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V. Basin Selection and Analysis

For this exercise we will continue working on the Burns Creek basin. You are expected to have a fully loaded database at this point. If you had troubles downloading data and puting together your database, you can download this zip file, which contains the database developed in the previous sections of this tutorial (click here to download).

First, a brief introduction to how to move around CUENCAS map display window using the projection icons and the mouse:

  • Home Icon []: Clicking this icon will make the map projection come back to its original state. Use it every time that you lose your map out of sight, or if you want to quickly return the original display projection.
  • Zoom In Icon []: Clicking this icon will double the current image size.
  • Zoom Out Icon []: Clicking this icon will reduce the current image size by half.
  • Left-Button-Drag (click and hold): This action allows you to change the center of the display. It is useful if the features that you are interested in are outside the visible range in the display window
  • Middle-Button-Drag (click and hold): This action activates the Box Zoom utility. Note: There are some buttons in the interface that will change the default action of the middle button. We will illustrate those changes along this tutorial.
  • Middle-Button-Click: This action will execute the currently selected behavior. The Behavior is determined by clicking on any of this icons:
    [], [], or [].
  • Right-Button-Click: This action will bring up the interface associated to the active element being clicked. Active elements are usually small squares in the display. We will illustrate the “Basin-Outlet” element later in this tutorial.

Now it’s time for River Network Analysis.

  1. Basin Selection:
    • Load the database by selecting “File => Open Data Base” and then choose the directory where your data is located.
    • Open your DEM by double clicking your DEM on the “Topography Database” tree, on the left panel of CUENCAS. Then click on the “Open” button in the “DEM and Derived Quantities” window.

      Topography database.

      Topography database.

       

       

    • Once the map has been displayed, select the “Show all orders” box, under the Plot Network icon []. The box shows up when you click on the icon.

      Show all orders.

      Show all orders.

    • Using the “Box Zoom” utitlity (click and drag the middle-button of your mouse) zoom into the area near the end of the longest dark green stream.

      Cuencas zoom to outlet.

      Cuencas zoom to outlet.


    • Make sure that you are close enough to the end of the stream to differentiate one link from another.
    • Now click on the “Select Outlet” icon []. It’s the third one after the “Show Network” icon []. You will notice that when you click on the icon, it changes to a darker grey color. What this means is while the button is selected a new behavior for the Middle-Button of your mouse is active. Do not try to “Box-Zoom” after you have activated this button.
    • Click near the end of the stream with your middle button (see figure above). A good place to do it, is where the direction changes in the green stream right before the junction.
    • The software automatically finds all the pixels in the terrain, whose drainage path crosses the point we defined. Then it outlines the contour around those points (This contour line is the Basin Divide). Click the “Home” icon to get a full view of the basin and the basin divide.

      Basin divide.

      Basin divide.


    • Deselect the “Select Outlet” icon [].
  2. River Network Topologic Analysis
    • Once you have defined your basin outlet, CUENCAS performs a number of geomorphometric analyses on the River network. To access them, Right-Click on the red square near the basin outlet. This small square is what we call an active element in the map. Notice that while the “Select Outlet” icon [] is active, you can select many basin outlets as you want in a region.
    • Right-Clicking on the outlet will launch a menu of options. Click on the “Geomorphology Analysis” button.

      Cuencas network tools.

      Cuencas network tools.


    • The “River Network Analysis” module is displayed.

      Network analysis module.

      Network analysis module.


    • Click on the individual tabs to explore the variety of analyses CUENCAS can do. Check the difference between the Geometric and Topologic Width Fucntions, and Horton Ratios for different network properties. (THIS MODULE IS BEING DEVELOPED – EXPECT A SUMARY OF THE NETWORK PROPERTIES IN THE “HTML REPORT” TAB).
    • Click here for some Homework exercises related to this module.
    • Close the “River Network Analysis” module window.
    • Right-Click on the outlet again to get the menu of options. Click on the “Rainfall-Runoff” button. It launches the “Rainfall-Runoff” module.

      Rainfall-runoff module.

      Rainfall-runoff module.


    • This module gives you a 3D view of your basin, which gives a sense of the basin topography and the meaning of flow aggregation on the terrain.
    • Select the “Hillslopes-Links System” tab, to view how CUENCAS decomposes the basin area into smaller pieces called hillslopes.

      Rainfall-funoff module hillslopes.

      Rainfall-funoff module hillslopes.


Last modified on January 17th, 2013
Posted on January 17th, 2013