WMS:Preparing Stage Data

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There are three basic ways to create stage data for flood plain delineation. The tutorial on floodplain delineation demonstrates all three methods.

Hydraulic Model Data

When running HEC-RAS or other supported hydraulic models, resulting water surface elevations are created as a scatter set for each cross section in the model. Typically the number of scatter points created from the cross sections is insufficient to adequately interpolate a flood plain on the TIN and so these points need to be interpolated along the river center line and cross sections in order to create a scatter set with sufficient points for interpolation. The additional points along cross sections are created with the same value as the first point which does not violate the assumptions of a 1D model like HEC-RAS. Additional points along center lines are created by linearly interpolating from the cross sections (again being consistent with the assumptions of 1D models).

Read a Scatter Dataset

Scatter sets can be read in as 2D scatter files, or imported using the File Import Wizard if existing data can be created in a spreadsheet or other consistent text file format. The interpolation tools for cross sections and center lines can also be used after a file has been read.

Manually Create Scatter Points by Digitizing in WMS

The 2D Scatter module provides a tool for creating new scatter points interactively. Water surface elevation can be entered for as the data value. Generally in such cases users will want to take advantage of a centerline and cross sections to develop a larger dataset for flood plain delineation. For example if having created a 1D-Hydraulic centerline to represent the stream, and optionally cross sections, a user can interpolate computed values along these feature objects.

Use the Channel Calculator

This is actually similar to the manual method. A new scatter point can be created along a cross section arc at the intersection point of a centerline using the water surface elevation (computed depth plus lowest elevation along the cross section) computed with the channel calculator.


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