Geography 387 – Fall 2011 Lab 4 Cartography and Classification 1 Lab 4: Cartography and Classification 1.0 Overview This lab will introduce you to two main concepts: 1) how to join an attribute table to the attribute table of an existing feature class, and 2) how to make choropleth maps using a variety of classification methods. We will continue with our counties feature class from Lab 3. We will then download year 2000 water use data from the National Atlas site and make a variety of maps for the conterminous United States. The overall steps of this lab are: - Import existing GIS data into a new file geodatabase - Compare fields in the original shapefile to fields in the geodatabase feature class - Download water use statistics from National Atlas - Read the metadata for the water use statistics - Relate water use statistics to the county feature class - Symbolize the counties with total water use - Create a map of total daily water use with different classification schemes - Create a map of annual ground water use per hectare - Create a map showing a large aquifer along with annual ground water use per hectareGeography 387 – Fall 2011 Lab 4 Cartography and Classification 2 2.0 Import existing GIS data into a new file geodatabase Make a Lab 4 working folder in your workspace (on your USB drive or local drive). Open ArcMap and establish a folder connection to your workspace that contains your Lab 3 and Lab 4 working folders. In this exercise, we are going to create a new File Geodatabase and import a feature class of counties from the 48 conterminous states (and Washington, D.C.) from your Lab 3 geodatabase. In the Catalog window in ArcMap, right-click on your Lab 4 working folder and select “New” and then select “File Geodatabase”. Rename your new geodatabase Lab4_US_water_use.gdb Now we are going to import a feature class from your Lab 3 geodatabase into your Lab 4 geodatabase. Right-click on the Lab 4 geodatabase in the Catalog window and select Import, and then Feature Class (single). Note: if you wanted to import multiple shapefiles all at once, you could select Feature Class (multiple).Geography 387 – Fall 2011 Lab 4 Cartography and Classification 3 The Feature Class to Feature Class window opens. In the Input Features window, browse to and select your feature class of counties of the 48 conterminous states in the Albers projection from your Lab 3 geodatabase. Do not use the dissolved feature class. For Output Location, chose your Lab 4 geodatabase, and for Output Feature Class name, use county_48_albers. Click the Show Help button to open the help if it is not already open. Click anywhere in the "Field Map (optional)" section of the "Feature Class to Feature Class" window to display the help information for field import. Use the help to answer the following question: Question 1: (2) a. How could we change the field names that will be displayed in the output feature class? Hint: To answer this thoroughly, right-click on the various attribute names (e.g. State) and select "Properties...”. FYI: you can remove a field from the final imported feature class by selecting the field and then clicking the button. b. What does the "Expression (optional)" parameter do? We are going to import all of the fields with the same names as found in the input feature class. Click OK. If everything works properly, you should see your feature class appear in your Lab 4 geodatabase, and the feature class is added to ArcMap. Save the map document to your Lab 4 folder as Lab4.mxd.Geography 387 – Fall 2011 Lab 4 Cartography and Classification 4 Recall that you created the counties feature class in Lab 3 by exporting the shapefile that you downloaded from the National Atlas website to your Lab 3 geodatabase, then selecting and exporting the features in the 48 conterminous states (and Washington D.C.) to a new feature class, then reprojecting the feature class to the Albers projection. From the Catalog window, open the Item Description (Preview: Table) to compare the attribute tables between the original shapefile in your Lab 3 folder (countyp020.shp), and the imported feature class in your Lab 4 geodatabase (county_48_albers). You should notice that the shapefile attribute table has AREA and PERIMETER fields with values in decimal degrees (squared-dd for area) corresponding to its original Geographic Coordinate System, and that these fields are still present in the imported feature class. When we imported the layer into a geodatabase feature class, the Shape_Length (i.e., perimeter) and Shape_Area (i.e., area) fields were added automatically by ArcMap. Unlike the AREA and PERIMETER fields of a shapefile, the feature class Shape_Length and Shape_Area fields are automatically updated when we physically change the coordinate system with the Project tool. You should now realize that the original AREA and PERIMETER fields from the shapefile are now redundant and miscalculated. To avoid confusion later on, we can delete these fields from the Geodatabase feature class. Open the attribute table for the Lab 4 county_48_albers feature class. Right-click on the AREA field and select Delete Field. Do the same for PERIMETER. Close the attribute table.Geography 387 – Fall 2011 Lab 4 Cartography and Classification 5 3.0 Download water use statistics from National Atlas We are now going to download an attribute table of water statistics from the National Atlas. Go to the web page at http://www.nationalatlas.gov/. From the front page, navigate to Mapping Professionals, and then to Raw Data. From the Water category, download Water Use 2000. Extract the data files into your Lab 4 folder using 7Zip or other program. You should notice that the Water Use 2000 archive comes with a DBF table and an associated metadata ASCII text file. Important, select the Lab 4 folder and press the F5 key to refresh the Catalog window so that your table .dbf and .txt files appear in the catalog tree. We will now import the table into your Geodatabase from the Catalog window in ArcMap. Right-click on the geodatabase and select Import, then Table (single). Chose the wu2000t.dbf file as your table to import. Name the output table wu2000t. Note: the .dbf extension is not required, since this will be a table within the Geodatabase, not a separate DBase formatted file. Leave the "Field Map" box with the default values and click OK. The imported table will