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v. 8.4WMS 8.4 TutorialModeling – Orange County Rational Method –GISLearn how to define a rational method hydrologic model for Orange County(California) from GIS dataObjectivesThis tutorial shows you how to define data for and run a rational method model for a watershed in OrangeCounty.Prerequisite Tutorials Watershed Modeling –Advanced DEM DelineationTechniquesRequired Components DataDrainageMapHydrologyHydrologic ModelsPage 1 of 14Time 30-45 minutes Aquaveo 2011

1Contents123456782Contents .2Introduction.2Automated Sub-area Delineation.33.1DEM Data .33.2Trimming the DEM.43.3Compute Flow Directions and Accumulations.43.4Add Concentration Point (Outlet) .53.5Delineate Sub-area (Basin).6Creating Multiple Models (Rational and Unit Hydrograph) .7Creating Additional Sub-areas .85.1Create Additional Concentration Points (Outlets).85.2Delineate Sub-areas (Basins).9Computing Loss Rates .106.1Add Land Use and Soil Type Coverages .106.2Add Land Use Data .106.3Add Soil Type Data.116.4Compute GIS Attributes.126.5View Results .13Getting a Background Image Using the TerraServer .13Data Catalog .138.1Open Background Image.138.2Get Data .14IntroductionWMS has many features and tools that will help you to get the most use out of digitalterrain and GIS data for delineating sub-areas and computing loss rates. This exercisedemonstrates how to use WMS to automate sub-area delineation with a Digital ElevationModel (DEM) for rational and unit hydrograph analyses and shows how to computeOrange County loss rates (Fm and Ybar) with soil type and land use GIS data. Refer tothe following chapters in the standard WMS tutorials for an in depth treatment of GISdata: Images (Volume 1 Chapter 2) Basic Feature Objects (Volume 1 Chapter 3) DEM Basics (Volume 1 Chapter 4) Advanced Feature Objects (Volume 1 Chapter 6) DEM Delineation (Volume 2 Chapter 1) Time of Concentration Calculations and Computing a Composite CN(Volume 2 Chapter 3)Page 2 of 14 Aquaveo 2011

WMS Tutorials3Watershed Modeling – Orange County Hydrology – Using GIS DataAutomated Sub-area Delineation3.1DEM Data1. Close all instances of WMS2. Open WMS3. Select File Open 4. Locate the folder C:\WMS80\tutorial\OrangeCounty\UnitHydro5. Open “LagunaBeach.asc” and “SanJuanCapistrano.asc”Figure 3-1: Preliminary DEM import information6. Select OK7. Select Edit Current Coordinates 8. Set Horizontal System to State Plane NAD 83 (US)9. Set Horizontal Units to Meters10. Set St. Plane Zone to California 6 – 040611. Set Vertical Units to MetersPage 3 of 14 Aquaveo 2011

WMS TutorialsWatershed Modeling – Orange County Hydrology – Using GIS Data12. Select OK3.2Trimming the DEMThe DEM often covers a much larger area than the user is really interested in. Todecrease the amount of computations required, it is often beneficial to “trim” the DEM.1. Switch to the Terrain Data module2. Select DEM Trim Polygon 3. Select Enter a polygon interactively4. Select OK5. Use the left mouse button to outline an area that approximates the rectangleshown in Figure 3-2 below. Double-click on the last corner to end thepolygon and trim the DEM.Figure 3-2: DEM trim area3.3Compute Flow Directions and Accumulations1. Select the Frame macro2. Switch to the Drainage module3. Select DEM Compute TOPAZ Flow Data 4. Select OK5. Set the Basin Areas units to Acres in the Parameters units section of thedialog (in order to specify the units to view upstream area of any DEMcell)6. Set the Distances units to FeetPage 4 of 14 Aquaveo 2011

WMS TutorialsWatershed Modeling – Orange County Hydrology – Using GIS DataFigure 3-3: Exhibited units7. Select OK8. Choose Close once TOPAZ finishes running (you may have to wait a fewseconds to a minute or so)9. Select Display Display Options 10. Select DEM Data and change Min Accumulation For Display to 5.0 acreson the DEM tab11. Select OK3.4Add Concentration Point (Outlet)1. Use the Zoom toolto zoom in to the rectangle shown in Figure 3-4Page 5 of 14 Aquaveo 2011

WMS TutorialsWatershed Modeling – Orange County Hydrology – Using GIS DataFigure 3-4: Zoom in to add concentration point2. Select the Create Outlet Point toolAs the cursor is moved over any DEM cell that has flow accumulation data, the totalupstream area is displayed in the bottom part of the screen. This feature helps you toplace concentration points at appropriate locations.3. Add a concentration point by clicking in or near a cell with the coordinates(1859845.18, 658073.87)4. Move the concentration point to the correct point by typing in thecoordinates in the Feature Point X and Y cells in the Properties window onthe right of the screen3.5Delineate Sub-area (Basin)1. Select DEM Delineate Basins Wizard2. Select OK3. Set Basin Areas to Acres in the Units dialogPage 6 of 14 Aquaveo 2011

WMS TutorialsWatershed Modeling – Orange County Hydrology – Using GIS DataNOTE: Set Basin Areas units to Square miles so that areas are computed in thecorrect units for a unit hydrograph (HEC-1) model or to Acres for a Rationalanalysis.4. Select OK5. Toggle off the display of the DEM in the Project Explorer6. Select the Frame macroThe sub-area (basin) will automatically be delineated and its area is displayed as shownin Figure 3-5.Figure 3-5: Delineated sub-area4Creating Multiple Models (Rational and Unit Hydrograph)If performing both Rational and Unit Hydrograph analyses on the same watershed, it maybe beneficial to create a second drainage coverage so that the Rational method can beperformed using one while the Unit Hydrograph method is performed using the other.The two hydrologic models require different parameters for analysis.1. Right-click on the Drainage coverage and select Duplicate2. Right-click on the Copy of Drainage coverage and select Rename3. Enter “Unit Hydro” for the coverage name4. In the Hydrologic Tree Data folder of the Project Explorer right-click onthe Copy of Drainage Coverage Tree and select RenamePage 7 of 14 Aquaveo 2011

WMS TutorialsWatershed Modeling – Orange County Hydrology – Using GIS Data5. Enter “Unit Hydro Tree”6. Switch to the Hydrologic Modeling module7. Select OC Hydrograph in the Model pull down menu at the top of thescreen8. In the Hydrologic Tree Data folder of the Project Explorer select theDrainage Coverage Tree to make it the active hydrologic tree9. Select OC Rational in the Model pull down menu at the top of the screen5Creating Additional Sub-areasWhen working with the rational method, the initial sub-area should be no more than 10acres and have a flow path less than 330 feet. Succeeding sub-areas will graduallyincrease in size until reaching the final concentration point. In order to create additionalsub-areas, the user merely needs to create the concentration points for each of the subareas and run the Delineate Basins Wizard.5.1Create Additional Concentration Points (Outlets)1. Toggle off the Unit Hydro coverage in the Project Explorer2. Select the Drainage coverage in the Project Explorer to make it active3. Zoom in to the rectangle shown in Figure 5-1Figure 5-1: Zoom to rectangle to add additional sub-areas4. Switch to the Drainage modulePage 8 of 14 Aquaveo 2011

WMS TutorialsWatershed Modeling – Orange County Hydrology – Using GIS Data5. Use the Create Outlet Point toolto add concentration points at or nearthe locations shown in Table 5-1 (remember that you can always add theconcentration point and enter the exact coordinates in the Propertieswindow on the right side of the screen):Table 5-1: Concentration 937.40Delineate Sub-areas (Basins)1. Select DEM Delineate Basins Wizard2. Select OK on the message to delete all existing feature data3. Select OK4. Select OK in the Units dialogFigure 5-2: Multiple sub-areasPage 9 of 14 Aquaveo 2011

WMS Tutorials6Watershed Modeling – Orange County Hydrology – Using GIS DataComputing Loss Rates6.1Add Land Use and Soil Type Coverages1. Select the Frame macro2. Right-click on the Coverages folder in the Project Explorer and select NewCoverage3. Change the Coverage type to Land Use4. Select OK5. Right-click on the Coverages folder in the Project Explorer again andselect New Coverage6. Change the Coverage type to Soil Type7. Select OK6.2Add Land Use DataLand use data can come from many different sources. It is possible to digitize polygonsrepresenting different land use types using a background image/map or an aerialphotograph. WMS also has tools for generating land use data from existing CAD data.1. Ensure that the Land Use coverage is the active coverage by selecting it inthe Project Explorer2. Switch to the GIS module3. Select Data Add Shapefile Data .4. Open “niguellanduse.shp”5. Select Mapping Shapes - Feature Objects6. Select Yes to use all shapes in all visible shapefiles for mapping7. Select Next Notice that the Level2 column is automatically mapped to the Level2 Mapping type andthat the LU CODE column is automatically mapped to the Land use Mapping type inWMS. This maps attributes in the shapefile database table to become attributes of thepolygons that will be generated as feature objects.8.Select Next 9. Select Finish10. Toggle off niguellanduse.shp in the Project Explorer11. Switch to the Map module12. Use the Select Feature Polygon toolpolygonsto select any one of the land use13. Select Feature Objects Attributes 14. Toggle on Percent impervious in the Display parameters sectionPage 10 of 14 Aquaveo 2011

WMS TutorialsWatershed Modeling – Orange County Hydrology – Using GIS DataThe Land use mapping dialog appears. This dialog shows the land use ID that wasmapped from the shapefile to the polygon, but there is no curve number or percentimpervious data for the land use IDs. Add this data by importing a land use table.15. For Import file type choose Orange County Land use file16. Click on the Import file button17. Select OK on the overwrite message18. Open “ocland.tbl”Notice that curve numbers and percent impervious values now exist for each land use ID.19. Select Close6.3Add Soil Type Data1. Make the Soil Type coverage the active coverage by selecting it in theProject Explorer2. Switch to the GIS module3. Select Data Add Shapefile Data 4. Open “Soilgroup Bdy.shp”The Soilgroup Bdy shapefile is a file that encompasses all of Orange County. Since weare only concerned with a small portion of the county, only a small section needs to beconverted to feature objects.5. Select the Select Shapes tool6. Use the mouse to drag a box that encompasses the area in question, whichappears grey within the box shown in Figure 6-1.Page 11 of 14 Aquaveo 2011

WMS TutorialsWatershed Modeling – Orange County Hydrology – Using GIS DataFigure 6-1: Selection for mapping soil type polygons7. Select Mapping Shapes - Feature Objects8. Select Next 9. In the Type column choose SCS soil type for Mapping10. Select Next 11. Select Finish12. Toggle off Soilgroup Bdy.shp in the Project Explorer6.4Compute GIS Attributes1. Select the Drainage coverage to make it active2. Switch to the Hydrologic Modeling module3. Select Calculators Compute GIS Attributes 4. Set Computation to Orange County Losses5. Verify that the Soil Type coverage will be used for determining soil typeand the Land Use coverage will be used for determining land use6. Select OK7. Accept the default filename for saving the GIS loss calculation details andselect SavePage 12 of 14 Aquaveo 2011

WMS Tutorials6.5Watershed Modeling – Orange County Hydrology – Using GIS DataView Results1. Select File Edit File 2. Open the file you just saved (ocgiscalcs.txt)3. Select OK to open the file with Notepad, if promptedThis file contains a listing of the area attributed to each combination of land use and soiltype within each sub-area.4. Close the file5. Toggle off the display of the Land Use and Soil Type coverages in theProject Explorer6. Select the Frame macro7. Use to Select Basin toolto select any one of the sub-basins8. Select OC Rational Edit Parameters The ap, Fp, and Fm values computed using GIS data are displayed in the Losses sectionof the dialog. Select any of the other sub-areas to view its Losses values.9. Select Done7Getting a Background Image Using the TerraServerSkip this section if you are not able to connect to the Internet using your computer.Using an Internet connection we will now download the topographic map image directlyfrom the TerraServer and open it in WMS.1. Select the Get Data tool2. Drag a box around the extents of the DEM to define the region of theimage3. Toggle on the TerraServer topo option4. Select OK to start the downloading process5. Enter “oc.jpg” and click Save6. Accept the suggested resolution by selecting OK. It may take 30 secondsto one minute to complete the downloading process.8Data CatalogThe remaining sections are to be completed only if the Orange County data files areaccessible.8.1Open Background Image1. Select File New2. Select No if prompted to save changes to the projectPage 13 of 14 Aquaveo 2011

WMS TutorialsWatershed Modeling – Orange County Hydrology – Using GIS Data3. Select File Open 4. Open “OCMap.tif”8.2Get Data1. Select the Get Data tool2. Drag a box over a location on the map in Orange County3. Choose the Catalog option4. Click on the Browse button5. Open “OCCatalog.txt”6. Toggle on DEM Data7. Change Resolution to 10 Meter8. Toggle on Image – Topo9. Toggle on Shapefile – Soil Type10. Select OKSelect OK to read in DEMsPage 14 of 14 Aquaveo 2011

Model (DEM) for rational and unit hydrograph analyses and shows how to compute Orange County loss rates (Fm and Ybar) with soil type and land use GIS data. Refer to the following chapters in the standard WMS tutorials for an in depth treatment of GIS data: Images (Volume 1 Chapter 2) Basic Feature Objects (Volume 1 Chapter 3)