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The floods that struck lower Tagus valley in February 1979 correspond to the most intense floods in this river and affected the largest number of people in a river flow event in Portugal, during the last 150 years. In fact, the vast area affected impacted significantly circa 10k people in the lower Tagus sector (and an additional 7k in other regions of Portugal), including thousands of people evacuated or made homeless. In this context, the present study focuses on an in depth analysis of this event from a hydrodynamic perspective by means of Iber+ numerical model and on developing strategies to mitigate the flood episodes that occur in the lower section of the Tagus river using the outstating floods of February 1979 as benchmark. In this sense, several large dams and reservoirs are located along the Tagus river basin, and for that, dam operating strategies were developed and analyzed to take advantage of these infrastructures to minimize the effect of floods. Overall, the numerical results indicate a good agreement with water marks and some descriptions of the 1979 flood event, which demonstrates the model capability to evaluate floods in the area under study. Regarding flood mitigation, obtained results indicate that the frequency of floods can be reduced with the proposed strategies. In addition, hydraulic simulations corroborated an important decrease in water depth and velocity for the most extreme flood events, and also a certain reduction of flood extension was detected. This confirms the effectiveness of the proposed strategies to help in reducing flood impact in lower Tagus valley through the efficient functioning of dams.

Número especial: Advances in machine learning for natural hazards risk assessment [Abstract:] Reservoirs play a key role in many human societies due to their capability to manage water resources. In addition to their role in water supply and hydropower production, their ability to retain water and control the flow makes them a valuable asset for flood mitigation. This is a key function, since extreme events have increased in the last few decades as a result of climate change, and therefore, the application of mechanisms capable of mitigating flood damage will be key in the coming decades. Having a good estimation of the outflow of a reservoir can be an advantage for water management or early warning systems. When historical data are available, data-driven models have been proven a useful tool for different hydrological applications. In this sense, this study analyzes the efficiency of different machine learning techniques to predict reservoir outflow, namely multivariate linear regression (MLR) and three artificial neural networks: multilayer perceptron (MLP), nonlinear autoregressive exogenous (NARX) and long short-term memory (LSTM). These techniques were applied to forecast the outflow of eight water reservoirs of different characteristics located in the Miño River (northwest of Spain). In general, the results obtained showed that the proposed models provided a good estimation of the outflow of the reservoirs, improving the results obtained with classical approaches such as to consider reservoir outflow equal to that of the previous day. Among the different machine learning techniques analyzed, the NARX approach was the option that provided the best estimations on average. FEDER; 0034_RISC_ML_6_E Xunta de Galicia; ED431C 2021/44 Xunta de Galicia; ED481B-2021-108 Universidade de Vigo; 0000 131H TAL 641

[Abstract:] River floods, which are one of the most dangerous natural hazards worldwide, have increased in intensity and frequency in recent decades as a result of climate change, and the future scenario is expected to be even worse. Therefore, their knowledge, predictability, and mitigation represent a key challenge for the scientific community in the coming decades, especially in those local areas that are most vulnerable to these extreme events. In this sense, a multiscale analysis is essential to obtain detailed maps of the future evolution of floods. In the multiscale analysis, the historical and future precipitation data from the CORDEX (Coordinated Regional Downscaling Experiment) project are used as input in a hydrological model (HEC-HMS) which, in turn, feeds a 2D hydraulic model (Iber+). This integration allows knowing the projected future changes in the flow pattern of the river, as well as analyzing the impact of floods in vulnerable areas through the flood hazard maps obtained with hydraulic simulations. The multiscale analysis is applied to the case of the Miño-Sil basin (NW Spain), specifically to the city of Ourense. The results show a delay in the flood season and an increase in the frequency and intensity of extreme river flows in the Miño-Sil basin, which will cause more situations of flooding in many areas frequented by pedestrians and in important infrastructure of the city of Ourense. In addition, an increase in water depths associated with future floods was also detected, confirming the trend for future floods to be not only more frequent but also more intense. Detailed maps of the future evolution of floods also provide key information to decision-makers to take effective measures in advance in those areas most vulnerable to flooding in the coming decades. Although the methodology presented is applied to a particular area, its strength lies in the fact that its implementation in other basins and cities is simple, also taking into account that all the models used are freely accessible. Xunta de Galicia; ED431C 2021/44 FEDER; 0034_RISC_ML_6_E Xunta de Galicia; ED481B-2021-108

Early warning systems have become an essential tool to mitigate the impact of river floods, whose frequency and magnitude have increased during the last few decades as a consequence of climate change. In this context, the Mi&ntilde, o River Flood Alert System (MIDAS) early warning system has been developed for the Mi&ntilde, o River (Galicia, NW Spain), whose flood events have historically caused severe damage in urban areas and are expected to increase in intensity in the next decades. MIDAS is integrated by a hydrologic (HEC-HMS) and a hydraulic (Iber+) model using precipitation forecast as input data. The system runs automatically and is governed by a set of Python scripts. When any hazard is detected, an alert is issued by the system, including detailed hazards maps, to help decision makers to take precise and effective mitigation measures. Statistical analysis supports the accuracy of hydrologic and hydraulic modules implemented to forecast river flow and flooded critical areas during the analyzed period of time, including some of the most extreme events registered in the Mi&ntilde, o River. In fact, MIDAS has proven to be capable of predicting most of the alert situations occurred during the study period, showing its capability to anticipate risk situations.

The present work describes the implementation of an advanced solitary wave generation system in the mesh-less SPH-based DualSPHysics model to simulate tsunami-like solitary waves. Three different g...

Using the convergence-confinement curves methodology, we analysed excavation behaviour for a range of rock masses of different geotechnical qualities, taking into account blast-induced damage. The novelty of the research is (i) we include blast-induced damage to the rock mass in ground reaction curve construction, and (ii) we analyse results for 54 rock mass and rock geotechnical quality scenarios. The research, an application of a previously developed methodology ( Gonzalez-Cao et al., 2013 ), provides practical guidelines for the preliminary design phase for an excavation resulting from blasting. Our main conclusions are (i) that rock mass quality has a greater bearing on the plastic radius and excavation maximum displacement than blast-induced damage, and (ii) that the plastic radius and maximum displacement around an excavation increase with the level of blast-induced damage, most especially for poor quality rock masses. This would justify the need to limit blast-induced damage in poor quality rock masses.

The upgrade of the hydrological safety of dams is a critical issue to avoid failures that can dramatically affect people and assets. This paper shows a numerical methodology to analyse the safety of the Belesar dam (NW, Spain) based on two different numerical codes. First, a mesh-based code named Iber, suited to deal with large 2-D domains, is used to simulate the impoundment. The initial conditions and the inlet provided to Iber correspond to the maximum water elevation and the maximum expected inflow to the impoundment defined in the technical specifications of the dam, which are associated to the more hazardous operation conditions of the dam. Iber provides information about the time needed for water to attain the crest of the dam when floodgates are closed. In addition, it also provides the velocity of discharge when gates are opened. Then, a mesh-free code named DualSPHysics, which is especially suited to deal with complex and violent 3-D flows, is used to reproduce the behaviour of one of the spillways of the dam starting from the results obtained with Iber, which are used as inlet conditions for DualSPHysics. The combined results of both model show that the left spillway can discharge the surplus of water associated to the maximum inflow to the reservoir if the gates of the spillways are opened before the overtopping of the dam was observed. In addition, water depth measured on the spillway is considerably lower than the lateral walls, preventing overtopping. Finally, velocities at different points of the spillway showed to be in good agreement with theoretical values.

In recent decades, the development of numerical tools has facilitated the ability to reproduce extreme flood events, which allows a far better understanding of their features, contributing to mitigate their negative effects in similar future scenarios. This paper analyzes the flood event that occurred in December 1876 in Badajoz (Spain-Guadiana basin), one of the most catastrophic flood events recorded in Europe, using a three-stage methodology. First, an estimation of the precipitation recorded in the Guadiana river basin during the days prior to the event was carried out starting from the precipitation data recorded in two precipitation stations located in the western part of the basin; second, Guadiana river flow in Badajoz was obtained by means of the HEC-HMS code using the precipitation estimated in the first stage. Third, the flood registered on December 1876 in Badajoz was reproduced using the numerical code Iber+. The peak flow obtained was equal to: 12,774 ± 1,360 m3s−1. This value improves the accuracy of estimated shown in previous works which, most of them, are lower limits of this value. Numerical results of the flood event in Badajoz and in areas surrounding the city show a good agreement with water marks and some descriptions of the event found in the literature. Results obtained in this work demonstrate the ability of the methodology to reproduce historical extreme flood events even when the availability of input data is relatively scarce.

The present work presents a fully comprehensive implementation of wave generation and active wave absorption for second-order long-crested monochromatic and random waves in a WCSPH-based (Weakly Compressible Smoothed Particle Hydrodynamics) model. The open-source code DualSPHysics is used for the scope. The numerical flume resembles a physical wave facility, so that, the moving boundaries mimic the action of a piston-type wavemaker. The second-order wave generation system, capable of generating both monochromatic (regular) and random (irregular) waves, is implemented jointly with passive and active wave absorption. A damping system is defined as solution for passive absorption and is used to prevent wave reflection from fixed boundaries in the numerical flume. The use of active wave absorption allows avoiding spurious reflection from the wavemaker. These implementations are validated with theoretical solutions and experimental results, in terms of water surface elevation, wave orbital velocities, wave forces and capacity for damping the re-reflection inside the fluid domain.

The mesh-free code DualSPHysics is applied to simulate the interaction between sea waves and an Oscillating Water Column device (OWC). In this work, capabilities and limitations of DualSPHysics are shown in simulating OWCs. On the one hand, the new capabilities of DualSPHysics are shown by simulating the effect of mooring systems on a floating offshore OWC. On the other hand, simulations only consider a single-phase (water) so that the full OWC behaviour is partially reproduced, i.e. air pressure fluctuations are not modelled. The model was first validated with one laboratory test that consists of a fixed OWC with an open chamber. Next, water surface oscillations inside the chamber of a real OWC (located in Mutriku, Spain) have been predicted using the prevalent wave conditions observed in the area. Finally, the capabilities of DualSPHysics were demonstrated by simulating an offshore OWC moored to the seabed.

In recent decades, the Tulancingo municipality (Mexico), has been affected by numerous extreme weather phenomena that caused heavy flooding events with severe damage to property and people. Most of the weather phenomena placed several dams under hydrologic risk. The hurricane “ Dean”, in 2007, led to the overflow of the dam “ La Esperanza”, generating inundations that reached levels of 1 m in Tulancingo. Mexico does not have a specific regulation that establishes critical thresholds for the construction of flooding hazard maps. With the aim to provide a tool for the flooding hazard assessment, we performed a numerical study of inundation waterdepths by means of the IBER software. The study is based on the construction of different inundation scenarios that are based on the hydrologic study of “ La Esperanza” dam's basin, associated to regional precipitation and different return periods. Inundation waterdepths, flow velocity and land use were used to construct flooding hazard maps. We calculated the occurrence probability of the considered inundation events. The hazard maps presented here and the evaluation of the flooding likelihood can support long-term planning that would help minimize the impact of such events in Tulancingo.

The hydrological safety of dams is a key factor to be analysed in order to avoid human and economic losses. The exceedance structures of the dams play a crucial role in its hydrological safety. They are usually designed by means of hydrological methods that solve analytical solutions that follow several simplifications. The numerical code IBER, which can combine a hydrologic study with a hydraulic model, could provide more accurate results in order to obtain peak flows and to calculate exceedance levels of a dam. In the present work, both analytical and numerical methods are applied to analyse the hydrological safety of “La Esperanza” dam (Tulancingo, Hidalgo State, Mexico). Numerical results show that this dam could be at hydrological risk for peak flow values associated to return periods higher than 15 years. In order to improve the hydrological safety of the dam, a series of modifications of the geometry of the exceedance structures are also simulated using the IBER software.

The efficiency of a low-reflective caisson built at the Outer Port of Punta Langosteira (A Coruña, Spain), with a front-wall porosity of ˜ 5%, has been numerically investigated by means of OpenFOAM® for different chamber configurations and different sea states. The numerical model is validated with data coming from experimental tests performed on a scaled prototype. First, two different water levels, low and mean tide levels, are analysed. Results show that the caisson is inefficient when the water level inside the chamber is low, and suggest its proper installation taking into account the tidal regime of the area. For mean tide level inside the chamber, the efficiency of the caisson shows to be strongly dependent on the wave period and height. However, it is shown to be more sensitive to the period for low wave heights than for the high ones. Overall, the reflection coefficient ranged from 0.365 ( s, m) to 0.660 ( s, m). Alternative configurations with one and two chambers are also examined instead of three. Overall, the reflection coefficient is very high ( > 0.95) for the configuration with only one chamber. For the two and three-chambered caissons the mean reflection coefficient is similar ( ˜ 0.5) but the dispersion of the values is much higher for the two-chambered caisson, with values ranging from 0.176 to 0.794. The first author of this manuscript wishes to express his gratitude to the IT support provided by Orlando Garcia-Feal, who made possible the use of the HPC system at monkey-island.uvigo.es. This work was partially financed by Xunta de Galicia (Spain) under project ED431C 2017/64 ”Programa de Consolidación e Estructuración de Unidades de Investigación Competitivas” and under project ED431F 2016/004 ”NUMANTIA”. This work was also funded by European Regional Development Fund under Interreg project ”MarRISK” (0262_MARRISK_1_E).

Iber is a software for simulating turbulent free surface unsteady flow and transport processes in shallow water flows. The hydrodynamic module of Iber solves the depth averaged two-dimensional shallow water equations (2D Saint-Venant Equations). A turbulent module allows the user to include the effect of the turbulent stresses in the hydrodynamics. These are evaluated with different depth-averaged turbulence models for shallow waters of different complexity. Additional capabilities include sediment transport modelling, water quality modelling and rainfall-runoff modelling. All the equations of the model are solved in a finite volume non-structured mesh made up of triangle and quadrilateral elements. A more detailed description of the model can be found in Bladé et al. (2014) and the references therein, as well as in the documents included in the Refences section of this document. Iber can be downloaded for free through www.iberaula.com. This document presents the performance of the software Iber in a series of two-dimensional modelling benchmark tests. Some of these tests were developed by the United Kingdom Joint Defra / Environment Agency under Defra’s Flood and Coastal Erosion Risk Management R&D program, and have been used to benchmark other 2D free surface flow models, as the 2D version of HEC-RAS. The Defra’s benchmarking report, which includes the comparison of several two-dimensional models, can be downloaded from: https://www.gov.uk/government/publications/benchmarking-the-latest-generation-of-2d-hydraulicflood-modelling-packages

An early warning system for flood prediction based on precipitation forecast is presented. The system uses rainfall forecast provided by MeteoGalicia in combination with a hydrologic (Hydrologic Modeling System, HEC-HMS) and a hydraulic (Iber+) model. The upper reach of the Miño River and the city of Lugo (NW Spain) are used as a study area. Starting from rainfall forecast, HEC-HMS calculates the streamflow and Iber+ is automatically executed for some previously defined risk areas when a certain threshold is exceeded. The analysis based on historical extreme events shows that the system can provide accurate results in less than 1 h for a forecast horizon of 3 d and report an alert situation to decision makers.

The accuracy of DualSPHysics and IHFOAM to reproduce the propagation of a regular wave train and its collision with a vertical sea wall with a hanging horizontal cantilever slab was compared by different metrics (skill index, normalized standard deviation, correlation coefficient and root-mean square error). These metrics were applied to elevation of the free-surface and to the horizontal force exerted on the wall. The numerical results of both models converge to experimental values when increasing the resolution, being the accuracy similar for both models at high spatial resolution, although IHFOAM has a slightly higher performance that DualSPHysics for low and medium resolutions. Overall, the analysis suggests that mesh-less models have attained the level of maturity required to provide results with an accuracy equivalent to mesh-based models. (C) 2018 Elsevier Ltd. All rights reserved.

Este artigo inclúese no número especial "Selected Papers from the 1st International Electronic Conference on the Hydrological Cycle (ChyCle-2017)" [Abstract:] This paper presents Iber+, a new parallel code based on the numerical model Iber for two-dimensional (2D) flood inundation modelling. The new implementation, which is coded in C++ and takes advantage of the parallelization functionalities both on CPUs (central processing units) and GPUs (graphics processing units), was validated using different benchmark cases and compared, in terms of numerical output and computational efficiency, with other well-known hydraulic software packages. Depending on the complexity of the specific test case, the new parallel implementation can achieve speedups up to two orders of magnitude when compared with the standard version. The speedup is especially remarkable for the GPU parallelization that uses Nvidia CUDA (compute unified device architecture). The efficiency is as good as the one provided by some of the most popular hydraulic models. We also present the application of Iber+ to model an extreme flash flood that took place in the Spanish Pyrenees in October 2012. The new implementation was used to simulate 24 h of real time in roughly eight minutes of computing time, while the standard version needed more than 15 h. This huge improvement in computational efficiency opens up the possibility of using the code for real-time forecasting of flood events in early-warning systems, in order to help decision making under hazardous events that need a fast intervention to deploy countermeasures. Water JPI—WaterWorks Programme, project Improving Drought and Flood Early Warning, Forecasting and Mitigation, IMDROFLOOD; PCIN-2015-243 European Commission; project RISC_ML 034_RISC_ML_6_E Xunta de Galicia; ED431C 2017/64-GRC Xunta de Galicia; ED481A-2017/314 Xunta de Galicia; ED481B-2018/020 European Commission; IMDROFLOOD PCIN-2015-243

Floods are one of the most dangerous extreme events that can affect people and properties. These events have intensified worldwide over the last decades due to climate change. Therefore, the capability to predict and analyse, in a quick and accurate way, the effects of these floods is of crucial importance to avoid or minimize the hazards associated to them. This task can be accomplished by means of numerical tools as Iber. Iber is a 2-D numerical model, developed by GEAMA (Universidade da Coruna) and Flumen (Universitat Politecnica de Catalunya), that uses the finite volume technique to solve the 2-D Shallow Water Equations in order to obtain the water depth and velocity components of the flow under different scenarios. To assess the capabilities of Iber a series of test cases have been reproduced following the document “Benchmarking the latest generation of 2D hydraulic modelling packages” published by the non-departmental public body Environment Agency of the U.K. Government. The results show that Iber is a suitable tool to reproduce accurately different flooding scenarios. A new implementation of the model has been developed by EPHYSLAB. This implementation takes advantage of the modern hardware capabilities and provides significant speedups over the original code. The new possibilities offered by a faster code will be studied.

Preserving the cultural heritage of antiquity is one of the most important tasks of the mankind. On this basis, the European Parliament, via the Policy Department Structural and Cohesion Policies, published the study entitled: “Protecting The Cultural Heritage From Natural Disasters”. This study analyses the actions that are being carried out to protect the cultural heritage from floods, earthquakes and other natural phenomena in Europe. In this work the numerical code Iber has been used to design the protection barriers from floods of the Roman Military Camp of “Aquis Querquennis” (69-79 A.C.). This roman camp, inside the Roman Itinerary “Via Nova”, is located in the shore of the “Las Conchas” impoundment in the Northwest of Spain. This camp is subjected to the floods associated to this impoundment of “Las Conchas”. Therefore, and according to the directives of the European Parliament, a series of protecting measures have been analysed using Iber, which is a 2-D numerical code developed by GEAMA (Universidade da Coruna) and Flumen (Universitat Politecnica de Catalunya) that uses the finite volume technique to solve the 2-D Shallow Water Equations.

a b s t r a c t Fast methods to solve the unloading problem of a cylindrical cavity or tunnel excavated in elasto-perfectly plastic, elasto-brittle or strain-softening materials under a hydrostatic stress field can be derived based on the self-similarity of the solution. As a consequence, they only apply when the rock mass is homoge- neous and so exclude many cases of practical interest. We describe a robust and fast numerical technique that solves the tunnel unloading problem and estimates the ground reaction curve for a cylindrical cavity excavated in a rock mass with properties depending on the radial coordinate, where the solution is no longer self-similar. The solution is based on a continuation-like approach (associated with the unloading and with the incremental formulation of the elasto-plastic behavior), finite element spatial discretization and a combination of explicit sub-stepping schemes and implicit techniques to integrate the constitutive law, so as to tackle the difficulties associated with both strong strain-softening and elasto-brittle behav- iors. The developed algorithm is used for two practical ground reaction curve computation applications. The first application refers to a tunnel surrounded by an aureole of material damaged by blasting and the second to a tunnel surrounded by a ring-like zone of reinforced (rock-bolted) material. © 2013 Institute of Rock and Soil Mechanics, Chinese Academy of Sciences. Production and hosting by Elsevier B.V. All rights reserved.

We describe a new model for predicting the extent of blast-induced damage (BID) in rock masses. The model is based on Langefors' theory of rock blasting and the hypothesis that the maximum burden parameter defined by Langefors is a good indicator of BID. We have incorporated the effect of decreased internal energy of the gases as they expand to reach the walls of the borehole and then fitted the model to the available experimental data. Our model involves three easily obtainable parameters, namely, the energy loaded in the borehole, the coupling factor and the rock constant, and the mean gas isentropic expansion factor, which depends on the type of explosive used and on borehole and cartridge diameters. For this factor, we used approximate values independent of the type of explosive. The model indicates that there is a positive relationship between the internal energy of the explosive gases, once they have expanded inside the borehole, and the volume of damaged rock. This relationship is a function of the rock constant, a fundamental rock mass property that defines the maximum extent of damage under predefined charge conditions. The proposed model provides quite acceptable estimates of the fitted data, considering that just a single parameter is incorporated in the statistical procedure: the relationship between maximum burden and BID.