George Mason University Department of Civil, Environmental and Infrastructure Engineering Dr. Celso Ferreira Prepared by Lora Baumgartner December 2015 Revised by Brian Ross July 2016 Exercise Topic: Getting started with HEC-GeoHMS Objectives: Create a HEC-HMS model of the George Mason University watershed using the GeoHMS toolbar in ArcMap. a) Terrain Preprocessing b) Generating a GeoHMS Project c) Basin Processing d) HMS Parameters e) HMS Export f) Running HMS Challenges: a) Find an appropriate CN table for the region and prepare a more elaborated land cover re-classification of the NLCD and create a CN look up table. Repeat your analyses. How does that impact your design hydrograph? b) After opening the GeoHMS file in HEC-HMS, what information is missing? Complete HMS set-up in order to run it. Change Metl model to a SCS storm and use Fairfax County IDF curves to estimate a 100 yr design storm. Run HMS and plot the final hydrograph. **Refer to the HEC-GeoHMS User Manual for definitions and context of the steps and tools in this tutorial, currently found at http://www.hec.usace.army.mil/software/hec-geohms/documentation/hec-geohms_users_manual_4.2.pdf** Tutorial DEM obtained from GMU Campus Lidar file (provided) Versions used for this tutorial: HEC-GeoHMS 10.2, ArcMap 10.2.2 (Student), ArcCatalog 10.2.2 1
Prepare Project Workspace 1. Enable the Hec-GeoHMS toolbar under the Customize > Toolbars menu in ArcMap. 2. Select Add Data under the File > Add Data menu. 2
3. Locate the folder location of the GMU Campus Lidar DEM. 4. Select the GMU DEM. 5. Click Add. 6. If ArcMap suggests pyramidbuilding at this point, click Yes. 7. Select Add Data under the File > Add Data menu. 3
8. Select Topographic or other preferred base map. 9. Click Add. 10. Disable the DEM layer to fully view the basemap. 11. Zoom to the campus area, leaving a generous border around the campus perimeter. 4
12. Select Data Frame Properties from the View menu. 13. Near the bottom of the dialog box, select Clip to shape from the Clip options drop-down menu. 14. Click Specify Shape. 15. Confirm that the Current Visible Extent radio button is selected. 16. Click OK. On the Data Frame Clipping dialog box. 17. Click OK to clip all data layers (DEM and basemap) to the applicable geographic area. Clipping the data layers limits the amount of data in the project and speeds processing. However, be sure that the extents of the watershed are completely included after clipping. 18. Save As to save the new project. 5
Terrain Preprocessing These Terrain Preprocessing steps correlate with the Spatial Analyst-Hydrology functions performed in the ArcGIS tutorial. 1. Select Fill Sinks from the Preprocessing menu on the HEC- GeoHMS toolbar in ArcMap. 2. Confirm that the Input DEM field was auto-filled with the correct raw GMU DEM file. 3. Confirm that the output location is correct and note the name of the new layer. GeoHMS will auto-generate layer names for each preprocessing step. The layer names can be changed, but customized names will not be recognized in future GeoHMS steps and will require manual entry. For this tutorial, do not change the default (auto-generated) layer output names. 4. Click OK. 5. Observe visual changes to the model and click Close. 6
1. Select Flow Direction from the Preprocessing menu on the HEC- GeoHMS toolbar in ArcMap. 2. Confirm that the Input Hydro DEM field was auto-filled with the new Filled DEM layer. 6. Confirm that the output location is correct and note the name of the new layer. 3. Click OK to generate the new layer. 4. Observe visual changes to the model and click Close. 7
1. Select Flow Accumulation from the Preprocessing menu on the HEC-GeoHMS toolbar in ArcMap. 2. Confirm that the Input Flow Direction Grid field was auto-filled with the new Flow Direction layer. 7. Confirm that the output location is correct and note the name of the new layer. 3. Click OK to generate the new layer. 4. Observe visual changes to the model and click Close. 8
1. Select Stream Definition from the Preprocessing menu on the HEC- GeoHMS toolbar in ArcMap. 2. Confirm that the Input Flow Accumulation Grid field was autofilled with the new Flow Accumulation layer. 3. Confirm that the output location is correct and note the name of the new layer. 4. Click OK to generate the new layer. 5. Observe visual changes to the model and click Close. 9
1. Select Stream Segmentation from the Preprocessing menu on the HEC-GeoHMS toolbar in ArcMap. 2. Confirm that the Input Stream Grid field was auto-filled with the new Stream Definition layer. 3. Confirm that the output location is correct and note the name of the new layer. 4. Click OK to generate the new layer. 5. Observe any changes to the model and click Close. 10
1. Select Catchment Grid Delineation from the Preprocessing menu on the HEC- GeoHMS toolbar in ArcMap. 2. Confirm that the Input Flow Direction Grid field was auto-filled with the correct layer. Confirm that the Input Link Grid field was auto-filled with the New Stream Segmentation layer. 3. Confirm that the output location is correct and note the name of the new layer. 4. Click OK to generate the new layer. 5. Observe visual changes to the model and click Close. 11
1. Select Catchment Polygon Processing from the Preprocessing menu on the HEC-GeoHMS toolbar in ArcMap. 2. Confirm that the Input Catchment Grid field was auto-filled with the new Catchment Delineation layer. 3. Confirm that the output location is correct and note the name of the new layer. 4. Click OK to generate the new layer. 5. Observe visual changes to the model and click Close. 12
1. Select Drainage Line Processing from the Preprocessing menu on the HEC-GeoHMS toolbar in ArcMap. 2. Confirm that the Input Stream Link Grid field was auto-filled with the new Stream Segementation layer. Confirm that the Input Flow Direction Grid field was auto-filled with the correct layer. 3. Confirm that the output location is correct and note the name of the new layer. 4. Click OK to generate the new layer. 5. Observe any changes to the model and click Close. 13
1. Select Adjoint Catchment Processing from the Preprocessing menu on the HEC-GeoHMS toolbar in ArcMap. 2. Confirm that the Input Drainage Line field was auto-filled with the new Drainage Line layer. Confirm that the Input Catchment field was auto-filled with the correct layer. 3. Confirm that the output location is correct and note the name of the new layer. 4. Click OK to generate the new layer. 5. Observe visual changes to the model and click Close. 14
When viewed in ArcCatalog, the project should appear similar to the image at right. 15
Generate a New Project 1. Select Data Management from the Project Setup menu on the GeoHMS toolbar in ArcMap. 2. Validate that all fields are autofilled properly. Pay particular attention to the Raw DEM field, which should be populated by the original GMU Lidar DEM. 3. Click OK. 4. Select Start New Project from the Project Setup menu. 5. Note the names of the new Project Area and Point; click OK. 16
6. Assign a Project Name and Project Description. 7. Confirm the save location. 8. Click Okay. 9. Review the steps listed in the dialog box and click OK. 10. On the left sidebar table of contents, uncheck all layer except for Drainage Line and Basemap. 17
11. Zoom in to the main campus outlet point just above Braddock Rd. A scale of 1:15 is recommended to provide optimum accuracy.. 12. Click the Pushpin ( Add Project Point ) icon on the GeoHMS toolbar. 18
13. Hover directly over the drainage line and click to place the outlet point exactly on the stream. 14. Note the name and description of the new Project Point and click OK. 15. Select Generate Project from the Project Setup menu. 16. When the Project has been generated, review the watershed area and click Yes. 19
17. Review the layers assigned to each field for the project. Make any corrections, again paying special attention to the raw DEM. 18. Click OK. 6. Observe visual changes to the model and click Close. 20
Prepare Slope Grid in ArcMap This layer is a required input for additional GeoHMS processing. 1. At the top of the ArcMap screen, select ArcToolbox from the Geoprocessing menu. 2. Select Slope from the Spatial Analyst > Surface menu. 3. Select the Filled DEM layer for the GeoHMS project. 4. Click Add. 21
5. Confirm that the output location is correct and note the name of the new layer. 6. Click OK. 7. Observe visual changes to the model and click Close. 22
Basin Processing 1. Select Data Management from the Basin Processing menu. 2. Confirm that all field were autofilled properly and make any corrections. 3. Click OK. 4. Zoom to the section of the basin nearest the outlet. 23
5. Click the Select Features icon from the main toolbar. 6. Select the border of the truncated basin. 7. Select the border of the neighboring large basin. *Both basins should be highlighted. Multiple attempts may be required. 24
8. Select Basin Merge from the Basin Processing menu. 9. Confirm that the crosshatched areas match the basins to be merge. Click OK. 25
Identify River and Subbasin Characteristics 1. Select Data Management from the Characteristics drop-down menu on the GeoHMS toolbar. 2. Confirm that all field were autofilled properly and make any corrections. 3. Click OK. 26
1. Select River Length from the Characteristics drop-down menu. 2. Input the new River layer. 3. Click OK. 4. Click Close. 5. To view the output of the River Length tool, right click on the River layer in the left sidebar and select Open Attribute Table. Note that a column named RivLen has been added. 27
1. Select River Slope from the Characteristics drop-down menu. 2. Input the RawDEM (original GMU Lidar DEM) and the River layers. 3. Click OK. 4. Click Close. 5. If there is an error due to a background exception, select Geoprocessing Options under the geoprocessing tab. Disable background processing by unchecking the enable box. Then, retry the river slope. 6. To view the output of the River Length tool, right click on the River layer in the left sidebar and select Open Attribute Table. Note that a column named Slp has been added. 28
1. Select Basin Slope from the Characteristics drop-down menu. 2. Input the Slope layers that was generated at the beginning of this section. Input the Subbasin layer. 3. Click OK. 4. Click Close. 5. To view the output of the Basin Slope tool, right click on the Subbasin layer in the left sidebar and select Open Attribute Table. Note that a column named BasinSlope has been added. 29
1. Select Longest Flowpath from the Characteristics drop-down menu. 2. Input the RawDEM (original GMU Lidar DEM) and the Flow Direction layers. 3. Click OK. 4. Click Close. 30
1. Select Basin Centroid from the Characteristics drop-down menu. 2. Confirm that the Center of Gravity method and the Subbasin layer are selected. 3. Click OK. 4. Note that centroid asterisks have been added to the project. Click Close. 31
1. Select Centroid Elevation from the Characteristics drop-down menu. 2. Input the Raw DEM (original GMU Lidar DEM) and the Centroid layers. 3. Click OK. 4. Click Close. 5. To view the output of the Centroid Elevation tool, right click on the Centroid layer in the left sidebar and select Open Attribute Table. Note that a column named Elevation has been added. 32
1. Select Centroidal Longest Flowpath from the Characteristics drop-down menu. 2. Confirm that the Subbasin, Centroid, and Longest Flowpath layer are selected. 3. Click OK. 4. Click Close. 33
1. Select Data Management from the Parameters drop-down menu. 2. Confirm that the auto-filled fields contain the correct layers. Several layers have not yet been generated and the associated fields will contain null values. 3. Click OK. 34
1. Select Select HMS Processes from the Parameters drop-down menu. 2. Input the Subbasin River layers. 3. Choose SCS from the Subbasin Loss Method drop-down menu. 4. Choose SCS from the Subbasin Transform Method drop-down menu. 5. Choose None from the Subbasin Baseflow Method. 6. Choose Muskingum from the River Route Method drop-down menu. 7. Click OK. 8. Click Close. 9. To view the output of the Select HMS Processes tool for the Subbasin and River, right click on the Subbasin and River layers in the left sidebar and select Open Attribute Table for each. Note that columns have been added for the outputs of steps 3 through 6 above. 35
1. Select River Auto Name from the Parameters drop-down menu. 2. Input the River layer. 3. Click OK. 4. Click Close. 5. To view the output of the River Auto Name tool, right click on the River layer in the left sidebar and select Open Attribute Table. Note that a column has been added for the output of the Auto Name tool. 36
1. Select Basin Auto Name from the Parameters drop-down menu. 2. Input the Subbasin layer. 3. Click OK. 4. Click Close. 5. To view the output of the Basin Auto Name tool, right click on the Basin layer in the left sidebar and select Open Attribute Table. Note that a column has been added for the output of the Auto Name tool. 37
1. Add the provided curve number grid to the project by selecting it in the File > Add Data menu. 2. Click Add. 3. Select Subbasin Parameters from Raster from the Parameters dropdown menu. 4. Input the Subbasin layer. 5. Input the Curve Number Grid. 6. Click OK. 38
7. Click Close. 8. To view the output of the Subbasin Parameters from Raster tool, right click on the Subbasin layer in the left sidebar and select Open Attribute Table. Note that a column has been added for the output of steps 3 through 6 above. 39
1. Select CN Lag from the Parameters drop-down menu. 2. Click OK. 3. To view the output of the CN Lag tool, right click on the Subbasin layer in the left sidebar and select Open Attribute Table. Note that a column has been added for the output of steps 1 through 3 above. 40
1. Select Data Management from the HMS drop-down menu. 2. Confirm that all fields have been auto-filled with the proper layers. 3. Click OK. 41
1. Select Map to HMS Units from the HMS drop-down menu. 2. Confirm that all fields have been auto-filled with the proper layers. 3. Click OK. 4. Select English units. 5. Click OK. 42
1. Select Check Data from the HMS drop-down menu. 2. Confirm that all fields have been auto-filled with the proper layers. 3. Click OK. 4. If data problems are found, click Yes to view. 5. It is common for a project point error to be generated. 6. Zoom to the project point (outlet) area. If the project point can be confirmed to lie directly on the River, disregard the Check Data Error. 43
1. Select HMS Schematic from the HMS drop-down menu. 2. Confirm that all fields have been auto-filled with the proper layers. 3. Click OK. 4. Note that new visual representations have been added. 5. Click OK. 44
1. Select HMS Legend from the HMS > Toggle Legend drop-down menu. 2. Note that HMS icons are shown. 45
1. Select Add Coordinates from the HMS drop-down menu. 2. Confirm that all fields have been auto-filled with the proper layers. 3. Click OK. 4. Click OK to accept 2-dimensional units. 5. Click OK. 46
1. Select Prepare Data for Model Export from the HMS drop-down menu. 2. Confirm that all fields have been auto-filled with the proper layers. 3. Click OK. 4. Click OK to accept 2-dimensional units. 5. Click OK. 47
1. Select Background Shape File from the HMS drop-down menu. 2. Confirm that all fields have been auto-filled with the proper layers. 3. Click OK. 4. Click OK. 48
1. Select Basin Model File from the HMS drop-down menu. 2. Note the name and location of the HMS model. 3. Click OK. 49
1. Select Specified Hyetograph from the HMS > Met Model File dropdown menu. 2. Confirm that all fields have been auto-filled with the proper layers. 3. Click OK. 4. Click OK. 50
1. Select Create HEC-HMS Project from the HMS drop-down menu. 2. Select the proper file location and file names of the newly-created basin and met models. 3. Name the Simulation Run 1. 4. Select 5-minute Time Intervals. 5. Click OK. 6. Confirm that all functions were successful. 7. Click OK. Refer to the HEC-HMS tutorial for context of the project components being created during steps 1 through 5. 51