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a Location of the Moose Jaw and the Qu’Appelle Rivers considered in the study, b typical terrain profile along the Moose Jaw River, and c typical terrain profile along the Qu’Appelle River
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In Canada, approaches for hazard mapping involve using a hydraulic model to generate a flood extent map that distinguishes between inundated and non-inundated areas in a deterministic way. The authors adapt a probabilistic approach to obtain flood hazard maps by accounting for uncertainty in boundary conditions and calibration parameters of a hydro...
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Citations
... Others have focused on including uncertainty in the inundation model through its most sensitive parameters such as roughness coefficients (G. T. Aronica et al., 2012;Bharath & Elshorbagy, 2018;Di Baldassarre et al., 2010;Kalyanapu et al., 2012;Kiczko et al., 2013;Romanowicz & Kiczko, 2016), Digital Elevation Maps (DEM) (Apel et al., 2008), or cross-section geometrical properties (Stephens & Bledsoe, 2020). Furthermore, many of these have included both the epistemic uncertainties in the discharges recurrence as well as in the inundation model (Apel et al., 2008 Kalyanapu et al., 2012;Kiczko et al., 2013;Romanowicz & Kiczko, 2016;Stephens & Bledsoe, 2020;Zahmatkesh et al., 2021). ...
... The typical outcome from most of these approaches is in the form of "probability of flood" maps for different return periods. That is, for a specific return period, different forcing events and/or inundation model parameters are randomly sampled and used to obtain an ensemble of flood maps from which the probability of flooding is computed empirically (Bharath & Elshorbagy, 2018;Di Baldassarre et al., 2010;Domeneghetti et al., 2013;Kiczko et al., 2013;Neal et al., 2013;Stephens & Bledsoe, 2020;Zahmatkesh et al., 2021). However, a flood risk analysis requires estimating potential damages from the hazard outcomes, and this type of input is not very helpful since most flood damage models use as input the water depth above ground level (and eventually flow velocity and flood duration) (Galasso et al., 2021;Mohanty et al., 2020;Nofal & Van De Lindt, 2022;Pregnolato et al., 2015). ...
... This review of the literature on uncertainty quantification in flood hazard assessments shows that epistemic uncertainties are always kept separate from aleatory uncertainty. As a result, the hazard output is always in the form of a distribution of the probability of exceeding an IM level; whether it is given as a "probability of flood map" for different return periods (Bharath & Elshorbagy, 2018;Di Baldassarre et al., 2010;Domeneghetti et al., 2013;Kiczko et al., 2013;Neal et al., 2013;Stephens & Bledsoe, 2020;Zahmatkesh et al., 2021), or as confidence intervals of IM exceedance curves for each point in space (G. T. Aronica et al., 2012;Nuswantoro et al., 2016;Romanowicz & Kiczko, 2016). ...
Classical approaches to flood hazard are obtained by the concatenation of a recurrence model for the events (i.e., an extreme river discharge) and an inundation model that propagates the discharge into a flood extent. The classical approach, however, uses “best‐fit” models that do not include uncertainty from incomplete knowledge or limited data availability. The inclusion of these, so called epistemic uncertainties, can significantly impact flood hazard estimates and the corresponding decision‐making process. We propose a simulation approach to robustly account for uncertainty in model's parameters, while developing a useful probabilistic output of flood hazard for further risk assessments via the Bayesian predictive posterior distribution of water depths. A Peaks‐Over‐Threshold Bayesian analysis is performed for future events simulation, and a pseudo‐likelihood probabilistic approach for the calibration of the inundation model is used to compute uncertain water depths. The annual probability averaged over all possible models’ parameters is used to develop hazard maps that account for epistemic uncertainties. Results are compared to traditional hazard maps, showing that not including epistemic uncertainties can underestimate the hazard and lead to non‐conservative designs, and that this trend increases with return period. Results also show that the influence of the uncertainty in the future occurrence of discharge events is predominant over the inundation simulator uncertainties for the case study.
... Within that framework, determining the frequencies of floods and their effects and appropriate responses by decision makers to those results have vital roles in the management of disaster scenarios. For the determination of high-risk areas based on the increased global flood rate, the importance of flood inundation mapping and land planning according to that mapping has gradually increased (Chen et al., 2009;Masood and Takeuchi, 2012;Alfieri et al., 2014;Bharath and Elshorbagy, 2018). HEC-RAS (Hydrologic Engineering Center's River Analysis System) software is also frequently used in flood analysis (Tate and Maidment, 1999;Yang et al., 2006;Quirogaa et al., 2016;Costabile et al., 2020;Namara et al., 2022). ...
Flood is one of the most widespread and catastrophic natural hazards for settlements in different parts of the world. Eskişehir has faced numerous floods at varying scales, especially in the last century. Porsuk Stream moves in an artificial channel through the Eskişehir city center. The bed of Porsuk Stream is expanded and cascaded at the entrance to the city center, and the stream has been turned into one of the attractions of the city by increasing its water level with nine regulators. Expanding the river bed is a frequently used method to reduce flood risk. However, in Eskisehir, the fact that the river bed is kept largely filled with water is a major source of risk in case of flooding. The study is based on a scenario in which flooding occurs due to the failure of regulator covers to open. In the study field, the sensitivity of the numerical field model that was created along the stream bed was further improved by measuring lengths and depths throughout the channel. Within the framework of the scenario, the water levels that can change with flood discharges were determined, and inundation areas were calculated. The results revealed that, according to the flood discharges in Porsuk Stream with probabilities of occurrence in every 50, 100, and 200 years, areas of 3.20 km 2 , 4.03 km 2 , and 4.48 km 2 would be flooded, respectively. The maximum discharge with a return period of 200 years (Q200) is 194.46 m 3 /s, which, if realized, would result in inundation of 1.58 km 2 of residential areas and 0.55 km 2 of agricultural land. Of the total flood area, 35% will be residential areas, 33% will be airports, 12% will be agricultural lands, 9% will be green areas, 7% will be industrial areas and 3% will be sports facilities.
... Within that framework, determining the frequencies of floods and their effects and appropriate responses by decision makers to those results have vital roles in the management of disaster scenarios. For the determination of high-risk areas based on the increased global flood rate, the importance of flood inundation mapping and land planning according to that mapping has gradually increased (Chen et al., 2009;Masood and Takeuchi, 2012;Alfieri et al., 2014;Bharath and Elshorbagy, 2018). HEC-RAS (Hydrologic Engineering Center's River Analysis System) software is also frequently used in flood analysis (Tate and Maidment, 1999;Yang et al., 2006;Quirogaa et al., 2016;Costabile et al., 2020;Namara et al., 2022). ...
Flood is one of the most widespread and catastrophic natural hazards for settlements in different parts of the world. Eskişehir has faced numerous floods at varying scales, especially in the last century. Porsuk Stream moves in an artificial channel through the Eskişehir city center. The bed of Porsuk Stream is expanded and cascaded at the entrance to the city center, and the stream has been turned into one of the attractions of the city by increasing its water level with nine regulators. Expanding the river bed is a frequently used method to reduce flood risk. However, in Eskisehir, the fact that the river bed is kept largely filled with water is a major source of risk in case of flooding. The study is based on a scenario in which flooding occurs due to the failure of regulator covers to open. In the study field, the sensitivity of the numerical field model that was created along the stream bed was further improved by measuring lengths and depths throughout the channel. Within the framework of the scenario, the water levels that can change with flood discharges were determined, and inundation areas were calculated. The results revealed that, according to the flood discharges in Porsuk Stream with probabilities of occurrence in every 50, 100, and 200 years, areas of 3.20 km2, 4.03 km2, and 4.48 km2 would be flooded, respectively. The maximum discharge with a return period of 200 years (Q200) is 194.46 m3/s, which, if realized, would result in inundation of 1.58 km2 of residential areas and 0.55 km2 of agricultural land. Of the total flood area, 35% will be residential areas, 33% will be airports, 12% will be agricultural lands, 9% will be green areas, 7% will be industrial areas and 3% will be sports facilities.
... R. Bharath et al. (2018) [18], stated that in Canada, hazard mapping methods include employing a hydraulic model to build a deterministic flood extent map that distinguishes between inundated and non-inundated areas. The Qu'Appelle River within the Canadian prairies was being used as a case study to demonstrate the value of using a deterministic method to produce flooding indications.. ...
... R. Bharath et al. (2018) [18], stated that in Canada, hazard mapping methods include employing a hydraulic model to build a deterministic flood extent map that distinguishes between inundated and non-inundated areas. The Qu'Appelle River within the Canadian prairies was being used as a case study to demonstrate the value of using a deterministic method to produce flooding indications.. ...
Disasters caused by climate change have wreaked havoc on the environment around the world in recent decades, to the point that even deserts have been flooded. Considering floods as a major disaster across various countries, this research has accumulated different methodologies and techniques to analyze flood mapping according to geography of many regions across the world. This paper discusses about flood plain mapping and analysis of the past two decades. Recently with the help of satellite images and the application of remote sensing and GIS this concept is widely used by various researchers. To simulate these flood plain areas, software such as HEC-HMS, HEC-RAS and ArcGIS are quite popular and widely used. The purpose of this review article is to divide the research into four primary sections: floodplain mapping, analytic method, digital elevation model, and software used.. It was observed that globally according to site and climate conditions the effect of floods changes geographically and as a result, the approaches and techniques employed by various researchers differ from one location to the next and according to their research goals. As a consequence, gaps have been identified, and the authors have applied strategies to tackle their problem. This document serves as an overview of the research's important literature review.
... GPU programming in CUDA is discussed here to give the reader some background to understand how it works with MPI. Further information about GPU programming can be found in [42], [18], and [31]. ...
This paper shows the development of a multi-GPU version of a time-explicit finite volume solver for the Shallow-Water Equations (SWE) on a multi-GPU architecture. MPI is combined with CUDA-Fortran in order to use as many GPUs as needed and the METIS library is leveraged to perform a domain decomposition on the 2D unstructured triangular meshes of interest. A CUDA-Aware version of OpenMPI is adopted to speed up the messages between the MPI processes. A study of both speed-up and efficiency is conducted; first, for a classic dam-break flow in a canal, and then for two real domains with complex bathymetries. In both cases, meshes with up to 12 million cells are used. Using 24 to 28 GPUs on these meshes leads to an efficiency of 80% and more. Finally, the multi-GPU version is compared to the pure MPI multi-CPU version, and it is concluded that in this particular case, about 100 CPU cores would be needed to achieve the same performance as one GPU. The developed methodolo
... Pluvial/ nival flooding is typical in the prairies under wet conditions as potholes can be filled and their surface area expanded, causing the surrounding areas to be flooded (Shook et al., 2015). However, assessing flooding impacts has been typically limited to fluvial flooding (e.g., Bharath and Elshorbagy, 2018;Elshorbagy et al., 2017) with less attention to landscape pluvial/nival flooding. Thus, it is important to accurately simulate the magnitude of floods and the corresponding areal extents of water over the landscape to contribute to the proper assessment of combined flood risks in the prairies. ...
The hydrology of the Canadian prairie region is complicated by the existence of numerous land depressions that change the contributing area dynamically and result in a non-linear and hysteretic relationship between contributing area and storage. Depressions are represented conceptually in most hydrologic models as simple storage (bucket) units. These conceptual approaches are simplified and might not adequately represent the dynamics of the depressions and the changing non-contributing area either temporally or spatially, and therefore, the simulation of streamflow remains challenging. This study advances a more physically based simulation of the hydrology, streamflow, and spatiotemporal pluvial/nival flooding extents and the associated non-contributing area in the prairies. This is achieved by coupling the MESH hydrology-land surface model with a newly developed surface routing component designed to explicitly deal with the prairie-pothole system (PRIMA) and is referred to as MESH-PRIMA. In this model, MESH handles the classical vertical water and energy balance calculations while PRIMA routes the water over the landscape and quantifies the depressional storage and runoff. The streamflow simulation of MESH-PRIMA is compared against that of MESH with its current conceptual prairie algorithm (MESH-PDMROF) on the Smith Creek Research Basin in Saskatchewan, Canada. MESH-PRIMA shows an improved streamflow and flood simulation compared to MESH-PDMROF and can replicate the non-linear and hysteretic relationship of the basin response. MESH-PRIMA allows for mapping the spatial distribution of water (pluvial/nival flooding) and the non-contributing area over landscape for different events. The results of MESH-PRIMA can help in updating the non-contributing area map and in identifying pluvial/nival flooding hazard, which is useful in flooding contexts.
... Roughness is a well-known input in flood inundation modeling and mapping, as well as a major source of uncertainty. The selection of the appropriate methodology for its reasonable mapping is of key importance [66,67]. The most common approach for large-scale applications is the use of typical values based on land use data, as suggested in the literature, combined with CORINE land cover data [42] for the floodplains, as made in this study (Figure 4). ...
Fluvial floods are one of the primary natural hazards to our society, and the associated flood risk should always be evaluated for present and future conditions. The European Union’s (EU) Floods Directive highlights the importance of flood mapping as a key stage for detecting vulnerable areas, assessing floods’ impacts, and identifying damages and compensation plans. The implementation of the EU Flood Directive in Greece is challenging because of its geophysical and climatic variability and diverse hydrologic and hydraulic conditions. This study addressed this challenge by modeling of design rainfall at the sub-watershed level and subsequent estimation of flood design hydrographs using the Natural Resources Conservation Service (NRCS) Unit Hydrograph Procedure. The HEC-RAS 2D model was used for flood routing, estimation of flood attributes (i.e., water depths and flow velocities), and mapping of inundated areas. The modeling approach was applied at two complex and ungauged representative basins: The Lake Pamvotida basin located in the Epirus Region of the wet Western Greece, and the Pinios River basin located in the Thessaly Region of the drier Central Greece, a basin with a complex dendritic hydrographic system, expanding to more than 1188 river-km. The proposed modeling approach aimed at better estimation and mapping of flood inundation areas including relative uncertainties and providing guidance to professionals and academics.
... Human-induced LULC changes and their consequent impact were the main reasons for the increase in runoff in the Oshiwara River basin in Mumbai (Zope et al. 2016). A hydraulic model was adopted for deterministic flood forecasting in Canada, to generate a floodplain map that differentiated between flooded and non-flooded areas (Bharath and Elshorbagy 2018). ...
Flooding in urban basins is a major natural catastrophe that leads to many causalities of life and property. The semi-urbanized Koraiyar River basin in Tamil Nadu has important cities like Tiruchirappalli and many towns located in it. The basin unfailingly experiences a flood event in almost every decade. It is anticipated that the basin will undergo rapid unplanned urbanization in the years to come. Such fast and erratic urban developments will only increase the risk of urban floods ultimately resulting in loss of human lives and extensive damages to property and infrastructure. The effects of urbanization can be quantified in the form of land use land cover (LULC) changes. The LULC change and its impacts on urban runoff are studied for the continuous 30-year present time period of (1986–2016) to reliably predict the anticipated impact in the future time period of (2026–2036). The analysis of land cover patterns over the years shows that urbanization is more prevalent in the northern part of the basin of the chosen study area when compared with the other regions. The extreme rainfall events that occurred in the past, and the probable future LULC changes, as well as their influence on urban runoff, are studied together in the current study. In order to minimize flood damages due to these changing land use conditions, certain preventive and protective measures have to be adopted at the earliest. There are some inevitable limitations while applying traditional measures in flood modeling studies. This investigative work considers a case study on the ungauged Koraiyar floodplains. The spatial scale risk assessment is assessed by coupling geographic information systems, remote sensing, hydrologic, and hydraulic modeling, to estimate the flood hazard probabilities in the Koraiyar basin. The maximum flood flow is generated from the Hydrologic Engineering Centre-Hydrologic Modeling System (HEC-HMS), the hydrologic model adopted in the present study. The maximum flood flow is given as input to the Hydrologic Engineering Centre-River Analysis System (HEC-RAS), an effective hydraulic model that generates water depth and flood spread area in the basin. The flood depth and hazard maps are derived for 2, 5, 10, 50, and 100-year return periods. From the analysis, it is observed that the minimum flood depth is less than 1.2 m to a maximum of 4.7 m for the 100-year return period of past to predicted future years. The simulated results show that the maximum flood depth of 4.7 m with flood hazard area of 4.32% is identified as high hazard zones from the years 1986–2036, located in the center of the basin in Tiruchirappalli city. The very high hazard flood-affected zone in the Koraiyar basin during this period is about 198.85 km². It is noticed that the very low hazard zone occupies more area in the basin for the present and future simulations of flood hazard maps. The results show that the increase in peak runoff and runoff volume is marginally varied.
... Whether due to tsunamis, ruptured dams, or heavy rainfall, they affect large areas and often require the evacuation of many people. Governments and agencies must therefore develop reliable and accurate maps of flood risk areas as part of their preventive measures (Raja and Elshorbagy, 2018;Das and Umamahesh, 2018;Haltas et al., 2016;Tsai and Yeh, 2017). Hence, predictive simulations should quantify the uncertainties that may arise from multiple sources (such as the boundary conditions, the geometry, the physical parameters, etc.) and that propagate through the modeling system. ...
This paper shows the development of a multi-GPU version of a time-explicit finite volume solver for the Shallow-Water Equations (SWE) on a multi-GPU architecture. MPI is combined with CUDA-Fortran in order to use as many GPUs as needed. The METIS library is leveraged to perform a domain decomposition on the 2D unstructured triangular meshes of interest. A CUDA-Aware OpenMPI version is adopted to speed up the messages between the MPI processes. A study of both speed-up and efficiency is conducted; first, for a classic dam-break flow in a canal, and then for two real domains with complex bathymetries: the Mille \^Iles river and the Montreal archipelago. In both cases, meshes with up to 13 million cells are used. Using 24 to 28 GPUs on these meshes leads to an efficiency of 80% and more. Finally, the multi-GPU version is compared to the pure MPI multi-CPU version, and it is concluded that in this particular case, about 100 CPU cores would be needed to achieve the same performance as one GPU.
... The choice of flood depth threshold is essential for the delineation of flooded areas and decision-making during the development of the floodplain (Bharath & Elshorbagy, 2018). The movements of aircrafts would be affected whenever substances, such as standing water and snow, are present in the airport's runway, taxiway, and apron (Federal Aviation Administration, 2019; Transport Canada, 2019). ...
The passage of a tropical storm, as the main driver of storm surge and high waves in many coastal regions, can also generate heavy rainfall and cause river overflow. The resulting combination of riverine, pluvial, and coastal flood hazard can result in catastrophic losses particularly in densely populated coastal environments. In this study, we characterize compound flooding caused by Tropical Storm Matthew and assess the significance and associated uncertainties of multiple contributing factors over a data-scarce coastal region. A hydrological model combined with a simplified two-dimensional hydrodynamic model are set up and validated to investigate the compounding effects of storm tide, wave runup, rainfall, and river overflow at the southern coast of Saint Lucia in the Caribbean Sea. Pléiades-1 and Sentinel-1 satellite imageries are used to determine the flood-impacted areas. The analyses are performed based on deterministic and probabilistic approaches and the effects of uncertain boundary conditions and model parameters are investigated. Results show that the individual analysis of flood hazards, in isolation, can lead to substantial underestimation of flood risks. Heavy rainfall and wave runup are the most significant contributors to compound flooding in Saint Lucia. In addition, the interactions between seawater and streamflow can exacerbate riverine flood hazards particularly upstream of the river mouth. Communities in western Vieux Fort, and the Hewanorra International Airport, have high exposure to compound flooding, which is projected to intensify under climate change.
