Download or read book Evaluation of One dimensional and Two dimensional HEC RAS Models for Flood Travel Time Prediction and Damage Assessment Using HAZUS MH written by Ekaraj Ghimire and published by . This book was released on 2019 with total page 178 pages. Available in PDF, EPUB and Kindle. Book excerpt: Even though flood damage cannot be fully controlled, its effect can be minimized to some extent by careful planning, flood mitigation measures, and an effective flood warning system. Therefore, flood warning systems with flood travel time and inundation area information, derived from accurate model prediction, can be very effective to reduce potential flood damage. While a one-dimensional (1D) model was developed in the former research for the flood warning system, there has not been many comparative assessment of model performance among 1D, two-dimensional (2D), and coupled one-dimensional and two-dimensional (coupled 1D/2D) models particularly in HEC-RAS. Therefore, this research is an extension of the prior research and was especially conducted to calculate and compare the predictive capability of 1D, 2D, and coupled 1D/2D HEC-RAS models for the computation of travel time of flood and extent of flooded area needed for a flood warning system. The research was carried out in the Grand River in Lake County, Ohio. The model performance of 1D, 2D and coupled 1D/2D models were evaluated and sensitivity analysis was conducted using the same set of flow conditions and geometric conditions. The analysis suggested that 2D model could incredibly improve the model performance compared to 1D and coupled 1D/2D models, which were evaluated through the model evaluation indicators for the observed and simulated model outputs. Additionally, sensitivity analysis of input parameters, including discharge and Manning's roughness, revealed that the 2D model was comparatively less sensitive to the changes in model inflow and Manning's roughness compared to the coupled 1D/2D and 1D models. Furthermore, the flood travel time computed using 1D model was more predicted than that of the 2D model, indicating that the 2D model would be most appropriate to provide a safe evacuation time for the community before flood events. The 1D model consistently over predicted than that of the 2D model, which was also true for the estimation of the inundation flood zone (4.1% higher). In addition, the appropriate assessment of flood damage in the aftermath of major flooding is crucial for flood management agencies, emergency responders, and insurance companies. Therefore, damage assessment is an important step in the evaluation of the flood mitigation measures, vulnerability analysis and flood risk mapping. This is particularly true in a context that the damage assessment so far has been primarily relying on either the coarse resolution, 30m digital elevation model (DEM), or 1D hydraulic model. As this researcher is not aware of any explicit incorporation of 2D HEC-RAS model for the damage assessment among the scientific communities, another major objective of this analysis is to outline the effects of some of the key factors including the mode of hydraulic simulation (1D vs 2D), the effect of inventory data, and the effect of topography on the flood loss estimation. This was accomplished using the 1D and 2D HEC-RAS models to produce the flood depth grids from the varying degree of topographic resolutions including 30m, 10m and LiDAR-derived DEM with and without incorporating actual field survey of the river in each case. The flood loss was estimated using Hazards United States Multi-Hazards (HAZUS-MH) loss estimation software developed by Federal Emergency Management Agency (FEMA) software, for each building within study area for flood events of various recurrence intervals from 10 to 500-year return periods. This was accomplished by updating the default-building inventory within Lake County to represent the actual building information in the model. The analysis indicated that 1D model consistently overestimated the loss in general by 61.48% for the default database and 86.12% for updated inventory. The estimation of the 1D model was consistently larger compared to the 2D model for different set of topographic resolutions and recurrence intervals. These loss estimations significantly increased when analyzed using a coarse resolution terrain, which was true regardless of selecting 1D or 2D models. Furthermore, the 2D model showed a lesser percentage increase (10.45% in 10m DEM, and 25.49% in 30m DEM), whereas the 1D model exhibited a larger increment (23.17% in 10m DEM and 76.81% in 30m DEM). This analysis suggested that the loss estimation would decrease in general by 76.21% after incorporating additional local building data into the HAZUS-MH database. More specifically, this analysis concludes that 2D model with high-resolution topographic data, including the additional incorporation of local data, in HAZUS-MH database are tremendously essential for appropriate flood damage assessment.

Download or read book 2d River Flood Modelling Using Hec ras 5 0 written by Joan Flotats Palau and published by . This book was released on 2016 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Flooding may occur as an overflow of water from water bodies, such as a river, lake or ocean, in which the water overtops or breaks levees, resulting in some of that water escaping its usual boundaries. Floods also occur in rivers when the flow rate exceeds the capacity of the river channel. Floods represent the deadliest natural hazard in Europe, resulting in loss of life, damage to buildings, homes, business and structures such as bridges and roads. Since such consequences are highly undesirable for human beings, the need to avoid or at least control them has become obvious. This led to the appearance of hydrodynamic models, numerical tools able to simulate the flow movement, also in case of flooding. Those models would let us know how the flow behaves in certain situations and how to act in consequence in order to avoid those undesirable effects. In April 2016, the new two-dimensional version of HEC-RAS has been released, the so-called HEC-RAS 5.0. This version is especially interesting since all previous versions of HEC-RAS had never been able to simulate flows in two dimensions. The main motivation of this document is to analyse the functionality and workability of HEC-RAS 5.0 regarding two-dimensional river flooding. In order to do so, three different work approaches have been carried out, with further analysis of the correspondent results. First, a detailed intercomparison between the main hydrodynamic models available has been carried out in order to check the features of the new version of HEC-RAS next to another four computational programs. Second, the same case simulation has been performed at the same time for HEC-RAS 5.0 and for Delft3D. The aim of this is to check the reliability and functionality of HEC-RAS new version regarding to 2D river flood modelling next to an already developed two-dimensional model such as Delft3D is. For this simulation, an ideal created prismatic channel has been chosen in order to work in a basic scenario and two approaches have been analysed: steady nonflooding and unsteady flooding cases. Finally, and once its workability has been checked, a more complex case has been simulated with HEC-RAS 5.0. In this case, the scenario is a real case study, consisting in a river flood in the Fluvià River, in Catalonia, Spain, with real data of a return period of 50 years, obtained from Agència Catalana de l'Aigua (ACA) in 2009. The results led to very sensitive output, realistic and similar to the expected and contrasted. Thus, one can conclude that, despite small instabilities were found, HEC-RAS 5.0 is able to perform simple 2D river flood modelling simulations at a similar level of the most advanced two-dimensional programs, such as Delft3D. However, when it comes to very complex simulations, some features, such as combination with transport of substances and water quality or combination with sediment transport and morphological evolution, are not yet available in two dimensions for HEC-RAS 5.0, so one would rather choose a more advanced model.

Download or read book Application of Two dimensional Hydraulic Modeling in Riverine Systems Using HEC RAS written by Abdulaziz Saeed Alzahrani and published by . This book was released on 2017 with total page 83 pages. Available in PDF, EPUB and Kindle. Book excerpt: Flood simulation models have a wide variety of approaches that are available to compute the water surface elevations associated with a flood event. Some of these models use a One-dimensional (1D) approach, others use a Two-dimensional (2D), and there are others allow the use of integrated 1D and 2D simulations. In 2015, the US Army Corps of Engineering Hydrologic Engineering Center (HEC) released HEC-RAS Version 5.0.3 which performs 1D steady and unsteady flow calculation, as well as 2D unsteady flow calculation. 2D modeling is likely to become more common due to HEC-RAS. This paper is the comparison of 1D and 2D models for a water level in the channel and the floodplain inundation. Two treatments of the problem are explored: (1) a 1D model based upon discretization of floodplain units into storage areas; (2) a 2D model for a channel and a floodplain surface. The two models were tested on the Great Miami River and Bear Creek. The models were assessed by comparison with measured inundation extent. Also, the study reviews the academic basis for modeling floodplain flow based on a two-dimensional analysis. The goal of the proposed research effort will be to include the application of 2D unsteady-state models in future releases of the HEC-RAS 2D model.

Download or read book HEC River Analysis System HEC RAS written by Gary W. Brunner and published by . This book was released on 1994 with total page 16 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Using HAZUS MH Flood Model as a Floodplain Management Tool written by Megan L. Carlson and published by . This book was released on 2010 with total page 104 pages. Available in PDF, EPUB and Kindle. Book excerpt: By combining FEMA's HAZUS-MH (Hazards U.S. Multi-Hazard) flood-loss estimation software and the HEC-RAS hydraulic modeling package, this study was able to quantify potential beneficial and adverse impacts of flood-control and navigational structures along the Middle Mississippi River (MMR; between Mississippi-Missouri River confluence and Thebes, IL). The goal of this investigation was to assess changes in water-surface elevations and associated flood losses to: 1) quantify the potential exposure of flooding under different flood-control configurations along the Middle Mississippi River (MMR), and 2) assess the relative contributions of various engineered structures and flood-loss strategies to potential flood losses. Assessment of the impact of engineering structures was accomplished by modeling five scenarios for the 100- and 500-year floods: 1) current MMR levee configuration (levee protecting for [less than or equal to] 50-year flood); 2) removal of all flood-control structures on the MMR; 3) increasing the height of levees and floodwalls in metropolitan St. Louis to protect urban areas to the 500-year flood level while simultaneously removing all agricultural levees downstream; 4A) a less engineered MMR channel and floodplain with fewer flood control and navigation structures, simulating conditions from 65 years ago (1942-1947) with 1940's levees; and 4B) a less engineered MMR channel and floodplain with fewer flood control and navigation structures, simulating conditions from 65 years ago (1942-1947) with current levee configuration.

Download or read book A Two Dimensional Flood Routing Calculation written by Charles Noble and published by . This book was released on 1982 with total page 18 pages. Available in PDF, EPUB and Kindle. Book excerpt: The desirability of accurately predicting the extent and duration of flooding resulting from the partial or total breach of a dam has been emphasized recently. The most practical way to meet this need is the development and use of good computer-based models. In order to predict the routing of floods, several hydrograph routing and one-dimensional models have recently been developed. Among the better known models are those employed in the code DAMBRK, Fread (1980) and in HEC-1 (1973). These models have proved to be quite good in predicting the flooding in those cases which have been amenable to a one-dimensional treatment. The accuracy of these models in situations which are clearly two-dimensional in nature is suspect, however. It is thus desirable to develop two-dimensional flood routing models to properly handle those situations in which the one-dimensional models are inadequate. Energy Incorporated (EI) has developed a computer code, FLOOD, that describes the two-dimensional motion of a flood. An analysis of the hypothetical Mackay Dam failure was performed using FLOOD. In this paper are given the equations used by EI, the numerical algorithm used for their solution, and the results of the Mackay Dam analysis.

Download or read book Evaluation of 1D 2D river flood simulation with HEC RAS 5 0 3 considering change of boundary conditions written by Maryellen Hearn and published by . This book was released on 2017 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book A Comparison Study of One and Two dimensional Hydraulic Models for River Environments written by Evan C. Deal and published by . This book was released on 2017 with total page 271 pages. Available in PDF, EPUB and Kindle. Book excerpt: Computer models are used every day to analyze river systems for a wide variety of reasons vital to the public interest. For decades most hydraulic engineers have been limited to models that simplify the fluid mechanics to the unidirectional case. With the advent of higher quality data and greater computational power, two-dimensional hydrodynamic models have become practical for widespread use. Two such models are considered in this report: HEC-RAS v.5.0, v.5.0.1, and v.5.0.3, and SRH-2D v.3.0. These two-dimensional models were compared to the most common one-dimensional model (HEC-RAS). While the latest version of HEC-RAS is capable of both one- and two-dimensional analyses, previous versions were restricted to one-dimensional flow. Findings in this report include: differences in the flow divisions for multiple opening bridges for all three models, less subjectivity in the construction of the 2D models than for the 1D, differences in the sensitivity of each 2D model to the Manning's roughness coefficient, great similarity in the expansion and contraction rates at bridges for the 2D models when using the full momentum equations with HEC-RAS 2D, differences in the response of the two-dimensional models at steady state conditions to vortex shedding through bridge openings with cylindrical piers, shorter computation times for HEC-RAS 2D than SRH-2D using highly comparable model setups, and in general, higher depths predicted by SRH-2D than HEC-RAS 1D but the highest depths overall predicted by the HEC-RAS 2D full momentum model.

Download or read book Issues of 2 D Modeling for Flood Mapping written by Devinder Singh Dhillon and published by . This book was released on 2014 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Numerical modeling is the standard tool in determining floodplain areas for engineering and insurance purposes. For many years one-dimensional (1-D) models have been primarily used for these purposes, with HEC-RAS arguably the most widely used 1-D model. Relatively robust guidelines and specifications, as well as an industry standard of practice, currently exists for 1-D models. While 1-D models are relatively simple to apply and rather inexpensive to develop, they are based on several assumptions that do not always hold true in overbank flooded conditions. These shortcoming are particularly significant for models intended to simulate flow over levees or in very flat areas, such as the Central Valley of California.In recent years, 2-D models have been used as an additional tool in floodplain mapping to allow for more detailed analyses. Unfortunately, the assumptions behind these 2-D models are not fully understood by all users. 2-D models are even less understood by decision and policy makers. The Federal Emergency Agency (FEMA) has recognized the need for greater understanding and improved guidelines for applying 2-D models in flood studies and intends to widely disseminate the advantages and limitations of 2-D models examined. This work develops a) a literature review of 2-D modeling use for floodplain mapping; b) presents the Blue Ribbon Panel's (BRP's) results of the 46 issues; c) develop a question form for 2-D software vendors; and d) produce written guidelines that address limitations and capabilities of 2-D models to help practitioners, decision and policy makers use 2-D models more effectively.The decision on model complexity and dimensionality for a given case, can be based on two main ideas: a) the goal of the analysis, and b) the modeler. Thus, the steps to consider when facing a modeling task should be: a) define the goal of the study; b) select the adequate modeler for the task; c) chose the right tool for the goal of the study and the modeler; and d) perform the study considering all conditions.

Download or read book Sensitivity of Hazus MH Flood Loss Estimates to Selection of Building Parameters written by Samir Shrestha and published by . This book was released on 2014 with total page 146 pages. Available in PDF, EPUB and Kindle. Book excerpt: In this study, Hazus-MH (v 2.1 SP 2) flood-loss estimation tools were assessed for their sensitivity to an array of different building and model parameters. The purpose of this study is to help guide users of the Hazus-MH flood-loss modeling tool in the selection of most appropriate model parameters. Six model parameters (square footage of the building, building age, construction types, foundation types, first floor heights, and the number of stories in the building) were assessed for their impacts on flood losses using the Hazus-MH user defined and aggregate flood-loss models. Building stock databases for these analyses were developed using county assessor records from two Illinois counties. A validation assessment was also performed using observed flood-damage survey data collected after the 2011 Mississippi River Flood which inundated the Olive Branch Area in Alexander County, Illinois. This analysis was performed to assess the accuracy of the detailed Hazus-MH User Defined Facility (UDF) flood-loss modeling tool. The foundation types and its associated first floor heights and number of stories in the building were found to substantially impact flood-loss estimates using the Hazus-MH flood-loss modeling tool. The model building parameters square footage, building age and construction type had little or no effect on the flood-loss estimates. The validation assessment reveled Hazus-MH UDF flood-loss modeling tool is capable of providing a reasonable estimate of actual flood losses. The validation assessment showed the modeled results to be within 23% of actual losses. The validation study results attained in this study using the detailed UDF flood-loss modeling tool where more realistic (within 23% of actual losses versus > 50% of actual losses) than previous Hazus-MH flood-loss validation assessments. The flood-loss estimates could be further improved by modifying or choosing a more region specific depth-damage curve, using higher resolution DEM and improving the flood-depth grid by incorporating more detailed flood elevation data or estimates using detailed hydraulic models that better reflects the local inundation conditions.

Download or read book Improvements in Fast response Flood Modeling written by and published by . This book was released on 2009 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: It is becoming increasingly important to have the ability to accurately forecast flooding, as flooding accounts for the most losses due to natural disasters in the world and the United States. Flood inundation modeling has been dominated by one-dimensional approaches. These models are computationally efficient and are considered by many engineers to produce reasonably accurate water surface profiles. However, because the profiles estimated in these models must be superimposed on digital elevation data to create a two-dimensional map, the result may be sensitive to the ability of the elevation data to capture relevant features (e.g. dikes/levees, roads, walls, etc ...). Moreover, one-dimensional models do not explicitly represent the complex flow processes present in floodplains and urban environments and because two-dimensional models based on the shallow water equations have significantly greater ability to determine flow velocity and direction, the National Research Council (NRC) has recommended that two-dimensional models be used over one-dimensional models for flood inundation studies. This paper has shown that two-dimensional flood modeling computational time can be greatly reduced through the use of Java multithreading on multi-core computers which effectively provides a means for parallel computing on a desktop computer. In addition, this paper has shown that when desktop parallel computing is coupled with a domain tracking algorithm, significant computation time can be eliminated when computations are completed only on inundated cells. The drastic reduction in computational time shown here enhances the ability of two-dimensional flood inundation models to be used as a near-real time flood forecasting tool, engineering, design tool, or planning tool. Perhaps even of greater significance, the reduction in computation time makes the incorporation of risk and uncertainty/ensemble forecasting more feasible for flood inundation modeling (NRC 2000; Sayers et al. 2000).

Download or read book Summary Report from Workshop on Two Dimensional Mathematical Models for Use in Hydraulic Problems written by Frank D. Masch and published by . This book was released on 1977 with total page 88 pages. Available in PDF, EPUB and Kindle. Book excerpt: American highway organizations are constantly faced with complex problems regarding stream crossings with the more challenging situations lying in low gradient streams common in the southeastern United States. Conventional and empirical one-dimensional methods are sometimes found to be inadequate and may eventually be supplanted by more sophisticated two-dimensional analytical methods. The subject workshop was conducted in order to consolidate ideas and opinions covering the feasibility of future development of two-dimensional mathematical models as might be applied to hydraulic problems.

Download or read book Development and Validation of a Two dimensional Fast response Flood Estimation Model written by and published by . This book was released on 2009 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: A finite difference formulation of the shallow water equations using an upwind differencing method was developed maintaining computational efficiency and accuracy such that it can be used as a fast-response flood estimation tool. The model was validated using both laboratory controlled experiments and an actual dam breach. Through the laboratory experiments, the model was shown to give good estimations of depth and velocity when compared to the measured data, as well as when compared to a more complex two-dimensional model. Additionally, the model was compared to high water mark data obtained from the failure of the Taum Sauk dam. The simulated inundation extent agreed well with the observed extent, with the most notable differences resulting from the inability to model sediment transport. The results of these validation studies complex two-dimensional model. Additionally, the model was compared to high water mark data obtained from the failure of the Taum Sauk dam. The simulated inundation extent agreed well with the observed extent, with the most notable differences resulting from the inability to model sediment transport. The results of these validation studies show that a relatively numerical scheme used to solve the complete shallow water equations can be used to accurately estimate flood inundation. Future work will focus on further reducing the computation time needed to provide flood inundation estimates for fast-response analyses. This will be accomplished through the efficient use of multi-core, multi-processor computers coupled with an efficient domain-tracking algorithm, as well as an understanding of the impacts of grid resolution on model results.

Download or read book The Hydrologic Modeling System HEC HMS written by William J. Charley and published by . This book was released on 1995 with total page 16 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Hazus MH Flood Loss Estimation on a Web based System written by Enes Yildirim and published by . This book was released on 2017 with total page 61 pages. Available in PDF, EPUB and Kindle. Book excerpt: In last decades, the importance of flood damage and loss estimation systems has increased significantly because of its social and economic outcomes. Flood damage and loss estimation systems are useful to understand possible impacts of flooding and prepare better resilience plans to manage and allocate resources for emergency decision makers. Recent web-based technologies can be utilized to create a system that can help to analyze flood impact both on the urban and rural area. With taking advantage of web-based systems, decision makers can observe effects of flooding considering many different scenarios with requiring less effort. Most of the emergency management plans have been created using paper-based maps or GIS (Geographical Information System) software. Paper-based materials generally illustrate floodplain maps and give basic instructions about what to do during flooding event and show main roads to evacuate people from their neighborhood. After the development of GIS (Geographic Information System) software, these plans have been prepared with giving more detail information about demographics, building, critical infrastructure etc. With taking advantage of GIS, there are several software have been developed for the understanding of disaster impacts on the community. One of the widely-used GIS-based software called Hazus-MH (Multi-Hazard) which is created by FEMA (Federal Emergency Management Agency) can analyze disaster effects on both urban and rural area. Basically, it allows users to run a disaster simulation (earthquake, hurricane, and flood) to observe disaster effects. However, its capabilities are not broad as web-based technologies. Hazus-MH has some limitations in terms of working with specific software requirements, the ability to show a limited number of flood scenarios and lack of representing real time situation.

Download or read book The New HEC 1 Flood Hydrograph Package written by Arlen D. Feldman and published by . This book was released on 1981 with total page 40 pages. Available in PDF, EPUB and Kindle. Book excerpt: This paper describes the new version of the HEC-1 Flood Hydrograph Package - a comprehensive simulation model computer program. The many hydrologic and hydraulic simulation capabilities of the model are described. Special emphasis is given to analysis of dam safety and dam failure flood damage studies, and urban hydrology. The general applicability and usage of the model are described. (Author).

Download or read book Flood Analysis of Bridge Stream Interactions Using Two Dimensional Models written by Rachel M. Seigel and published by . This book was released on 2021 with total page 250 pages. Available in PDF, EPUB and Kindle. Book excerpt: The 2011 Tropical Storm Irene resulted in considerable property and infrastructure damage in Vermont and neighboring states, including damages to and failure of over 300 bridges and 800 km (500 miles) of roads in Vermont alone, which brought to light the vulnerability of regional transportation infrastructure to extreme flood events. The northeastern United States is experiencing more frequent precipitation events of longer duration (i.e., extreme events). Infrastructure therefore must be able to withstand more frequent flood events of greater magnitude. It is not feasible to analyze and retrofit each structure for the rigorous hydraulic demands of extreme flood events; so prioritizing limited resources to locations at greatest risk in order to minimize flood damage is critical. Current state of practice is often limited in scope to steady-state analysis in the immediate vicinity of a specific structure or feature, and the far-reaching impacts up- and downstream the river are often not understood and considered in decision making. To better understand the interactions among rivers, hydraulic structures and surrounding hydrogeological features, a two-dimensional (2D) transient HEC-RAS (Hydraulic Engineering Center's River Analysis System) model of a Mad River Reach was constructed and calibrated. Available 2D HEC-RAS models of two additional Vermont river reaches supplemented the study allowing comparisons across a range of river gradients. The analyses considered the 2011 Tropical Storm Irene, as well as flood events that have annual exceedance probabilities of 50%, 4%, 2% and 1%, to analyze hydraulic impacts and interactions surrounding transportation infrastructure. A screening framework, that uses the 2D hydraulic modeling results, was developed to identify bridges and sites best suited for hydraulic intervention such as floodplain lowering and reconnection and addition of culverts for mitigating the impacts of extreme flood events along the bridge-river network. These interventions were then simulated in the developed 2D HEC-RAS models of the three study reaches. The results of the baseline and intervention models were examined to quantify bridge-river interactions on a reach scale, evaluate the overall effectiveness of the screening framework, and identify reach-level impacts of flood mitigation interventions. The results indicate that the developed screening framework that combines geomorphic and hydraulic characteristics can identify suitable bridges and other locations along a river for flood mitigation intervention. The screening framework is comparatively more applicable to moderate to high gradient rivers, but may still be applied to lower gradient rivers with supplementary data from prior flood damage reports and inspection records. The results demonstrate that the interventions have cascading effects up and downstream of the intervention locations. Interventions simulated on a moderate or high gradient river have farther-reaching effects that are often less intuitive up and downstream compared to a low gradient river highlighting the importance of a transient, two-dimensional hydraulic analysis. Overall, the results suggest that bridge flood mitigation projects in similar geographic and climate settings should consider the up and downstream geomorphic and hydraulic characteristics to better understand the potential impact the intervention will have on the bridge-river network.