Attribute tables and joins: wildfire extent in CA

Analyzing wildfire extent and response in California

The plan for this lab tutorial

Complete the tutorial and create a document with brief responses to Q1 - Q5.
Create a simple map layout with a legend, scale bar, north arrow, and brief map description.

In this exercise, you will:

Create a new project and map
Add layers to a new map
Examine a layer’s attributes
Create a new geodatabase
Import data into your geodatabase
Summarize data in your layers or tables
Join tabular data with vector layers
Change the symbology of features

Analyzing wildfire extent and response in California

Introduction

Start a project, add and explore the data

Create a geodatabase and import data

Summarize attribute data

Join a table to a polygon feature class

Adjust layer symbology and print the map

To complete the lab

Introduction

California is no stranger to wildfires. However, what is novel for the state is the intensity and length of recent fire seasons. Unlike the “typical” fire season of the past which lasts from June to October, a year-long fire season with more frequent and more destructive wildfires is becoming the new normal due to climate change (Adams, 2008; Ortiz, 2018; Thorne et al., 2018). Specifically, a lethal mix of (1) prolonged droughts and record-breaking heat waves which left vegetation “tinder dry”, (2) an epidemic of bark beetles that caused the death of millions of trees, and (3) the usual dry and gusty Santa Ana Winds have combined to create more and more destructive and expensive wildfire seasons (Ortiz, 2018; Adolphe, 2018). As an example, the 2007 wildfire season killed 17 people, injured 140 firefighters and an unknown number of civilians, destroyed 3,069 structures, and cost property damages in excess of $2 billion (Mitchell et al., 2007; Girnius et al., 2008). To make matters worse, as California’s population continues to grow, people and developers are increasingly building in areas of high fire risk, which increases the population’s vulnerability to wildfire hazards (Adolphe, 2018; Ortiz, 2018).

MODELED AREA BURNED BY WILDFIRES FOR THE CURRENT TIME PERIOD (MODELED AS 1961-1990), FOR MID-CENTURY (2035-2064), AND FOR LATE CENTURY (2070-2099). (SOURCE: STATE OF CALIFORNIA’S FORTH CLIMATE CHANGE ASSESSMENT)

Of the 6043 fires that occurred in California in 2007 alone, an estimated 1,520,362 acres were affected (CalFire, 2018). CAL FIRE responded to about 60% of the fire incidents, while Federal Firefighting Agencies and Local Governmental Agencies responded to about 32% and 8% of the fires, respectively (CalFire, 2018).

SMOKE FROM THE LILAC FIRE ON DECEMBER 7, 2017 IN OCEANSIDE, CA (LEFT). STAFF FROM 2-1-1 USING ARCGIS ONLINE MAPS PROVIDED BY THE SAN DIEGO COUNTY OFFICE OF EMERGENCY SERVICES TO ASSIST EVACUEES AND RESIDENTS (RIGHT).

WILDFIRES IN NORTHERN CALIFORNIA TRIGGERED BY THUNDERSTORMS AS OF AUGUST 2008. SATELLITE IMAGE WAS CAPTURED WITH THE MODERATE RESOLUTION IMAGING SPECTRORADIOMETER (MODIS) ON NASA’S TERRA SATELLITE. (SOURCE: NASA)

In this exercise, you will explore a small subset of the wildfires that occurred during the 2007 wildfire season in California. You will not only see information such as the alarm date, and containment date, but also the fire’s name and the agency that handled the primary response to the fire.

Start a project, add and explore the data

1. First, create a new folder in your ArcGISPro_tutorials folder with the name table_joins_wildfires.
2. Download the data for the tutorial and place the files in the new folder.
3. Create a new ArcGIS Pro project and save the project in the folder you created. Remember to unselect Create a folder for this local project when you create the project.
4. Add a layer that shows the extent of wildfires in California in 2007.

Go to Add data (found under the Map tab on the top menu ribbon), and add CAFires2007.shp to your map.

1. Right-click on the CAFires2007 layer in the Contents pane, and select Attribute Table to examine the attribute table of the CAFires2007.shp file.

Q1. How many fields are present in the CAFires2007 layer?

Q2. What other fields may be useful for researchers in a layer depicting the size of wildfire extents?

Create a geodatabase and import data

1. Go to the Catalog pane (or go to View --> Catalog Pane if the Catalog pane is not already open), and expand the Databases icon. Note that a database with the same name (e.g. Fires.gdb) as your project has already been automatically created for you when you started this new project.
2. We will create our own geodatabase to store the data that we will be working with in this exercise.

Right-click on the Databases icon within the Catalog tab, and select New File Geodatabase. Navigate to the location where you want to save this new database. Name the new database Wildfires. You should now see Wildfires.gdb under the Database icon.

1. We will now import the CAFires2007 shapefile and a standalone table into the newly created Wildfires geodatabase.

Right-click on the Wildfires.gdb within the Catalog pane, and select Import --> Feature Class(es)…

Select CAFires2007 as the Input Features
Make sure that Wildfires.gdb is selected as the Output Location
Click Run

You should now see a new feature class called CAFires2007 in the Wildfires.gdb geodatabase when you expand it in the Catalog pane.

1. Right-click on the existing CAFires2007 layer in the Contents pane and select Remove to take it off the map.

1. Add the new CAFires2007 layer that was just created in step c to the map, by dragging it from the Catalog pane to anywhere in the map.

1. Next, we will import the standalone table called 2007FireTable into the Wildfires.gdb. The process is the same as the previous step, except you will select the Import>Table(s)… option since we are now working with tables.
2. Once the Table to Geodatabase dialog opens, enter the following:
  - Input Rows: 2007FireTable.dbf (browse to the lab data folder to locate)
  - Output Location: Wildfires.gdb
  - Click Run

You should now see a new T2007FireTable item when you refresh the Wildfires.gdb geodatabase in the Catalog pane (i.e. right click Wildfires.gdb and select refresh).

***Tip: ArcGIS Pro automatically added the T to the start of the filename, because a filename cannot start with a number.***

1. Add the new T2007FireTable that was just created in step g to the map, by dragging it from the Catalog pane to anywhere in the map.

1. Open the T2007FireTable by right-clicking on it in the Contents pane, and selecting Open to see the information stored in the table.

Q3. How many fields are present in the T2007FireTable?

Summarize attribute data

1. To see which agency handled the most wildfires in 2007 within California, right-click on the AGENCY field name within the T2007FireTable, and select Summarize. Enter the following:
  - - Input Table: T2007FireTable
    - Output Table: FireInfo2007_Statistics
    - Statistics Field(s): select AGENCY for Field, and Count for Statistic Type
    - Case field: AGENCY
    - Click OK

You should now see the FireInfo2007_Statistics table in the Contents pane.

Q4. Open the FireInfo2007_Statistics table, which AGENCY handled the most fires in California in 2007?

Q5. How many fires did the AGENCY from question 4 handle?

Join a table to a polygon feature class

1. We will now join the CAFires2007 feature class with the T2007FireTable table in order to bring the tabular information from the table to the feature class. This will allow us to symbolize the polygons in the feature class based on the information that was initially only in the T2007FireTable table.

Right-click on the CAFires2007 layer name in the Contents pane, select Joins and Relates>Add Join.

1. In the Add Join dialog, enter the following:
  - Input Table: CAFires2007 (This is the layer to which we are attaching the table information)
  - Input Join Field: OBJECTID (This is the field that will map how each feature/polygon in the CAFires2007 feature class matches up with each row in the T2007FireTable table)
  - Join Table: T2007FireTable (This is the item from which we are getting the tabular information)
  - Output Join Field: OBJECTID (This is the field that will map how each row in the T2007FireTable table connects to each feature/polygon in the CAFires2007 feature class)
  - Click OK

The following graphic demonstrates how the join process work, and the importance of the Input Join Field and Output Join Field. By using fields containing common data (i.e. OBJECTID, OBJECTID_1*) to match the polygons in the feature class up with the records in the table, we can temporarily bring the information from the table to the feature class for analysis and visualization purposes.

NOTE: you can also use the OBJECTID field for both the input and the join field.

3. Open the attribute table for the CAFires2007 layer, you should now see the fields from the CAFires2007 layer as well as the T2007FireTable table all in one place.

Adjust layer symbology and print the map

1. To symbolize each wildfire polygon based on the agency responsible for it, select CAFires2007 in the Contents pane, click on the Feature Layer tab, and select Symbology.
2. In the Symbology pane, enter the following:
  - Select Unique Values under Primary symbology.
  - Field 1: select AGENCY

Color scheme: pick any color ramp that provides contrast between the different agency values.

1. Go to the Contents pane, right-click on the CAFires2007 layer, and select Zoom To Layer. Center the layer in your map extent as needed.
2. Create a visually pleasing and informative map with the essential map elements. Review the skills in this tutorial (https://pro.arcgis.com/en/pro-app/get-started/add-maps-to-a-layout.htm) if helpful.

To complete the lab

You do not need to submit this lab on Brightspace, but here are the steps to save your work:

Complete the tutorial and create a document with brief responses to Q1 - Q5.
Create a simple map layout with a legend, scale bar, north arrow, and brief map description. Export as a .png or PDF.

Source

Wing Cheung, Ph.D., GISP. Earth, Space, and Environmental Science Explorations with ArcGIS Pro

Page updated

Report abuse