Philippe Gourbesville - Academia.edu (original) (raw)

Papers by Philippe Gourbesville

Advances in Hydroinformatics, 2020

With the fast-urban development in all the country, Vietnam cities are currently facing aging pro... more 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+.

The multi-reservoirs system in Vu Gia Thu Bon rivers catchment plays a significant role in produc... more 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 ...

Advances in Hydroinformatics, 2020

For the French municipalities, crisis management system involves by law, two main responsible and... more 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 Prefet [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.

Advances in Hydroinformatics, 2018

Vietnam is located in the region of the Southeast Asia monsoon. Most of the population work in ag... more Vietnam is located in the region of the Southeast Asia monsoon. Most of the population work in agriculture and inhabitants essentially concentrate on the coastal plain, Vietnam is one of the countries most heavily affected by the consequences of climate change. For these reasons, predicting the potential damages due to extreme flood events, especially under climate change impact is mighty necessary for the coastal area in this country. This paper will present the potential risk maps in Vu Gia Thu Bon catchment, the largest river system in Viet Nam central. These flood risk maps were built with tree GCMs under A2 scenario at the end of the twenty-first century by overlapping the flood hazard and land use map in 30 m resolution. The result is hoped to provide adequate scientific evidence to help local authority make suitable strategies for adapting with the variation of climate in the future.

Advances in Hydroinformatics, 2018

Stormwater management in suburban areas shows a developing interest due to the expanding cities t... more Stormwater management in suburban areas shows a developing interest due to the expanding cities toward their suburbs and the drained areas to their centers. Drainage network is thus highly expanding. Moreover, when the topography comes to add steep slopes to the situation, the level of difficulties in managing stormwater raises leading to flash floods in the downstream area with associated damages and casualties. Recent storm events on the French Riviera have recalled how quick and violent flash floods can be. The 17 km2 Magnan basin, located in the western part of Nice city, is drained by an urban river characterized by complex changes in the geometry along its watercourse. The river stream is first natural in the upstream part (for 9.5 km) and then flows to a 1-km long artificial riverbed along the first urbanized areas. In the denser urban area, it enters a piped underground section until its outlet to the Mediterranean Sea 2.5 km further. There is a need for more local knowledge regarding runoff and flood dynamic in order to improve preparation and crisis management. This chapter presents a method to answer the following questions applied to the above-mentioned specific case: how rainfall should be modeled over urbanized areas to better represent runoff processes? How to model flow interactions between surface runoff (an urban river) and the stormwater network? Are the modeled results improved by taking into account such processes and interactions? These three aspects can be summarized as the following problematic: how to improve the understanding, the modeling, and the monitoring of a specific suburban study case? To answer these questions, available high-resolution photogrammetric terrain data are used to build a detailed digital elevation model (DEM). The specific study case is divided into two main parts: (1) the upstream area drained to the open-surface part of the river where the hydrology processes are simplified within Mike SHE (DHI) software; and (2) the downstream area drained to the underground piped river where the drainage network is modeled with Mike URBAN (DHI) and the overland flow of the selected area is modeled with Mike 21 (DHI). Modeling tools are based on the shallow water equations (SWEs). An innovative modeling method will be presented and guidelines for further research given to help improving modeling tools for stormwater management.

It is necessary for decision makers and stakeholders to have the necessary information and tools ... more 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 ...

Groundwater modeling is an efficient tool for the groundwater management. The accuracy of the gro... more Groundwater modeling is an efficient tool for the groundwater management. The accuracy of the groundwater model output depends on both quantity and quality of the input data. In many areas, the data scarcity is often mentioned as a common problem of the model setup. Hence, one of the most important issues in groundwater modeling is to find an approach to build valid and operational models with limited data sets, so that the model is able to provide reliable simulation results that can be applied in the decision-making process. In the current project, a groundwater model is developed on the lower Var river valley. Some simplifications and assumptions are made in order to adapt to data scarcity. The model has been validated with a simulation of 3 years, which contains an extreme flood event and several dry periods. The average Nash coefficient for the 6 points is 0.74 and the average value of the mean absolute error is 0.21 m. The model evaluation indicated that the simplifications an...

In the last two decades, flooding has caused the most devastating and costly natural disasters in... more 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...

Extreme hydrological events are more and more frequent due to the ongoing climatic variations. In... more Extreme hydrological events are more and more frequent due to the ongoing climatic variations. Indeed, flash flood events are more intense and drought periods are increasing significantly. In the meantime, cities are expanding worldwide, concentrating in vulnerable areas, population, and economical assets. With the concern to protect their growing urbanized areas, municipalities tend to use new decision support tools in order to forecast extreme events. These tools include numerical modeling tools which represent the reality by simulating hydrodynamic processes. When flooding on dry land is the issue, modeling objectives clearly focus on the fluid dynamics, thus on the determination of the flooding front. This means that the characterization of the flood extent and its dynamics are directly related to the model definition of wetting and drying areas. With the goal of improving the accuracy of the modeled results, numerical flood and dry transitions should be closer to the reality. T...

Due to the impacts of global warming or climate changes, the hazard caused by extreme weather eve... more 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 hydraul...

Water, 2021

The digital elevation model (DEM) is crucial for various applications, such as land management an... more The digital elevation model (DEM) is crucial for various applications, such as land management and flood planning, as it reflects the actual topographic characteristic on the Earth’s surface. However, it is quite a challenge to acquire the high-quality DEM, as it is very time-consuming, costly, and often confidential. This paper explores a DEM improvement scheme using an artificial neural network (ANN) that could improve the German Aerospace’s TanDEM-X (12 m resolution). The ANN was first trained in Nice, France, with a high spatial resolution surveyed DEM (1 m) and then applied on a faraway city, Singapore, for validation. In the ANN training, Sentinel-2 and TanDEM-X data of the Nice area were used as the input data, while the ground truth observation data of Nice were used as the target data. The applicability of iTanDEM-X was finally conducted at a different site in Singapore. The trained iTanDEM-X shows a significant reduction in the root mean square error of 43.6% in Singapore....

Advances in Hydroinformatics, 2020

Climate change affects the patterns of precipitation and evapotranspiration and therefore can aff... more 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.

IOP Conference Series: Earth and Environmental Science, 2020

The water quality of Danang Bay is one of the major issues on the coast of Danang City. The disch... more The water quality of Danang Bay is one of the major issues on the coast of Danang City. The discharge will be inserted into this study domain through the outlet of the Phu Loc Channel. Mike 21 FM Hydrodynamics module coupled to a water quality model using Mike 21 FM ECOLab module is applied to simulate the water quality and to identify the spreading of NH4 +, which is used as a pollutant tracer. Currently, the outlet of Phu Loc channel has a flow-directed wall which leads the water toward the centre of Danang city. As a result, the study suggests three scenarios of wastewater management from the outlet of Phu Loc channel. The first scenario is that the wastewater will discharge along with the current flow-directed wall. Second, the flow-directed wall will be reconstructed toward the reverse direction compared to the current direction. Third, the current flow-directed wall will be destroyed. Out of three proposed scenarios, the first one generates the longest polluted area toward the...

The Climate change is judged to impact seriously to human society. Hence, assessing the variation... more The Climate change is judged to impact seriously to human society. Hence, assessing the variation of climatic factors in this process is indispensable to mitigate its negative impacts. Quang Nam Da Nang area covered 3 large river catchments (Vu Gia Thu Bon, Tam Ky, Cu De) is predicted to be affected violently by the change of climate, especially on water resources security, as well in hydrological disasters. With the aim of evaluating the consequences of climate change, the study utilizes a semi distributed hydrological model (SWAT model) to simulate the stream flow variation in Quang Nam Da Nang area. The model is constructed with specific catchment characteristics. It is calibrated and validated over a period of 38 years from 1979 to 2016 with the impressive coefficients (NASH reachs to 0.87, R reachs to 0.94). The data about climate change is supplied by Vietnamese Ministry of Natural Ressources and Environments.

E3S Web of Conferences, 2018

After three hours of intense rainfall, the city of Nice was flash flooded on October 3, 2015, res... more After three hours of intense rainfall, the city of Nice was flash flooded on October 3, 2015, resulting in casualties and severe damages in property. This study presents a porous shallow water-model based numerical simulation of the flash flood event in a district of Nice, and compares the results with a high-resolution conventional shallow water model. This contribution aims to discuss practical aspects of applying a porous shallow water model to a real world case. The porous shallow water model is an integral porosity-type shallow water model. It uses unstructured triangular meshes. The conventional shallow water model is a distributed memory parallelized high-performance computing code, that uses a uniform Cartesian grid. The study site is an approximately 5 km2 spanning district of the city of Nice, France. Topography information is available in a 1m resolution and in addition, the available digital elevation model includes inframetric structures such as walls and small bridges....

La Houille Blanche, 2018

Current topographic survey technology provides high-resolution (HR) datasets for urban environmen... more Current topographic survey technology provides high-resolution (HR) datasets for urban environments. Incorporating this HR information in models aiming to provide flood risk assessment is desirable because the flood wave propagation is depending on the urban topographic features, i.e. buildings, bridges and street networks. Conceptual, numerical and practical challenges arise from the application of shallow water models to HR urban flood modeling. For instance, numerical challenges are occurrence of wet-dry fronts, geometric discontinuities in the urban environment and discontinuous solutions, i.e. shock waves. These challenges can be overcome by using a Godunov-type scheme. However, the computational cost of this type of schemes is high, such that HR two-dimensional shallow water simulations with practical relevance have to be run on supercomputers. The porous shallow water model is an alternative approach that aims to reduce computational cost by using a coarse resolution and acco...

La Houille Blanche, 2018

Complex alluvial aquifers are frequently essential resources for cities that are looking for reli... more Complex alluvial aquifers are frequently essential resources for cities that are looking for reliable and safe resources for water supply. The location of such aquifers is frequently combined with intense urban developments that may, potentially, generate pollutants that could affect badly the quality of the resources. An efficient and safe management of water supply system requests to develop a good knowledge of the dynamics of the aquifer and to characterize the exchanges that could exist with free surface flows in associated rivers. The most efficient way to understand the behaviour of the aquifer is to implement a 3D physically-based hydrodynamic model that could represent all physical processes. However, this approach, in order to become an operational tool, requests a structured methodology for data integration and validation. The paper describes the construction of a 3D hydraulic model of groundwater flow in the Var lower valley, on the French Riviera, with FEFLOW modeling sy...

Environmental science and pollution research international, Jan 22, 2018

Integrated hydrodynamic modelling is an efficient approach for making semi-quantitative scenarios... more Integrated hydrodynamic modelling is an efficient approach for making semi-quantitative scenarios reliable enough for groundwater management, provided that the numerical simulations are from a validated model. The model set-up, however, involves many inputs due to the complexity of both the hydrological system and the land use. The case study of a Mediterranean alluvial unconfined aquifer in the lower Var valley (Southern France) is useful to test a method to estimate lacking data on water abstraction by small farms in urban context. With this estimation of the undocumented pumping volumes, and after calibration of the exchange parameters of the stream-aquifer system with the help of a river model, the groundwater flow model shows a high goodness of fit with the measured potentiometric levels. The consistency between simulated results and real behaviour of the system, with regard to the observed effects of lowering weirs and previously published hydrochemistry data, confirms reliabi...

Hydrology Research, 2016

Dongting Lake, a large river-connected lake in the Yangtze River watershed, plays important roles... more Dongting Lake, a large river-connected lake in the Yangtze River watershed, plays important roles in flood control, drought mitigation, and biodiversity conservation. Its ecosystem has recently been severely affected by upstream water resource development such as reservoir operations. In this study, an optimization model is developed for the operation of a multi-reservoir system, including the Three Gorges Reservoir (TGR) on the upper Yangtze River and 8 major reservoirs on the tributaries to Dongting Lake. The optimal target in pursuit of the ecological objective is to maximize the environmental water demand (EWD) satisfaction of the lake. A support vector regression-based model is used to predict the response of the lake level to reservoir operations. The optimization is carried out under different scenarios for both normal and dry conditions, and the results show that: (i) the existing operation policy could result in significant hydrologic alteration; (ii) in the normal conditio...

Journal of Hydroinformatics, 2016

In order to create a tool to help hydrologists and authorities to have good understanding about o... more In order to create a tool to help hydrologists and authorities to have good understanding about occurrences in stream flow regime together with its variation in the future under the impact of climate change in the Vu Gia Thu Bon catchment, a deterministic distributed hydrological model has been developed and constructed. This model covers the major processes in the hydrologic cycle including rainfall, evapotranspiration, overland flow, unsaturated flow, groundwater flow, channel flow, and their interactions. The model is calibrated and validated against the daily data recorded at seven stations during 1991–2000 and 2001–2010, respectively. The quality of results is demonstrated by Nash–Sutcliffe and correlation coefficients that reach 0.82 and 0.92, respectively, in discharge comparison. With water levels, the obtained coefficients are lower but the quality of results still remains high; Nash–Sutcliffe and correlation coefficients reach 0.77 and 0.89, respectively, in the upstream p...

Advances in Hydroinformatics, 2020

With the fast-urban development in all the country, Vietnam cities are currently facing aging pro... more 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+.

The multi-reservoirs system in Vu Gia Thu Bon rivers catchment plays a significant role in produc... more 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 ...

Advances in Hydroinformatics, 2020

For the French municipalities, crisis management system involves by law, two main responsible and... more 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 Prefet [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.

Advances in Hydroinformatics, 2018

Vietnam is located in the region of the Southeast Asia monsoon. Most of the population work in ag... more Vietnam is located in the region of the Southeast Asia monsoon. Most of the population work in agriculture and inhabitants essentially concentrate on the coastal plain, Vietnam is one of the countries most heavily affected by the consequences of climate change. For these reasons, predicting the potential damages due to extreme flood events, especially under climate change impact is mighty necessary for the coastal area in this country. This paper will present the potential risk maps in Vu Gia Thu Bon catchment, the largest river system in Viet Nam central. These flood risk maps were built with tree GCMs under A2 scenario at the end of the twenty-first century by overlapping the flood hazard and land use map in 30 m resolution. The result is hoped to provide adequate scientific evidence to help local authority make suitable strategies for adapting with the variation of climate in the future.

Advances in Hydroinformatics, 2018

Stormwater management in suburban areas shows a developing interest due to the expanding cities t... more Stormwater management in suburban areas shows a developing interest due to the expanding cities toward their suburbs and the drained areas to their centers. Drainage network is thus highly expanding. Moreover, when the topography comes to add steep slopes to the situation, the level of difficulties in managing stormwater raises leading to flash floods in the downstream area with associated damages and casualties. Recent storm events on the French Riviera have recalled how quick and violent flash floods can be. The 17 km2 Magnan basin, located in the western part of Nice city, is drained by an urban river characterized by complex changes in the geometry along its watercourse. The river stream is first natural in the upstream part (for 9.5 km) and then flows to a 1-km long artificial riverbed along the first urbanized areas. In the denser urban area, it enters a piped underground section until its outlet to the Mediterranean Sea 2.5 km further. There is a need for more local knowledge regarding runoff and flood dynamic in order to improve preparation and crisis management. This chapter presents a method to answer the following questions applied to the above-mentioned specific case: how rainfall should be modeled over urbanized areas to better represent runoff processes? How to model flow interactions between surface runoff (an urban river) and the stormwater network? Are the modeled results improved by taking into account such processes and interactions? These three aspects can be summarized as the following problematic: how to improve the understanding, the modeling, and the monitoring of a specific suburban study case? To answer these questions, available high-resolution photogrammetric terrain data are used to build a detailed digital elevation model (DEM). The specific study case is divided into two main parts: (1) the upstream area drained to the open-surface part of the river where the hydrology processes are simplified within Mike SHE (DHI) software; and (2) the downstream area drained to the underground piped river where the drainage network is modeled with Mike URBAN (DHI) and the overland flow of the selected area is modeled with Mike 21 (DHI). Modeling tools are based on the shallow water equations (SWEs). An innovative modeling method will be presented and guidelines for further research given to help improving modeling tools for stormwater management.

It is necessary for decision makers and stakeholders to have the necessary information and tools ... more 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 ...

Groundwater modeling is an efficient tool for the groundwater management. The accuracy of the gro... more Groundwater modeling is an efficient tool for the groundwater management. The accuracy of the groundwater model output depends on both quantity and quality of the input data. In many areas, the data scarcity is often mentioned as a common problem of the model setup. Hence, one of the most important issues in groundwater modeling is to find an approach to build valid and operational models with limited data sets, so that the model is able to provide reliable simulation results that can be applied in the decision-making process. In the current project, a groundwater model is developed on the lower Var river valley. Some simplifications and assumptions are made in order to adapt to data scarcity. The model has been validated with a simulation of 3 years, which contains an extreme flood event and several dry periods. The average Nash coefficient for the 6 points is 0.74 and the average value of the mean absolute error is 0.21 m. The model evaluation indicated that the simplifications an...

In the last two decades, flooding has caused the most devastating and costly natural disasters in... more 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...

Extreme hydrological events are more and more frequent due to the ongoing climatic variations. In... more Extreme hydrological events are more and more frequent due to the ongoing climatic variations. Indeed, flash flood events are more intense and drought periods are increasing significantly. In the meantime, cities are expanding worldwide, concentrating in vulnerable areas, population, and economical assets. With the concern to protect their growing urbanized areas, municipalities tend to use new decision support tools in order to forecast extreme events. These tools include numerical modeling tools which represent the reality by simulating hydrodynamic processes. When flooding on dry land is the issue, modeling objectives clearly focus on the fluid dynamics, thus on the determination of the flooding front. This means that the characterization of the flood extent and its dynamics are directly related to the model definition of wetting and drying areas. With the goal of improving the accuracy of the modeled results, numerical flood and dry transitions should be closer to the reality. T...

Due to the impacts of global warming or climate changes, the hazard caused by extreme weather eve... more 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 hydraul...

Water, 2021

The digital elevation model (DEM) is crucial for various applications, such as land management an... more The digital elevation model (DEM) is crucial for various applications, such as land management and flood planning, as it reflects the actual topographic characteristic on the Earth’s surface. However, it is quite a challenge to acquire the high-quality DEM, as it is very time-consuming, costly, and often confidential. This paper explores a DEM improvement scheme using an artificial neural network (ANN) that could improve the German Aerospace’s TanDEM-X (12 m resolution). The ANN was first trained in Nice, France, with a high spatial resolution surveyed DEM (1 m) and then applied on a faraway city, Singapore, for validation. In the ANN training, Sentinel-2 and TanDEM-X data of the Nice area were used as the input data, while the ground truth observation data of Nice were used as the target data. The applicability of iTanDEM-X was finally conducted at a different site in Singapore. The trained iTanDEM-X shows a significant reduction in the root mean square error of 43.6% in Singapore....

Advances in Hydroinformatics, 2020

Climate change affects the patterns of precipitation and evapotranspiration and therefore can aff... more 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.

IOP Conference Series: Earth and Environmental Science, 2020

The water quality of Danang Bay is one of the major issues on the coast of Danang City. The disch... more The water quality of Danang Bay is one of the major issues on the coast of Danang City. The discharge will be inserted into this study domain through the outlet of the Phu Loc Channel. Mike 21 FM Hydrodynamics module coupled to a water quality model using Mike 21 FM ECOLab module is applied to simulate the water quality and to identify the spreading of NH4 +, which is used as a pollutant tracer. Currently, the outlet of Phu Loc channel has a flow-directed wall which leads the water toward the centre of Danang city. As a result, the study suggests three scenarios of wastewater management from the outlet of Phu Loc channel. The first scenario is that the wastewater will discharge along with the current flow-directed wall. Second, the flow-directed wall will be reconstructed toward the reverse direction compared to the current direction. Third, the current flow-directed wall will be destroyed. Out of three proposed scenarios, the first one generates the longest polluted area toward the...

The Climate change is judged to impact seriously to human society. Hence, assessing the variation... more The Climate change is judged to impact seriously to human society. Hence, assessing the variation of climatic factors in this process is indispensable to mitigate its negative impacts. Quang Nam Da Nang area covered 3 large river catchments (Vu Gia Thu Bon, Tam Ky, Cu De) is predicted to be affected violently by the change of climate, especially on water resources security, as well in hydrological disasters. With the aim of evaluating the consequences of climate change, the study utilizes a semi distributed hydrological model (SWAT model) to simulate the stream flow variation in Quang Nam Da Nang area. The model is constructed with specific catchment characteristics. It is calibrated and validated over a period of 38 years from 1979 to 2016 with the impressive coefficients (NASH reachs to 0.87, R reachs to 0.94). The data about climate change is supplied by Vietnamese Ministry of Natural Ressources and Environments.

E3S Web of Conferences, 2018

After three hours of intense rainfall, the city of Nice was flash flooded on October 3, 2015, res... more After three hours of intense rainfall, the city of Nice was flash flooded on October 3, 2015, resulting in casualties and severe damages in property. This study presents a porous shallow water-model based numerical simulation of the flash flood event in a district of Nice, and compares the results with a high-resolution conventional shallow water model. This contribution aims to discuss practical aspects of applying a porous shallow water model to a real world case. The porous shallow water model is an integral porosity-type shallow water model. It uses unstructured triangular meshes. The conventional shallow water model is a distributed memory parallelized high-performance computing code, that uses a uniform Cartesian grid. The study site is an approximately 5 km2 spanning district of the city of Nice, France. Topography information is available in a 1m resolution and in addition, the available digital elevation model includes inframetric structures such as walls and small bridges....

La Houille Blanche, 2018

Current topographic survey technology provides high-resolution (HR) datasets for urban environmen... more Current topographic survey technology provides high-resolution (HR) datasets for urban environments. Incorporating this HR information in models aiming to provide flood risk assessment is desirable because the flood wave propagation is depending on the urban topographic features, i.e. buildings, bridges and street networks. Conceptual, numerical and practical challenges arise from the application of shallow water models to HR urban flood modeling. For instance, numerical challenges are occurrence of wet-dry fronts, geometric discontinuities in the urban environment and discontinuous solutions, i.e. shock waves. These challenges can be overcome by using a Godunov-type scheme. However, the computational cost of this type of schemes is high, such that HR two-dimensional shallow water simulations with practical relevance have to be run on supercomputers. The porous shallow water model is an alternative approach that aims to reduce computational cost by using a coarse resolution and acco...

La Houille Blanche, 2018

Complex alluvial aquifers are frequently essential resources for cities that are looking for reli... more Complex alluvial aquifers are frequently essential resources for cities that are looking for reliable and safe resources for water supply. The location of such aquifers is frequently combined with intense urban developments that may, potentially, generate pollutants that could affect badly the quality of the resources. An efficient and safe management of water supply system requests to develop a good knowledge of the dynamics of the aquifer and to characterize the exchanges that could exist with free surface flows in associated rivers. The most efficient way to understand the behaviour of the aquifer is to implement a 3D physically-based hydrodynamic model that could represent all physical processes. However, this approach, in order to become an operational tool, requests a structured methodology for data integration and validation. The paper describes the construction of a 3D hydraulic model of groundwater flow in the Var lower valley, on the French Riviera, with FEFLOW modeling sy...

Environmental science and pollution research international, Jan 22, 2018

Integrated hydrodynamic modelling is an efficient approach for making semi-quantitative scenarios... more Integrated hydrodynamic modelling is an efficient approach for making semi-quantitative scenarios reliable enough for groundwater management, provided that the numerical simulations are from a validated model. The model set-up, however, involves many inputs due to the complexity of both the hydrological system and the land use. The case study of a Mediterranean alluvial unconfined aquifer in the lower Var valley (Southern France) is useful to test a method to estimate lacking data on water abstraction by small farms in urban context. With this estimation of the undocumented pumping volumes, and after calibration of the exchange parameters of the stream-aquifer system with the help of a river model, the groundwater flow model shows a high goodness of fit with the measured potentiometric levels. The consistency between simulated results and real behaviour of the system, with regard to the observed effects of lowering weirs and previously published hydrochemistry data, confirms reliabi...

Hydrology Research, 2016

Dongting Lake, a large river-connected lake in the Yangtze River watershed, plays important roles... more Dongting Lake, a large river-connected lake in the Yangtze River watershed, plays important roles in flood control, drought mitigation, and biodiversity conservation. Its ecosystem has recently been severely affected by upstream water resource development such as reservoir operations. In this study, an optimization model is developed for the operation of a multi-reservoir system, including the Three Gorges Reservoir (TGR) on the upper Yangtze River and 8 major reservoirs on the tributaries to Dongting Lake. The optimal target in pursuit of the ecological objective is to maximize the environmental water demand (EWD) satisfaction of the lake. A support vector regression-based model is used to predict the response of the lake level to reservoir operations. The optimization is carried out under different scenarios for both normal and dry conditions, and the results show that: (i) the existing operation policy could result in significant hydrologic alteration; (ii) in the normal conditio...

Journal of Hydroinformatics, 2016

In order to create a tool to help hydrologists and authorities to have good understanding about o... more In order to create a tool to help hydrologists and authorities to have good understanding about occurrences in stream flow regime together with its variation in the future under the impact of climate change in the Vu Gia Thu Bon catchment, a deterministic distributed hydrological model has been developed and constructed. This model covers the major processes in the hydrologic cycle including rainfall, evapotranspiration, overland flow, unsaturated flow, groundwater flow, channel flow, and their interactions. The model is calibrated and validated against the daily data recorded at seven stations during 1991–2000 and 2001–2010, respectively. The quality of results is demonstrated by Nash–Sutcliffe and correlation coefficients that reach 0.82 and 0.92, respectively, in discharge comparison. With water levels, the obtained coefficients are lower but the quality of results still remains high; Nash–Sutcliffe and correlation coefficients reach 0.77 and 0.89, respectively, in the upstream p...