Docsity
Docsity

Prepare for your exams
Prepare for your exams

Study with the several resources on Docsity


Earn points to download
Earn points to download

Earn points by helping other students or get them with a premium plan


Guidelines and tips
Guidelines and tips

watershed modelling using wms, Thesis of Ecosystem Modelling

modelling of watershed using WMS

Typology: Thesis

2016/2017

Uploaded on 12/10/2017

meenakshi-verma
meenakshi-verma 🇮🇳

1 document

1 / 14

Toggle sidebar

This page cannot be seen from the preview

Don't miss anything!

bg1
Page 1 of 14 © Aquaveo 2016
WMS 10.1 Tutorial
Watershed Modeling DEM Delineation
Learn how to delineate a watershed using the hydrologic modeling wizard
Objectives
Read a digital elevation model, compute flow directions, and delineate a watershed and sub-basins using
outlet points.
Prerequisite Tutorials
Introduction Images
Introduction Basic Feature
Objects
Editing Elevations DEM
Basics
Required Components
Data
Drainage
Map
Time
30-60 minutes
v. 10.1
pf3
pf4
pf5
pf8
pf9
pfa
pfd
pfe

Partial preview of the text

Download watershed modelling using wms and more Thesis Ecosystem Modelling in PDF only on Docsity!

WMS 10.1 Tutorial

Watershed Modeling – DEM Delineation

Learn how to delineate a watershed using the hydrologic modeling wizard

Objectives

Read a digital elevation model, compute flow directions, and delineate a watershed and sub-basins using outlet points.

Prerequisite Tutorials

 Introduction – Images  Introduction – Basic Feature Objects  Editing Elevations – DEM Basics

Required Components

 Data  Drainage  Map

Time

 30-60 minutes

v. 10.

1 Introduction ......................................................................................................................... 2 2 Objectives ............................................................................................................................. 2 3 Setting up a Project with the Hydrologic Modeling Wizard ........................................... 2 3.1 Starting the Hydrologic Modeling Wizard ................................................................... 2 3.2 Project Filename ........................................................................................................... 3 3.3 Define Project Bounds ................................................................................................. 3 3.4 Watershed Data using Web Services ............................................................................ 4 3.5 Watershed Data by Reading Files ................................................................................ 6 3.6 Trimming the DEM ...................................................................................................... 6 3.7 DEM Fill Command ..................................................................................................... 7 4 Watershed Delineation using the Hydrologic Modeling Wizard .................................... 8 4.1 Compute Flow Directions and Accumulations ............................................................. 8 4.2 Choose Outlet Locations .............................................................................................. 9 4.3 Create Sub-basins ....................................................................................................... 10 4.4 Save the WMS Project File ........................................................................................ 12 5 Delineation Display Options ............................................................................................. 12 5.1 Display Flow Paths .................................................................................................... 12 5.2 Basin Labels ............................................................................................................... 13 5.3 Display Options .......................................................................................................... 13 5.4 Color Fill Basins ........................................................................................................ 13 6 Conclusion.......................................................................................................................... 13

1 Introduction

Watershed delineation from DEMs is straightforward and relatively simple, provided the project area is not entirely flat or completely dominated by man-made structures. The DEM method does not work if there is no relief in the DEM elevations. This exercise teaches DEM delineation using the hydrologic modeling wizard, a step-by-step delineation approach that makes the process even simpler.

2 Objectives

In this exercise, the basics of DEM delineation are explained using the hydrologic modeling wizard. This includes the following:

  1. Importing DEM Data
  2. Computing flow paths and flow accumulations
  3. Delineating watersheds from DEMs
  4. Delineating sub-basins within a watershed

3 Setting up a Project with the Hydrologic Modeling Wizard

3.1 Starting the Hydrologic Modeling Wizard

  1. Locate the icon for the Hydrologic Modeling Wizard located near the menu bar of the WMS window. Click the icon to open the wizard.
  1. A Display Projection dialog will pop up. Select the Global Projection option.
  2. Click on the Set Projection button.
  3. In the Select Projection dialog set:  Projection to “UTM”

Datum to “NAD83”  Planar Units to “METERS”

Zone to “12 (114°W - 108°W – Northern Hemisphere)”

  1. Select OK.
  2. Back in the Display Projection dialog, set the Vertical Projection to “Local” and Vertical Units to Meters”.
  3. Select OK.
  4. Back in the Define Project Bounds section of the Hydrologic Modeling Wizard , find Project boundary. Under Project boundary , click on the Define… button.
  5. In the Microsoft Virtual Earth Map Locator window, enter a latitude of “38.6469” and a longitude of “-112.4291” and click Jump to location.
  6. Zoom in or out, as necessary, until the Virtual Earth window looks similar to Figure 2 and then select OK.

Figure 2 Project Bounds in Virtual Earth

  1. Click Next to advance to the next step.

3.4 Watershed Data using Web Services

This section requires a working internet connection. Proceed directly to section 3.5 if a working internet connection is not available.

  1. The name of the Hydrologic Modeling Wizard should now be Watershed Data. Toggle on the Web Services option for the data source.

Figure 3 Use web services option

  1. Click Next to advance to the next step.
  2. The window will now be called Download Data (Web Services). In the Data Type column of the Web Services spreadsheet, toggle on the option for United States Elevation Data (NED) (10m Resolution).

Figure 4 Download Data (Web Services) dialog

  1. Make sure that all other Data Type options are toggled off.
  2. Click Download Data from Web.
  3. An Elevation Cell Size dialog will appear. Enter a DEM resolution of “ 30 ” meters. Then click OK.

WMS will proceed to download the requested data for the project area that was specified.

7. In the main window, click on the drop-down arrow next to the Add GIS Data located in the tool bar and select Get Online Maps…

  1. Select both the World Imagery and the World Topo Map options in the Get Online Maps dialog and select OK.

Once the image files have been downloaded from Web Services, WMS automatically opens the files into the WMS project.

  1. Click Next to advance to the next step.

Figure 5 DEM Trim Area for Web Services Data

Figure 6 DEM Trim Area

  1. Toggle off the images in the “GIS Data” section of the Project Explorer, if necessary.
  2. Select the Frame macro.

3.7 DEM Fill Command

The DEM Fill command is useful for filling gaps in DEM data. It interpolates missing (no data) values using inverse distance weighting of the neighboring eight cells. This functionality is useful when tiling multiple DEMs files together in WMS, particularly if a thinning factor is applied when the DEMs are read. It is not necessary to use this command on seamless DEMs obtained from the NED. If seamless NED data was

obtained by successfully completing section 3.4 (Watershed Data using Web Services), then skip this section.

  1. Select Display | Display Options.
  2. The Display Options dialog will appear. In the DEM Data tab toggle on the No Data Cells option.
  3. Select OK.
  4. Right-click on “DEM (Trimmed)” (rather than DEM, the file name will still read josephpeak, marysvalecanyon, redridge, trailmountain (trimmed)) in the Terrain Data section of the Project Explorer and select Fill. Interior No Data cells disappear as elevations at those locations are interpolated using the surrounding cells.
  5. Select Display | Display Options.
  6. The Display Options dialog will appear. In the DEM Data tab toggle off the No Data Cells option.
  7. Select OK.

4 Watershed Delineation using the Hydrologic Modeling Wizard

4.1 Compute Flow Directions and Accumulations

WMS computes flow directions and flow accumulations to create streams on the DEM using a program called TOPAZ.

  1. If the Hydrologic Modeling Wizard has been closed, locate the icon for the Hydrologic Modeling Wizard at the bottom of the WMS window. Click the icon to open the wizard. If the wizard has not been closed, go to the wizard window. Select the Compute Flow Directions and Accumulations (TOPAZ) step.
  2. Make sure the option to Write TOPAZ files to a temp directory is selected.
  3. Set the computational units for sub-basin areas to “Square Miles”.
  4. Set the computational units for distances to “Feet”.
  5. Select Compute TOPAZ.
  6. Click Close when TOPAZ terminates.
  7. Set Min flow accumulation threshold to “2.0” mi^2.
  8. Select Apply to Display. Notice how the display of flow accumulations cells changes.
  9. Set Min flow accumulation threshold to “0.5” mi^2.
  10. Select Apply to Display.
  11. Set Min flow accumulation threshold to “1.0” mi^2.

Delineate Watershed

  1. The window should now be called Delineate Watershed. Verify that the stream threshold value is “1.0” mi^2.
  2. Leave the Computation Units with the default values. 3. Select Delineate Watershed. When selecting Delineate Watershed, WMS digitizes stream arcs using the DEM streams, which are DEM cells with flow accumulations greater than the stream threshold value, defines the basin boundary, and computes geometric parameters for the basin including basin area, average basin slope, mean basin elevation, and maximum flow distance. A hydrologic model will not be set up in this exercise, so the rest of the steps in the wizard do not need to be completed. However, sub-basins will be created later in the tutorial.

4.3 Create Sub-basins

  1. On the left side of the Hydrologic Modeling Wizard select the heading “Choose Outlet Locations” or select the Back button to return to the previous step.
  2. Zoom in around the area shown in Figure 9.

Figure 9 Zoom Area

  1. Choose the Create Outlet Point tool from the wizard window.
  2. Create another outlet at the location shown in Figure 10, just below the stream junction.

Figure 10 Node Location

  1. Select the Frame macro.
  2. Zoom in around the branch shown in Figure 11.

Figure 11 Zoom Area

  1. Choose the Create Outlet Point tool from the wizard window.
  2. Place an outlet immediately downstream of the most downstream feature node visible, as shown in Figure 12.

Figure 12 Create an outlet at the indicated location (below the stream junction)

5.2 Basin Labels

  1. Make sure the Drainage module is selected.
  2. Select Display | Display Options.
  3. The Display Options dialog will open up. In the Drainage Data tab toggle on the Basin Names , Basin Slopes , and Max Flow Distance options.
  4. Select OK. Feel free to move the basin labels displaying the area, slope, etc., to more convenient locations in the graphics window.
  5. Choose the Move Basin Label tool.
  6. Move the label to another point in the basin just by clicking on any point within the basin
  7. Click on any point within a basin and drag the mouse to display the basin label with an arrow.

5.3 Display Options

When finished using the elevation data, turn off the DEM contours and extra streams displays if desired.

  1. Right-click on “DEM” in the Project Explorer and select Display Options .
  2. In the dialog, uncheck the Flow Accumulation , Color Fill Drainage Basins , Fill Basin Boundary Only, and DEM Contours options.
  3. Select OK.

5.4 Color Fill Basins

WMS also allows each basin to be filled with a different color. This is useful when the background image does not need to be showing.

  1. Right-click on the “Drainage” coverage and select Zoom to Layer.
  2. Right-click on the “Drainage” coverage and select Display Options.
  3. Check the Color Fill Polygons option.
  4. Select OK.

6 Conclusion

This concludes the “Watershed Modeling – DEM Delineation” tutorial. Feel free to work through any of this tutorial using copies of other data. Once completed, save a project file for future reference. This exercise explained how to use DEM data in WMS. Topics included the following:

  1. Importing DEM Data
  1. Computing flow paths and flow accumulations
  2. Delineating watersheds from DEMs
  3. Delineating sub-basins within a watershed