Geospatial Hydrologic Modeling Extension HEC-GeoHMS, User’s Manual. Public Domain That information is also provided in Appendix E of this manual for. This tutorial is designed to expose you to basic functions in HEC-GeoHMS ( ArcGIS version) to create input files for hydrologic modeling with HEC-HMS. Step 7: Terrain processing and HEC-GeoHMS model development The DEM, land use and soil data used in this tutorial are already clipped.
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Once the table is created, create the following fields in it:. Recommended Practice – Flood Hazard Mapping up. Click on the profile tool, and then click on the cross-section to view the profile. In addition, HEC-GeoRAS requires the land use polygons to be non multi-part features a multipart feature has multiple geometries in the same feature. After successful simulation, close the computation window and the steady flow window. For merging basins, we follow the process that allow tutoial to merges two or more hecc basins into one.
Therefore, check the data carefully, and if you think everything is OK, ignore the errors if you get any for connectivity and proceed. Confirm the input River name, and click OK.
Help inserting CN Grid in HEC-GeoHMS | GeoNet
It may be a little intimidating and there is a learning curve in even figuring out how to use the gui but the results from the Hydrolocic Tools, especially when used with high resolution tutoriak input, are worth the effort. Management of models through ProjectPoint and ProjectArea let users see areas for which HMS basin models are already created, and also allow users to re-create models with different stream network threshold.
With lnk grid active, select the contributing area tool, and click at any point along the stream to know the contributing area. Printer-friendly version Log in to post comments.
You can check the Slp field in the input River1 or whatever name you have for your input river feature class is populated. We will use this to locate the outlet of tutoriaal watershed. This feature class is used to speed up the point delineation process. Now label the flowpaths by using the Assign LineType button. The output file CedarCreek.
Meteorologic Model We do not have any meteorologic data temperaturerainfall etc at this point. Again, select PF3 profile with highest geobmsand click OK. All the cells in water surface grid that result in positive values after subtraction are converted to a polygon, which is the final flood inundation polygon.
Adjust the symbology of the Flow Accumulation layer Fac to a multiplicatively increasing scale geobms illustrate the increase of flow accumulation as one descends into the grid flow network.
HydroID is a unique number for a given feature in a geodatabase. These feature classes are added to the same geodatabase cedar.
To create the river centerline in River feature classstart editing, and choose Create New Feature as the Task, and River as the Geohmss as shown below: Certain guidelines must be followed in creating cross-section cutlines: When you come close to the junction, zoom-in, and you will notice that the tool will automatically try geobms snap or hug!
HEC-GeoRAS Export Error | GeoNet
Similar to Ineffective flow areas, the positions and elevations of the intersection of this obstruction with cross-sections needs to be stored in a table. Creating Bridges and Culverts After creating cross-sections, the next step is to define bridges, culverts and other structure along the river. We tuforial approximate the bridge width to about ft station todeck elevation as 84 ft high chord and 6ft deep low chord as shown below: Close tutodial attribute table, and save the map document.
If you expand the CedarCreek basin in watershed explorer, you will see the list of junctions, reaches and subbasins. Confirm that the input of the Flow Direction Grid is Fdr. As a result of this merging, we now have 12 sub-basins and 15 river segments in the project. This function populates the BasinLag field in gekhms subbasin feature class geogms numbers that represent basin lag time in hours. If cells with higher elevation surround a cell, the water is trapped in that cell and cannot flow.
Bank lines are used to distinguish the main channel from the overbank floodplain areas. This function creates a grid of stream segments that have a unique identification. ArcGIS uses an old algorytm that my be failing under certain conditions.
Click on Bridge Design buttonand enter the information as shown below:. Set the Agree parameters as shown. This will display the Cedar yec schematic. This function captures the geographic information x,y of the subbasin boundaries and stream alignments in a text file that can be read and displayed within HMS.
Step by Step: Flood Hazard Mapping
Another annoying fact is that GRASS uses proprietary raster and vector layer formats but those can be fairly easily exported to Shapefile or other spatial data types. Upon successful completion hecc the process, the polygon feature class Catchment is added to the map.
We are done with geometric data!