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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This finishes the processing of spatial data for creating the curve number grid. Arc Hydro toolbar also provides an extensive set of tools for delineating watersheds and subwatersheds.

The area with positive results meaning water surface is higher than the terrain is flood area, and the area with negative results is dry. This function creates a grid of stream segments that have a unique identification. You can check the RiverLen field in the input River1 or whatever name you have for your input river feature class is populated. A new map data frame with the analysis name Steady Flow will be added to ArcMap with the terrain data.

The intersection of cutlines with other RAS layers such as centerline and flow path lines are used to compute HEC-RAS attributes such as bank stations locations that separate main channel from the floodplaindownstream reach lengths distance between crosssections and Mannings number. For this exercise, we will create three hypothetical profiles. Bank lines are used to distinguish the main channel from the overbank floodplain areas.

This can be done using the cross-sections profile tool. You can also open the. So create a field named LandUse type: If you click at a point along the profile, a corresponding point showing its location on the river reach will be added to the map display shown below as red dot.


Both are Integer type you can check the field properties of BatchPoint. Open the attribute table of Catchment. Click Yes on the message box. All of the preprocessing must be completed before Watershed Processing functions can be used.

The Muskingum method is added to RouteMet field in the River feature class.

Drainage Line Polygons file name: Generally these many points are not required, and also when we extract cross-sections from a terrain using HEC-GeoRAS, we get a lot of redundant points. Therefore, creating adequate number of cross-sections to produce a good representation of channel bed and floodplain is critical.

The next step is to enter flow data. With the attribute table open, right click on SoilCode field to open the field calculator and then equate SoilCode to component. Each line in the feature class carries the identifier of the catchment in which it resides. Select the options shown above. The output is the Catchment Grid layer.

HEC-GeoRAS Export Error | GeoNet

Check Data This tool will verify all the input datasets. We will use this to locate the outlet of the watershed. Click on the Flow Path.

To create the left and right flow paths in Flowpaths feature classstart editing, and choose Create New Feature as the Task, and Flowpaths as the Target as shown gwohms.

By using our site, you acknowledge that you have read and understand our Cookie PolicyPrivacy Policyand our Terms of Service. Each catchment also has its Length and Area attributes. In addition to these datasets, go ahead and ehc get the slope grid by using the Arc Hydro Toolbar. In the next window, provide the following inputs:. Digitize banks for all three reaches and save the edits and the map document. DEM reconditioning involves modifying the elevation data tutoriql be more consistent with the input vector stream network.


Help inserting CN Grid in HEC-GeoHMS | GeoNet

All other cells in the Stream Grid contain no data. Towards the end of the section 6. Follow the above guidelines and digitize cross-sections using the sketch tool. The Fill Sinks function modifies the elevation value to eliminate these problems. After the computations are complete, the BasinSlope field in the input Subbasin feature class is populated.

Cedar creek basin and enters St.

For geeohms tutorial we will run the model in steady state condition. Save your HMS project. The function needs as input a raw DEM and a linear feature class like the river network that both have to be present in the map document.

Step by Step: Flood Hazard Mapping

Save the map document. Upon successful completion of the process, the Fil layer is added to the map. The bridge should now look similar to the figure shown below: If you face problems in creating Project Tutoial, just delineate a watershed using the point delineation tool in Arc Hydro for the Project Point feature, and load this watershed polygon into ProjectArea feature class.