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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If you have an existing shapefile or feature class with a set of geoyms that you would like to use instead of interactively creating points, you can do so by using the following guidelines:. We will use this to locate the outlet of the watershed.

We are modifying the editing environment because when we digitize the Tule tributary we want its downstream end coincide with the downstream end of the upper Baxter Reach. We will not split any river segments in this exercise. The flowpath lines are used to determine the downstream reach lengths between cross-sections in the main channel and over bank areas. You can click on any reach and see its associated methods.

Step by Step: Flood Hazard Mapping

Create a new empty map, and save it as cngrid. Obstructions represent blocked flow areas areas with no water and no flow. Click OK, and a polygon feature class named AdjointCatchment is added to the map. Flow Direction Grid This function computes the flow direction for a given grid. Prepare Data for Model Export. Click on the outlet grid cell at the watershed outlet as shown below:.


Help inserting CN Grid in HEC-GeoHMS | GeoNet

Click with your mouse at any point to determine the flow path. BegElev and EndElev are the elevations of the first and last intersecting points of the ineffective area with the crosssection. You may get a message asking you to index fields.

Email Required, but never shown. You can use the tools in Geometric editor to perform the quality check.

HEc Geo HMS | GeoNet

You will see the reach will get selected, invoking the following window: You should get a message after the data check saying the check data is completed successfully as shown below. The cross-section cutlines are 2D lines with no elevation information associated with them Polyline.

You can use this option to trace the flow path the path along which water will flow to the outlet for any point in the watershed.

Catchment Grid file name: Since all these attributes are based on the intersection of cross-sections with other layers, make sure each cross-section intersects with tutorual centerline and overbank flow paths to avoid error messages.

AdjointCatchment Save the map document. Give some name for the Run, and leave the geoh,s information for time and time interval unchanged. For merging basins, we follow the process that allow us to merges two or more adjacent basins into one.

Choose the lookup parameter as Curve Number which is default in the next window, Click OK, feohms then select the inputs for the next window as shown below:. You can also play with the contributing area tool to find out contributing area at different points in the cedar creek stream network.


Notice that each catchment has a HydroID assigned that is the unique identifier of each catchment within Arc Hydro.

Upon successful completion of the process, the flow accumulation grid Fac is added to the map. Expand the Basin Models folder and click on CedarCreek.

The resulting attribute table should look like below: Since we ran the model with three profiles, we can choose which profile we would like to export. Click Yes on the message box. Upon successful completion of the process, the polygon feature class Catchment is added to the map. Another annoying fact is that GRASS uses proprietary raster and gutorial layer formats but those can be fairly easily exported to Shapefile or other spatial data types.

The flow path defines the path of flow from the selected point to the outlet of the catchment following the steepest descent. Flow Accumulation Grid This function computes the flow accumulation grid that contains the accumulated number of cells upstream of a cell, for each cell in the input grid.