George Mason University Department of Civil, Environmental and Infrastructure Engineering

Transcription

1 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: GIS and Water Resources Engineering (ArcGIS Spatial Analyst) Objective: Delineate GMU Watershed using ArcGIS Spatial Analyst-Hydrology Tools Challenges: a) Set up a model builder model to automate your analyses b) Compare and contrast the results from the three resolutions (1 arc-second, 1/3 arc-second, 1/9 arc-second) in terms of computational time and precision c) Compare and contrast the results from multiple Stream Network thresholds (500, 1000, 5000, 10000). **Refer to the ArcGIS Resource Center for definitions and context of the steps and tools in this tutorial, currently found at Tutorial DEM obtained from GMU Campus Lidar file (provided) Versions used for this tutorial: ArcMap (Student), ArcCatalog

2 Part 1: Prepare Project Prepare Arc Catalog 1. Open ArcCatalog. Click the icon labeled Connect To Folder. 2. Select the preferred file folder location for ArcGIS project components. The default Geodatabase location is not recommended. The campus DEM file and all project data should be saved to a separate file location. 3. Click Okay. 4. Note that ArcCatalog is now showing the GMU Campus DEM file. The associated folder must be selected in the Catalog Tree window. Press F5 throughout the project to refresh ArcCatalog. 2

3 5. Under the File Menu, hover over the New drop-down menu. 6. Select File Database. 7. Specify the preferred name for the new File Database. The File Database ( GDB ) will hold ArcMap components. 3

4 Create New Project 1. Open ArcMap. Select Blank Map from the New Maps menu. 2. Set the Default Geodatabase as the newly-created GDB from the previous section of this tutorial. 3. Click OK. 4. Select Extensions from the Customize menu on the top toolbar. 5. Enable (checkmark) all extensions. 6. Click Close. Extensions enable specific analytical functionality within ArcMap. 4

5 7. Select ArcToolbox from the Geoprocessing menu on the top toolbar. 8. Note the ArcToolbox menu in the right sidebar. This tutorial will focus on Spatial Analyst Tools > Hydrology. 5

6 Create Project 1. Select Save As from the File menu on the top toolbar. 2. Select the preferred file folder location. 3. Specify the preferred project name. 4. Click Save. 6

7 Add Data 1. Select Add Data from the File menu. 2. Locate the file location of the previously-downloaded GMU Campus DEM. 3. Select the GMU Campus DEM file. 4. Click Add. 5. Note that a DEM Layer has been added in the Table of Contents window on the left sidebar. 7

8 6. Select Add Basemap from File > Add Data. 7. Select the preferred map. Topographic is recommended for this tutorial. 8. Click Add. 8

9 9. Note that a Basemap Layer has been added in the Table of Contents window on the left sidebar. The basemap provides helpful visual context for the DEM. However, graphical rendering of the basemap can slow computations and rendering of later graphics. Any layer can be hidden by unchecking the box next to the layer title. Any layer can be removed from the ArcMap project by right-clicking on the Layer name. Removing a layer in ArcMap does not delete the layer from the project. The layer is still filed with the project in ArcCatalog. 9

10 Part 2: Terrain Preprocessing Fill Sinks 1. Double-click Fill from the ArcToolbox > Spatial Analyst > Hydrology menu. 2. Click on the file folder icon to the right of the Input Surface Raster field. 3. Locate the file folder containing the GMU Campus DEM. 4. Select the GMU Campus DEM file. 5. Click Add. 6. Click Okay to create the Fill Sinks layer. 10

11 7. Note that a Filled-DEM Layer has been added in the Table of Contents window on the left sidebar. No change will be rendered to the DEM graphic. 11

12 Flow Direction 1. Double-click Flow Direction from the ArcToolbox > Spatial Analyst > Hydrology menu. 2. Click on the file folder icon to the right of the Input Surface Raster field. 3. Navigate to the project file database that was created earlier in this tutorial. 4. Select the Filled-DEM file. 5. Click Add. 6. Click Okay to create the Flow Direction layer. 12

13 7. Note that a Flow Direction Layer has been added in the Table of Contents window on the left sidebar. 13

14 Flow Accumulation 1. Double-click Flow Accumulation from the ArcToolbox > Spatial Analyst > Hydrology menu. 2. Click on the file folder icon to the right of the Input Flow Direction Raster field. 3. Navigate to the project file database that was created earlier in this tutorial. 4. Select the Flow Direction file. 5. Click Add. 6. Click Okay to create the Flow Accumulation layer. 14

15 7. Note that a Flow Accumulation Layer has been added in the Table of Contents window on the left sidebar. 15

16 Extract Stream Network 1. Double-click Raster Calculator from the ArcToolbox > Spatial Analyst > Map Algebra menu. 2. Click Con in the right window. 3. Click the Flow Accumulation Layer in the left window. 4. Add the threshold for stream delineation. The recommended threshold for this tutorial is 50, Click Okay to create the Stream Extraction (Raster Calculator) Layer. 6. To improve the visual representation of the Stream Network, right-click on the Stream Extraction (Raster Calculator) Layer. 7. Select Properties. 16

17 8. Select the tab labeled Display. 9. Select Majority (for discrete data) from the Resample dropdown menu. 10. Select the tab labeled Symbology. 11. Right-click the Color Block to the left of the Select the preferred color for Streams. 13. Click Okay. 17

18 14. To show the stream network, enable the Basemap and Raster Calculator layers and disable all other layers. 18

19 Stream Link 1. Double-click Stream Link from the ArcToolbox > Spatial Analyst > Hydrology menu. 2. Click on the file folder icon to the right of the Input Stream Raster field. 3. Navigate to the project file database that was created earlier in this tutorial. 4. Select the Raster Calculator (Stream Network) file. 5. Click Add. 19

20 6. Click on the file folder icon to the right of the Input Flow Direction Raster field Navigate to the project file database that was created earlier in this tutorial. 8. Select the Flow Direction file. 9. Click Add. 10. Click Okay to create the Stream Link layer. 11. Repeat steps 6 through 9 of the previous task ( Extract Stream Network ) to improve the visual representation of the stream links. 20

21 13. Note that a Stream Link Layer has been added in the Table of Contents window on the left sidebar. 21

22 Stream Order 1. Double-click Stream Order from the ArcToolbox > Spatial Analyst > Hydrology menu. 2. Click on the file folder icon to the right of the Input Stream Raster field. 3. Navigate to the project file database that was created earlier in this tutorial. 4. Select the Raster Calculator (Stream Network) file. 5. Click Add. 22

23 6. Click on the file folder icon to the right of the Input Flow Direction Raster field. 7. Navigate to the project file database that was created earlier in this tutorial. 8. Select the Flow Direction file. 9. Click Add. 10. Click Okay to create the Stream Order layer. 11. Repeat steps 6 through 13 of the previous task ( Extract Stream Network ) to improve the visual representation of the stream links. 23

24 12. Note that a Stream Link Layer has been added in the Table of Contents window on the left sidebar. 24

25 Stream to Feature 1. Double-click Stream to Feature from the ArcToolbox > Spatial Analyst > Hydrology menu. 2. Click on the file folder icon to the right of the Input Stream Raster field. 3. Navigate to the project file database that was created earlier in this tutorial. 4. Select the Raster Calculator (Stream Network) file. 5. Click Add. 25

26 6. Click on the file folder icon to the right of the Input Flow Direction Raster field. 7. Navigate to the project file database that was created earlier in this tutorial. 8. Select the Flow Direction file. 9. Click Add. 10. Click Okay to create the Stream Order layer. 26

27 11. Note that a Stream Link Layer has been added in the Table of Contents window on the left sidebar. 27

28 Flow Length 1. Double-click Flow Length from the ArcToolbox > Spatial Analyst > Hydrology menu. 2. Click on the file folder icon to the right of the Input Flow Direction Raster field. 3. Navigate to the project file database that was created earlier in this tutorial. 4. Select the Flow Direction file. 5. Click Add. 6. Click Okay to create the Flow Accumulation layer. 28

29 7. Note that a Flow Length Layer has been added in the Table of Contents window on the left sidebar. 29

30 Identify Basins 1. Double-click Basin from the ArcToolbox > Spatial Analyst > Hydrology menu. 2. Click on the file folder icon to the right of the Input Flow Direction Raster field. 3. Navigate to the project file database that was created earlier in this tutorial. 4. Select the Flow Direction file. 5. Click Add. 6. Click Okay to create the Flow Accumulation layer. 30

31 7. Right-click on the new Basin Layer and select Properties. 8. Select the tab labeled Display. 9. Set the transparency to 50%. 10. Click Okay. 31

32 11. Note the new Basin Layer overlaid on the Base Map. 32

33 Create Watershed Outlet (Point Feature) 1. In ArcCatalog, select Shapefile from File > New. 2. Specify a name for the new outlet Point. 3. Confirm that the Feature Type is Point in the drop-down menu. 4. Click Edit to assign a coordinate system to the new Point. 33

34 5. Click the plus sign next to Projected Coordinate Systems. 6. Click the plus sign next to State Plane. 7. Click the plus sign next to NAD 1983 (US Feet). 8. Select NAD 1983 StatePlane Virginia North FIPS (US Feed). 9. Click Okay. 34

35 10. Click Okay on the Create New Shapefile window. 11. In ArcMap, select Add Data from File > Add Data. 12. Select the new outlet Point. 13. Click Okay. 35

36 14. Right-click the outlet Point and select Start Editing from the Edit Features menu. 15. If a warning about spatial references is shown, check the box indicating that work can continue. 16. Click Continue. 36

37 17. Zoom in on the Braddock Road outlet point on the map, as shown to the right. A scale of approximately 1:35 is recommended for this step to ensure optimal accuracy. 18. Click the Point in the Create Features work menu at the right of the screen. 37

38 19. Place the outlet Point at the campus outlet, as shown to the right. 20. Click Stop Editing from the Editor Toolbar. 38

39 Identify Watershed 1. Double-click Watershed from the ArcToolbox > Spatial Analyst > Hydrology menu. 2. Click on the file folder icon to the right of the Input Flow Direction Raster field. 3. Navigate to the project file database that was created earlier in this tutorial. 4. Select the Flow Direction file. 5. Click Add. 39

40 6. Click on the file folder icon to the right of the Input Flow Direction Raster field. 7. Navigate to the project file database that was created earlier in this tutorial. 8. Select the Flow Direction file. 9. Click Add. 10. Click Okay to create the Stream Order layer. 40

41 11. Note that the new Watershed Layer has been created. If watershed is not visible, the Outlet (Point) may not be placed accurately. Enable the Stream Link Layer and zoom in to approximately 1:35 scale on the Point. If the Point Feature is not placed directly in the stream line, repeat steps 14 through 20 in the Create Watershed Outlet task. Repeat the Create Watershed task (this section). 41