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Über dieses Buch

This book features a collection of extended papers based on presentations given at the SimHydro 2019 conference, held in Sophia Antipolis in June 2019 with the support of French Hydrotechnic Society (SHF), focusing on “Which models for extreme situations and crisis management?” Hydraulics and related disciplines are frequently applied in extreme situations that need to be understood accurately before implementing actions and defining appropriate mitigation measures. However, in such situations currently used models may be partly irrelevant due to factors like the new physical phenomena involved, the scale of the processes, and the hypothesis included in the different numerical tools. The availability of computational resources and new capacities like GPU offers modellers the opportunity to explore various approaches to provide information for decision-makers.

At the same time, the topic of crisis management has sparked interest from stakeholders who need to share a common understanding of a situation. Hydroinfomatics tools can provide essential information in crises; however, the design and integration of models in decision-support systems require further development and the engagement of various communities, such as first responders. In this context, methodologies, guidelines and standards are more and more in demand in order to ensure that the systems developed are efficient and sustainable.

Exploring both the limitations and performance of current models, this book presents the latest developments based on new numerical schemes, high-performance computing, multiphysics and multiscale methods, as well as better integration of field-scale model data. As such, it will appeal to practitioners, stakeholders, researchers and engineers active in this field.

Inhaltsverzeichnis

Frontmatter

Decision Support Systems and Crisis Management

Frontmatter

Chapter 1. Which Models for Decision Support Systems? Proposal for a Methodology

Management of water uses requests to harmonize demands and needs which are getting more and more complex and sophisticated especially with the growing urbanization. Modern cities request a larger number of services for their inhabitants and expect, at the same time, to limit investments in order to constrain the tax pressure. The need of optimization appears at various levels and request the wide spread of monitoring strategies. At the same time, urban growth mobilizes last available spaces that are frequently under the thread of natural hazards like inundations or landslides. The current situation, characterized by the fast increase of monitoring devices mainly in the urban environments, requests an integration of the modeling tools into the Information Systems (IS) that are now dedicated to the global management of urban environments and related services. Decisions Supports Systems (DSSs) that may integrated various components both for real-time monitoring and forecast through model, appear as one of the most relevant answer to the urban environment management’s expectations. The models integration is a challenging task that requests to build a global vision that ensures both technical feasibility and sustainability. As demonstrated with the AquaVar approach, several models can be orchestrated within a single environment that can address the diversity of the water related issues handled by local technical services. The models selection has to integrate the evolution of the tools and the possibility to integrate gradually new approaches and methods that are more data oriented and using the results produced from the implemented deterministic tools.

Philippe Gourbesville

Chapter 2. Aquavar: Decision Support System for Surface and Groundwater Management at the Catchment Scale

Due to the impacts of global warming or climate changes, the hazard caused by extreme weather event becomes more frequent and serious. At same time, the last available place such as the floodplain has been strongly encroached by the growing of urbanization, which could lead more citizens to be exposed to flood risks. In current situation, the flood caused by extreme rainfall event could be characterized with shorter response time and higher flood damages. To efficiently manage this kind of flood hazard and effectively reduce the damage cost, the Decision Support System (DSS) applied in urban management has been requested to be able to produce comprehensive view of current situation in real time and further provide accurate forecast as faster and possible. Benefited from the progress of informatics and monitoring techniques, the fast increase of monitoring devices lets the real time data collection become more feasible. And the development of modelling system of hydrology and hydraulic has reach a higher level during last decades, which nowadays is bale to integrated assess the existing catchment water system and further forecast the incoming situation. Integration of those new techniques into DSS, the design of the DSS architecture should be reorganized to make the system become more operational and functional. This paper presents a generic operational DSS approach in order to address the management of natural hazards (floods & draughts) in a sophisticated urban environment and provide both real time assessment and forecast on a Web-based information platform. The proposed approach is illustrated with one model integrated real time DSS application (AquaVar DSS) on Var catchment (2800 km2) located at French Riviera. Three deterministic distributed model applications of hydrology, hydraulic and groundwater has been integrated into the modelling system at analytic part of the DSS and linked with a Web-based user interface to provide sufficient information for real time risk management in the area. The integrated representation provided by AquaVar DSS has confirmed the feasibility of applying this DSS approach for dealing with extreme hazards. And similar approach could also be implemented in other managements of urban environment and related services such as energy distribution or water distribution.

Qiang Ma, Philippe Gourbesville, Marc Gaetano

Chapter 3. Anywhere: Enhancing Emergency Management and Response to Extreme Weather and Climate Events

ANYWHERE project aims to produce a platform to empower exposed responder institutions and citizens to enhance their anticipation and pro-active capacity of response to face extreme and high-impact weather and climate events. This is achieved through the operational implementation of cutting-edge innovative technology as the best way to enhance citizen’s protection and saving lives. ANYWHERE has implemented a Pan-European multi-hazard platform providing a better identification of the expected weather-induced impacts and their location in time and space before they occur. This platform is composed of a unique Multi-Hazard Early Warning System (MH-EWS) that supports a fast analysis and anticipation of risks prior the event occurrence, an improved coordination of emergency reactions in the field and help to raise the self-preparedness of the population at risk. The A4EU platform was designed to be adapted to provide early warning products and locally customizable decision support services proactively targeted to the needs and requirements of the regional and local authorities, as well as public and private operators of critical infrastructures and networks. It has been implemented and demonstrated in 7 pilot sites to validate the prototype and was successfully transferred to the real operation. The ongoing market uptake is ensured by the cooperation with a SME and Industry Collaborative Network, covering a wide range of sectors and stakeholders in Europe, and ultimately worldwide.

Morgan Abily, Philippe Gourbesville, Eurico De Carvalho Filho, Xavier Llort, Nicolas Rebora, Alexandre Sanchez, Daniel Sempere-Torres

Chapter 4. Use of Anywhere Products to Assess Risky Events on Southern France and Corsica (October 2018)

This last October was scene for some unusual and extreme weather events on the Mediterranean basin. Liguria, Catalonia, Mallorca, Corsica, Aude and Var were some of the many regions affected by heavy rains, floods, storm surge and gusty winds. More than damages on goods and infrastructure, these risky events claimed the life of several people and grave a deep scar on the soul of citizens, mayors and safety officers. The European Commission has been financing some projects to enhance early warning systems, in order to cope with potentially dangerous events, such as ANYWHERE. On this panorama, Predict Services was invited to implement a platform to test several data arising from that project for Northern Corsica firemen department in order to assist it during its safety and logistics decision-making. The platform was made available on early October; thus, Predict Services on-call engineer team was able to closely monitor some of the aforementioned events. The present paper presents the results and the return of experience of using these data on the events of Southern Corsica and Var departments (October 10th to 11th), Aude department (October 14th to 16th) and Haute Corsica (October 16th to 17th). In these events, the main products related to rainfall and flash floods nowcast were used and provided pertinent information both on geographical location and chronology, which could be translated into savings.

Eurico de Carvalho Filho, Guillaume Lahache, Alix Roumagnac

Chapter 5. Decision-Making Support System for Crisis Operations and Logistics Aspects in Extreme Weather-Induced Events

Extreme weather and climate events are causing several hazards affecting our society, and when interacting with exposed and vulnerable human and natural systems they can lead to disasters. Critical infrastructures such as transportation (roads, rails, etc.) can be affected and their capacities collapsed in critical points. In these situations, logistics and distribution tasks are considered in many EU countries among the priorities services both for commercial entities and for emergency operators. Early-warning measures and decision-making tools should enable to improve protection measures and, in case of catastrophic situations, improving the coordination of rescue operations.In the framework of ANYWHERE project, the aim of the current work was to design and test software solutions for decision-making able to support the emergency operators and transportation stakeholders affected by weather disruptive events, improving preparedness and planning capabilities.A platform was developed to support the implementation of actions related to emergency plan effectively presented with step-by-step operative checklists without affecting nor changing procedures and legacy systems in place.Furthermore, it also implements weather forecast and impact estimation on the local road network of interest through a dedicated simulation service for transport modeling.The outcome are indications useful for emergency operators to have a wider awareness of the current situations, understand the weather impact on traffic and viability but also for logistics-related companies (i.e. food distribution) and transportation stakeholders enabling the identification of best route (i.e. alternative road, multimodal path) between two locations in such weather disruptive situations.

Ivan Tesfai, Giovanni Napoli, Salvatore Ferraro, Andrea Poggioli, Marta Speranza

Chapter 6. Operational Resilience Index Computation Tool as a Decision Support System Integrated in Eu Risks Management Platforms—Test on Biguglia Catchment, a Mediterranean Intense Precipitations Regime Prone Area

A Decision Support tool, relying on resilience assessment approach has been developed to reinforce decision makers for climate related emergency management operations. The method proposes the calculation of an Operational Resilience Index (ORI) at city building/block scale. The ORI tool is developed based on a previous innovative research line, which was allowing computing flood resilience index for mid-term urban planning, adapted here to specificities of emergency management operations.The adaptations in the method for ORI tool, allows to use the existing concept of specific resilience, where the anthropized system is characterized in categories of urban functions and urban services. Dependencies between urban functions and services according to the impact of a given hazard is directly parameterized through a web-based GUI. The adapted new method takes into consideration for the ORI computation: multi-hazard, integration of critical infrastructures as well as social events occurrences in the adjustment parameters of the ORI computation. The requirements for the tool uses are: (i) a training of the end-user and (ii) a specific formatting for the input data. The ORI tool has been implemented and tested by end-users in the framework of a H2020 Research and Innovation project- ANYWHERE- in web-service based Pan-European multi hazard platforms DSS. Tests performed presented here, are those related to flood hazard initiated by Mediterranean intense rainfall events, which were performed on the 182 km2 Biguglia catchment in Corsica island (France). A six hours long rainfall runoff event cumulating 165 mm has been simulated over a 20,000,000 cells grid using a full 2D SWE based modeling approach on a HPC structure, to generate 5 m resolution flood hazard maps, used as inputs for the ORI computation. The other inputs of the ORI method are OGC standards compliant format GIS information: building, networks (electricity, transport, communication, water supply) local critical infrastructure and social events, preformatted for the ORI computation process.This paper details respectively: ORI tool method, ORI tool interface and API development for integration within the ANYWHERE Pan-European platform and an application illustration through flood hazard map computation scenario and method. Then, a summary of the user guide is presented, explaining the needs and prerequisites for end-users to use the tool and understand the outputs. Lastly, the main advantages of this ORI computation tools and the principal limits raised by end-users (here, SIS2B fire brigade command and control center) for improvements are exposed and analyzed.

Morgan Abily, Philippe Gourbesville, Hézouwé Amaou Tallé, Marc Gaetano, Jelena Batica, Patric Botey, Marien Setti

Chapter 7. Realtime High Resolution Flood Hazard Mapping in Small Catchments

All over the world a lot of cities are located in flood-prone areas and millions of people are exposed to inundation risk. To cope with that the civil protection organism demands efficient tools able to predict flooding risk and the associated ground effects with the goal of social safety. For this reason, the flood forecasting systems on specific river sections, also called hydro-meteorological chains, has become very useful due to the ability to use rainfall observations and predictions to provide in advance a quantitative evaluation of possible ground effects in term of discharge and peak flow.Recently, thanks to the advancement in computing performances, the hydro-meteorological chains can be completed with the hydraulic models able to compute bi-dimensional flooding maps. Unfortunately, the use in real time is still a challenging task both in large basins, for the extension of the potentially flooded areas, and in small-medium basin for the temporal scale of the phenomena.To overpass the problem, an abacus of flood scenarios has been used to create in real time inundation scenarios useful for civil protection and authorities to evaluate flood risk. The abacus is created with a full bi-dimensional hydraulic model able to assess flood extension and flow depth maps accordingly to different statistical quantiles of discharge.An algorithm able to join the different return period scenarios has been created to define the maximum flood extensions expected given the flow forecast or the observations of the hydrometric level converted in discharge for some river sections. The algorithm has been tested on past events on Liguria region where there are several small and very small catchments (<15 km2) and now runs operationally within EU funded projects as ANYWHERE H2020 project and POR framework.

Flavio Pignone, Lorenzo Campo, Daniele Dolia, Rocco Masi, Giacomo Fagugli, Daniele Ferrari, Simone Gabellani, Francesco Silvestro, Nicola Rebora, Francesca Giannoni

Chapter 8. Visualization of Flood Simulation with Microsoft HoloLens

It is necessary for decision makers and stakeholders to have the necessary information and tools needed to make sound decisions for mitigation plans for flooding. However, most of the decision makers and stakeholders are not technically-trained, it is often difficult for them to envisage the flood impacts based on the reports of the flood damages analysis. Thus, in order for them to visualize the impacts of the floods, a virtual reality tool is developed where the user is transported to the flooding location where they are able to access the flood damage and the benefits of mitigation in first person perspective. The visualization of the flood simulations using virtual reality transports users into a simulated world and transforms watching the screen into a living experience. Compared with the original plane drawing, screen watching, and sand table model, exhibition with virtual reality will no longer be limited by time or space. It also provides more comprehensive information with lower cost and better viewing experience. The scenes that are presented in this work are produces using the AR device of Microsoft HoloLens. They have the following functions: (1) exhibition of the city model, (2) interactions to manipulate the model, flood simulation. The city model was firstly designed using CAD (Computer Aided Design) software. The exported model files are then imported into the Unity3D, where IDE (Integrated Development Environment) is used to design the virtual scenes. Flood simulation data are also imported into Unity3D which are fed into the program to compute the level of the flood at every location in the scene.

Shanyu Wang, Jianrong Wang, Philippe Gourbesville, Ludovic Andres

Chapter 9. Anycare: A Serious Game to Evaluate the Potential of Impact-Based and Crowdsourced Information on Crisis Decision-Making

Extreme weather and climate events challenge weather forecasting and emergency response operations and are often related to high social, environmental and economic impacts worldwide. Effective disaster risk management relies not only on the accuracy and precision of official hazard predictions and related warnings issued by forecasters but also on how those are communicated to and interpreted by end-users to support informed decision-making on allocating human and material resources before and during the crisis. Recent decision-support tools promote the elaboration of multi-hazard ‘impact-based’ or ‘risk-based’ forecasts that translate meteorological and hydrological hazards and related cascading effects into sector- and location- specific impact estimations as the core to improve responder’s and public’s understanding and coping capacity to those risks. To take a first step towards exploring this hypothesis, we propose a new role-playing experiment that engages participants in the decision-making process at different levels of the weather-related emergency system. ANYCaRE serious game experiment explores the value of modern impact-based weather forecasts on the decision-making process to (i) issue warnings and manage the official emergency response under uncertainty and (ii) communicate and trigger protective actions at different levels of the warning system. Flood/flash flood or strong wind game simulations seek to reproduce realistic uncertainties and dilemmas embedded in the real-time forecasting-warning processes. A tabletop version of the game was first tested in scientific workshops in Finland, France and Spain where European researchers, developers, forecasters and civil protection representatives helped refine the concept. An improved version was then implemented with undergraduate University students in France and with stakeholders involved in the management of hazardous weather emergencies in Finland. First results indicate that (i) multi-model developments and crowdsourcing tools increase the level of confidence in the decision-making under time pressure, and (ii) facilitates interdisciplinary cooperation and argumentation on emergency response in a fun and interactive manner. ANYCaRE tabletop version appears as a valuable learning tool to enhance participants’ understanding of the complexities and challenges met by various actors in weather-related emergency management.

Galateia Terti, Isabelle Ruin, Milan Kalas, Arnau Cangròs i Alonso, Tommaso Sabbatini, Ilona Lang, Balazs Reho

Chapter 10. From Catstrophe to Resilience

How do we cope with catastrophe events using existing models? Are we going a step forward and focus on sustainable solutions taking into account a more holistic approach and resilience concept? Natural disasters are characterized by different patterns in recent years. Urban communities have developed assets too vulnerable to disasters and now they are about to have high damage. There is a need for a new framework that takes into consideration models, crisis management, new holistic concepts along with social components. The concept of resilience to natural disasters, preferably resilience to floods will be the main subject of this paper.

Jelena Batica, Philippe Gourbesville

Chapter 11. Marine Dispersion Modelling and Expertise Tools for Accidental Radiological Contamination of French Coasts

IRSN develop tools to manage any marine contamination of French coastal areas. In case of radioactive accidental marine contamination, we should be able to evaluate and anticipate the post-accidental situation: contaminated areas localisation and contamination levels, and possible consequences. Many sites should be considered for potential source terms into the sea: Coastal Nuclear Facilities, Military Harbours as homeports of nuclear powered vessels, and different river mouths that could be contaminated by any accidental release from a nuclear power plants situated upstream.The modelling tool, STERNE (Simulation du Transport et du transfert d’Eléments Radioactifs dans l’environNEment marin), simulates radionuclide dispersion and contamination of water and marine species, incorporating spatial and temporal processes. To operate it, 3D hydrodynamic data should be provided routinely to IRSN crisis center. Different possible radiological source terms can be taken into account: direct liquid releases, atmospheric depositions or river inputs of radionuclides. STERNE calculates radionuclides transport using advection and diffusion equations offline from hydrodynamic calculation. Radioecological model based on dynamic transfer equation to evaluate concentrations in marine organisms is also implemented. Needed radioecological parameters (concentration factors and single or multicomponent biological half-lives) have been compiled for some important radionuclides and for generic marine species (fishes, molluscs, crustaceans). Dispersion and transfer calculations are carried out simultaneously on a 3D grid. Results, available as netcdf files can be represented on maps, with possibility to follows temporal and spatial evolution. Post-treatment and representation are then possible.In parallel, marine environment stakes and characteristics are compiled for the different sites, identifying potential stakes for human protection like aquaculture areas, beaches, or industrial water intakes, and ecological richness. This information will be used to facilitate decision-making during an emergency and could serve as a basis for post-accident sampling strategies leading to realistic environmental impact assessment.

Céline Duffa

Chapter 12. A Study on Water Crisis Management Techniques by Fallout in Case of Radiation Accident Using Environmental Multimedia and Air Transport Diffusion Model

Northeast Asia has a high density area of nuclear power plants and recognizes the need for crisis management from radioactive accidents due to actual nuclear power plant. When a radioactive exposure accident occurs, the cesium in the radionuclide has a long half-life and is released into the atmosphere, and it can move through the wind. We need to be able to analyze the effects of deposition by fallout on the water system in our country, along with transport and diffusion from the atmosphere in order to accurately predict radioactive materials. In addition, we can be decided pollution levels in watersheds and rivers by using an environmental multimedia model about the phenomena of transport through air, watershed and rivers. Therefore, it can be predicted and controlled with the whole process of radioactive accident using the result of this study as a crisis management technique.

Daemin Oh, Youngsug Kim, Sungwon Kang, Soungjong Yoo, Noriyuki Suzuki, Yoshitaka Imaizumi

Chapter 13. Challenges in Defining Alarm Thresholds to Improve Crisis Management Procedures: A Case Study on the French Riviera

When dealing with crisis management in the context of river floods, clear and straightforward procedures must be established. SMIAGE (Syndicat Mixte Inondation, Aménagement et Gestion de l’Eau maralpin) is a public structure dealing with flood, river and water management in the AlpesMaritimes department in the South-East of France. This structure was created to gather the department operational forces to consider water management from the river basin’s point of view, rather than from the administrative limits point of view. Indeed, SMIAGE was created after the deadly event that occurred on the October 3rd, 2015, when the needs of a wider consideration of flood events were demonstrated on the French Riviera. Moreover, in the Mediterranean context, flash floods must be considered. These events are widespread and poorly understood. One of the main missions of this entity is to assist municipalities by operating a flood warning system, especially for the Siagne catchment.Everywhere else on the SMIAGE’s territory, the objective is to maintain dikes and other hydraulic structures and to be able to help municipalities to get accurate and clear information while a flood event is happening and afterwards.While crisis procedures are implemented already, warning thresholds are mainly defined by historical experience and local knowledge. Water depths generating road flooding are often well-known by municipalities. However, intense urbanization has changed catchments’ response and vulnerable areas’ location. Meanwhile, hydrometric and rain gauges together with radar data are available. A reflection is undertaken about a large-scale modelling system. Data of different types are examined with several modelling philosophies. First results show that large-scale modelling can help defining warning water depths at selected river sections. Event management procedures can be refined and improved thus reducing false and missed alarms.

Stan Nomis, Leslie Salvan, Raphaëlle Dreyfus, Franck Compagnon, Pierre Brigode

Chapter 14. Integrations of an Early Warning System and Business Continuity Plan for Disaster Management in a Science Park

Extreme weather events such as typhoons and torrential rain can cause loss of life, damage of property and business. Recent research and events showed that flood damage to industrial areas not only cause damage to high-tech instruments and products but also lead to the supply chain disruption. The later one has a significant impact on the global market. Therefore, this study proposes a system that integrates weather and flood forecasts with a concept of business continuity plan (BCP) to minimize the disruption of business operation due to floods. BCP consists of a series of actions of preparedness, information analysis, response, recovery and maintenance, providing constructive suggestions to decision-makers. Given information from a purpose-driven design flood routing model and the BCP, the decision makers can react to the disaster accordingly. This study selected a science park in central Taiwan as the study area. A custom-made BCP and associated decision support system (DSS) were established for analyzing information and retrieving relevant suggestions of actions based on the factories within the science park. The administration office of the park along with the factories conducted several flood drills and the results showed that the system improves the emergency preparedness and responses. The science park can strengthen their resilience to disasters through the system. The system and concept can be easily adopted and applied to other industrial parks because of its effectiveness and performance.

Tsun-Hua Yang, Hao-Ming Hsu, Hong-Ming Kao

Chapter 15. Natural Hazard Crisis Management Exercice at Metropolitis Scale: Methodolgy for Holistic Involvement of Municipalities

For the French municipalities, crisis management system involves by law, two main responsible and decision-making actors who are the city Mayor, and the state representative at the county level, the Préfet [1]. Nonetheless, since the development of the French Metropolis entity system—cluster of geographically close municipalities aiming mutual management of sets of selected transversal urban functions—many competencies that were handled by the municipalities in case of crisis are now transferred to the newly created Metropolis entity. Municipal Council Safeguarding Plans (PCS) are established at municipalities level whereas, the Metropolis entity has to handle coordination and support of its application—without having the full legal responsibility which remains in metropolis Mayor hands-, and with limited means, whereas at the same time, solicitations at Metropolis level increase. PCS are the key strategic procedure in case of extreme climatic alerts and catastrophic events. The presented paper focuses on how, after having provided support to setup the PCS at municipal levels, the Metropolis of Nice Cote d’Azur design a crisis management exercise aiming to test basis and good reflexes of PCS application as well as to test their coordination. The exercise for PCS activation was based on intense rainfall and flooding event scenarios. This exercise took place on the 3rd of October 2018, echoing to the 3rd of October 2015 flood events in the French Rivera [2]. This paper focuses on the development—methodological and organizational aspects—of a crisis management exercise project dedicated to trained main stakeholders and raised awareness. The step-by-step elaboration process of the exercise is presented. Organizational, technical means such as scenario and numerical models elaboration and multi-objective matrixes are detailed. Main feedback enhanced in this paper are the results focused on the necessary equilibrium to achieve in order to adapt such type of exercises to different nature and organizational levels divergent objectives and political constraints shared—or not—by the Metropolis municipalities and by the Metropolis itself. The proposed and implemented method is synthesized as guidelines and can be used as template for management crisis exercise design.

Yannick Dorgigne, Morgan Abily, Philippe Gourbesville

Chapter 16. Check Dam Behavior Under Extreme Circumstances at Villeneuve (Switzerland)

The Tinière torrent is located in the western part of Switzerland and has its exutory in the Lake of Geneva. In 2006 and 2007, major flood events generated deposition of 10,000 m3 of solid material along the canalized part and more than 100,000 m3 in the upstream ravines. These deposits have caused the inundation of urbanized areas as well as erosion of torrent banks upstream. Also, several bridges have been destroyed. Detailed hazard mapping has shown significant risk of damage to the federal highway A9 as well as to the main railway and cantonal highway crossing Villeneuve for flood events between 100 and 300 years. Hence, three check dams have been constructed in the upstream part of the torrent. The retention volumes created by these dams aim at retaining the major part of the solid material that is being transferred during major flood events. However, during construction of the check dams, in July 2013, a major flood event has occurred at the construction site. A series of debris flows filled up the volume behind the most upstream located dam (~5,000 m3). This structure was not yet finished at the time of the event, only the concrete core of the dam was put into place. The event has caused damage to the structure but has saved Villeneuve from potential damage. In the following, the 2013 flood event and its crisis management are presented, together with the behavior of the partially constructed check dam and its positive impact on downstream safety.

Charlotte Dreger, Erik Bollaert, Olivier Stauffer, Yves Châtelain

Chapter 17. Development of the Similar Typhoon Search System Based on the Deep Neural Network Using Deep Learning

We present a method for improving the search accuracy of the similar typhoon research system by leveraging deep neural networks, which are an extension of artificial neural networks. To the search engine, we apply three parameters of typhoons: course, temporal central pressure, and speed. We show that these parameters can improve accuracy when searching for past typhoons having characteristics similar to the target. Furthermore, the accuracy of functions designed to support the expected disaster prevention actions and flood fighting services was assessed based on the results from the search system.

Kohji Tanaka, Eisaku Yura, Tatsuya Yoshida, Shigeho Maeda

Chapter 18. An Innovative DEM Improvement Technique for Highly Dense Urban Cities

This paper presents an innovative approach to derive an improved Digital Elevation Model (DEM) using multispectral imagery and Artificial Neural Network (ANN). The DEM is crucial in land and water management which reflects the actual topographic characteristic on earth surface. However, a high accuracy DEM is very difficult to acquire because it is often very costly and is treated as confidential.DEM from Shuttle Radar Topography Mission (SRTM) has been improved using multispectral imagery of Sentinel 2 and the ANN with its strength of pattern recognition in big data processing. SRTM is widely used in the area where the high accuracy DEM is not available as it is easily accessible to the public with no cost. However, its accuracy is limited due to its coarse resolution (≈30 m) and sensor limitations. Sentinel 2 provides the 13 spectral band spans from the visible and the near infrared to the short wave infrared at different resolutions ranging from 10 to 60 m. Sentinel 2 produces different reflectance values in different land-uses. These two remote sensing data are used in ANN as input data. The ANN is trained with reference DEM which has a high accuracy level and different weights are calculated to reduce the error between the elevation of SRTM and reference DEM. The trained ANN is applied to a different place to evaluate the performance. The improved SRTM presents clearer images with higher resolution than the original SRTM with 6 to 26% lower Root Mean Square Error (RMSE). The paper should be of interest to readers in the areas of remote sensing, artificial intelligence and land/water management, especially for the policymakers who require land surface simulation with higher accuracy of topography.

Dongeon Kim, Shie-Yui Liong, Philippe Gourbesville, Jiandong Liu

Chapter 19. An Integrated Approach to Water Resources and Investment Planning for Water Utilities

Traditionally, water companies in England and Wales use supply-demand modelling methods as decision-making tools for water resources evaluation and investment planning. Companies use separate models for water resources planning and for water resources investment-planning. This approach entails calculating deployable output in a water resources model, for an assumed level of service. That deployable output calculation is exported to an investment model. There is no two-way integration between the water resources model and water resources investment model in the traditional approach, hence any investments do not affect deployable output estimated first in the former model. This paper proposes a new integrated approach—where water resources modelling and investment modelling are integrated, by way of a single modelling tool. The aim of this paper is to compare and contrast traditional water resources and investment planning with the proposed new integrated approach. The new integrated model will allow for the impact of investment choices on the supply and demand position at any point over the planning horizon. The new tool is run for the baseline scenario and for climate change supply scenarios. The results from the integrated model are compared with the results presented by Bristol Water in their Water Resources Management Plan. The level of service metric is calculated in the new model for both baseline and climate change supply scenarios. Finally, this paper proposes further improvement of the integrated model, including potential multi-objective optimisation and new approach to represent uncertainty.

Damian Staszek, Dragan Savic, Guangtao Fu

Chapter 20. Model Improvement for Effect Evaluation of Low Impact Development Measures

Low impact development (LID) practices, such as bioretention and green roof, aim to increase infiltration and retention to manage urban flood. Flood simulation model is an effective tool for scheme comparison at the design stage. In addition, it is also a good method to evaluate the effects of LID after construction. The Flood Risk Analysis Software (FRAS), developed independently by China Institute of Water Resources and Hydropower Research (IWHR), is integrated software that can simulate the whole flood process, mainly including 1D-2D coupling hydraulic model, hydrological model and drainage model. And FRAS also has accurate and reasonable structure routines for urban flood simulation because of the coupling calculation of different models. In order to reflect the influences of LID measures on runoff generation and confluence more accurately, the following improvements were made based on the original software: (1) The SCS method is added to the original rainfall-runoff model due to its simple but sensitive parameter, which can comprehensively reflect initial soil moisture, soil type and land use type of different LID measures. Additionally, it is coupled with the 2D surface hydraulic model in real-time to precisely describe the infiltration process. (2) According to the main functions and characteristics of different LID practices, three typical measures, i.e., green roof, bioretention and porous pavement, are set as special land use types, respectively. The parameters and calculation methods are adjusted accordingly in the model. After these improvements, the model can have more precise simulation about the increased infiltration and flood retention of LID measures.

Yuting Meng, Na Li, Jing Wang, Qian Yu, Nianqiang Zhang

Chapter 21. Multiple Feedback Linkage in the Process of Urban River Water Treatment

According to the measurement data of hydrology and water quality, the decision support system in the multiple feedback linkage system is used for calculation, combined with the judgment and decision of the expert system in the water treatment expert assistant decision analysis system, the precise control of the Internet of Things equipment in the water treatment project were realized. an intelligent water body management system was established that combined human intelligence with machine intelligence to realize the process of water body treatment and monitoring technology to collect, analyze and process data, to achieve more efficient water treatment and more accurate water body monitoring. Use the comprehensive water-related data collected to provide decision support for regional industry development.

Lunyan Wang, Shoukai Chen, Xiangtian Nie, Shichao Liu

Flood Forecasting (21)

Frontmatter

Chapter 22. Real-Time Flood Management and Preparedness: Lessons from Floods Across the Western Japan in 2018

With a seasonal rain front hovering over the western Japan, extreme heavy rainfall hits the western Japan in July in 2018. The torrential rainfall caused severe floods and landslides across the western Japan, leaving more than 230 people dead or missing, and more than 29,000 houses inundated. Looking into the processes of the disasters and responses by authorities or residents, issues and challenges in flood awareness, preparedness and response can be revealed for more resilient society against those extreme flood events. In this paper, the processes of the floods and responses in the floods in the western Japan in July, 2018 are reported in this paper to draw a lesson for more effective flood management system against extreme flood events. The paper firstly describes the processes of flood disasters in two case study river basins. The case studies show the importance to increase awareness and preparedness in advance of occurrence of extreme flood events in order to ensure the designed crisis management strategy is still effective under the extreme conditions.

Daisuke Nohara, Yasuhiro Takemon, Tetsuya Sumi

Chapter 23. Flood Forecasting in Alpine Regions Using a Multi-model Approach: Operational Performance and Experiences After Two Years of Experience

Flood forecasting is an important tool for flood management, as it allows to anticipate these extreme events. The main difficulty is to provide sufficiently accurate forecasts, giving a quantitative prediction of the flood discharge and its timeline. The uncertainties can be high and lead to inappropriate decisions. For this reason, ensemble or multi-model deterministic forecasts provide numerous flood scenarios and help the decision-making.The Leysse river basin is located in the Rhône-Alpes region in France. It is a typical pre-alpine catchment of 294 km2, benefiting from a mild mountainous continental climate. Flood events can occur in winter after a long precipitation with moderate temperature, leading to snow melt. They can also occur in summer during violent thunderstorms.A flood forecast system is developed for this basin, based on a hydro-meteorological cascade. Numerical weather forecasts, issued from different deterministic or ensemble models, are used as precipitation and temperature input data. A semi-distributed rainfall-runoff model is used to simulate the river flows. Gauged as well as ungauged catchments are considered in the forecast system.Different numerical weather models are compared, in order to define the best forecasting scenario. High-resolution models such as Arome (Meteofrance) of cosmo-1 (Meteoswiss) are compared to the ensemble probabilistic model cosmo-e (Meteoswiss) and the deterministic verification run of IFS (Ecmwf). In this region, the models show a real complementarity, as no one outperforms systematically the others. This contribution presents the operational strategy to cope with the non-systematic precipitation forecasting errors and the other uncertainties related to the rainfall-runoff simulation.

Frédéric G. Jordan, Raphael Mutzner, Alexandre Prina, Christophe Guay

Chapter 24. Application of an Ensemble Kalman Filter to A Semi-distributed Hydrological Flood Forecasting System in Alpine Catchments

One of the key success factors for hydrological forecasts is initial conditions that represent well the conditions of the simulated basin at the beginning of the forecast. Real-time Data Assimilation (DA) has been shown to allow improving these initial conditions. In this article, two DA approaches are compared with the reference scenario working without DA (Control). In both approaches, discharge data at gauging stations are assimilated. In the first approach, a volume-based update (VBU) compares the simulated and observed volumes over the past 24 h before the start of a forecast to compute a correction factor used to update the initial soil water saturation in the upstream part of the semi-distributed hydrological model. In the second approach, an ensemble Kalman filter (EnKF) is implemented to account for the uncertainty in initial conditions, precipitation, temperature and discharge data. The comparison is carried out over two sub-basins of the Upper Rhone River basin upstream of Lake Geneva, in Switzerland, where the MINERVE flood forecasting and management system is implemented. Results differ over the two studied basins. In one basin, the two DA simulations perform better than the Control simulation, with the EnKF simulation providing the best forecasting performance. In the second basin, where the Control simulation performs best, possible challenges with hydropower-based discharges are highlighted.

Alain Foehn, Anne Schwob, Damiano Pasetto, Javier García Hernández, Giovanni De Cesare

Chapter 25. Real-Time Inundation Mapping with a 2D Hydraulic Modelling Tool Based on Adaptive Grid Refinement: The Case of the October 2015 French Riviera Flood

The vulnerability of the French Riviera territories to hydro-meteorological hazards has been highlighted by the flash flood of the 3rd of October 2015, which had catastrophic consequences. In the view of the speed and violence of these phenomena, the development of warning systems able to provide real-time flood mapping should make it possible to limit their impacts. In this context, the main objective of this work is to study the feasibility of using a 2D hydraulic modelling tool with adaptive grid refinement, the Basilisk calculation code – http://basilisk.fr/ , which is based on state-of-the-art finite volume methods. This code has been used to model the October 2015 flood event on one French Riviera coastal catchment, the Brague River catchment. Results obtained with Basilisk were compared with available information from post-event surveys, showing promising performances in terms of simulated peak discharges, inundation extent and water levels in the floodplain. These results highlight that forecasting inundation extents generated by flash flood events on small watersheds (less than 100 km2) is possible at a moderate computational cost.

Geoffroy Kirstetter, François Bourgin, Pierre Brigode, Olivier Delestre

Chapter 26. Early Warning System for Flood Warning in Campings

The following paper explain a new methodology for an early warning system for rain events at a campsite over the Pyrenees in Lleida in the Northeast of Spain. The typology of rainfall events is well known in this part of the Pyrenees. They are normally events with high intensity and short duration and are mainly distributed over summer and springtime. This temporal distribution of the rainfall becomes the main treat in this part of the country, due to during this period of the year there is a great amount of tourist mobility that search for natural environments. Most of the campsites of the zone are located next to the rivers; therefore, many of them are subjected to a high probability to suffer damages under heavy rain events and the consequent floods. Due to that and considering that the campsites might be full of people during this time, it is highly recommended to have and early warning system in the case the campsites may be flooded by a heavy rain event.

Gonzalo Olivares, Manuel Gómez, Joan Gurrera, Marcos Sanz-Ramos

Chapter 27. An Automated Anomaly Detection Procedure for Hourly Observed Precipitation in Near-Real Time Application

For setting up an early warning system or for making a decision of disaster mitigation, real-time precipitation observation collected by in situ stations are necessary. However, the data easily become corrupted because of sensor failure or communication error. The simulations of a relevant hydrologic model under an extreme situation could be ridiculous due to incorrect precipitation observations as model inputs. Anomaly detection approaches are essential to flag anomalous data that not conform to expected behavior from normal data in near-real time. Manual inspection was used as an anomaly detection approach, but no longer applicable for big data and near-real time application due to manpower limitation. Therefore, this study proposes an automated anomaly detection procedure for precipitation including neighboring station selection and spatial consistency checking. First, the neighboring stations are not manually selected by a fixed distance, but automatically selected by the self-organizing maps (SOM) with recent historical records. Second, the target observation pairwise compares against concurrent neighboring observations to flag inconsistent data as anomalies. Because a suitable estimation of the target station is unnecessary in this procedure, it is applicable in areas with high spatial and temporal variability.

Sheng-Chi Yang, Ming-Chang Wu, Hong-Ming Kao, Tsun-Hua Yang

Chapter 28. Storm Water Management Model Parameter Optimization in Urban Watershed Using Sewer Level Data

The growth of severe rain storm in the world has increased flood damage severely, and the precipitation distribution is getting more erratic. The unpredictability in precipitation increases the seriousness of the existing flood damage especially during rainy seasons. Structural measures such as installation or expansion of drainage facilities and improvement of reverse gradient of sewer pipes can be applied to decrease the flood damage. However, these measures require high cost, lots of time, and large site. For these reasons, non-structural measures can be alternatives, and a rainfall-runoff analysis model must be established to apply non-structural measures. SWMM (Storm Water Management Model) is a representative model for rainfall-runoff analysis of urban watersheds. While this model is based on many parameters and provides relatively reliable results, it contains many ambiguous parameters. Therefore, parameter estimation is essential and can be done using optimization algorithms. In present study, harmony search algorithm, one of the widely known meta-heuristic algorithms was used to automatically estimate the parameters of the SWMM. Unlike the previous other studies, the parameters were estimated by considering not only the inflow data but also the sewer level data. After the calibration of the model, other rainfall events were applied to confirm the validity of the model. The proposed methodology was applied to a watershed in Yongdap pump station basin, Seongdong-gu Seoul, South Korea. The parameter estimation of SWMM using both inflow data and sewer level data in urban watershed showed reasonable results compared to results of common methodology which considering only inflow data.

Oseong Lim, Young Hwan Choi, Joong Hoon Kim

Chapter 29. From Meteorological Forecasting to Floodplain Forecasting for the Protection of Populations in Urban and Peri-Urban Areas

The best measure to protect residents in flood areas remains anticipating relief efforts. This requires early availability of reliable spatial and temporal information on future flood risk. We will present 2 case studies on which flood forecasting and warning systems have been set up. These systems all have the objective of translating rainfall forecasts into flood risk for the safety of people, however we will see that the flood risk information can be different depending on the context and the need of each administrator. These systems have been set up in the MIKE OPERATIONS platform to import and process rainfall data, carry out hydraulic simulations and provide flood risk information adapted to each user.The first case studies is about the flood forecast system of Pointe à Pitre developed for the CAP Excellence where the real time system can show a map with red point where the network can overflow in the next 24 h gives the flood risk information. The second case studies concern the flood forecast system developed for the SIAVHY which integrates a 1D/2D model running in real time with rainflow model based on spatial rainfall forecast. The flood risk information is a flood map with discretization of the water depth on the flood area. The main objective of all these systems is to provide an understanding of the expected risk for better anticipation, based on the transformation of the rainfall forecast information.

Sandrine Vidal, Jean Paul Ducatez

Chapter 30. Feedbacks on the Deployment of and Experimental Real-Time Flood Forecasting and Crisis Management System

Flood forecast and crisis management are part of real time operational management. Including the representation and analysis of river hydraulic response in the forecast seems to improve the anticipation of an event and could add valuable information in the operational management. An experimental real-time system has been implemented in two sectors in France to evaluate the capacity of such a system as a decision-aid tool for flood crisis management.One of the pilot sites is a catchment in South of France with the challenge to represent karstic cavities. The full system includes 4 data streams of discharge and water level measurements, 9 rain gauges and the Météo France forecast AROME model. It is based on hydrological and hydraulic models, and an automated system runs simulations of the models, post process the results and provides operational data. The latter can be visualized into a dedicated interface for the operator.Furthermore, alerts are triggered and can concern any observed or calculated data. These alerts are used to trigger new runs, provide flood forecast information useful in crisis management, and automatically send emails or SMS.This system allows the anticipation of floods in key places and add a view of the entire situation, even in unmonitored sectors, which could be valuable to the river management authorities.This experiment highlights several challenges facing the engineers such as the availability and accuracy of data streams inputs, and the accuracy and reliability of models, which must be improved in a cyclic approach for each new flood event.

Arnaud Koch, Armonie Cossalter

Chapter 31. Application of Recurrent Neural Network for Inflow Prediction into Multi-purpose Dam Basin

This paper aims to investigate the applicability of dam inflow prediction model using recurrent neural network theory. To achieve this goal, the Artificial Neural Network (ANN) model and the Elman Recurrent Neural Network (RNN) model were established for Soyanggang and Chungju dam basin using meteorological and hydrological data accumulated from dam operation since constructed. For the model training, inflow, rainfall, temperature, sunshine duration, wind speed are used as input data and daily inflow of dam for 10 days are applied as output of the model. And predictions of dam inflow for 2 years from July, 2016 to June, 2018 are carried out for verification purpose. The results showed that there was no significant difference in prediction performance between ANN model and the Elman RNN model in Soyanggang dam basin but the prediction results of the Elman RNN model are comparatively superior to those of the ANN model in Chungju dam basin. Consequently the Elman RNN prediction performance is expected to be similar to or better than the ANN model. Especially, the prediction performance of Elman RNN is also superior during low dam inflow period. In addition, it is shown that the multiple hidden layer structure of Elman RNN is analyzed to be more effective in prediction performance improvement than single hidden layer structure.

Juhwan Kim, Myungky Park, Yungsuk Yoon, Hyunho Lee

Chapter 32. Pre-release Strategy for Flood Control in the Multi-reservoir and Rivers System

In the last two decades, flooding has caused the most devastating and costly natural disasters in the central of Vietnam in general and Quang Nam province in particular. Reservoirs play an important role in reducing the damage of flooding downstream. Due to the increase in energy demand, more than twenty hydropower plants have been constructed on the upstream of Vu Gia Thu Bon rivers catchment. The steep slope of mountainous topography significantly limits reservoir capacity and influences on the decrease in flood control capacity. The pre-releases operation is an effective way in flooding control for reservoirs which limits in storage capacity. A procedure is proposed in this paper to evaluate the impact of pre-releases strategy on flood control and hydropower generation. The pre-release operation strategy has considered two operational objectives: minimizing the flood damage risk for downstream areas and achieving operation water level target at the end of flood event. The control strategies are set up in the Mike 11 model to guide the releases of the reservoir system depending on storage level, inflow and time of the year. This paper investigated the operation of the four major reservoirs in Vu Gia Thu Bon catchment during flood event of 2009, which aims to demonstrate capability of the approach in pre-release operation of reservoirs system. The results show that pre-release strategy is more effective regarding to both reduce maximum water level at downstream and maintains a high reservoir level aspect comparing to regular operation.

Thanh Hao Nguyen, Philippe Gourbesville, Ngoc Duong Vo, Nguyen Duc Phuoc Vo

Chapter 33. Optimization of Spillway Operation for Flood Mitigation in Multi-reservoirs River System

The multi-reservoirs system in Vu Gia Thu Bon rivers catchment plays a significant role in production of annually alternative electrical and mitigation of flood damage. However, in the flood season, operational problems of the rivers and multi-reservoirs system are more likely to increases which result from developing conflicts objectives and the number of reservoir. In this research, a flood mitigation operation approach based on a simulation-optimization model is developed for minimizing vulnerability of flood in downstream of the system. For this purpose, an optimization algorithm is introduced, in which maximum water level at downstream control points is objective function and the spillway release discharges are the decision variables. A global optimization tool, Shuffled Complex Evolution (SCE) algorithm which implemented in the AUTOCAL software was coupled with the Mike 11 from DHI simulation model for optimizing stages level of spillway gates. Vu Gia Thu Bon rivers catchment including four major reservoirs of A Vuong, Song Tranh 2, Dak Mi 4 and Song Bung 4 is examined in historical flood events that happened in 2009. The results show that the reservoir system using the optimal operation is more effective in reducing maximum water level at the downstream control points comparing to the current regulations.

Thanh Hao Nguyen, Philippe Gourbesville, Ngoc Duong Vo, Nguyen Duc Phuoc Vo

Chapter 34. Flood Forecast Tool to Help Dam Management from France to Thailand

The three dams of Haute Vilaine provide flood protection upstream of the city of Rennes and constitute a drinking water reserve for the eastern sector of the department. This system of three dams requires different management during the hydrological year: during the filling period the storage is used to reduce floods, while the available storage will be used to meet the water supply demands during the low flow period. To manage efficiently these conflicting objectives, a real-time forecasting decision support system (DSS) has been developed using MIKE OPERATIONS software. The system includes a NAM conceptual hydrological model coupled with the integrated basin management tool MIKE HYDRO Basin. The system can simulate river flows with lead-time period of 5 days. Dam operators use this tool to monitor in real-time the upcoming state of the system as well as plan for scenarios. Management of the ESAN basin dams in Thailand presents some of the same challenges as the dams of the Haute Vilaine with a much larger risk of flooding. A DSS based on the same framework has been developed however it comprises an optimization model coupled to a 1D hydrodynamic simulation model. The DSS has been set up to optimise in real-time the operation of the Ubol Ratana dam in order to determine the optimal releases of the dams to best meet all the conflicting objectives. The output of the tool guides the operators to implement a very robust solution for flood management.

Sandrine Vidal, Bertrand Richaud, Finn Hansen, Jimmy Courtigne

Chapter 35. Early-Warning System for Cyclone-Induced Wave Overtopping Aided by a Suite of Random Forest Approaches

Full process-based hydrodynamic models allows reproducing with high fidelity the complexity of cyclone-induced wave dynamics and their potential impact regarding overtopping-induced inundation. Yet, their major drawback is the high computational time cost (typically of several hours), which prevents them from a direct integration in a real-time early-warning system to support crisis/emergency management. A possible alternative relies on the statistical exploitation of pre-calculated simulation results to build a fast (low computation time cost) prediction model given the offshore conditions (wave and sea level). In the present study, we present a suite of random forest (RF) techniques for fast prediction of key indicators to support forecasting of cyclone-induced wave overtopping, namely: (1) the occurrence likelihood of the overtopping event using a RF-based classification method; (2) the maximum cumulative volume overtopping using a RF-based regression method; (3) the starting time of the overtopping event (referred to as time-to-event) using a multi-output RF-based classification method. We apply the technique at Sainte-Suzanne city at Reunion Island (Indian Ocean basin) using a database of simulation results, which relates offshore conditions (wave and sea level) induced by ~500 synthetic cyclones and their consequences in terms of wave overtopping, namely the time evolution of the cumulative overtopping volume in the vicinity of the emergency center. Through an extensive cross-validation exercise, we show the high performance of the RF models with respect to the prediction of the three indicators. More specifically, the accuracy and the area under the ROC curve (AUC) of the RF-based classifier reaches values above 95%; the R-squared of the RF-based regression model reaches values above 80%; the time-averaged accuracy of the multi-output RF-based classifier reaches values above 80%. As a complementary analysis, the comparison to simulated historical cases (Dumile in 2013, and Dina in 2002) shows error less than 10% on flooding indicators 2 and 3. Finally, we take advantage of the probabilistic information provided by RF models to evaluate some measure of confidence associated to the prediction result.

Jeremy Rohmer, Sophie Lecacheux, Rodrigo Pedreros, Deborah Idier, François Bonnardot

Chapter 36. Water Level Short-Term Forecasting Using Statistical Approaches: A Case Study on the Parisian Region

Forecasting water level from natural resources like rivers is very challenging due to the complexity of water sections and various environmental effects. In the Île-de-France region around Paris, the Syndicat des Eaux d’Ile de France (SEDIF) provides drinking water for more than 4 million inhabitants. Most of this water is produced by three large interconnected plants located on rivers Seine, Marne and Oise. When a flood happens, the water utility may change its operating strategy. If necessary, a plant is stopped another one takes over to maintain the Water Distribution System (WDS) while consumers are always supplied with drinking water. In this paper, a statistical approach is adopted to forecast river water levels when flood event occurs. Two ensemble models are designed to estimate values of the water level up to 48 h. The first modeling is a combination of a single-layer neural network tuned by Gradient Boosting (GB). The second method is a sequential version of the first one where a gradient boosting model is trained at each time step and the training includes the prediction of previous step models. These two models are evaluated to forecast water level located at the three production plants with horizons of 6, 12, 24 and 48 h. Real data from plants are used as well as upstream monitoring stations i.e. six stations on Marne, eighteen stations on Seine and ten stations on Oise. The extensive experiments show that the sequential model outperforms the other one and allow us to highlight the effectiveness of the proposed approach.

Nicolas Cheifetz, Hugo Senetaire, Cédric Féliers, Véronique Heim

Chapter 37. Uncertainty Propagation in Telemac 2D Dam Failures Modelling and Downstream Hazard Potential Assessment

This work addresses uncertainty propagation in Telemac 2D models with respect to two major types of risks in river hydrodynamics: flood hazard and dam failures. The studied case is a Telemac 2D model that extends over approximately 14.4 km2 with a river length of 41 km including 3 major tributaries to the main river and 3 dams. The implementation of the uncertainty propagation approach would not have been feasible and accomplished without the open source platform Salome-Hydro and the TelApy module (Python API) of the Telemac-Mascaret System. The first step consisted of quantifying uncertain parameters for the acquired hydraulic model and defining adequate probability distributions based on expert judgment and previous specific studies that have been provided by EDF. A sensitivity analysis based on Morris screening method was then carried out to reduce the number of uncertain factors. Uncertainty propagation algorithms such as Monte Carlo and Polynomial Chaos expansion were used to estimate the maximum water depths and velocities, as well as their statistical moments such as the mean and variance and the Sobol indices of the considered parameters. The use of parallelism proved to be necessary to optimize the computation time. The final results are then used to assess the flood casualties and the flood damages. This second estimation is based on the FloodRisk plugin of QGIS.

Layla Assila, Matthieu Sécher, Thomas Viard, Benoît Blancher, Cédric Goeury

Chapter 38. Defining Uncertainty for a Simplified Method Dedicated to the Mapping of Extreme Floods

The risk assessment for extreme floods is a key point to anticipate and to dimension a set of measures to improve the resilience of the territories. Because extreme floods can seldom be observed, the calculation of hazard in the flooded areas comes from an extrapolation of models calibrated on more frequent events. This latter extrapolation can be based on a detailed representation of the processes that may influence the flood features or on a more simplified approach that permits much faster calculations. For the specific cases of the Rhône and Gardons valleys in the Southern France, an estimation of the uncertainty is carried out in order to compare a detailed representation and a simplified approach. called “Additional Depths Method” that guesses the flooded areas of a reference flood are accurately estimated. Then, the topography of the valley above the reference flood level permits to define a set of cross sections in which a uniform flow is calculated for a flow discharge calculated as the difference between the extreme flow and the reference flow. Finally, the limits of the flooded areas are drawn starting from the water elevation interpolated between the values obtained at the cross sections. This simplified approach is encapsulated in a plug-in of the QGIS software. The uncertainty linked to the simplified approach can vary a lot from as low as 10% up to 100%. The plug-in is convenient in the more favourable cases in which the hypothesis of a 1D flow can be kept and the topography agrees with the reference map.

André Paquier, Quentin Royer, Christine Poulard, Pascal Billy

Chapter 39. Experimental and Numerical Modelling of the Influence of Street-Block Flow Exchanges During Urban Floods

During urban floods, the flow is generally concentrated in streets, but lateral exchanges with building blocks can alter locally the flow pattern. These blocks include buildings, courtyards, parking lots, gardens, into which water enters through different openings, such as windows, doors, gates, fences, etc. In order to study these exchange processes and their influence on flow depth and velocity in the streets during flood events, experiments were conducted on a devoted physical model termed MURI (Urban Model for the study of Inundation Risk), at Irstea Lyon-Villeurbanne centre, France. A 2D numerical model was also used to simulate the experiments, using a constant eddy viscosity and then an eddy viscosity in relation to the flow depth. The present study focusses on two geometric configurations. The first one consists of a straight street flanked by two lateral cavities, and the second one a straight street flanked by one-side opening. These flows are compared to a reference configuration under quasi-uniform flow conditions (without openings). The results obtained with the numerical model are consistent with the experiments, mainly in terms of flow depths. The experiments and simulations show that a detailed description of the building blocks is required if the flow pattern is estimated locally.

Miguel Angel Mejía-Morales, Sébastien Proust, Emmanuel Mignot, André Paquier

Chapter 40. Width Parameter Analysis on Runoff Model for Storm Water Drainage System

The paper focuses on the width parameter study of runoff model, including the calculation and selection of width for subcatchments, subcatchment size selection, as well as equivalence of width for storm water drainage planning system. Varied methods of calculation for typical subcatchments are discussed and analyzed when surface runoff equation is solved. It found out that width parameter in runoff model is key factor that determines runoff peak flow which is very important for storm water drainage system planning and designing. The effect to runoff by the subcatchment size is also analyzed and an appropriate size is suggested as well. And the equivalence of width is studied as well which can avoid the inaccurate runoff flow for large scale subcatchments, especially for planning drainage system. Two cases of storm water drainage system are chosen to simulate. The simulation proves that runoff flow can be fit well between large scale and small scale subcatchments of storm water drainage system if equivalence of width is adopted in drainage model. This paper can provide some technical reference and support for storm water drainage system planning and modeling.

Xiancheng Tao

Chapter 41. Potential Application of LID Techniques to Reduce Urban Flooding in Different Rainfall Pattern, Case Study for Quy Nhon, Vietnam

Cities are more vulnerable to flooding due to the reducing of pervious areas influenced by urbanization and increases in extreme precipitation resulted from climate change. Conveying enlarging rainwater runoff requires an expansion of the draining system, which may cost a huge amount of grant investment. To deal with the problem, Low Impact Development (LID) techniques can be taken into consideration as a sustainable alternative option for urban drainage systems. However, the understanding of LID’s effects on urban flooding in different extreme rainfall characteristics is still limited. This study investigates potential performances of integration LID techniques (swale and infiltration trenches) in a drainage system by simulations EPA-SWMM models under different rainfall patterns for Quy Nhon, Vietnam. These performances have shown the effectiveness of the techniques in reducing the risks of flooding because of climate change. It also demonstrates that swales work more effectively in reducing flood probabilities which are caused by long duration and small peak rainfall compared to infiltration trenches. Whereas, infiltration trenches are more effective in reducing surface flooding but less efficient in cutting down the peak of generated runoff.

Nguyen Duc Phuoc Vo, Thi Thu Tram Huynh, Trung Dung Vo

Methods and Models for Hydrology and Climate Change (20)

Frontmatter

Chapter 42. Possible Roles of Artificial Neural Networks in Hydraulic and Hydrological Models

This paper presents 2 past and 1 on-going works on the applications of Artificial Neural Networks (ANN). The 2 past works are river flow forecasting in Bangladesh (a country with vast delta and severe floods perennially) and forecasting of maximum wave height and its time of arrival of the devastating Aceh tsunami in 2004. The on-going work is on deriving a cost effective and high accuracy Digital Elevation Model (DEM) from publicly accessible satellite data.The paper first demonstrates the ANN application on the river stage forecasting at Dhaka, Bangladesh, from 1 to 7 lead day forecast horizons. Although the input nodes used only the water levels at most upstream reaches of 3 main transboundary rivers (Ganges, Brahmaputra, Meghna), the goodness-of-fit R2 values are very high ranging from 0.99 (for 1 lead day) to 0.91 (for 7 lead days). The reason, even without rainfall data in the input nodes, is that 80–95% of the catchments of these 3 large rivers lie in India; thus, the main flow contributions come from India. The high degree of accuracy, accompanied with very short computational time (less than 1 min), makes ANN a desirable advanced warning flow forecasting tool.The paper continues with a second ANN application demonstrating its effectiveness and efficiency as a forecasting tool for devastating Indian Ocean/Aceh tsunami in 2004. The ANN was trained with simulation output data of a widely used process-based tsunami propagation model, TUNAMI-N2. The input nodes comprised, among others, the earthquake magnitude and epicenter with spatial values of maximum tsunami heights and tsunami arrival times (snapshots) for the most probable ocean floor rupture scenarios as its target. Validation tests demonstrated that with a given earthquake magnitude and location, the ANN method provides accurate and near instantaneous forecasting of the maximum tsunami heights and arrival times for the entire computational domain covering South China sea (the Philippines inclusive) and the Indian Ocean (India inclusive).The 3rd ANN application shows the on-going DEM improvement scheme, which significantly improves DEM originating from a publicly accessible satellite SRTM (Shuttle Radar Topography Mission). The scheme uses the DEM data of SRTM and the multispectral data of another publicly accessible satellite Sentinel-2 as the input to the ANN while the target is the high spatially resolution and high accuracy DEM from German Aerospace Center (DLR). Thus far the present improvement scheme manages to reduce the Root Mean Square Error up to 42.3%. Equally interesting is that the trained ANN can also be used to provide DEM in another part of the world with accuracy much higher than the raw DEM from SRTM.

Shie-Yui Liong, Dongeon Kim, Jiandong Liu, Philippe Gourbesville, Ludovic Andres

Chapter 43. Multi-model Approach for Reducing Uncertainties in Rainfall-Runoff Models

In our changing world, there is a need for preventing hydrological extremes, studying impacts of severe changes in climate, operating water resources planning and management, etc. In this context, it is important to surge our capacity in forecasting the water availability, by improving the hydrological models. The recognition of models imperfections leads to the integration of uncertainty analysis into the modelling procedures. The present study promotes the concept of combining the estimated outputs of different rainfall-runoff models to produce an overall combined output to be used as an alternative to that obtained from a single individual model. The conceptual rainfall-runoff models used are MEDOR, GR4J and HBV. They are applied on Nahr Ibrahim watershed, which is a typical Lebanese coastal Mediterranean watershed. Several methods of combination are considered, namely the weighted average (WA), the neural network (NN) and the genetic algorithm (GA). Better discharge outputs have been generated by these methods. This study leads to an improvement in the hydrological modelling by increasing the performances of the models and the reliability of the results.

Cynthia Andraos, Wajdi Najem

Chapter 44. Rainfall-Runoff Modeling to Investigate Flash Floods and Mitigation Measures in the Wadi Bili Catchment, Egypt

The aim of this study is to analyze the rainfall-runoff behavior in the Wadi Bili catchment in the Red Sea Governorate of Egypt as well as the impact on the city of El Gouna, which is located in the downstream part of the catchment. To analyze the runoff from the wadi catchment a hydrological catchment model was set-up with the STORM software and calibrated to runoff measurements during the flash flood event in March 2014. Three different rainfall scenarios were simulated and compared: 34 mm of accumulated rainfall (event in March 2014), 45 mm (estimated 100-year event) and 90 mm (assumed worst-case scenario). The results show a strongly non-linear relation between rainfall and runoff, where an increase in the rainfall amount leads to a much stronger increase in peak discharge. A proposed strategy to mitigate the flooding and store the water could completely capture the flood event in March 2014, while the peak discharge during the 100-year event could be reduced by only 30% and the peak discharge during the assumed worst-case scenario could not be reduced at all. To simulate in more detail the flooding conditions in the city area, a 2D shallow water model was applied using the output from the hydrological model as inflow. Regarding the simulated water depths in El Gouna, it could be shown that for the cases with 34 mm and 45 mm of accumulated rainfall the local rainfall played are more important role than the inflow from the upstream catchment, while for the case with 90 mm of accumulated rainfall the inflow from upstream was more important than the local rainfall.

Franziska Tügel, Abdelrahman Ali Ahmed Abdelrahman, Ilhan Özgen-Xian, Ahmed Hadidi, Reinhard Hinkelmann

Chapter 45. Flood Risk Assessment in the Tra Bong River Catchment, Vietnam

Extreme flood events often cause tremendous damage and enormous risks to people, infrastructure and nature worldwide and especially in Vietnam. Therefore, flooding is considered as one of the most costly kinds of natural disasters in this country. Tra Bong is an ungauged river catchment located in Quang Ngai province, Vietnam. Annually, due to the effect of typhoons that originate from the South China Sea, many extreme floods occur in the river system every year. Considering the impacts of severe flooding in the Tra Bong River Catchment plays an important role in mitigating and adapting flood risk. In this paper, the hydrological model MIKE11 NAM and some hydro-dynamic models such as the MIKE 11 HD, MIKE 21 FM, and MIKE Flood models were applied as effective tools to simulate the flooding and inundation in the downstream area of the catchment. These models simulated the high flows accurately by depicting all of the peak flow discharges in accordance with observed high flows. Two flood risk maps for the year of 2009 and the design flood events (100 year return period) were created based on the intersection of hazard and vulnerability maps which were obtained from flood maps, land-use and population density. Accordingly, more than 80% of the total flooded area is at high and very high risk. Almost 35 km2 of the flooded area were at high and very high risk in the year 2009, while, approximately 45.5 km2 would be at high and very high risk in the 100 year return period flood event.

Manh Trinh Xuan, Frank Molkenthin

Chapter 46. Innovative Solutions for Climate-Resilient Flood Management in the Poorer and Vulnerable Province of Leyte, The Philippines

Floods and extreme events are increasing with the rapid urbanization and in particular with disproportionally high impacts on the poor and most vulnerable. The Philippines is one of the most populated countries and ranked high as number 2 or 3. The province of Leyte including Tacloban city was the most severely affected by Super Typhoon Haiyan in 2013. Therefore, with the review of the policy and institutional frameworks to adaptation and disaster risk reduction in the Philippines and the case study of post-disaster response after Typhoon Haiyan, this paper aims at bringing a paradigm shift to effective adaptation strategies, which combine sound governance and nature-based solutions.

Jihyeon Park, Ilpyo Hong

Chapter 47. Modelling Strategy of Deterministic Distributed Hydrological Model Development at Catchment Scale

During past decades, the progress of hydrological modeling systems have obviously raised the performance of models in representing sophisticated and complex catchment water system. Among various kinds of hydrological model, characterized by the emphasis on spatial discretization of catchment physical behaviors, the deterministic distributed hydrological model shows higher performance in producing comprehensive view of catchment hydrological phenomenon. However, the applicability of this model is still affected by its higher level of data demands, which often requests an effective modelling strategy to overcome the obstacles caused by lack of field measurements. This paper presents an optimized modelling strategy of setting up the deterministic distributed hydrological simulation (MIKE SHE) of one extreme rainfall flood occurred at November 2011 in Var catchment (2800 km2) located at French Mediterranean area. Compared to other model variables, the topography resolution shows premier sensitivity in the simulation and its impact on runoff generation has been further assessed based on a series of simulations set up with 300, 150, 100 and 50 m DEMs, respectively. Comparison among different simulated hydrographs, the impact of topography resolution in MIKE SHE simulation is mainly addressed in their representations of distributed surface slope and the channel network. By increasing the resolution of inputted topography, the simulation performance can be quickly enhanced with more accurate simulated flood peak. However, this improvement contains one threshold, which limits the effects of raising topography accuracy in the simulation after reaching a certain resolution. Integrated optimized the balance between simulation accuracy and running time consumption, the MIKE SHE simulation of extreme rainfall flood in Var catchment has been set up based on the 100 m resolution DEM with river network abstracted from 5 m DEM. At the end, the MIKE SHE simulation is well match the observation with only 8.3% difference of peak value and runs in less than 1 h (15 days simulation), which is feasible to be used in assessment of extreme event in the study area.

Qiang Ma, Philippe Gourbesville

Chapter 48. Application of Satellite Remote Sensing Technology in River Monitoring and Governance

According With the development of space remote sensing technology, the emergence of various multi-temporal, multi-spectral, hyperspectral, high-resolution remote sensing image technologies and corresponding products makes the information of the earth’s surface resources and topography more quickly and effectively presented, which not only provides a lot of information, but also provides abundant information for accurate and scientific geological prediction. Compared with the middle and low-resolution remote sensing image, the high-resolution target image has clearer contour and richer spatial details. For a long time, the monitoring and analysis of river course changes and environmental evolution in river basins has been lacking effective automatic and intelligent analysis tools to solve large spatial and time-span problems. By combining with high resolution satellite remote sensing technology, making full use of the spatial and temporal advantages of high resolution satellite remote sensing image information, automatic identification and analysis of the evolution of river course and surrounding environment in the basin, timely discovery of existing problems and analysis of the effect of river course management can effectively support the scientific research and decision-making support for River Basin management. It provides a new idea for the wide application of water resources industry in river basin monitoring and control. In this paper, the development of satellite remote sensing system, high resolution satellite remote sensing image analysis, main analysis methods and related application results are introduced. The application and Prospect of satellite remote sensing technology in river monitoring and harnessing are briefly described.

Lunyan Wang, Shoukai Chen, Xiangtian Nie, Shichao Liu

Chapter 49. The Uncertainty in Spatial Rainfall Distribution––A Case Study for Binh Dinh Province, Vietnam

The rainfall is considered as the key factor, greatly affecting the hydrological regime of the basin. This has been confirmed through many previous studies. Therefore, the distribution of rainfall by space has a certain impact on the study results and analyses of the flow regime of the basin, especially for large basins. The quality of rainfall data which is distributed by space depends on many factors, within a basin, the density of the rain gauge station is considered as the most important factor and has the greatest influence on the formation of the flow. The more the density of the rain gauge station, the more detailed the rainfall process takes in the basin, from that give for more accurate results in researching on the hydrological regime of the basin. For the purpose of improving the quality of distribution of rainfall by space, building a spatial rain database for the study of hydrological regime of basins in the province. This research conducts comparison about advantages and disadvantages of different rainfall distribution method. The study is realised with 21 rain gauge station over 6071 km2 of Binh Dinh province. The study is expected to provide useful basics for the catchment hydrological modelling, as well as demonstrating the uncertainty of different spatial interpolated methods in rainfall distribution.

Ngoc Duong Vo, Ma Qiang, Vinh Khanh Ngo, Philippe Gourbesville

Chapter 50. Assessing Future Water Availability Under a Changing Climate in Kabul Basin

Climate change affects the patterns of precipitation and evapotranspiration and therefore can affect the future water availability and its spatial and temporal distribution. Climate change is also likely to intensify the global hydrological cycle, which can increase the risk of floods and droughts. This study focuses on Kabul basin which lies in the northeast quarter of Afghanistan. It accounts for thirty-five percent of the population’s water supply, and has the fastest population growth rate in the country. The main objective of this study is to assess the impacts of climate change on water resources. The climate projections are regionally available at finer resolution. Here in this study the future precipitation data were obtained from the selected models available from the Coordinated Regional Downscaling Experiment (CORDEX) program of the South Asian domain. The APHRODITE precipitation and temperature datasets were also used as observations in the lack of in situ measurements for the data-scarce Kabul basin. The SWAT hydrological model was then developed to understand hydrologic response of the Kabul basin and future projections of water availability under future climate scenarios. The median of the results from all used RCMs suggests an increasing trend in maximum and minimum temperature in the future, as compared to the baseline while the projections for precipitation mainly show a decreasing trend under both RCPs. Based on the results of hydrological modeling, the future runoff would likely increase due to the increased snowmelt in the study area. However lack of infrastructures might lead to further problems due to the possibility of more frequent and extreme floods and droughts.

Masoud Ghulami, Philippe Gourbesville, Philippe Audra

Chapter 51. A Modeling Approach for Critical Source Areas Identification and Sources Apportionment for Nitrogen Load in Yuan River Catchment, China

Excessive load of nitrogen from anthropogenic sources is a threat to a healthy aquatic ecosystem. The analysis of nitrogen load, in terms of identifying the critical source areas and apportioning the instream nitrogen to individual sources is supportive to the catchment management. The difficulty of the analysis spatially and seasonally, including the processes of transformation and transportation, has made the Soil and Water Assessment Tool (SWAT), a physically-based hydrological model, a useful tool to quantify the nitrogen load at the catchment scale. This study is focused on the application of the SWAT model at the Yuan River Catchment (YRC), which has been under the threat of extensive nitrogen load in the previous years. The major nitrogen sources identified in the research are urban drainage, as the point source; fertilizer, rural feedlot and rural household, as the diffusive sources. The calibrated hydrological model indicated that the downstream plain region with paddy field and denser rural population released the highest rate of total nitrogen. Fertilizer and waste from feedlots contributes to the 85% of the nitrogen in the stream. The results show the applicability of the SWAT model at the YRC in terms of nitrogen load simulation, and indicate the necessity to tackle the nitrogen from diffusive sources and the critical areas at the YRC.

Qianwen He, Frank Molkenthin

Chapter 52. Coupling Methods for Urban Areas Large Scale Hydraulic Modelling

This paper presents a hydraulic modelling method to interconnect different domains in order to assess the role played by a large scale sanitary structure in managing major flood events which affect large populated areas. Main features of this method are illustrated with the sanitary system of Ile de France central zone, faced with a major flood along the Seine river basin. This system plays a major role to evacuate excess flow from rainfall, aquifer and direct overflow from the river. It can also be an aggravating factor in case of pumping saturation or equipment failure. The coupling method which is presented lies on the use of Hydra software platform. Emphasis is placed on a compromise between fast computation time and result accuracy.Final objective is to produce a decision making tool to improve management of the sanitary system during a flood event, in relation with potential damages as a function of flood level.

Camille Duran, Thierry Lepelletier, Simon Olive, Hubert Chièze

Chapter 53. Urban Lakes: From Lack of Regard to Smart Deal?

This paper deals with hydrogeological modelling of urban alluvial lakes and flood hazard––Case of a 40 ha gravel-pit lake located at the close upstream from confluence of the Seine and Marne rivers, Paris, France. A combined 3D approach is introduced through geographic information system (GIS), geological data modelling (GDM), finite element method (FEM), by using geological and topographic data and hydrodynamic monitoring. This methodology has both deterministic and statistical ability. The deterministic ability allows the model to provide optional design parameters for digital elevation model (DEM), lake artificial banks, sewers and foundations. The statistical ability can be used to model the geological layers of the urban underground and check the consistency between boreholes, DEM, layer interfaces and geological-map data. The purpose of the model is to help decision makers to choose a balanced set of actions in order to monitor the level of a gravel pit lake in a hyper-urbanised area of the Paris region. One consequence for water managers is that there is no need to invoke any intervention as rainwater drainage management. Water table rising hazard management in the floodplain of the Seine and Marne rivers is suggested.

Olivier Fouché, Jérôme Brun, Behzad Nasri

Chapter 54. Reconstruction of Hydraulic Data by Machine Learning

Numerical simulation models associated with hydraulic engineering take a wide array of data into account to produce predictions: rainfall contribution to the drainage basin (characterized by soil nature, infiltration capacity and moisture), current water height in the river, topography, nature and geometry of the river bed, etc. This data is tainted with uncertainties related to an imperfect knowledge of the field, measurement errors on the physical parameters calibrating the equations of physics, an approximation of the latter, etc. These uncertainties can lead the model to overestimate or underestimate the flow and height of the river. Moreover, complex assimilation models often require numerous evaluations of physical solvers to evaluate these uncertainties, limiting their use for some real-time operational applications. For problems with high uncertainty and vast amounts of measurements available such as hydraulics, a new emerging paradigm has been gaining traction in recent years, namely the data-driven approach. Based mostly on machine learning techniques, these optimization techniques aim to build fast surrogate models entirely inferred from the data. Indeed, a large variety of function classes are available today in this context, and can be rapidly tested to find those who best match the underlying trends in the data. In this approach, these trends are therefore not hand-designed by physicists, but selected based on performance on a given dataset.In this study, we explore the possibility of building a predictor for river height at an observation point based on drainage basin time series data. An array of data-driven techniques is assessed for this task, including statistical models, machine learning techniques and deep neural network approaches. These are assessed on several metrics, offering an overview of the possibilities related to hydraulic time-series. An important finding is that for the same hydraulic quantity, the best predictors vary depending on whether the data is produced using a physical model or real observations.

Corentin J. Lapeyre, Nicolas Cazard, Pamphile T. Roy, Sophie Ricci, Fabrice Zaoui

Chapter 55. Assessment of the Impact of Changes in Storm Rainfall and Landscape Characteristics on the Maximum Flow of Small Rivers

Significant amount of researches has established that storm rain began to appear more frequently and their intensity increases in many regions of the world. This trend increases the maximum water discharges on small catchments. However, their increase may occur due to a change in the landscape during the urbanization of the territory. Satellite information and GIS can reflect landscape changes. Thus, the main purpose of the research is to assess the effect of an increase in storm precipitation and the effect of landscape changes in the increase in maximum water discharge on a specific catchment. Accordingly, the problems were decided: an estimation of the increase in maximum precipitation over the past decades; assessment of landscape changes over the past decades using the geographic information system; an assessment of their contribution to an increase in the maximum discharge of water over the past decades. The obtained results of calculations have showed that more short time series of observations for the storm precipitation during last decades (in comparison to full long time of observation) give more real represent about dangerous quantile of distribution for random values ( $$ P = 1\% $$ ), which is used for the projecting of the construction objects and evaluation of possible inundation of territory. Impact of the increasing of values of storm precipitations at the maximum water discharge is significant, however the discharge is changed under impact of change of the catchment landscape too, which we can and must take to consideration.

Vitali Ilinich, Aleksey Perminov, Aleksandr Belolybcev, Anna Naumova

Chapter 56. Novel Quantification Method for Hydrograph Similarity

We propose an additional elaborate hydrological signature index to quantify similarity (and dissimilarity) between recurring flood dynamics and between observation and model simulation as implied by their phase space trajectories. These phase space trajectories are reconstructed from their corresponding hydrographs (i.e., event time series) using Taken’s time delay embedding method. This reconstructed phase space allows multi-dimensional relationship between observation points (i.e., at different time of the event) to be analyzed. Such approach considers the relationships of set of magnitude points in their unique time sequence that are relevant to the complex temporal cascading processes in flood. In a simpler terms, the new index considers the characteristics shape dynamics of a hydrograph and optionally the antecedent discharge conditions that may implicitly cascade to the subsequent rainfall-runoff event and cause an extreme or unusual hydrograph shape. This new similarity index can be used to comprehensively assess the recurrence of extreme event characteristics, change of flood dynamics, shift of seasonality, and as additional metric or objective function to evaluate and calibrate hydrological and hydraulics models.

Dadiyorto Wendi, Bruno Merz, Norbert Marwan

Chapter 57. New Tools to Assess the Suitability of Physical Habitat (SPH) and the Weighted Usable Area (WUA) for Fishes

The assessment of the Suitability of Physical Habitat (SPH) and the Weighted Usable Area (WUA) for fishes has been traditionally performed by means of simple habitat models based on experimental campaigns. In parallel with the improvements of the computer capabilities, some eco-hydraulic numerical models have been developed for the detailed analysis of river hydrodynamics. Recently, specific modules for habitat simulation have been introduced in several 2D hydraulic models. This work presents a new modelling tool to assess fish suitability based on the hydraulic model Iber. The model has been developed to work in a coupled way with the other modules, using the same easy workflow of Iber. The model includes enhances as tools for the geometry/mesh built-up process (LIDAR points cloud), the possibility to choose several fish species from a database or defined by the user, the possibility to calculate different steady flows in the same simulation and a specific postprocess tools to represent the WUA as a function of discharge.

Ernest Bladé, Marcos Sanz-Ramos, Damià Vericat, Antoni Palau-Ibars

Chapter 58. Coastline Change Assessment for Quang Ngai Province Using Landsat Image

Coastlines vary from year to year, especially at the estuary of large rivers. Due to cost and time constraints, measurement, survey and collection of information on change is not routinely conducted. This leads to limited resources for planning and management. The introduction of remote sensing technology is expected to help overcome these limitations. With data from 1972, remote sensing technology combined with the Arcgis tool has been widely used to assess coastal performance. In this study, the author will use remote sensing technology to analyze and evaluate the shoreline of Quang Ngai sea route through four different periods. From the results of the calculation, the area has large changes around the big estuaries: Tra Khuc estuary.

Duc Tho Bui, Quang Binh Nguyen, Ngoc Duong Vo, Thi Thanh Thu Thai, Nguyen Philippe Gourbesville

Chapter 59. 20 Years of Coastal Events Modelling

Engineering studies on coastal risks require continuous improvement of the numerical tools to represent the physical processes involved as accurately as possible. Through various studies carried out over the past twenty years, the developments and other improvements of tools or methodologies are presented. This may involve reproducing as closely as possible the crossings or ruptures of linear protection structures in order to assess and map their hazards. To do this, the interface between the maritime and land areas has been specifically developed to provide a detailed representation of the protection system and to calculate the flows transiting the structures (phenomena of overflow or sea packages due to waves). This model then makes it possible to determine the hazards resulting from the combination of a hydro-meteorological event and a scenario concerning the protection system. Several references of studies have allowed to improve the method and make it more reliable (Gironde estuary, Somme bay, Seine estuary, Charente pertuis…). Some sites are also subject to tsunami flooding risks. It is then a question of being able to model this type of event for which the source can be very distant geographically. The initial elevation at the seismic source is obtained by the Okada method and the signal is then propagated to the coast by different nested models. The results obtained make it possible to define levels to characterize floods near a protection or flood maps in coastal areas (Turkey, Haiti…). The variability of the spatial scales to be represented requires the use of different software, which must then be well understood and controlled. For some studies, the combination of these tools is mandatory and the use of computational clusters allows to subdivide the modelled domain on several processors to reduce computation times. All these techniques and methodological choices respond to a growing demand to control the hazards and the necessary adjustments to reduce them. The engineer has a duty to explain the uncertainties associated with the input data, assumptions considered and simplifications inherent on the tools used.

Olivier Bertrand, Thibault Oudart, Eric David, Aurélie Ledissez, Christophe Coulet

Chapter 60. Modelling NH4+ Dispersion from Wastewater of Urban Drainage to the Coastal Area of Danang City, Vietnam

With the fast-urban development in all the country, Vietnam cities are currently facing aging problems on networks and frequent flooding events that are significantly affecting the populations and cities activities. In most of the cases, combined solutions have been implemented, the wastewaters are treated in treatment plants before discharging into the natural environment such as rivers, lakes or coastal areas. Unfortunately, in the South-East and North-West areas of Danang city, the wastewaters from the drainage system are discharged directly into nearby water environment that is the coast of the East sea at the mouth of Han river. The selected approach combines modeling tools—Mike Urban and Mike 21 FM EcoLab—that allow to simulate jointly the behavior of the sewage system, the production of pollutants and their impact within the coastal area. NH4+ is chosen to simulate the coastal water quality. A hypothesis has been formulated for the event observed in July 2016 in Danang city. Through the results of simulation in the dry season, the ammonium concentration distribution along the coast of Danang is higher than 0.5 mg/l—the standard limited value of National Technical Regulation on marine water quality of Vietnam with a small area approximately 0.03 km2 during a short time. On the other hand, the high NH4+ concentration will disperse in larger areas after rainy events following a dry period. Findings indicated that 0.3 km2 areas are covered over 0.5 mg/l NH4+ after a rainfall of 8 mm/h. In addition, the 4 km2 area in the coast of Danang is covered by 0.14–0.5 mg/l NH4+.

Phuoc Quy An Nguyen, Philippe Gourbesville, Ngoc Duong Vo, Philippe Audra, Morgan Abily, Qiang Ma

Chapter 61. Uncertainty Quantification of Bathymetric Effects in a Two-Layer Shallow Water Model: Case of the Gibraltar Strait

The flow occurring in the strait of Gibraltar raises an interface as a result of different water temperatures and salinities in the Atlantic Ocean and the Mediterranean Sea. These differences yield to the well-established exchange flow problem in hydraulics. Many numerical models have been designed for solving this particular problem including the shallow water equations. In the current study, we consider a two-layer shallow water problem accounting for friction terms in the topography. We present a class of numerical techniques to examine effects of the bathymetric parameters on the water free-surface and the interface between the two layers. Special attention is given to a coupled algorithm of polynomial chaos expansions and proper orthogonal decomposition and its performance to accurately assess the uncertainty in two-layer shallow water flows. In addition, using the Karhuen-Loève decomposition, high dimensions in stochastic input and physical output are also dealt with in our simulations. Numerical results are presented for the problem of exchange flow in the strait of Gibraltar.

Nabil El Moçayd, Alia Alghosoun, Driss Ouazar, Mohammed Seaid

High Performance Computing and Complex Hydraulics Applications

Frontmatter

Chapter 62. Vortex Siphon – From 1:1 Scale Physical Model to SPH Simulation and Prototype

The rail link between Geneva Cornavin Station, Eaux-Vives Station and Annemasse (CEVA) is currently under construction including a cut-and-cover tunnel built by slurry walls located in the alluvium of the Foron River. The covered trench cuts the groundwater table flow which causes a rise of the water table on one side of the tunnel. Thirty wells were built in order to convey water from the aquifer on one side of the tunnel to the other. For each well, traditional pumping has been replaced by a self-priming multiphase siphon in order to lower energy costs. The operating principle of the system is based on the sustaining of a free-surface vortex flow in a vacuum chamber. In this way, the multiphase siphon is primed to allow water to be transferred from either side of the tunnel. A physical model of the conveyance system has been constructed at a scale of 1:1 in order to avoid scale effects from the presence of air water mixture and due to the free-surface vortices sensitivity to scaling, particularly in a vacuum atmosphere. In this study, the results from the physical model are used to validate a Smoothed Particle Hydrodynamics (SPH) numerical simulation of the complex flow conditions. The DualSPHysics code is employed and the results presented herein regarding the depth discharge relationship are encouraging for further application in vortex flows and such devices where conventional Eulerian modelling approaches can be challenging. As far as the authors are aware, this is the first application of SPH in simulating vortex chamber flows and the result bodes well for further application in this area.

Arnaud Bart, Thibault Macherel, Giovanni De Cesare, Sean Mulligan, Khalid Essyad

Chapter 63. Hydrodynamics of an Innovative Discontinuous Double Breakwater, Mixed Modeling: 2D Flume Physics and 3D Digital Modelling

An improved design method of shore parallel discontinuous submerged breakwaters with optimal geometry is presented. In particular, the effect of breakwater openings on hydrodynamic conditions around the structures is experimentally and numerically investigated. The challenge of this study is not only validating the experimental findings using numerical methods but also investigating further alternative forms and geometries which cannot be reproduced in the wave flume. This research concerns a submerged coastal structure made out of two shore-parallel rouble mound breakwaters with openings (channels) whose main objective is to limit wave-induced set-up by pumping out and generating transverse seaward flows. Our wave flume (Fig. 63.1), extended 31 m in cross-shore and 1.8 m in along-shore direction, is equipped with a piston type wavemaker and the sea-bed is represented by a 1/36 scale distorted movable bed model. The main experimental results concern the hydrodynamic conditions in the channels, where offshore-oriented currents are presented. The numerical modeling is performed using OpenFOAM software. After the validation of experimental findings, a second task consists in expanding the structure in along-shore direction. The main objective is to assess the bias committed by the wave flume configuration. Thus, the simulations are realized with identical bathymetry, but for models four and eight times wider than the original one and with either a finite or an infinite structure. The results show that the local three-dimensional flow always exists and is negligibly influenced by reflexions on the wave flume walls. The initial physical model can therefore be considered as the representation of an infinite structure.

Christian Raffourt, Charlie Vergnet, Vasileios Afentoulis, Philippe Bardey

Chapter 64. Simulating the Hydrodynamics of Sewer-Inlets Using a 2D-SWE Based Model

Sewer inlets are one of the most important elements for avoiding floods in urban areas, capturing runoff and introducing into the sewer system. Traditionally the inlets have been designed by resistance criteria, without including or analysing their hydraulic efficiency. Currently CFD techniques plays an important role in order to assess more efficient inlets, minimizing the need for flume experiment and taking into account the hydraulics for their design. 2D models are good enough to represents the hydrodynamics, which is mainly 1D on the street and 2D on the surroundings of the inlet. These models cannot properly capture 3D phenomena over the inlet, where the discharge through the inlet is not well represented. This work presents different techniques, based on the similarity between the hydrologic infiltration models and the discharge captured by the inlet, aiming to enhance the 2D model Iber to adequately reproduce the discharges captured by the inlets, even without representing the complex three-dimensional hydrodynamics around and over the inlet. The results fit well with the observed data, properly reproducing the hydraulic structures as hydraulic jumps, recirculation and cross waves.

Marcos Sanz-Ramos, Jackson D. Tellez Alvarez, Ernest Bladé, Manuel Gómez-Valentín

Chapter 65. Modelling of Surcharge Flow Through Grated Inlet

This paper presents the results of the three-dimensional numerical simulations of surcharge flow from the sewer through the inlet when the flow exceeds the hydraulic capacity of the pipe. The assembly of the model was according to the platform of grated inlet located in the hydraulic laboratory of the Technical University of Catalonia. The purpose of this study was to build a model using the commercial code Flow 3D [1] in order to estimate the discharge coefficient “Cd” for the grated inlet. Moreover, it was possible to visualize the structure of the outflow of the inlet for different combinations of inflow below the grate (range between 10 and 50 l/s) and different combinations of longitudinal and transversal slopes. For instance, the comparison between experimental and numerical simulation of the shape of surcharge flow through the grated inlet and comparison of the discharge coefficient were studied.

Jackson D. Tellez Alvarez, Manuel Gómez, Beniamino Russo

Chapter 66. A Predictive Data-Driven Approach Based on Reduced Order Models for the Morphodynamic Study of a Coastal Water Intake

For many environmental applications, field measurement techniques are increasingly evolving, resulting in more complex and complete datasets. The statistical analysis of these datasets is challenging, and requires the use of relevant mathematical tools. Furthermore, the access to a richer collection of data offers a new optimistic perspective on data-driven modeling, to complement, or even replace, process-based modeling. The presented work is within the context of a power plant water intake monitoring. The intake channel is subject to massive sediment arrivals, which represents a clogging risk. One of the challenges is therefore to better understand the sediment dynamics observed in the channel, and to characterize their correlation to environmental forcing. The final goal is to proceed to the forecasting of the dynamics using the knowledge of forcing parameters. Luckily, due to monitoring needs, bathymetric measurements of the channel are realized on a regular basis, along with meteorological and hydrodynamic survey. A statistical study is hereby proposed on the basis of this data. Firstly, a Proper Orthogonal Decomposition (POD) is applied to the two-dimensional bathymetric data set, in order to reduce it to a low-dimensional set of time dependent scalar coefficients. The latter are linked to the physical forcings via an adapted statistical model. In this study, a Polynomial Chaos Expansion (PCE) is used for this purpose. Consequently, a data-driven model is proposed, on the basis of a POD-PCE coupling. The proposed step-by-step methodology could also be transposed to other applications.

Rem-Sophia Mouradi, Cédric Goeury, Olivier Thual, Fabrice Zaoui, Pablo Tassi

Chapter 67. Hybrid-Parallel Simulations and Visualisations of Real Flood and Tsunami Events Using Unstructured Meshes on High-Performance Cluster Systems

We present simulations of real flood and tsunami events using a hybrid OpenMP-MPI model on high-performance cluster systems. The two-dimensional shallow water equations were solved by means of the in-house code NUFSAW2D, using an edge-based cell-centred finite volume method with the central-upwind scheme for millions of unstructured cells, thus ensuring spatial accuracy, especially near buildings or hydraulic structures. Each node of a cluster system performed simulations using OpenMP and communicated with other nodes using MPI. We explain strategies on reordering the meshes to support contiguous memory access patterns and to minimise communication cost; to this end, a simple criterion was proposed to decide the strategy used. Despite employing static domain decompositions for such unstructured meshes, the computation loads were distributed dynamically based on the complexity level, to each core and node during runtime to ensure computational efficiency. Our model was tested by simulating two real-life cases: the 2011 flood event in Kulmbach (Germany) and the Japan 2011 tsunami recorded in Hilo Harbour, Hawaii (USA). The numerical results show that our model is robust and accurate when simulating such complex flood phenomena, while the hybrid parallelisation concept proposed proves to be quite efficient. We also provide an outlook for an advanced visualisation method employing the Sliding Window technique with an HDF5 data structure. With such a combination of high-performance computing and interactive visualisation, users have a comprehensive predictive tool to take immediate measures and to support decision makers in developing a well-integrated early warning system.

Bobby Minola Ginting, Punit Kumar Bhola, Christoph Ertl, Ralf-Peter Mundani, Markus Disse, Ernst Rank

Chapter 68. Analysis of the Unsteady Flow Around a Hydrofoil at Various Incidences

The oscillating hydrofoils used in underwater propulsion devices often experience large variations of the flow incidence, which favors cavitation at large angle of attack, and therefore a severe degradation of the performance, additional flow instability, and even cavitation erosion. These various phenomena make numerical simulations of the flow around oscillating hydrofoils quite challenging, especially in cases where the laminar-turbulent transition usually occurs when the blade has a high angle of attack. In the present study, the unsteady flow around a stationary Clark-Y hydrofoil is simulated at five fix incidence angles using the Star CCM+ software. The results show that the lift coefficient increases continuously with the incidence angle up to 15°, even after a separation vortex is generated near the trailing edge. Then, as a slight stall occurs at 20°, the lift coefficients obtained with the k-ω SST and SST $$\gamma - \overline{{Re_{\theta t} }}$$ transition models become significantly different, mostly because of the different prediction of laminar to turbulence transition at the hydrofoil leading edge. Under deep stall condition at 25°, the flow is much more complex and the hydrofoil performance decreases dramatically. The lift force predicted by the SST transition model is more periodic than with the SST k-ω model. Although the general vortex evolution predicted by the two turbulence models is similar, the local pressure experiences larger amplitude variations with the k-ω SST model, as can be also observed from the evolution of the lift coefficient.

Lei Shi, Annie-Claude Bayeul-Lainé, Olivier Coutier-Delgosha

Chapter 69. Analysis of High Energy Impact of a Raindrop on Water

The present paper is devoted to the analysis of the impact of a raindrop on water. The studied configuration is focused on the effects of high energy splash regimes, caused by the impact of large droplets at high velocity. Such cases, which mimic raindrops falling on the surface of the ocean at their terminal speed, are characterized by short time scales and complex mechanisms, and they have received little attention until now. The GERRIS opensource solver is used to perform three-dimensional simulations of the impact. The capabilities of octree adaptive mesh refinement enable to capture the small-scale features of the flow, while the Volume Of Fluid (VOF) approach combined with a balanced force surface tension calculation is applied to advect the volume fraction of liquid and reconstruct the interfaces. A post-processing of the results has been developed to identify each object resulting from the splash and characterize their evolution in time. Specifically, the contour of the liquid/gas structure created at the impact is reconstructed as well as the size and position of the ligaments and droplets aerosolized in the atmosphere. The results are compared to experimental data obtained previously by Murphy et al. (J Fluid Mech 780:536–577): both the crown formation above the cavity created by the impact, the ligaments emanating from the rim at the top of the crown, and the downward liquid jet that pierces through the bottom of the cavity, are correctly reproduced by the model. A very good quantitative agreement is also obtained regarding the time evolution of the crown dimensions, including its closure after the initial phase of expansion.

Mohamed Houssein Ghandour, Annie-Claude Bayeul-Lainé, Olivier Coutier-Delgosha

Chapter 70. Experiment and Numerical Analysis of a Rotating Hollow Cylinder in Free Flight

The present purpose is to reveal the mechanism of a flying pipe from an aerodynamic point of view. At first, we conduct field observations of a flying pipe using a pair of high-speed video cameras, together with three-dimensional motion analyses. In addition, we conduct numerical analyses by a finite difference method based on the MAC scheme. As a result, the observed orbit is approximated to be not an obvious parabolic curve but rather a straight line, after an initial instable and complicated curve. The stable flight with this approximately-straight orbit suggests the importance of aerodynamics in flying mechanism. More specifically, the model is in an unstable and complicated flight during an initial flight, afterwards becomes in a stable and approximately-straight flight. In the initial instable and complicated flight, the model flies fluctuating its posture upward, downward, left-ward and right-ward. As flight distance increases, the absolute value and the amplitude of moment becomes small to zero. During such a decaying and stabilising process, the gyroscopic effect plays a primary role balancing not angular acceleration of the model but aerodynamic fluid moment. In the stable and approximately-straight flight, the flow in the stable and approximately-straight flight is nearly the velocity-potential one, and accompanies very-small drag force. And, we could ignore the influence of model’s rotation upon the flow and the orbit. In this context, the model’s rotation is only to stabilise its posture, and gives negligible contribution upon its aerodynamics.

Yusuke Naito, Romain Montini, Hirochika Tanigawa, Jun Ishimoto, Masami Nakano, Katsuya Hirata

Chapter 71. High-Speed Computation on Fluid Forces Acting on Various Oscillating 3D Objects

In many fluid-structure-interaction problems, the added mass, or the virtual mass, is one of important interests. In the present study, we propose a simple and efficient method to specify fluid-force coefficients of an oscillating object in fluid. In this method, we consider incompressible-and-viscous fluid under the assumption of an infinitesimal oscillation amplitude of a three-dimensional object, and properly modify the Navier-Stokes equations into linear equations, namely, the Brinkman equations. The solving method is based on a discrete singularity method. In order to confirm the method’s effectivity and validity, we compute a sphere and a short cylinder, comparing our computations to theories and experiments which show good agreement.

Kyohei Matsumoto, Yusuke Yamaoka, Hideki Shimohara, Hirochika Tanigawa, Katsuya Hirata

Chapter 72. Approach of Dynamic Modelling of a Hydraulic System

In response to environmental degradation, particularly due to greenhouse gas emissions, renewable energy is increasing significantly today. Their development is also a major concern with regard to the depletion of non-renewable energies. However, their use is limited due to the instability induced in the electrical grid. Energy storage aims to regulate these fluctuations and thus smooth electricity production. Compressed air energy storage (CAES) is a type of high-capacity, low-cost energy storage on the market. REMORA, the storage system studied here is an underwater isothermal CAES system. This innovative system consists of compressing and relaxing the air in a quasi-isothermal way using liquid pistons. This method minimizes overall energy loss by maximizing heat transfer during air compressions and expansions. Compressed air is stored in underwater tanks and takes advantage of the hydrostatic pressure associated with the depth of the water. The architecture and operation of the hydraulic system are specific in order to maximize performance. During the energy storage and restitution processes, the exchange flow become transient due to several valve commutations. It occurs frequently during REMORA hydraulic system operation. Modeling the system become complex. A simple example of a hydroelectric plant, similar to the case study, is modeled using two different software. The results show the most appropriate tool, to model the hydraulic system, with an integrated approach based on dynamic modeling.

Naly Ratolojanahary, Joel-A ​Gonzalez-Vieyra, Patrick Dupont, Annie-Claude Bayeul-Lainé, Christophe Sueur, Thibault Neu, David Guyomarc’h

Chapter 73. Numerical Simulations of an Innovative Water Stirring Device for Fine Sediment Release: The Case Study of the Future Trift Reservoir

Reservoir sedimentation and consequently lack of storage volume and perturbation of the operation of intakes and bottom outlet is a key challenge affecting both hydropower production as well as dam safety and flood management. In the framework of a peer-reviewed research project [8] an innovative countermeasure, called SEDMIX, was proposed allowing to keep in suspension or re-suspend the fine particles near the power water intakes, thanks to an optimized arrangement of four water jets producing an upward whirling flow like produced by a mixer. With such a system, the suspended particles can be conveyed downstream at acceptable rates through the power waterways during the normal operation of the hydropower plant. Although experimental studies have shown the very promising efficiency of such a device in simple cases and by numerical simulations in a laboratory reservoir, SEDMIX performance has not been investigated yet in a real-life reservoir under prototype conditions.The aim of this study is therefore, to analyze the performance of a real-sized SEDMIX operating in the future Trift reservoir via numerical analyses. This study allows to validate or to improve SEDMIX optimal configuration experimentally determined.The numerical simulations are performed for different positions and heights for the SEDMIX device. The performance of SEDMIX in each position has been evaluated and tested for different jet discharges. The analysis of the numerical simulation results shows that the presence of SEDMIX does create a vortex flow pattern and sediment movement upward. The sediment volume fraction in the higher layers of the reservoir increases and consequently the evacuated volume of fin sediments increases for simulation using the SEDMIX device comparing those without the device.

Azin Amini, Anass Chraibi, Pedro Manso

Chapter 74. Assessment of the Performance of a Protection Bell for a Micro Power Station on the Rhône

VNF protected the operating devices of the Ormes and Dracé locks from flooding through a bell designed to trap an air bubble despite the rise of the water level. The operating equipment includes a micro hydraulic power station and an electrical box. A rise of the water in the bell would therefore be prejudicial to the operation of the entire lock. However, during a recent flood (April 2016), the protection system showed some weaknesses that VNF wishes to resolve. Indeed, a flood level reaching nearly the lower part of the electrical box was observed, i.e. a much higher than previously announced in the calculations already made. A 3D model of the bell, without singularity in its close vicinity, allowed reproducing in a satisfactory way the consequences of the event the flood of April 2016. It has confirmed that the static study, considering a body of water at rest and a rise in water only by air compression effect, was insufficient with regard to the technical implementation of the solution. Indeed, the installation of support crossties perpendicular to the flow, added to the vertical part of the tray, generates a dynamic effect of water rising along this surface. The flow coming from upstream passes through the protection rake, rushes under the front of the bell and causes the water line to swell in the bell. This dynamic effect is independent of the outside water level, and depends only on the flow velocity as the structure approaches. An easy-to-implement solution was found to avoid this phenomena.

Julien Schaguene, Luc Bazerque, Philippe Mauger, Olivier Bertrand

Chapter 75. Comparison Between Two Hydraulic Models (1D and 2D) of the Garonne River: Application to Uncertainty Propagations and Sensitivity Analyses of Levee Breach Parameters

In recent years, flooding hazard is usually assessed through numerical modelling. However, depending on the nature (e.g. 1D, 2D) and the breach characteristics (e.g. river geometry, bottom roughness, levees geometry) of the numerical model, the uncertainties on the corresponding parameters should be taken into account in a rigorous way, for improving the assessment of the simulated flooding hazard. In fact, levee behaviour during a flooding event is one of the major sources of uncertainties impacting the water level at a given location.In this context, the objective of our work is to better understand the impact of uncertain parameters related to levee breaches, on the generated overflows, through Uncertainty Quantification (UQ) and Global Sensitivity Analysis (GSA) of these parameters.With this purpose, two numerical models of the Garonne River were built and validated, between Tonneins and La Réole sections (for a river length of nearly 50 km): a 1D hydraulic model with storage areas, developed with HEC-RAS and a 2D model with TELEMAC-2D. These modelling approaches (1D and 2D) are classically used to carry inundation studies. Moreover, the simulated river reach is of interest as protected by a levee system to reduce the flood risk. These levees have been damaged during flood periods, by physical mechanisms as erosion due to overtopping for instance, such as during the 1981 historical flood event. The study evaluates the influence of levee breach parameters (breach triggering parameter, breach length and breach depth) on the maximum water level at four points located within the upper part of the study area, through UQ and GSA. These approaches are carried out with a meta-model built with 200 simulations runs using a Monte-Carlo approach for both models. In both cases, the breach parameters are uniformly distributed and randomly sampled in order to generate a large number of breach scenarios.Globally, the Monte-Carlo and FAST (Fourier Analysis Sensitivity Test) analyses performed have shown some differences between the results coming from both meta-models and between the upstream and the downstream storage areas, more sensitive to levee breaches. These analyses also indicated the slight effect of the breach length parameter contrary to the triggering and depth breach parameters.

Lucie Pheulpin, Vito Bacchi, Nathalie Bertrand

Chapter 76. PID Controllers as Data Assimilation Tool for 1D Hydrodynamic Models of Different Complexity

Flood risks management is based on data obtained by different forecasts. Forecasts are often based on hydrological-hydrodynamic models. These models are calibrated using selected time-series from the past. However, even calibrated models in later exploitation phases can produce solutions of unsatisfying accuracy. Some of the reasons are uncertainty in the initial and boundary conditions, uncertainty of the input data and uncertainty in riverbed geometry. The aim of the assimilation is to improve the results obtained from the previously calibrated model by coupling it with observed data. To assimilate, the model is run for a short previous period and the state of the model is adjusted to observed data. The corrected model state is then used as an initial state to run the model with for short-term forecast of input data. Assimilation method based on the PID controller for 1D river hydrodynamic models is analyzed in this paper. This method adjusts the state in the hydrodynamic models according to the measurements indirectly by adding or subtracting the discharge in the junction/sections with measured water level. The influence of the hydrodynamic model complexity is analyzed, comparing three models: non-inertia model, diffusion wave and dynamic wave model. Results show that PID control can be adequately used even coupled with simplified hydraulic models for short-term assimilation and forecast, without significant loss of accuracy. PID control-based data assimilation also yields significant reduction in the computational runtime.

Miloš Milašinović, Budo Zindović, Nikola Rosić, Dušan Prodanović

Chapter 77. Validation of a Semi-automatically Calibrated 1-D Open-Channel Model Against Experimental Data with Changes in Channel Geometry

We validated a 1-D numerical code designed for open-channel flows simulations in subcritical conditions against existing experimental data and simulations published in Lilas et al. [13] and others. Such benchmark was performed after recent improvements and maintenance of the code including the development of a semi-automatic calibration module (Rothé et al. [23]). That code, named Fudaa-Crue, was developed by Compagnie Nationale du Rhône (CNR) to the purpose of river engineering and power production management. It is operated both in operational conditions (industrial process) and for engineering studies.In that paper, we focused on different methodological aspects related to cross comparisons between data and simulations. To that purpose, parts of the calibration guidelines proposed in Malaterre et al. [14] and Rothé et al. [23] were tested. The metrics defined in Lilas et al. [13] were also discussed and specific new metrics dedicated for calibration procedure were proposed. Therefore, parts of the numerical results published in Lilas et al. [13] were re-processed in order to derive those new metrics.In many cases, the calibration procedure was proven to play a role as significant as the modelling technique in the simulation quality. Nevertheless, the present data set does not allow concluding firmly on the predictive capabilities of the model for rare events.

Adeline Visse, François-Xavier Cierco, Luc Duron, Pierre-Loïk Rothé, Yoan Gressier

Chapter 78. Analysis of River Bed Variation Based on Hydrological and Hydraulic Models: A Case Study on Hosan Stream Watershed, South Korea

These days, the irrigation facilities and the facilities in the vicinity of river are classified into different categories and managed based on the purpose of low flow and high flow, and are constructed according to the plans designed to maximize economic effects. Both hydrologic analysis and hydraulic analysis need to be conducted as part of preliminary basic investigation and analysis before these facilities are installed. The hydrologic analysis has been taken to an advanced level through many applications. On the other hand, the hydraulic analysis was based on hydraulic model experiment and therefore much difficulty was involved in its application in Korea. However, the advancement of computers in contemporary era has helped resolve those problems to some degree, enabling the hydraulic properties to be analyzed based on numerical model. This study presents a prediction of river bed variation in near future on assumption that the changes in upstream flow rates and past flow rates. For that, the hydrological analysis of Hosan Stream Basin was conducted first, which was followed by the analysis of hydraulic properties based on the 2-dimensional numerical model by using the daily discharge, derived by the hydraulic analysis, and the observed precipitation as the input data. In this study future changes in river bed were forecasted under the assumption that flow velocity of past and changes in flow rate at upstream river due to construction of large-scale artificial structures downstream occur in the future. Therefore, the long-term runoff volume from the downstream part of Hosan Stream was estimated using the SSARR (Stream Synthesis and Reservoir Regulation Model). Changes in the river bed were simulated using hydraulic models named; RMA-2 and SED-2D. As a result, it was found that the river bed variation is significantly affected by the inclusion of sediment in flood flow at upstream. In this regard, there is a need to devise measures to mitigate future flood damage to artificial structures by reflecting sedimentation trends downstream before the construction of large-scale artificial structures at downstream of river.

Seung Jin Maeng, Muhammad Azam, Seung Wook Lee, Ju Ha Hwang

Chapter 79. Hybridizing Optimization Method and Artificial Neural Network for Urban Drainage System Design

Urban Drainage System (UDS) design has been performed to determine the pipe layout and sizes mostly by optimization-based models. However, function evaluations of the UDS design problem are often very time-consuming because of the computation time for rainfall-runoff and network hydraulics of Strom Water Management Model (SWMM). Therefore, various surrogate models have been proposed during the last decade to overcome the limitation. This study first proposes a hybrid models that combine an optimization method and a surrogate model based on Artificial Neural Network (ANN) for UDS pipe layout and size optimization. Then, various versions of the proposed model are applied to the design problem of a real large urban drainage network: (1) Version 1 determines the optimal pipe sizes by the optimization module whereas the pipe layout is derived from the ANN module; (2) Version 2 determines the former by the ANN module, and the latter by the optimization module; and (3) Version 3 produces the optimal pipe sizes and layout solely by the ANN module. We compared the three different versions with respect to their computational efforts and times and estimation accuracy (e.g., Mean Square Error and R2). Finally, this study will provide guidelines for using the hybrid models in the UDS design.

Soon Ho Kwon, Donghwi Jung, Joong Hoon Kim

Chapter 80. Recycling of TBM-Excavated Materials of the Paris Basin into Technosol: A Numerical Assessment of Its Hydrological Transfer Functions

The new face of Paris will emerge by the Grand Paris Express, a new mass transit network as part of the broader Grand Paris urban renewal and agglomeration initiative. However, this project will generate more than 45 million tons of excavated materials, still legally considered as wastes. This study is based on a scientific solution suggested for recycling those geological materials which will be excavated mainly by tunnel boring machines. The concept is to transform them into new soil called “Technosol” in the World Reference Base for soil Resources or “Anthroposol” in the French Pedology Referential. With a dedicated mode of implementation, those technosols should have interesting hydraulic, thermal, geotechnical and pedological properties. Technosols will allow to re-vegetate and minimize heat island effect and flooding hazard in urban areas, and this will bring new life to the urban ecosystem. In this study, to explore some properties of a patented technosol, COMSOL Multiphysics software is used to couple a soil hydraulic model with a thermal model of a porous medium in unsaturated state. The main result of running transfer functions through “dry” soil is production of realistic initial conditions of temperature and humidity profiles. Knowing these initial conditions and ensuring numerical stability of the model are requested for future hydrological simulations (runoff, infiltration, recharge of the saturated zone) with real material, rainfall and atmospheric temperature data.

Ghada Snoussi, Yijue Yang, Imen Bel Hadj Ali, Essaieb Hamdi, Olivier Fouché
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