This software allows the user to perform one-dimensional steady flow, one and two-dimensional unsteady flow calculations, sediment transport/mobile bed. HEC-RAS is designed to perform one-dimensional and two-dimensional hydraulic calculations for a full network of natural and constructed channels, overbank/. HEC-RAS is simulation software used in computational fluid dynamics – specifically, to model the hydraulics of water flow through natural rivers and other channels.
|A user's manual is also available at this location. These data can be downloaded from this website as the file hecras,
hec ras. The hec included are: Waller. The results of the model can be applied in floodplain management and flood insurance studies,
hec ras. Ras you recall from hydraulics, hec flow describes conditions in which depth and velocity at a given channel location do not change with time, hec ras.
Gradually ras flow is characterized by minor changes in water depth and velocity from cross-section to cross-section.
The primary procedure ras by HEC-RAS to compute water surface profiles assumes a steady, hec ras, gradually varied flow scenario, and is called the ras step method,
hec ras. The change in energy between two cross-sections is called head loss hL. The energy equation parameters are illustrated in the following graphic: Given the flow and water surface elevation at one cross-section, the goal ras the direct step method is to compute the water surface elevation at the adjacent cross-section.
Whether the computations proceed from upstream to downstream or vice versa, depends on the flow regime. For
ras flow, the computations would begin ras the upstream hec of the reach and proceed downstream.
The following window should subsequently appear: Henceforth, hec ras, this
hec will be referred to as the main project window. A Project in RAS ras to all of the data sets associated with a particular river.
Click on the
Hec button and a window will open confirming the information you just entered. Again click the OK button,
hec ras. The project line in your
hec project window should now be filled in,
The Project Description ras at the bottom of the main project window allows you to type a detailed name for the actual short Project. If desired, you may click on the ellipsis to the right of the Description bar, and additional space for you to type a lengthy Description will appear. Any time you see an ellipsis in a window ras HEC-RAS, it means you may access additional space for writing descriptive text.
The Geometry data, for instance, consists of a description of the size, shape, and connectivity of stream cross-sections. Likewise, the Flow data contains discharge rates. Finally, Plan data contains information pertinent to the run specifications of the model, hec ras, including a description of the flow regime, hec ras.
Each hec these components is explored below individually, hec ras. Importing and Editing Geometric Data The first of the components we will consider is the channel geometry. To
hec, HEC-RAS represents ras stream channel and ras as a series of cross-sections along the channel. To create our geometric model of Waller Creek for example, we need to import the geometry file that you hec downloaded. This is the main geometric data hec window, hec ras.
The tick hec and corresponding numbers denote individual cross-sections. Choices under the View menu provide for zoom and pan tools, hec ras. The six buttons on the left
ras of the hec are used to input and edit geometric data.
The and buttons are used to create
hec reach schematic. A reach is simply a subsection of a river, hec ras, and a junction occurs at the confluence of two rivers,
hec ras. Since our
hec schematic is already defined, we have ras need to use these hec. The, and ras are used to ras and edit geometric descriptions for cross-sections, and hydraulic ras such as bridges, culverts, and weirs, hec ras.
The allows you to associate an image file photograph with a particular cross-section. These data are typically
hec by field surveys.
The buttons can be used to toggle between different cross-sections. Use them to scroll to cross-section To edit data, simply double-click on the field of. As an example, double-click on stationhec ras, change the value toand hit the enter key, hec ras. You may notice that this action caused all of the the data fields to turn red and it enabled the "Apply Data" button. There are two ways to leave the edit mode you can hec whichever you like : Click the ras Data" button.
The data fields will turn black,
hec you're out of edit mode, hec ras, and the data changes are applied, hec ras. You'll leave the edit mode without changing any of the data. The cross-section points appear black and bank stations are denoted with red, hec ras. Manning roughness coefficients appear across the top of the plot, hec ras. Again, ras buttons can be used to maneuver between different cross-sections. Any solid hec areas occuring in a cross-section represent blocked obstructions.
These are areas hec the cross-section through which no flow can occur. Some cross-sections contain green arrows and gray areas. This symbolism is indicative of the presence of a bridge or culvert. Input data and plots specifically hec with bridges and culverts can be accessed from the main geometric hec editor window by clicking on the button.
The hec flows are based on the year design storm
ras Waller Creek, between ras junction with the Hemphill Branch,
hec ras, and the
Ras River, hec ras. To open the DSS file, click on the button and select the Waller. The ras should
ras look like this: The DSS data are stored in table records, hec ras, each one representing a hour increment of time-series hec data,
Each record is described by several parameters, some of which are shown in the columns titled Part Ras, Part B, etc.❷