direction Implicit (ADI) scheme has been proven to be incapable of modelling trans-critical flows. Its inherent lack of shock-capturing capability results in spurious oscillations and computational instabilities. However, the ADI scheme is still widely adopted in flood modelling software, and various special treatments have been designed to stabilise the computation. Modification of the Boussinesq coefficient to adjust the amount of fluid inertia is a numerical treatment that allows the ADI scheme to be applicable to rapid flows. A comprehensive study has been undertaken to examine the impact of this numerical treatment over a range of flow conditions. A shock-capturing TVD-MacCormack model is used to provide reference results. In the solute transport modelling, a mesh-free, depth-averaged and highly robust random walk model has been developed for simulating the two-dimensional solute transport processes. The development of the random model consists of two stages. In the first stage, extensive parametric studies have been undertaken to investigate the influences of the number of particles, the size of time steps and the technique of sampling processes used in the random walk model. The model is then applied to investigate the solute oscillation along a tidal estuary subject to extensive wetting and drying during tidal oscillations. The flow velocities are interpolated from the grid-based TVD-MacCormack flow solver. Finally, the model is applied to investigate wind-induced chaotic mixing in a circular shallow basin. The effect of diffusive processes on the chaotic mixing is investigated. The results of the first stage research provide a guideline for properly presenting the outputs of the random walk method for scientific analyses. In the second stage, the random-walk model is further developed to investigate the advection, diffusion and reaction processes of non-conservative materials. First, several classical test cases are presented to showcase the capability of the random walk model in addressing the problem of continuous release of non-conservative substances. Then, the method is applied to model the BOD-DO balance along a hypothetical river. The numerical results are in good agreement with the analytical solution. Finally, the developed scheme is used to study the pollutant transport in Thames Estuary. The current model is illustrated to be able to accurately predict the interaction between multiple pollutants in real-world situations with uneven bathymetry and extensive intertidal floodplains.

Unlike more established renewable energy conversion technologies, such as wind turbines, wave power systems have reached neither commercial maturity,nor technological convergence. The significant variation in device geometries and operating principles has resulted in a diversification of effort, with little coordination or true comparative analysis. The situation is compounded by the relative lack of systematic optimisation applied to the sector, partly explained by the complexity and uncertainty associated with wave energy system models, as well as difficulties in the evaluation of appropriate target function metrics. This review provides a critical overview of the state-of-the-art in wave energy device geometry optimisation, comparing and contrasting various optimisation approaches, and attempting to detail the current limitations preventing further progress, and convergence, in the development of optimal wave energy technology.

A coupled numerical hydrodynamic model is presented for the Cape Peninsula region of South Africa. The model is intended to support a range of interdisciplinary coastal management and research applications, given the multifaceted socio-economic and ecological value of the study area. Calibration and validation are presented, with the model reproducing the mean circulation well. Maximum differences between modelled and measured mean surface current speeds and directions of 3.9 × 10−2 m s−1 and 20.7°, respectively, were produced near Cape Town, where current velocities are moderate. At other measurement sites, the model closely reproduces mean surface and near-bed current speeds and directions and outperforms a global model. In simulating sub-daily velocity variability, the model’s skill is moderate, and similar to that of a global model, where comparison is possible. It offers the distinct advantage of producing information where the global model cannot, however. Validation for temperature and salinity is provided, indicating promising performance. The model produces a range of expected dynamical features for the domain including upwelling and vertical current shear. Nuances in circulation patterns are revealed, specifically, the development of rotational flow patterns within False Bay is qualified and an eddy in Table Bay is identified.

Flood simulations are important for flood (fatality) risk assessment. This article provides insight into the sensitivity of flood fatality risks to the model resolution of flood simulations and to several uncertain parameters in the loss of life model used. A case study is conducted for river flooding in a polder in the Netherlands (the Bommelerwaard) where the Dutch approach for loss of life estimation is applied. Flood models with resolutions of 100, 25, and 5 m are considered. Results show locally increased mortality rates in higher resolution simulations nearby structures including road embankments, dikes, and culverts. This causes a larger maximum individual risk value (annual probability of death for a person due to flooding) which has consequences for safety standards based on the individual risk criterion. Mortality rate in the breach zone is also affected by representations of buildings as solid objects versus as roughness elements. Furthermore, changes in the loss of life estimation approach via alternative ways of including people's behaviour, building characteristics, and age of the population, have a significant impact on flood fatality risk. Results from this study can be used to support future risk assessments and decision making with respect to safety standards.

For any coastal desalination plant, the most effective and practical way to dispose of their brine is to thermally discharge it into the sea via outfalls at some distance from the coast. This study focused on the environmental impacts associated with brine and thermal discharge arising from seawater desalination plants at Yanbu, Saudi Arabia, on the southeastern coast of the Red Sea. The impacts associated with recirculation patterns and dispersions were investigated with the calibrated three-dimensional numerical model Delft3d. The environmental impact assessment and the process of identification and characterisation could help improve strategies for better planning and management of the technological solutions related to desalination. Analysis of the model simulations for the different seasons also suggested that around the outfall location, the magnitude of the flow was always high when considered together with the presence of seasonal eddy circulations. Although the tidal flow is lower, the ambient current and wind cause the far-field discharge to spread along the north–south direction during the winter and summer. The thermal and brine dispersion and environmental compliance were assessed in terms of the extent of dispersion. The well-mixed environment caused more rapid dispersion. From the impact level assessment perspective, the study indicated rapid dilution and dispersion of the wastewater at the study region. The present offshore outfall and further offshore locations were far enough to ensure quick dispersion.

Climate change takes more and more challenges to the water management. Future predictions show that the possibility of extreme floods and drought events are increasing, thus an additional task of the water management can be the fulfilment of the increasing water demands. These new extreme hydrological situations need to be properly handled in water management. The paper presents the first modelling results of the JOINTISZA project carried out on a selected sub-basin of the Tisza River, which is endangered by hydrological extremes. Our aim was to demonstrate the applicability of a one-dimensional hydrodynamic model to study the effects of the climate change. Future hydrological trends were introduced in the river basin and it was assessed how the results of climate models can be used for further hydrodynamic modelling. To address challenges of climate change and supply the stakeholders with an adequate amount of water, proper operation of the reservoir and the irrigation canals are needed. The use of hydrological modelling can be helpful to adequately distribute water resources.

Urban pluvial flooding is a global challenge that is frequently caused by the lack of available infiltration, retention and drainage capacity in cities. This paper presents RUFIDAM, an urban pluvial flood model, developed using GIS technology with the intention of rapidly estimating flood extent, depth and its associated damage. RUFIDAM integrates a 1D hydraulic drainage network model (SWMM or MOUSE) with an adapted version of rapid flood inundation models. One-metre resolution topographic data was used to identify depressions in an urban catchment. Volume-elevation relationships and minimum elevation between adjacent depressions were determined. Mass balance considerations were then used to simulate movement of water between depressions. Surcharge volumes from the 1D drainage network model were fed statically into the rapid inundation model. The model was tested on three urban catchments located in southeast Melbourne. Results of flood depth, extent and damage costs were compared to those produced using MIKE FLOOD; a well-known 1D-2D hydrodynamic model. Results showed that RUFIDAM can predict flood extent and accumulated damage cost with acceptable accuracy. Although some variations in the simulated location of flooding were observed, simulation time was reduced by two orders of magnitude compared to MIKE FLOOD. As such, RUFIDAM is suitable for large-scale flood studies and risk-based approaches that rely on a large number of simulations.

Around the world, there is growing interest in the use of rainwater retention, and in particular channel retention, as part of urban drainage systems. This is made possible by means of intentional damming of rainwater in the existing sewer collectors in order to maximise the use of gravitational spaces in the channels. This approach is particularly favourable for drainage types related to high levels of urban development, where construction of a building is difficult due to the low amount of space available. This article explains the results of a study concerning the efficiency assessment of three retention devices characterised by different hydraulic systems, one of which uses channel retention in its operation. The analysis conducted within the simulation study has demonstrated that the use of standard single-chamber reservoirs is the least efficient solution. A comparison of the functions of different hydraulic systems of retention reservoirs under equal conditions has shown that the necessary retention capacity of a single-chamber reservoir is many times greater in comparison to highly efficient solutions and it may constitute up to 582% of the reservoir’s capacity and works in conjunction with the channel retention system. At the same time, it has been demonstrated that the application of channel retention is not the most efficient solution for all hydraulic conditions for a drainage system or for all hydrological conditions. In addition, the article proposes a set of retention efficiency indices that may be used in the future assessment of individual rainwater storage solutions. Estimation of the necessary capacity of the retention facilities operating in specific hydraulic conditions was made on the basis of model tests—hydrodynamic modelling with the use of SWMM 5.0 software. The course of the research was planned using the theory of experiment planning (DOE) with the use of Statistica software, whereas efficiency indices were developed with the use of artificial neural networks (ANNs). The study results include practical and cognitive aspects. These may constitute guidelines for the designers and potential investors, as well as a tool with the aim of promoting the most efficient rainwater retention solutions in urban drainage systems.

Worldwide, many estuaries have the potential to harness tidal stream energy via the conversion of current velocities into a consumable energy source. However, the effects of future sea level rise on the tidal stream energy resource within different estuary types are largely unknown. To address this knowledge gap, 978 idealised hydrodynamic simulations were carried out to first identify estuary types and the location of hotspots within them that are promising for tidal energy exploitation in present-day conditions, and then provide insights into the altered tidal stream energy of different estuary types under various future sea level rise and river inflow scenarios. The results indicate that, under sea level rise, the tidal stream energy of prismatic estuaries reduces more than that of converging estuaries. This implies that estuaries that are currently worth exploiting for tidal power may cease to be in the future due to accelerating sea level rise. Further, as sea level rise may bring about geomorphic adjustments, the spatial energy patterns within an estuary may shift and optimal energy sites may be eliminated or displaced. These climate change effects pose a serious challenge for the management of tidal energy generation in future. In this context, the findings of this study are of practical significance for decision-makers in designing long-term strategies for the development of tidal energy installations in estuaries under rising mean sea levels.

The impact of air temperature rise is eminent for the large deep lakes in the Italian subalpine district, climate change being caused there by both natural phenomena and anthropogenic greenhouse-gases (GHG) emissions. These oligomictic lakes are experiencing a decrease in the frequency of winter full turnover and an intensification of stability. As a result, hypolimnetic oxygen concentrations are decreasing and nutrients are accumulating in bottom water, with effects on the whole ecosystem functioning. Forecasting the future evolution of the mixing pattern is relevant to assess if a reduction in GHG releases would be able to revert such processes. The study focuses on Lake Maggiore, for which the thermal structure evolution under climate change in the 2016-2085 period was assessed through numerical simulations, performed with the General Lake Model (GLM). Different prospects of regional air temperature rise were considered, given by the Swiss Climate Change Scenarios CH2011. Multiple realisations were performed for each scenario to obtain robust statistical predictions, adopting random series of meteorological data produced with the Vector-Autoregressive Weather Generator (VG). Results show that a reversion in the increasing thermal stability would be possible only if global GHG emissions started to be reduced by ~ 2020, allowing an equilibrium mixing regime to be restored by the end of the twenty-first century. Otherwise, persistent lack of complete-mixing, severe water warming and extensive effects on water quality are to be expected for the centuries to come. These projections can be extended to the other lakes in the subalpine district.

The frequency of glacier lake outbursts floods (GLOFs) is likely to increase with the ongoing glacier retreat, which produces new glacial lakes and enlarges existing ones. Here, we simulate the outburst of a potentially dangerous glacial lake in Bhutan by applying hydrodynamic modelling. Although the lake volume is known, several parameters connected to the dam breach and the routing of the flood are rough estimates or assumptions, which introduce uncertainties in the results. For this reason, we create an ensemble of nine outburst scenarios. The simulation of magnitude and timing of possible inundation depths is an important asset to prepare emergency action plans. For our case study in the Mo Chu River Basin, the results show that, even under the worst case scenario, little damage to residential buildings can be expected. However, such an outburst flood would probably destroy infrastructure and farmland and might even affect the operation of a hydroelectric powerplant more than 120 km downstream the lake. Our simulation efforts revealed that, by using a 30-m elevation model instead of a 5-m raster, flood magnitude and inundation areas are overestimated significantly, which highly suggests the use of high-resolution terrain data. These results may be a valuable input for risk mitigation efforts.

21 p. - The data presented in this study are available on request from the corresponding author. The data are not publicly available due to their file size, which is greater than 4 Gb. - Supplementary Materials: The following are available online at https://www.mdpi.com/article/10.3390/app11199267/s1, Figure S1: Scatter plot of the 100-year return period residual values for calibrated models, Figure S2: Box plot of the 100-year return period residual values for calibrated models, Table S1: Statistical results for the 100-year return period hydraulic models., [EN] The accurate estimation of flood risk depends on, among other factors, a correct delineation of the floodable area and its associated hydrodynamic parameters. This characterization becomes fundamental in the flood hazard analyses that are carried out in urban areas. To achieve this objective, it is necessary to have a correct characterization of the topography, both inside the riverbed (bathymetry) and outside it. Outside the riverbed, the LiDAR data led to an important improvement, but not so inside the riverbed. To overcome these deficiencies, different models with simplified bathymetry or modified inflow hydrographs were used. Here, we present a model that is based upon the calibration of the Manning’s n value inside the riverbed. The use of abnormally low Manning’s n values made it possible to reproduce both the extent of the flooded area and the flow depth value within it (outside the riverbed) in an acceptable manner. The reduction in the average error in the flow depth value from 50–75 cm (models without bathymetry and “natural” Manning’s n values) to only about 10 cm (models without bathymetry and “calibrated” Manning’s n values), was propagated towards a reduction in the estimation of direct flood damage, which fell from 25–30% to about 5%., This research was funded by the project DRAINAGE, CGL2017–83546–C3–R (MINEICO/ AEI/FEDER, UE); it is specifically part of the assessments carried out under the subproject DRAINAGE–3–R (CGL2017–83546–C3–3–R). The participation of M.G.-J. is supported by the National System of Youth Guarantee (activity with reference PEJ2018-002477) co-financed under the Youth Employment Operational Program, with financial resources from the Youth Employment Initiative (YEI) and the European Social Fund (ESF).

There is growing evidence that traditional response to floods and flood-related disaster is no longer achieving desirable results. Nature-Based Solutions (NBS) represent a relatively new response towards disaster risk reduction, water security, and resilience to climate change, which has a potential to be more effective and sustainable than traditional measures. However, in practice, these measures are still being applied at a slow rate while traditional grey infrastructure remains as a preferred choice. This can be attributed to several barriers which range from political and governance to social and technological/technical. More generally, there is a lack of sufficient knowledge base to accelerate their wider acceptance and uptake. The present work provides contribution in this direction and addresses the question of effectiveness of different types of NBS (i.e., small- and large-scale NBS) and their hybrid combinations with grey infrastructure. The work has been applied on the case of Ayutthaya, Thailand. The results suggest that the effectiveness of small-scale NBS is limited to smaller rainfall events whereas the larger (or extreme) events necessitate combinations of different kinds of measures with different scales of implementation (i.e., hybrid measures).

The potentialities of averting a further salinization of the Tyligulskyi Liman lagoon were identified on the basis of the results of the hydrodynamic modelling, using the numerical model Delft3D-FLOW. The means to prevent the salinization in the lagoon include a reconstruction of the “lagoon-sea” interconnecting channel and the changing of its operational schedule, as well as the increasing of the river inflow considering the climatic conditions of the first half of the XXI century. The results of the verification of the hydrodynamic model are given. It is shown that for stabilizing water levels and reducing the rate of the water salinity in the lagoon the most effective option is the year-round operation of the deepened “lagoon-sea” connecting channel. This will be facilitated by a multi-directional exchange of water through the channel caused by wind-induced water level oscillations in the lagoon and in the sea. However, while maintaining the current level of the water management activity in the catchment area of the lagoon, a long-term trend of increasing water salinity in the lagoon still remains. Only the restoration of natural river discharge into the lagoon could reduce the tendency of growing water salinity to a minimum.

We present a new framework for flexible testing of flood risk adaptation strategies in a variety of urban development and climate scenarios. This framework couples the 1D-2D hydrodynamic simulation package MIKE FLOOD with the agent-based urban development model DAnCE4Water and provides the possibility to systematically test various flood risk adaptation measures ranging from large infrastructurechanges over decentralised water management to urban planning policies. We have tested the framework in a case study in Melbourne, Australia considering 9 scenarios for urban development and climate and 32 potential combinations of flood adaptation measures. We found that the performance of adaptation measures strongly depended on the considered climate and urban development scenario and the other implementation measures implemented, suggesting that adaptive strategies are preferable over one-off investments. Urban planning policies proved to be an efficient means for the reduction of flood risk, while implementing property buyback and pipe increases in a guideline-oriented manner was too costly. Random variations in location and time point of urban development could have significant impact on flood risk and would in some cases outweigh the benefits of less efficient adaptation strategies. The results of our setup can serve as an input for robust decision making frameworks and thus support the identification of flood risk adaptation measures that are economically efficient and robust to variations of climate and urban layout.

In the context of global change, increasing mariculture production has raised particular concerns regarding its environmental impact and sustainability. Molluscs and particularly blue mussel account for a significant part of this total production. Although blue mussels are considered to be pretty resilient to environmental disturbances, we report in this study an unprecedented mussel mortality event that occurred during the winter of 2014 in the Breton Sound. 9000 metric tonnes of mussels were lost and mortality rates up to 100% were recorded at some farming areas. Through a coupling approach, the present work aims to better understand the potential environmental drivers associated with those mortalities. Firstly, we analysed long-term in situ and satellite data from environmental monitoring networks (available since 1998) to characterize the variability of seawater masses of the sound during the winter of 2014. Secondly, we used modelling simulations to study the possible relationship between seawater hydrodynamics and observed spatio-temporal patterns of mussel mortalities. From January to April 2014 at the long-line culture site where mortalities started, seawater temperatures ranged from 8.3 to 13.3 °C (10.2 ± 0.8 °C). Salinity and turbidity values showed successive and short drops (below 16; 29.3 ± 2.3) and numerous peaks (above 70 NTU; 17.4 ± 13.4 NTU) respectively. Winter conditions of 2014 were encountered along the entire French Atlantic coastline and linked to the sixth highest positive North Atlantic Oscillation (NAO +) index recorded since 1865. These particular environmental variations characterized the winter of 2014 but also others whereas no comparable mussel mortality rates were reported. Exact causes of the 2014 mortality event are still unknown but we showed these environmental variations could not alone be responsible. These have likely affected the sensitivity of the blue mussel populations that were already weakened by early spawning. Meanwhile, these may have facilitated the apparition of a pathogenic strain of Vibrio splendidus isolated on moribund mussels at that time. Our modelling simulations suggested that this pathogenic strain could spread through hydrodynamic patterns and drive the observed mussel mortalities. If this pathogenic strain recurs in future years, particularly with the added stress associated with climate change, mussel mass mortality events may exceed the resilience of this species.

Anthropogenic impacts on marine habitats are a global problem, particularly in coastal areas. While boulder reefs in temperate waters hold high biomass and biodiversity, and may be unable to recover from anthropogenic stressors without restoration efforts, little is known about how to restore and conserve this important marine habitat. Limited knowledge is a serious impediment to projects aimed at restoring boulder reefs that have been degraded or removed by substrate extraction. In 2008, a boulder reef was restored in Kattegat, the transitional waters between the North Sea and the Baltic Sea, using differently sized boulders. The restored reef covered approximately 27,600 m 2 seafloor and included 100,712 tons of boulders added at depths ranging between 4 and 11 m. This paper describes methodology and lessons learned during the restoration project. Before the restoration, geological and geotechnical surveys confirmed that the sea bed could support added boulders, and high resolution bathymetric surveys provided input for the design of the reef, particularly for numerical modelling of the hydrographic and sediment transport conditions. Numerical modelling was used to derive hydrographic design conditions for boulder placements and further, to ensure that the restored reef would not affect the sea bed morphology and hydrographic conditions at a local harbour and at a protected habitat, both situated in the vicinity of the restoration area. Data on the physical structure of the restored boulder reef, collected in 2009, demonstrated that cavernous structures and shallow reef areas were restored. Moreover, data collected in 2012 confirmed the stability of the restored reef. Finally, results highlighted the importance of stakeholder mapping at the outset, appropriate timing of stakeholder involvement and ongoing consideration of stakeholder perceptions. Charting strategy and introducing a checklist for marine restoration projects, this paper outlines important considerations and methodology needed to ensure that restoration of temperate reef structures meet the objectives, without having undesirable effects on existing hydrographic and morphological conditions, including nearby coastal areas and protected marine habitats.

During the past decades, the aquaculture industry has developed rapidly, due to drop in wild fish catch. Water quality variables play major role in aquaculture operations, specifically seawater temperature has major impact on the metabolism of the fish species and therefore on the growth rate too. Since the fish farming business relies on the growth rate of the species to plan and operate the farm, seawater temperature becomes crucial information. With the availability of hydrodynamic modeling tools and global ocean information source such as Copernicus Marine Environment Monitoring Service (CMEMS), seawater temperature can be simulated for practically any coast with dynamic downscaling approach. However, the simulated data needs to be assessed for uncertainties for enabling informed decision making using such model predictions. In this paper, a coastal 3D hydrodynamic model aiming at simulating seawater temperature is developed for the southern Aegean Sea, Greece using the Delft3D Flexible Mesh modeling tool. Seawater temperature is impacted by atmospheric forces; therefore, uncertainties are assessed for seawater temperature using ensemble atmospheric forcing functions of the European Centre for Medium-Range Weather Forecasts (ECMWF) ERA5. Spatial analysis of the uncertainty indicates regions of different seawater temperature behavior within the model domain. Seasonal behavior of the vertical temperature gradient suggests that farms need to adapt different operational strategies in different seasons to make best use of the seawater temperature. The application of CMEMS data along with ECMWF ERA5 ensemble atmospheric forcing members proves to be beneficial in analyzing the uncertainties both in spatial and vertical gradient of seawater temperature.

The past few years have seen the raise of unmanned aerial vehicles (UAV) in geosciences for generating highly accurate digital elevation models (DEM) at low costs, which promises to be an interesting alternative to satellite data for small river basins. The reliability of UAV-derived topography as input to hydraulic modelling is still under investigation: here, we analyse potentialities and highlight challenges of employing UAV-derived topography in hydraulic modelling in a tropical environment, where weather conditions and remoteness of the study area might affect the quality of the retrieved data. We focused on a stretch of the Limpopo River in Mozambique, where detailed ground survey and airborne data were available. First, we tested and compared topographic data derived by UAV (25 cm), RTK-GPS (50 cm DEM), LiDAR (1 m DEM) and SRTM (30 m DEM); then, we used each DEM as input data to a hydraulic model and compared the performance of each DEM-based model against the LiDAR based model, currently used as benchmark by practitioners in the area. Despite the challenges experienced during the field campaign—and described here—, the degree of accuracy in terrain modelling produced errors in water depth calculations within the tolerances adopted in this typology of studies and comparable in magnitude to the ones obtained from high-precision topography models. This suggests that UAV is a promising source of geometric data even in natural environments with extreme weather conditions.

Understanding the spatiotemporal dynamics of surface water in varied, remote and inaccessible isolated floodplain lakes is difficult. Seasonal inundation patterns of these isolated lakes can be misestimated in a hydrodynamic model due to the short time of connectivity. The seasonal and annual variability of the Dinder River flow has great impact on what is so called Mayas wetlands, and hence, on the habitats and the ecological status of the Dinder National Park. This variability produces large morphological changes due to sediment transported within the river or from the upper catchment, which affects inflows to Mayas wetlands and floodplain inundation in general. In this paper, we investigated the morphological dimension using a quasi-3D modelling approach to support the management of the valuable Mayas wetlands ecosystems, and in particular, assessment of hydrological and morphological regime of the Dinder River as well as the Musa Maya. Six scenarios were developed and tested. The first three scenarios consider three different hydrologic conditions of average, wet and dry years under the existing system with the constructed connection canal. While the other three scenarios consider the same hydrologic conditions but under the natural system without an artificial connection canal. The modelling helps to understand the effect of human intervention (connection canal) on the Musa Maya. The comparison between the simulated scenarios concludes that the hydrodynamics and sedimentology of the Maya are driven by the two main factors: a) the hydrological variability of Dinder River; and b) deposited sediment plugs in the connection canal.

This study is dedicated to the hydrodynamic climate of Port Phillip Bay (PPB)—a largest coastal lagoon system in Victoria, Australia. Novelty of the present study includes long-term hydrodynamic hindcast simulations integrated with a spectral wave model. Specifically, a coupled unstructured grid wave–current modelling system (SCHISM + WWM) was built upon a high resolution and advanced wave physics (ST6). This coupling system was thoroughly calibrated and validated against field observations prior to applying for 27-year hindcast and case scenarios. Data from these simulations were then used to investigate the hydrodynamic climate of PPB focusing on three main aspects: water levels, waves and currents. For sea levels, this study shows that tidal and extreme sea levels (storm tides) across a large part of PPB have a similar magnitude. The highest storm tide level is found along eastern coasts of the bay in line with the wind pattern. In the vicinity of the entrance, the extreme sea level slightly reduced, in line with wave decay due to coupling effects. This extreme level is lower than results reported by previous studies, which were not built on a wave–current coupled system. For the wave field, the mean wave direction inside PPB is strongly affected by seasonality, in line with wind patterns. The 100-year return significant wave height is above 2 m along the eastern coasts. At PPH, waves get refracted after passing the narrow entrance. For currents, this study shows that both mean variations and high percentile currents are not affected by seasonality. This highlights the fact that tidal currents dominate flow movements in PPB. However, in extreme conditions, the circulation in PPB is also driven by wind patterns, forming two gyre systems. Based on case scenarios simulations, the strongest magnitude of wind-driven currents is above 0.5 m/s and found in the confined shallow region in the southern portion of PPB.

(IF 1.54; Q2); International audience; As an introduction to this thematic issue on “Modelling approaches in sedimentology”, this paper gives an overview of the workshop held in Paris on 7 November 2013 during the 14th Congress of the French Association of Sedimentologists. A synthesis of the workshop in terms of concepts, spatial and temporal scales, constraining data, and scientific challenges is first presented, then a discussion on the possibility of coupling different models, the industrial needs, and the new potential domains of research is exposed.

Recent research developments indicate that citizens observatories, a novel approach for data collection, management and governance, can provide valuable contributions to strategic delta planning processes. Most citizen observatories are limited to data collection done randomly, according to the citizens’ availability and wishes. However, there are times in which citizens participate as trained volunteers during data collection field campaigns. In this later scenario, an important aspect in organising and maintaining citizen observatories is having a clear plan for data gathering activities, including determination of routes to be followed by these citizens. This article addresses the issue of determining such routes (called pathways) related to the specific problem of gathering data in deltaic areas, which are composed of intricate canals and wetlands. Data collection activities consist of citizens acquiring images and videos with mobile phones at pre-determined locations (Points of Interest) that are only accessible by boats. A pathway selection approach is presented, supported by a hydrodynamic model, developed to capture the specific processes of the delta. The aim of the approach is to define: where to send the citizens to fulfil stakeholder’s interest and planning goals, how to reach these points and which pathways should be selected (prioritised based on such interests), considering possible flood patterns. The developed methodology is part of an ongoing H2020 funded research., The proof of concept is carried out in the Sontea-Fortuna area, of the Danube Delta, which, as many wetlands, contains a large variety of unique, endemic species. With the developed approach, pathways to be followed by citizens during data collection campaigns were generated and scored considering local interests. Analysis of the boats accessibility into the delta during different hydrological scenarios showed that the wetland is more accessible than expected, hence the proposed pathway approach was useful in prioritizing some canals over others. The determined pathways will be applied in field campaigns. The approach can be applied to other delta regions with different environmental problems, such as water quality or ecosystem assessment, contributing to organise an effective active citizen data collection.

Climate change is presenting one of the main challenges to our planet. In parallel, all regions of the world are projected to urbanise further. Consequently, sustainable development challenges will be increasingly concentrated in cities. A resulting impact is the increment of expected urban flood risk in many areas around the globe. Adaptation to climate change is an opportunity to improve urban conditions through the implementation of green-blue infrastructures, which provide multiple benefits besides flood mitigation. However, this is not an easy task since urban drainage systems are complex structures. This work focuses on a method to analyse the trade-offs when different benefits are pursued in stormwater infrastructure planning. A hydrodynamic model was coupled with an evolutionary optimisation algorithm to evaluate different green-blue-grey measures combinations. This evaluation includes flood mitigation as well as the enhancement of co-benefits. We confirmed optimisation as a helpful decision-making tool to visualise trade-offs among flood management strategies. Our results show that considering co-benefits enhancement as an objective boosts the selection of green-blue infrastructure. However, flood mitigation effectiveness can be diminished when extra benefits are pursued. Finally, we proved that combining green-blue-grey measures is particularly important in urban spaces when several benefits are considered simultaneously.

Bangladesh, one of the most disaster-prone countries in the world, has a dynamic delta with 123 polders protected by earthen dikes. Cyclone-induced storm surges cause severe damage to these polders by overtopping and breaching the dikes. A total of 19 major tropical storms have hit the coast in the last 50 years, and the storm frequency is likely to increase due to climate change. The present paper presents an investigation of the inundation pattern in a protected area behind dikes due to floods caused by storm surges and identifies possible critical locations of dike breaches. Polder 48 in the coastal region, also known as Kuakata, was selected as the study area. A HEC-RAS 1-D–2-D hydrodynamic model was developed to simulate inundation of the polder under different scenarios. Scenarios were developed by considering tidal variations, the angle of the cyclone at landfall, possible dike breach locations and sea level rise due to climate change according to the Fifth Assessment Report (AR5) of the Intergovernmental Panel on Climate Change (IPCC). A storm surge for a cyclone event with a 1-in-25-year return period was considered for all the scenarios. The primary objective of this research was to present a methodology for identifying the critical location of dike breaching, generating a flood risk map (FRM) and a probabilistic flood map (PFM) for the breaching of dikes during a cyclone. The critical location of the dike breach among the chosen possible locations was identified by comparing the inundation extent and damage due to flooding corresponding to the developed scenarios. A FRM corresponding to the breaching in the critical location was developed, which indicated that settlements adjacent to the canals in the polders were exposed to higher risk. A PFM was developed using the simulation results corresponding to the developed scenarios, which was used to recommend the need of appropriate land use zoning to minimize the vulnerability to flooding. The developed hydrodynamic model can be used to forecast inundation, to identify critical locations of the dike requiring maintenance and to study the effect of climate change on flood inundation in the study area. The frequency and intensity of the cyclones around the world are likely to increase due to climate change, which will require resource-intensive improvement of existing or new protection structures for the deltas. The identification and prioritization of the maintenance of critical locations of dike breaching can potentially prevent a disaster. The use of non-structural tools such as land use zoning with the help of flood risk maps and probabilistic flood maps has the potential to reduce risk and damage. The method presented in this research can potentially be utilized for deltas around the world to reduce vulnerability and flood risk due to dike breaching caused by cyclone-induced storm surge.

Recent research developments indicate that citizens observatories, a novel approach for data collection, management and governance, can provide valuable contributions to strategic delta planning processes. Most citizen observatories are limited to data collection done randomly, according to the citizens’ availability and wishes. However, there are times in which citizens participate as trained volunteers during data collection field campaigns. In this later scenario, an important aspect in organising and maintaining citizen observatories is having a clear plan for data gathering activities, including determination of routes to be followed by these citizens. This article addresses the issue of determining such routes (called pathways) related to the specific problem of gathering data in deltaic areas, which are composed of intricate canals and wetlands. Data collection activities consist of citizens acquiring images and videos with mobile phones at pre-determined locations (Points of Interest) that are only accessible by boats. A pathway selection approach is presented, supported by a hydrodynamic model, developed to capture the specific processes of the delta. The aim of the approach is to define: where to send the citizens to fulfil stakeholder’s interest and planning goals, how to reach these points and which pathways should be selected (prioritised based on such interests), considering possible flood patterns. The developed methodology is part of an ongoing H2020 funded research., The proof of concept is carried out in the Sontea-Fortuna area, of the Danube Delta, which, as many wetlands, contains a large variety of unique, endemic species. With the developed approach, pathways to be followed by citizens during data collection campaigns were generated and scored considering local interests. Analysis of the boats accessibility into the delta during different hydrological scenarios showed that the wetland is more accessible than expected, hence the proposed pathway approach was useful in prioritizing some canals over others. The determined pathways will be applied in field campaigns. The approach can be applied to other delta regions with different environmental problems, such as water quality or ecosystem assessment, contributing to organise an effective active citizen data collection.

Embora a analise de tempos hidraulicos caracteristicos seja uma ferramenta importante para estudar trocas de massas de agua e identificar areas propensas a estagnacao de aguas, que sao potencialmente vulneraveis a efeitos de eutrofizacao, seus conceitos e usos sao interpretados de forma errada com frequencia. Este artigo compara as diferencas e similaridades entre tempos hidraulicos caracteristicos, CHT, amplamente utilizados, tais como: Tempo de Residencia, Tempo de Taxas de Renovacao e Idade da Agua. Definicoes precisas de cada um destes tempos caracteristicos sao incluidas neste trabalho com o intuito de evitar confusao entre os multiplos conceitos presentes na literatura. Sao apresentadas metodologias para o calculo destes CHT utilizando sistemas de modelagem hidrodinâmica e, a fim de aprimorar o entendimento, aplicadas a tres casos idealizados em canais de fluxo constante: (1) Canal com fluxo uniforme; (2) canal com um afluxo lateral; (3) Canal com uma baia lateral. Posteriormente, um exemplo pratico e discutido aplicando as metodologias a Lagoa dos Patos (RS). Os resultados para os casos de canais idealizados nao sao intuitivos. A discussao teorica esclarece a interpretacao e os usos dos diferentes tempos caracteristicos e destaca a Idade da Agua como o mais versatil e multifuncional, se comparada com os outros CHT abordados neste trabalho. Os resultados da Lagoa dos Patos sao um exemplo do grande valor das informacoes que os CHT oferecem para a gestao ambiental em corpos hidricos naturais.

Despite numerous studies across the large geographic range of the sperm whale (Physeter macrocephalus), little is known about the diet and mitochondrial DNA haplotypes of this strongly female philopatric species in waters off Southeast Asia. A female sperm whale found dead in Singapore waters provided the opportunity to study her diet and mitochondrial DNA haplotype. Here we report on the identification of stomach contents and mitochondrial DNA haplotype of this individual, and we include coastal hydrodynamic modelling to determine the possible geographic origin of the whale. At least 28 species of prey were eaten by this adult female whale, most of which were cephalopods. The mesopelagic squids Taonius pavo, Histioteuthis pacifica, Chiroteuthis imperator,and Ancistrocheirus lesueurii made up over 65% of the whale’s stomach contents. Plastic debris was also found in the whale’s stomach. Based on the diet, genetics, and coastal hydrodynamic modelling that suggest an easterly drift of the whale carcass over several days, the dead sperm whale in Singapore probably originated from a pod in the Southern Indian Ocean. This study provides an increase in the understanding the diet and natural history of the sperm whale in Southeast Asia. The combined analyses of stomach contents, DNA, and hydrodynamic modeling could provide a context to future studies on the sperm whale strandings, and have broader applicability for other marine mammals in the region.

A series of meteotsunamis hit a few locations in the Mediterranean and Black Seas during 22– 27 June 2014. Meteot- sunamis were particularly numerous on 25 and 26 June in the Adriatic Sea, where at least six harbours and bays were stricken by ˇ powerful waves: strongest events occurred in Vela Luka (Korcula Island), a known meteotsunami hot-spot, where waves reached ˇ height of *3 m, and in Rijeka dubrovacka Bay, where strong *5 m/s currents accompanied *2.5 m high waves. Inten- sification of high-frequency sea level activity was observed at both the eastern and western Adriatic tide gauge stations, with maximum recorded wave heights reaching *68 cm (Ortona, Italy). A series of individual air pressure disturbances characterized by pronounced rates of air pressure change (up to 2.4 hPa/5 min), limited spatial extent (*50 km) and high temporal variability, propagated over the Adriatic on 2 days in question. Numerical hydrodynamic model SCHISM forced by measured and idealised air pressure distur- bances was utilised to reproduce the observed Adriatic sea level response. Several important conclusions were reached: (1) meteotsunamis occurring at various parts of the coast were gen- erated by different atmospheric air pressure disturbances ; (2) topographic influence can be removed from sea level spectra by computing spectral signal- to-background ratios ; the result, being related to the external forcing, resembles atmospheric pressure spectra ; (3) sea response is strongly dependant on details of atmospheric forcing ; and (4) over complex bathymetries, like the middle and south Adriatic ones, numerous effects, including Proudman resonance, edge waves, strong topographical enhance- ment and refractions on the islands placed on the pathway of atmospheric disturbances should be taken into account to fully understand meteotsunami generation and dynamics. An in- depth numerical study is planned to supplement the latter conclusion and to quantify contribution of each process.

A number of studies have predicted more frequent and intensive storms as a result of climate change in UK and other parts of the world, which may consequently cause more hazardous flash floods in steep catchments of small to medium size (e.g. up to 100 km 2 ). These flash floods are commonly characterized by high-velocity overland flow as a result of rapid catchment response to the intense rainfall. The hydrological processes related to the rapid catchment response are poorly understood and reliable prediction is generally beyond the capability of traditional hydrological models or simplified hydrodynamic models. This work aims to present a shock-capturing hydrodynamic modelling system to simulate the complex rainfall-runoff and the subsequent flash surface flooding process in a rapid-response catchment. The model solves the fully 2D shallow water equations using a finite volume Godunov-type shock-capturing numerical scheme for the rapidly varying overland flow hydrodynamics following intense rainfall. Typically, this type of shock-capturing hydrodynamic models is not able to provide efficient and high-resolution simulations for large-scale flash flood events due to their high computational demand. In order to substantially improve the computational efficiency and enable catchment-scale simulations at very high resolution involving millions of computational nodes, the model is implemented on GPUs for high-performance parallel computing. After being validated against the analytical benchmark of Tilted V-catchment test, the GPU-accelerated hydrodynamic modelling system is applied to simulate the rainfall-runoff process in the 42 km 2 Haltwhistle Burn Catchment in England.

Landslides and debris flows can strongly interact with the river network and its mass transport processes, determining modifications of the river pattern with consequent effects on the hydrodynamic phenomena, alterations of the existing morphologies and possible interferences with anthropic works. Modifications of the cross section geometry and channel slope may produce changes in the sediment budget, with consequent repercussions on the stream evolutionary dynamics and its equilibrium configuration, leading to a new river branch arrangement. In this paper, investigations were carried out on a gravel-bed reach in the middle valley of the Noce River in Basilicata (Italy), which in 2007 suffered a progressive morpho-hydrodynamic change caused by a landslide. Because of the phenomenon complexity, mainly due to the mutual interaction between the landslide and the river transport dynamics, an integrated approach that combines field observations and numerical modelling in a spatial scale and natural environment, rarely available in literature, is suggested. The results highlight a satisfying correspondence between the altimetric profiles obtained through the numerical models and those deriving from the field surveys.

International audience; This paper reviews key issues in the physical and numerical modelling of marine renewable energy systems, including wave energy devices, current turbines, and offshore wind turbines. The paper starts with an overview of the types of devices considered, and introduces some key studies in marine renewable energy modelling research. The development of new International Towing Tank Conference (ITTC) guidelines for model testing these devices is placed in the context of guidelines developed or under development by other international bodies as well as via research projects. Some particular challenges are introduced in the experimental and numerical modelling and testing of these devices, including the simulation of Power-Take-Off systems (PTOs) for physical models of all devices, approaches for numerical modelling of devices, and the correct modelling of wind load on offshore wind turbines. Finally, issues related to the uncertainty in performance prediction from model test results are discussed.The paper is based on the report of the International Towing Tank Conference specialist committee on Hydrodynamic Modelling of Marine Renewable Energy Devices to the 27th ITTC held in Copenhagen, Denmark in 2014 (ITTC Specialist Committee on Hydrodynamic Modelling of Marine Renewable Energy Devices, 2014a. Final Report and Recommendations to the 27th ITTC Proc. 27th International Towing Tank Conference, Copehagen, Denmark, vol. 2, pp. 680–725).

An extension of MUFITS reservoir simulator for modelling oil and gas reservoirs using black-oil approach is presented. We give an overview of multi-segment well technique implemented in MUFITS for coupled reservoir-wellbore simulations. SPE comparative studies with vertical wells are simulated in order to verify the correctness of technique implementation in the code. The simulation results, in particular calculated wells bottom-hole pressures, match results of other codes.