Exercise 1: Introduction to ArcView

Hydro GIS Short Course 
University of Padua 
Spring 2000

Prepared by David Tarboton, Utah State University.

Table of Contents

Brief Overview of ArcView

ArcView is a software program, developed by Environmental Systems Research Institute (ESRI), which is used to do GIS analysis. It differs from ArcInfo in that ArcInfo is designed to develop GIS data while Arcview is designed to interact with GIS data which has already been created.

All activities within Arcview are organized with a Project, which may consist of a number of Views, Tables, Charts, Layouts and Scripts (Scripts are programs in the Avenue language and this exercise does not include user-defined scripts). The functions of Arcview include: displaying coverages in a view, viewing the related attribute tables of these coverages, relating attribute tables using a key field, plotting charts to display spatial information, and creating layouts of the view and related tables and charts.

Goals of the Exercise

Computer and Data Requirements

To carry out this exercise, you need to have access to a computer which runs Arcview, version 3.0 or later. You need to download the following themes:
  1. A shape file of part of the Idaho flow network (U.S. EPA reach files, 17050103.shp).
  2. A shape file giving the outline of Reynolds Creek (rcout.shp)
  3. A table of annual rainfall data called reyrain.txt.
  4. A digital elevation model grid file called reydem.asc.
The themes which you need to complete this exercise consist of several files:  rcout.shp, rcout.shx, rcout.dbf, 17050103.shp, 17050103.shx, 17050103.dbf, reydem.asc, reyprecip.asc.  You can get them from this Winzip file: ex1.zip which you have to unzip using the Windows utility Winzip.  Unzip all the files into a single directory.  For illustrative purposes I will assume this directory is 'c:\giscourse\reydata\'  (See here if you want to learn more about the data sources.).  You are encouraged to do this exercise with data from Italy if you can locate equivalent data.

Procedure

Please Note: The following procedure is a general outline which can be followed to complete this lesson. However, the user is encouraged to experiment with the program and be creative.

1. Start Arcview

Execute ArcView on your machine. On PC's this can be done by clicking on the Arcview Icon in the Program Manager Window.

When ArcView is first executed, a new untitled Project window is opened (click cancel when prompted to open a new view). This window includes several icons marked Views, Tables, Charts, Layouts, and Scripts. This is the main Project window, which allows you to create new Views, Charts, etc., or to open existing ones that you have already created in that project.

Help! If you are lost and don't know how to do something, ArcView has on-line help which is accessed by hitting the  symbol in the top right corner of the display window.

2. Display Themes in a View

Highlight the View icon in the Project window and click on New for a new view (or double click on the View icon in the Project window). Drag the view window out of the way and resize it if necessary. From the File menu select set working directory and enter your working directory (e.g. c:\giscourse\reydata).  Add a new theme to the view by clicking on the  (add theme) button on the top tool bar.  Go to your local workspace directory either by typing the directory name into the pathname box or double-clicking on the directory with the mouse. Highlight the rcout.shp coverages shown and click on OK to add it to your View. It will each show up as a bar in the legend portion of the View window with the name of the coverage shown on it. For the View you are working with, the coverage rcout.shp is called a Theme.Click on the raised box to the left of the Theme name rcout.shp to make a check mark and see the coverage displayed in the View window.  It should look like the outline of a watershed.

Now we will add the rainfall data if file reydata.txt.  Click on the Project window and highlight the Tables icon.  Click on Add.  At the bottom where it says 'List files of type' change the dropdown menu to 'Delimited text (*.txt)'.  Select the file named 'reyprecip.txt' and click OK.  Now bring the View window to the front by clicking on it, or if it is hidden use the 'Window' menu.  From the View menu select 'Add event theme'.  In the X Field select UTME and in the Y Field select UTMN.  Click on OK.  This should show up on the bar in the legend portion of the View window.  Click on the raised part of the box to the left of the theme reyprecip.txt to make a check mark to see the coverage displayed in the View window.  These are locations of raingauges.

Save the Project

The Legends for these Themes can be modified as described below. Once you've got your Project set up, you can save it to a file by making the Project window active and choosing the menu option File / Save Project. The Project file that you save has the extension .apr and contains information about the structure of your project, including the pathnames to the data dislayed in it. The Project file is an ASCII file that can be viewed with a text editor if you are curious about what it looks like. It is wise to periodically save the Project as you carry out this exercise so that you can recover all your work in the event that Arcview crashes before you complete the exercise.

3. Adjust the Display of the Themes

The legend for a Theme can be adjusted by double-clicking on that Theme's name. This brings up the Legend Editor. Adjust the coloring of a theme by clicking on its Symbol box and using the  paint brush in the top right corner of the Color Palette which appears. Select Apply in the Legend Editor to get the new color.  You can also use the same interface to adust marker symbol and size.  Close the Color Palette and Legend Editor boxes using the icon in their upper right corner.

You can zoom in or zoom out from a portion of the View window using  or . To zoom to the extent of active Themes, use the  tool in the upper row of the tool bar. A Theme is active if its legend bar in the View window appears raised.

By clicking the  icon in the View tool bar and then clicking on a map feature in the View you can find out information about any feature in the active Theme (a display of its record in the data table). If you click on a feature and don't see the correct record displayed, check to see that the correct theme is highlighted in the View window legend bar.

Report the coordinates of the rain gage that is furthest west in this set.

4. Open a Table

To View tabular information associated with a Theme, first activate the Theme of interest by clicking on the Theme name in the legend bar of the View window, then click on  in the top row of buttons to open the Table. By clicking on a row in a Table you can highlight that row and the corresponding feature (precipitation station location) in the map.

Notice how there is a one to one correspondence between a record in the data table and a geographic feature in the map. This table-map linkage is one of the key things that makes a GIS operate effectively. To make sure that the row you've selected is easy to see, promote to the top of the table using the  icon.By holding down the shift key you can highlight several features at once.

Selecting Features Geographically in the View

Geographic features from a particular theme can be selected graphically by highlighting the theme, clicking on the  tool, and then selecting the features in the view. Again, by holding down the shift key and you can add features to the set you've previously selected. You can also drag a box over a region on the screen and select all the features in that region. If you attempt to select features graphically and don't succeed, check that you've clicked on the theme name in the legend bar so that it is highlighted.

By clicking on the  icon you can unselect all records. By holding down the shift key and clicking on a selected record, it will be unselected.

The data that you are examining are precipitation recorded between October 1992 and August 1993.  The table contains summary data computed from data recorded hourly.  The attributes of the data, shown in column in the data table, include the name of the station, the location in UTM north and east coordinates and precipitation totals for the entire period (in inches and mm) and for each month (in inches).  You'll see that the values for one station are very small, suggesting an error that needs to be investigated.

Selecting Particular Fields in the Table

In large tables you can see all of the fields by scrolling to the right using the scroll bar at the bottom of the Table. You can determine summary statistics for a particular field by selecting that field (depressing its header label) and then selecting Field/Statistics from the Menu Bar. If you have records selected in the table, the statistics function will summarise the statistics of these records only. If you want the statistics of all the records to be summarised, make sure that you have cleared all the selected records using the  button before calculating the statistics.

Report the mean total precipitation over this period for 10 Southernmost gages.  Select these using the  tool on the view, then open the theme table and select Field/Statistics.

5.  Add Elevation Data

Analysis of grid digital elevation model (DEM) data requires the Spatial Analyst Extension.  In the project window, choose Extension from File menu and check Spatial Analyst from the available extensions.  If you don't have the Spatial Analyst extension you will not be able to complete this exercise.

The file reydem.asc contains digital elevation data on a 30 m grid for Reynolds Creek.  It is in an ASCII export format.  In a View window select the File menu Import Data Source.  Select import file type as ASCII raster and click OK.  Select the file name reydem.asc.  Give the output grid the name reydem, selecting the folder where you would like the grid file to be saved.  Respond NO to cell values as integer (This data is actually integer data, but it is generally better to treat elevation data as real).  Respond YES to add grid as theme to the view.  The digital elevation model theme named reydem should now be displayed.  To show the watershed outline and raingauges with this, drag the legend bar for the digital elevation model (reydem) below that for the precipitation and outline themes. Dragging a theme is accomplished by clicking beside the theme symbol, holding down the mouse and dragging the box that appears.

Determine the elevation of each rain gauge.  With the theme reyprecip.txt selected (and no features selected ) choose Summarize by Zones from the Analysis menu.  Pick the field 'Name' to define zones and click OK.  Pick the theme 'reydem' containing the variable to summarize and click OK.  Click CANCEL for selection of the statistic to chart.  A table 'Stats of Reydem Within Zones of Reyprecip.txt' is created.  Since Reyprecip.txt is a point theme, each zone is a point that can only have one elevation.  The table shows the elevation in  four columns mean, min, max and sum, with range and standard deviation 0.  (If the field being summarized had been a line or polygon theme then the concepts of min, max, range, standard deviation and sum would have been non trivial).  Edit this table to clean it up.  From the Table menu select Start Editing.  Fields (columns) may be selected by clicking on the grey name at the top.  Select and Delete (Edit/Delete Field) all fields except 'Name' and 'Mean'.  From Table/Properties set the alias 'elevation' for the field 'mean'.
From the Table menu choose stop editing and save edits.  Now join this table to the reyprecip.txt table.  First select the field 'name' (by clicking on the grey name) in the table 'Stats of Reydem Within Zones of Reyprecip.txt'.  Then select the field 'name' in the 'reyprecip.txt' table.  Then choose Join from the Table menu.  You will see that the table 'Stats of Reydem Within Zones of Reyprecip.txt' disappears and a new field (column) with the elevation data appears in the table 'reyprecip.txt'.   The table 'Stats of Reydem Within Zones of Reyprecip.txt' has been joined to the table 'reyprecip.txt' using the field 'name' as a key field.  This join can be undone by choosing Remove All Joins from the Table menu.  A table can be sorted by selecting a field (clicking on the grey name) then clicking one of the sort buttons  for an ascending or descending sort. Sort the table by elevation and report the name of the lowest elevation station.

6.  Add River Reach File data and change the projection

The river reach information for this region is in the shape file 17050103.shp.  This is in geographic coordinates (latitude and longitude).  The digital elevation model, watershed outline and rainfall data we have so far displayed is in UTM coordinates relative to the NAD27 datum (NorthAmerican Datum 1927).  To display and analyze this data together the different coordinate systems need to be reconciled.  ArcView has the capability to project from geographic coordinates to other coordinate systems (but not the other way) so we will project the geographic coordinates onto UTM.

Open a new view, by double clicking on the Views icon  in the project menu. Add the 17050103.shp theme to this view ( add theme button).  From the View menu select properties

Click on Projection and select category UTM -1927, type Zone 11.  Click OK to the projection dialog and OK to the View Properties dialog.  You should notice a shift in the orientation of the displayed reaches, and that the coordinates in the top left are now UTM (100,000's of meters) rather than latitude and longitude (~100 degrees).

With the 17050103.shp selected from the Theme menu select Convert to Shapefile.  Give a new name (17050103utm.shp).  Say yes to the dialog to save in rojected units.  Say OK to the message about the converted shape not being added to the view.

Close the projected view (X at the top right) and open the first view (with the basin outline, elevation and rainfall data). Add ( add theme button) the new theme 17050103utm.shp to this view.  The streams should match nicely with the watershed outline and topography.

Select the river network within the Reynolds Creek basin outline.  With the17050103utm.shp active (raised legendbar) choose Select by Theme from the Theme menu.  In the Select by Theme dialog box, select features of active themes that Intersect the selected features of Rcout.shp.  Since Rcout.shp is a polygon shape file this means that all reach segments which are within or intersect the Reynolds Creek Basin will be selected.

Click New Set.  You will see that all of the river reaches that intersect the Rcout.shp are highlighted.  Now with the17050103utm.shp active (raised legendbar) and Reynolds Creek streams selected (Yellow) choose Convert to Shapefile from the Theme menu.  Provide a name (reystreams.shp) for the new shapefile.  You will see that this comprises only the streams of Reynolds Creek Watershed.

7. Make a Chart

A chart can be plotted of one or more records selected from a table. Select a particular gage record by clicking on its symbol on the view or its record in the table. With the table open, double click on the Chart icon in the Project window.  At the pick a table prompt select the table you are working with.  (Beware - there are two tables, one named 'reyprecip.txt' and one named 'Attributes of Reyprecip.txt' that was created when you added the event theme.  As you proceed with ArcView analyses you will see that tables get added along the way by various operations and you need to recognize this and delete ones no longer needed) Select the items from the table to be added to the chart in the properties box and give the chart a name. For our exercise, we wish to plot the monthly precipitation, so highlight the months on the left hand side and click on the box labeled Add.

Again, multiple fields can be selected by holding down the shift key. Once this is done, click on the box labeled Add. After clicking OK, a Chart will be plotted. You can change the form of the Chart using items in the top tool bar.
The horizontal axis of the Chart is automatically labeled using the field names you selected for plotting. If these are too long to fit on the chart, you can make shorter aliases for these field names by making the Table active, selecting the menu item Table / Properties, and entering text into the column labeled Alias. For example, you can replace the label Jan with J, etc.

To Edit Features of the Chart, select the Chart Edit tool  and then click on the feature you wish to Edit. You can change the nomenclature of the legend and the chart title and location in this way.

If you hold down the shift key and highlight a second station in the View or the Table, its data will be automatically added to the chart.  Here is a comparison between the P095 and P098 stations

8. Make a Layout

A Layout allows a user to combine Views, Tables, Charts, Legends, and Text into one document for printing. To create a new Layout, double-click on the  icon in the Project window. To work with a Layout, it is useful to enlarge the Layout window (by dragging on the window corner(s) with the mouse). After enlarging the window, click on the Zoom to page  tool to maximize use of the window space. As illustrated in the image below, by clicking and holding the left mouse button on the furthest icon to the right on the lower tool bar, you can add a number of different objects to the Layout. From top to bottom, the objects that you can add are a View, a Legend, a Scale, a North Arrow, a Chart, a Table, or a Graphic. After selecting one of these items, you can draw a box on the Layout to specify the location and size of the selected object.

Begin by selecting a view  and drawing a box to accomodate it. When you've drawn the box, a dialog box will come up asking you to select the view to show in the box. Select View1, and you should see your view of Reynolds Creek show up.

You can add another object template to the layout using the right hand side tool in the lowest row of the upper tool bar. Select the chart object  to add a chart. To connect the chart visually to the corresponding point in the view using the draw tool  which is selected from the list of icons under the  button. When drawing the line you'll find that it automatically snaps the end points of the line to the grid points shown in the Layout window. To stop that happening, click off Snap to Grid in the Layout/Properties window.  In case you choose to add a scale bar (fourth icon down) to your layout and get a grey bar that says 'Unknown Units: View 1' you need to switch back to the view window and select properties from the view menu.  Then set the map units pull down menu to meters.  When you switch back to the Layout the scale bar should show units, which can be adjusted by double clicking on it.

You can add text to a Layout using the  button. You can also draw points, lines, and polygons using . If you find that the lines you are drawing are not in quite the right locations, use Layout/Properties and click off the "Snap to Grid" box. To change the size of the text you've added, highlight the text and use Window/Show Symbol Palette and the text icon to alter the text size. Text size of 14 point is the default. Usually 24 or 36 point looks good in layouts. Similarly, to change the line thickness use the same pallete and select the Line icon. Line thickness of 1 is the default.   You can directly print your layout from the Layout window, or you can export the layout as a Placeable WMF (Windows MetaFile) and then import it into MS Word using Insert/Picture/From File so that you can add a commentary on what you did on the exercise.

9. Do Something Creative!!

Now that you are familiar with the operation of Arcview, make some new maps, charts or tables of different variables or analyses that are of interest to you. Some possibilities include:

10.To be Turned In

Ok, you're done!

Some of this material is based on exercises prepared by David Maidment at the Center for Research in Water Resources at the University of Texas at Austin and used in his GIS in Water Resources Online course.

These materials may be used for study, research, and education, but please credit the authors and the Utah Water Research Laboratory, Utah State University. All commercial rights reserved. Copyright 2000 Utah State University.