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Hydraulic Modelling
Published in Monzur A. Imteaz, Urban Water Resources, 2019
HEC-RAS stands for Hydrologic Engineering Center’s River Analysis System and is the most widely-used hydraulic model for one-dimensional analysis. Hydrologic Engineering Center is a part of the US Army Corps of Engineers (http://www.hec.usace.army.mil) who have developed this software. Although this chapter only describes the steady flow analysis, in fact, HEC-RAS also performs unsteady flow analysis. In addition, HEC-RAS is capable of performing some more sophisticated analyses, such as sediment flow calculations, flow calculations through a bridge, culvert, sluice gate, drop structure, weir and spillways. These analyses are not discussed in this chapter. Details of the software functionalities can be obtained from the HEC-RAS Users Manual (USACE, 2010b).
Designing reservoir sediment management alternatives with automated concentration constraints in a 1D sediment model
Published in Silke Wieprecht, Stefan Haun, Karolin Weber, Markus Noack, Kristina Terheiden, River Sedimentation, 2016
HEC-RAS includes a one-dimensional hydraulic model, which computes water surface profiles and inundation boundary maps based on steady flow back water computations or unsteady solutions to the Saint-Venant equation. HEC-RAS also includes a sediment transport model, which routes sediment through control volumes centred around each cross section. The sediment model updates the cross sections after each time step based on deposition or erosion in the control volume. HEC-RAS 5.0 couples sediment transport with unsteady flow. Coupling sediment transport with unsteady flow makes the “Operational Rules” feature, which changes gate operations mid-simulation based on model results (e.g. water surface elevation or flow at a specified cross section), available sediment transport studies (Gibson and Boyd, 2015). Sediment variables were added to the Operational Rules to automate model reservoir operations based on sediment concentration or bed change.
Impact of Urbanization on Flooding
Published in Saeid Eslamian, Faezeh Eslamian, Flood Handbook, 2022
Floodplain management including structural and nonstructural approaches was summarized. It is very important to incorporate both approaches into flood protection and management plans to reduce flood damage while helping to restore stream ecosystems. The equations for floodplain hydraulic analysis and application of HEC-RAS software were introduced to provide useful tools for floodplain management and flood insurance studies to evaluate floodway encroachments and to delineate flood hazard zones.
Hydraulic modelling of irrigation canals for improved flow conditions in surface irrigation systems
Published in ISH Journal of Hydraulic Engineering, 2023
Joshua Wanyama, Erion Bwambale
Several studies have performed hydraulic analysis on irrigation canals using different models (Barkhordari and Hashemy Shahdany 2022a; Cruz-Mayo and Aguilar 2022; Kamran et al. 2021; Maatooq and Wahad 2018). HEC-RAS (Hydrologic Engineering Center’s River Analysis System) is a widely used computer program for hydraulic analysis of irrigation canals and other types of watercourses (USACE, 2016). It was developed by the United States Army Corps of Engineers and is used to analyze the steady and unsteady flow of water in rivers, streams, and irrigation canals (USACE, 2016). There have been several recent studies that have used the HEC-RAS model to analyze the hydraulic performance of irrigation canals. For example: Syarifudin et al. (2022) used HEC-RAS to model the hydraulic performance of a canal network in India. The study found that the model was able to accurately predict the water levels and discharge in the canals, and it was able to identify areas of the network that were experiencing high velocities and erosion. Similarly, Kamran et al. (2021) used HEC-RAS to simulate flow conditions in the Punjab irrigation systems. The study found that the model was a useful tool for effective canal operation to determine the losses and find out the expected discharge for the tail-end users. The HEC-RAS model was found to be suitable for comprehending the hydraulic properties of the irrigation system after Serede et al. (2014) conducted research in Kenya’s Mwea Irrigation Scheme to ascertain the canal capacity potential.
Flood hazard mapping of the Welang river, Pasuruan, East Java, Indonesia
Published in Journal of Applied Water Engineering and Research, 2023
Entin Hidayah, Gusfan Halik, Indarto Indarto, Dian Wahyu Khaulan
Flood mapping using a hydraulic model (HEC-RAS) adequately and effectively maps inundation to assess future flood risk in riverbank areas (Aryal et al. 2020; Mourato et al. 2017; Shustikova et al. 2019). besides that, The HEC-RAS models can be calibrated against discharge or inundated area data and give good predictions of inundated area, The predictive power of the models calibrated against inundation extent or discharge for one event can thus be measured using independent validation data for the second (Horritt and Bates 2002). This hydraulic 1D model estimates flood inundation only for a simple grid system (Vojtek et al. 2019). Meanwhile, for complex network systems, 2D models are more adequate (Shustikova et al. 2019; Vojtek et al. 2019). To overcome the lack of high-resolution rain data in flood mapping, these complex systems use the HEC-RAS 2D flood model with DSM input from UAV images which showed significant results (Yalcin 2019). The HEC-RAS modeling is effective based on the match between the UAV image resolution and its mesh resolution and accurately depicts depth by simulating various mesh resolutions (Shustikova et al. 2019). For a 2D HEC-RAS hydrodynamic modeling process, a resolution match between the Digital Elevation Model DEM and the mesh is required to obtain optimal accuracy (Ongdas et al. 2020; Shustikova et al. 2019).
Simulation of the flood wave caused by hypothetical failure of the Haditha Dam
Published in Journal of Applied Water Engineering and Research, 2023
Harith Hamad Mhmood, Meric Yilmaz, Sadeq Oleiwi Sulaiman
Hydraulic modeling of dam failure using HEC-RAS software includes three basic steps: routing the inflow through the reservoir, estimating dam breach characteristics and outflow hydrograph, and routing the outflow hydrograph through the downstream channel. The HEC-RAS model can achieve reservoir flood routing in two ways, either by routing the unsteady flow or by level pool reservoir routing. In this study, the latter one is utilized. The second step is comprised of estimating the characteristics and dimensions of the breach to correctly calculate the outflow hydrograph. Moreover, it contains a large percentage of uncertainty since a hypothetical failure is modeled, not the actual situation, but the important characteristics are the location and the final breach geometry, formation time, and the breach progression parameters that will inform the modeler what the initial form is and how it forms over time. The third step is modeling the downstream flood wave. Required data for the accurate modeling of flood wave propagation downstream by using HEC-RAS is explained in the next section.