The default is to have equal conveyance reduction

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Unformatted text preview: The default is to have equal conveyance reduction turned on. The second item under global information is the Left bank offset and the Right bank offset. The left and right offsets are used to establish a buffer zone around the main channel for further limiting the amount of the encroachments. For example, if a user established a right offset of 5 feet and a left offset of 10 feet, the model will limit all encroachments to 5 feet from the right bank station and 10 feet from the left bank station. The default is to have no right or left offset, this will allow the encroachments to go up to the main channel bank stations, if necessary. 10-4 Chapter 10 Performing a Floodway Encroachment Analysis River, Reach and River Station Selection Boxes. The next piece of data for the user to select is the river and reach in which to enter encroachment data. The user is limited to seeing one reach at a time on the encroachment data editor. Once a reach is selected, the user can then enter a Starting and Ending River Station to work on. By default, the program selects all the sections in the reach. The user can change this to any range of cross sections within the reach. Profile. Next, the user should select a profile number to work on. Profiles are limited to 2 through the maximum number set in the currently opened flow data (e.g., 2 through 4, if the user has set 4 profiles in the flow data editor). The user can not set encroachments for profile 1. Method and Target Values. The next step is to enter the desired encroachment method to be used for the currently selected profile. Once a method is selected, the data entry boxes that corresponds to that method will show up below the method selection box. Some of the methods require only one piece of data, while others require two. The user should then enter the required information that corresponds to the method that they have selected. For example, if the user selects encroachment method 4, only one piece of information is required, the target change in water surface elevation. The available encroachment methods in HEC-RAS are: Method 1 Method 2 Method 3 Method 4 Method 5 - User enters right and left encroachment station User enters a fixed top width User specifies the percent reduction in conveyance User specifies a target water surface increase User specifies target water surface increase and maximum change in energy Set Selected Range. Once the encroachment method is selected, and its corresponding data are entered, the user should press the Set Selected Range button. Pressing this button will fill in the table below with the selected range of river stations; the selected method; and the corresponding data for the method. Note that, if the selected method only has one data item, that method’s data will go under the Value 1 column of the table. If the selected method has two data items, the first goes into the Value 1 column and the second goes into the Value 2 column. Once the data is put into the table, the user can change the method and corresponding data values directly from the table. A...
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