Map Marin County forests
In this lesson, you'll add data for counties and land cover in the United States to an ArcGIS Pro project. Then, you'll extract information for your area of interest, Marin County.
Create a Marin County polygon
First, you'll create a polygon layer to show the Marin County boundaries. You'll download United States county data from the ArcGIS Living Atlas of the World and extract the data for Marin County.
The Living Atlas is an online collection of authoritative geographic information from around the world. It contains many ready-to-use data layers, including the political boundary and land cover layers you'll use in this lesson.
- Start ArcGIS Pro. If prompted, sign in using your licensed ArcGIS or Enterprise account.
If you don't have ArcGIS Pro or an ArcGIS account, you can sign up for an ArcGIS free trial. If you are signing in to an Enterprise account, ensure that ArcGIS Pro is configured to use your organization's portal.
When you open ArcGIS Pro, you're given the option to create a project or open an existing one. If you've created a project before, you'll see a list of recent projects.
- For Blank Templates, choose Map.
The Create a New Project window appears.
- For Name, type Marin County Smoke Detector Analysis. Click OK.
The project is created. Next, you'll add data.
- On the ribbon, click the Map tab. In the Layer group, click the Add Data button.
The Add Data window appears. You can add data from several sources, including the Living Atlas.
- Under Portal, click Living Atlas.
- In the search box, type USA Counties and press Enter. In the list of search results, click USA Counties.
- Click OK.
The layer is added to the map. It contains all county and county equivalents in the United States. You only need the data for one county, however. You'll select Marin County and export it to a new feature layer.
- On the ribbon, on the Map tab, in the Selection group, click Select By Attributes.
The Geoprocessing pane appears, displaying the Select Layer By Attribute tool. You'll create an expression so that this tool will only select counties named Marin.
- In the Geoprocessing pane, click New expression.
- Using the menus, create the expression Where County Name is equal to Marin.
- Click Run.
The tool runs and Marin County is selected. Next, you'll export the selected feature to a new feature layer.
- In the Contents pane, right-click USA_Counties, point to Data, and choose Export Features.
The Feature Class to Feature Class tool opens in the Geoprocessing pane.
- In the Geoprocessing pane, for Output Feature Class, type Marin_County.
- Click Run.
The tool runs and the new layer is added to the Contents pane. You no longer need the original layer, so you'll remove it. You'll also zoom to Marin County on the map.
- In the Contents pane, right-click USA_Counties and choose Remove. Right-click Marin_County and choose Zoom To Layer.
The map zooms to Marin County.
- On the Quick Access Toolbar, click the Save button.
Create a polygon of Marin County forests
Next, you'll map forests in Marin County. You'll add a National Land Cover Database (NLCD) layer from the Living Atlas and use a raster function to display only forest land cover. Then, you'll extract a polygon layer representing Marin County's forests.
- On the ribbon, on the Map tab, in the Layer group, click the Add Data button. In the Add Data window, under Portal, click Living Atlas.
- Search for NLCD. Add the USA NLCD Land Cover layer to the map.
The layer is added. The NLCD is produced by the Multi-Resolution Land Characteristics Consortium, a group of United States federal agencies that produces land cover information at the national scale.
- In the Contents pane, turn off the Marin_County layer.
Marin County has some developed areas (displayed in red) on the county's eastern coast, but a large portion of the county's interior is forest (displayed in green). Next, you'll display only forested areas.
- On the ribbon, click the Analysis tab. In the Raster group, click the Raster Functions button.
The Raster Functions pane appears. Raster functions apply processing operations to raster layers, such as the USA NLCD Land Cover layer. They apply these operations on the fly, which means that no new dataset is created, saving time and storage space.
- In the Raster Functions pane, search for Remap. In the list of results, click Remap.
Raster layers are composed of cells, and each cell has a value. For instance, in the USA NLCD Land Cover layer, each land cover type has a unique numeric value (which can be found in the layer's metadata). The values for forested land cover types range between 41 and 44.
The Remap Properties raster function changes cell values based on parameters you choose. You'll remap the USA NLCD Land Cover layer so that all forested land cover values are changed to 1, and all nonforest land cover types are removed.
- In the Remap Properties raster function, for Raster, choose USA NLCD Land Cover.
- In row 1, for Minimum, type 41, and for Maximum, type 44. For Output, type 1. Check Change Missing Values to NoData.
- Click Create new layer.
The Remap_USA NLCD Land Cover layer is added to the map. It displays forested areas with black cells. Nonforested areas have no data.
Your area of interest is Marin County, so you'll clip the dataset to the correct extent.
- In the Raster Functions pane, search for and open the Clip raster function. Set the following parameters:
- For Raster, choose Remap_USA NLCD Land Cover.
- For Clipping Geometry / Raster, choose Marin_County.
- Check Use Input Features for Clipping Geometry.
You'll also change the output layer name.
- Click the General tab. For Name, type Marin County Forest.
- Click Create new layer.
The Marin County Forest_Remap_USA NLCD Land Cover layer is added to the map. Next, you'll convert the raster layer to a polygon layer, so that it can be enriched later.
- On the ribbon, on the Analysis tab, in the Geoprocessing group, click Tools.
The Geoprocessing pane appears.
- In the Geoprocessing pane, search for and open the Raster to Polygon tool. Set the following parameters:
- For Input raster, choose Marin County Forest_Remap_USA_NLCD Land Cover.
- For Output polygon features, change the output name to Marin_County_Forests.
- Uncheck Simplify polygons.
- Click Run.
The Marin_County_Forests layer is added to the map. It represents all locations in Marin County where land cover is predominantly forest. However, it may exclude adjacent areas classified as scrub or grassland because they lacked sufficient tree canopy. You'll create a small buffer around the forest polygon to encompass adjacent areas.
- In the Geoprocessing pane, click the Back button.
- Search for and open the Buffer tool. Set the following parameters:
- For Input Features, choose Marin_County_Forests.
- For Output Feature Class, change the output name to Marin_County_Forested_Area.
- For Distance, type 30 and choose Meters for the type of unit.
- For Dissolve Type, choose Dissolve all output features into a single feature.
- Click Run.
The tool runs and the layer is added to the map. You've created the forest polygon. Next, you'll remove intermediary layers that you no longer need.
- In the Contents pane, remove the following layers:
- Marin County Forest_Remap_USA_NLCD Land Cover
- Remap_USA NLCD Land Cover
- USA NLCD Land Cover
Only the forested area polygon remains.
- Save the project.
In this lesson, you added Living Atlas data for county boundaries and land cover to an ArcGIS Pro project. Then, you extracted a polygon layer of forested area in Marin County.
Map smoke detector adoption
In this lesson, you'll enrich your polygon layer of forested area in Marin County with information about the percentage of households with smoke detectors. County supervisors also want to know where these households are distributed across the county. To show them, you'll create a tessellation of hexagons and enrich them as well. Together, your enriched layers will provide the supervisors with the information they need to create a targeted fire education program for the community.
Enrich the forested area layer
First, you'll enrich the Marin_County_Forested_Area layer to see what percentage of households in high risk areas across the county have smoke detectors.
- If necessary, open your Marin County Smoke Detector Analysis project in ArcGIS Pro.
- If necessary, open the Geoprocessing pane (or click the Back button if a tool is already open). Search for and open the Enrich tool.
The Enrich tool determines demographic information for a polygon using the ArcGIS GeoEnrichment Service. The GeoEnrichment Service can be used for over 130 countries, some of which have thousands of demographic and consumer behavior variables for the most recently available annual estimates.
The Enrich tool consumes credits assigned to your ArcGIS account. In this section, you'll enrich one with four fields, which will cost 0.04 credits. In the next section, you'll enrich 463 features with 4 variables for a total cost of 18.63 credits. The ArcGIS Online help topic Understand credits contains more information about credit usage.
- For Input Features, choose Marin_County_Forested_Area. For Output feature class, change the output name to Marin_County_Forested_Area_Smoke_Detectors.
Next, you'll change the demographic data source from the default source to a source that specializes in United States data.
- Click the Environments tab and click the Browse button.
The Business Analyst Data Source window appears.
- Under Portal, click North America. Under United States, choose Standard, and click OK.
The data source is updated. Next, you'll choose the demographic variables with which to enrich the area.
- Click the Parameters tab. For Variables, click the plus button.
The Add Variable window appears.
- In the search box, type Smoke Detector and press Enter. Under 2019 Household Furnishings & Appliances (Market Potential), check HH owns smoke/fire detector.
Demographic data is updated periodically. Feel free to choose more recent demographic data if it is available.
The data provider, Market Potential, is indicated in parentheses. At the end of the lesson, you'll add the data source to the map.
You'll also add variables to contextualize the count of households that own smoke or fire detectors. These variables will include information about people who may be at particular risk during a fire (such as people with asthma or the elderly) and the total number of households.
- Search for Asthma. Check Used prescription drug for asthma.
- In the left pane, under United States (Standard), click Categories. Double-click the Age category.
- Double-click Age Dependency. Check 2019 Senior Population.
- In the left pane, click Categories. Double-click the Households category.
- Double-click Common Household Variables and check 2019 Total Households.
You have chosen four variables. An indicator in the upper right corner of the window confirms the number.
- Click OK. In the Geoprocessing pane, click Run.
The tool runs and the Marin_County_Forested_Area_Smoke_Detectors layer is added to the map. You no longer need the original forested area layer.
- In the Contents pane, right-click Marin_County_Forested_Area and choose Remove.
You'll explore the results of your GeoEnrichment by opening the layer's pop-up.
- If necessary, on the Map tab, in the Navigate group, click Explore.
- On the map, click anywhere inside the result polygon.
A pop-up appears with information about the polygon's attributes, including the fields with which you enriched the layer.
You can resize the pop-up to better see all of the fields.
- Close the pop-up. Save the project.
Create and enrich a tessellation
Your results include demographic data for all households in the forested area of Marin County. That information will be useful for providing county supervisors with an overall picture of the region. However, the forested area covers a large amount of space within the county and there is no indication of where households are concentrated.
To map the spatial distribution of the data, you'll create a tessellation. A tessellation divides a polygon into smaller geometric shapes. You'll divide your forested area polygon into hexagons and enrich them with the same demographic variables to better show where the households are located.
- In the Geoprocessing pane, click the Back button. Search for and open the Generate Tessellation tool.
- In the tool, set the following parameters:
- For the name of the Output Feature Class, type Marin_Hexagon_Bins.
- For Extent, choose Same As layer: Marin_County_Forested_Area_Smoke_Detectors.
- For Size, type 2 and choose Square Miles as the unit of measurement.
Two square miles is the smallest recommended size when using the Enrich tool on a polygon. Smaller polygons will contain less reliable results.
- Click Run.
The tool runs and adds the Marin_Hexagon_Bins layer to the map. The layer contains a hexagon grid that covers the entire rectangular extent of Marin County. Many of these hexagons either do not intersect Marin County or contain areas other than forested land. You'll clip the layer to the extent of the forested area polygon.
- In the Geoprocessing pane, click the Back button. Search for and open the Clip tool.
- For Input Features, choose Marin_Hexagon_Bins. For Clip Features, choose Marin_County_Forested_Area_Smoke_Detectors.
- Click Run.
The tool runs (it may take a few minutes) and the layer is added to the map.
- In the Contents pane, right-click Marin_Hexagon_Bins and choose Remove.
The default symbology of the layer is random and may differ from the example image.
Next, you'll enrich the hexagons with the same demographic variables. Rather than choose the variables again, you can access your geoprocessing history and run the Enrich tool with the same parameters that you used before.
- On the ribbon, click the Analysis tab. In the Geoprocessing group, click the History button.
- Double-click Enrich.
The Geoprocessing pane appears, displaying the Enrich tool. All of the parameters you chose the first time you ran the tool are unchanged. You only need to change the input and output parameters. Because you'll enrich more features this time, the tool will consume 18.63 credits.
- Change Input Features to Marin_Hexagon_Bins_Clip. For Output feature class, change the output name to Marin_Hexagon_Bins_Enriched. Click Run.
The tool runs and the layer is added to the map. You no longer need the original hexagon layer.
- In the Contents pane, right-click Marin_Hexagon_Bins_Clip and choose Remove.
- Save the project.
Symbolize the results
You intend to share your results with county officials. You'll symbolize the enriched data so that your findings are intuitive to understand.
- In the Contents pane, right-click Marin_Hexagon_Bins_Enriched and choose Symbology.
The Symbology pane appears. Currently, the hexagons are symbolized with a single color. You'll change the symbology so that hexagons with a higher percentage of houses without smoke detectors have a red or orange color, indicating danger.
- In the Symbology pane, for Primary symbology, choose Graduated Colors. For Field, choose HH owns smoke/fire detector.
Many of the hexagons on the map have no residents. You'll symbolize these hexagons with a different symbol than the rest of the data.
- Click the Advanced symbol options tab.
- Expand Data exclusion and click New expression. Create the expression Where HasData is equal to 0.
This expression will create a symbology class for hexagons with no data. Next, you'll adjust the number of classes and color scheme for the hexagons that do have data.
- Click Apply. Click the Primary symbology tab.
- For Classes, choose 4.
The legend updates. It shows five classes total, four for hexagons with data and one for hexagons without data. The values in the legend are the total count of households with smoke detectors. To show the percentage of households, you'll normalize the data by the total number of households.
- For Normalization, choose 2019 Total Households.
The legend updates. The classes show values from 0 to 1, which correspond to percentages. Currently, the range of values for each class is determined by statistical trends in the data. You'll change the values to easily understandable intervals.
- For Classes, for the second class, double-click the cell in the Upper value column, type 0.5, and press Enter.
- Change the upper value for the third row to 0.75.
You'll also update the labels for each class so that they are expressed as percentages.
- For the first row, change the Label value to 0.0%. Change the second label to under 50.0%, the third to 50.1% to 75.0%, the fourth to over 75.0%, and the fifth to No residents.
Last, you'll change the colors. First, you'll change the color ramp for the graduated colors. Then, you'll change the color for the excluded class.
- For color scheme, choose the Yellow-Orange-Red color scheme.
You'll reverse the symbol order so that the lowest percentages (the places with fewer smoke detectors) have the darkest colors.
- Right-click the Symbol column heading and choose Reverse symbol order.
- Click the symbol in the first column of the excluded class.
- In the Format Polygon Symbol pane, click the Properties tab. For Color, choose Sage Dust, and for Outline color, choose Lotus Pond Green.
- Click Apply and close the Symbology pane. In the Contents pane, turn off the Marin_County_Forested_Area_Smoke_Detectors layer.
The color for hexagons with no data is updated in the legend and on the map.
Most hexagons either have no residents or 50.1 to 75.0 percent smoke detector ownership. Only a few have ownership levels under 50 percent, and very few have no smoke detector ownership. You'll look at some of the 0 percent ownership hexagons to learn more.
- On the map, click any red hexagon.
Its pop-up appears. Almost all of the red hexagons have extremely low numbers of total households. Most have only one household, which does not have a smoke detector. While it's not necessary to explain this trend on the map, there are two potential factors for why hexagon bins may have such low counts of households.
The first factor is that the Enrich tool uses the United States Census Bureau's Block Point Centroids as the basis to apportion variables. In rural areas, there are usually more residences than block points, so the Enrich tool may omit some residences.
The second factor is that the United States Census Bureau does not publish small counts of people to protect privacy. Some hexagons with few or no residences may actually have some residents, but the data is not publicly available.
Because of these factors, small counts in Enrich results for rural areas may not be exact.
- Close the pop-up.
Format the data
You'll finish your work by hiding unneeded fields from the data and citing the data source.
- In the Contents pane, right-click Marin_Hexagon_Bins_Enriched and choose Attribute Table.
The table contains several fields that are not of interest to county officials.
- Right-click the heading of each of the following fields and choose Hide Field:
- Close the attribute table. Open the attribute table for the Marin_County_Forest_Area_Smoke_Detectors layer and hide the following fields:
- Close the attribute table.
Next, you'll rename the layers to be more meaningful.
- In the Contents pane, double-click Marin_Hexagon_Bins_Enriched. In the Layer Properties window, on the General tab, change Name to Marin County Forested Area Smoke Detector Adoption Rate and click OK.
- Open the Layer Properties window for the Marin_County_Forested_Area_Smoke_Detectors layer, change Name to Marin County Total Forested Area Smoke Detector Adoption Rate, and click OK.
Last, you'll cite the data sources for variables provided by the Enrich tool.
You can find the source for all demographic data used by Esri services on the Esri Demographics documentation page. To find a specific data source, click the Data tab and navigate to the appropriate section based on the data's geography. For instance, to find the source of the data used in this lesson, you would expand the United States section, click Market Potential, and scroll to Methodology. Then, download the 2019 Esri Market Potential PDF file. Page 1 of the PDF document lists the data source as MRI Survey of the American Consumer, 2018 Doublebase® from MRI-Simmons.
- Open the Layer Properties window for the Marin County Forested Area Smoke Detector Adoption Rate layer. On the Metadata tab, for Show metadata from data source (read-only), choose Layer has its own metadata.
- For Credits, paste the following text:
Esri 2019 Market Potential data derived from MRI Survey of the American Consumer, 2018 Doublebase® from MRI-Simmons.
- Click OK.
- Open the Layer Properties window for the Marin County Total Forested Area Smoke Detector Adoption Rate layer. On the Metadata tab, choose Layer has its own metadata and add the same citation to the Credits box.
- Click OK. Save the project.
In this lesson, you provided Marin County supervisors with insight about residential adoption of smoke detectors within the county's forested areas. You accomplished this task with ArcGIS Pro, ArcGIS Living Atlas of the World, and ArcGIS GeoEnrichment Service. Your analysis relied on authoritative data that you presented with intuitive symbology to help inform county officials.
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