- Hec ras cross section placement update#
- Hec ras cross section placement software#
- Hec ras cross section placement free#
The general approach to laying out cross sections is to ensure that the cross sections are perpendicular to the flow lines. Every effort should be made to obtain cross sections that accurately represent the stream and floodplain geometry.Īn example cross section layout is shown in the below figure. Occasionally it is necessary to layout cross sections in a curved or dog‑leg alignment to meet this requirement. The cross sections should extend across the entire floodplain and should be perpendicular to the anticipated flow lines. Cross sections are located at intervals along a stream to characterize the flow carrying capability of the stream and the adjacent floodplain.
Hec ras cross section placement software#
To return to the blog from time to time, I regularly post similar tutorials, the result of my experiments with various modeling software or my opinion on the evolution of practices on the theme of modeling in environmental hydraulics.This article discusses the requirements for HEC‑RAS cross section placement, spacing, layout, geometry, and other data.īoundary geometry for the HEC‑RAS analysis of flow in natural streams is specified in terms of ground surface cross sections and the measured flow distances between them (reach lengths).Note : you can also process directly a point cloud of XYZ points if they are ordered correctly in the cross section and if you have an identifier to group the points into the corresponding cross sections.Īnd if this tutorial pleased you, do not hesitate :
Hec ras cross section placement update#
> if you create or update the profiles contained in the CSV file. > if you create a reach or if you insert profiles in an existing reach > the corresponding unit system (SI or US)
> In the import interface that follows, select the appropriate options : We obtain an attribute table grouping the x, y, z of each point as well as the identifier of the Cross Section to which it belongs.Ĥ - Copy the attributes and format this table to obtain a table similar to the following capture, giving for each point: its coordinates X, Y and Z, the identifier of the profile (Station) resulting from the initial profile layer, and two columns representing the river and the reach (River and Reach).ĥ - Import this profile data via the HEC RAS import tool:
This step can be done automatically by crossing with a layer of mileage points if available.Ģ - Extract vertex lines, to have a layer of points:ģ - the addition of geometry attributes to the vertex layer (vector / geometry tools / Add geometry attributes) makes it possible to have direct access to the coordinates x, y, z in the attribute table of the point layer, in the latest versions of Qgis (3.xx minimum). Procedure :ġ - Open the file of lines with QGIS, save it in Shapefile or in memory if necessary to be able to handle it, add a column of attributes corresponding to the station in HEC RAS and complete this attribute (decreasing from upstream to downstream, corresponding to the topological order of river sections across the model). You should also have Qgis version 3.xx at a minimum, a spreadsheet (Excel or Calc), and software to process DWG files ( Draftsight works well). Pre requisite :Īll you need is a file containing 3D polylines (each point is defined by its coordinates X, Y, Z) in format DXF or Shapefile, cleaned, containing only the profiles cross (if the file is in format DWG, save it in DXF ASCII format so that it is easily compatible with QGIS). Generate HEC RAS .csv file for importing cross sections from 3D polylines representing cross sections of the river.
Hec ras cross section placement free#
The detailed approach here is certainly not the only solution, nor necessarily the optimal approach, but it is based on free and easily accessible tools. In this post, I detail a way to import profiles across streams available in the form of 3D polylines in HEC RAS to speed up this build process. In the HEC RAS training courses that I run, the question of optimizing the building of the models comes out regularly.