Explore the study area
First, you'll start a new map in ArcMap and locate your study area of Rondônia, a Brazilian state in the Amazon rainforest. Then, you'll add data layers and visually examine satellite imagery to become familiar with the geography.
Find the study area
You'll start a new map, become familiar with ArcMap's user interface, and find the project's study area.
- Start ArcMap.
If you don't have ArcMap, you can get it by purchasing ArcGIS Desktop from the Esri Store.
The ArcMap - Getting Started window opens. This window allows you to open previous maps or map templates.
- Close the ArcMap – Getting Started window.
A blank map opens. Above the map are toolbars. By default, the Standard and Tools toolbars are turned on. To the left of the map is the Table Of Contents, which shows the geographic content of your map. Like the map, the Table Of Contents is empty.
If you've used ArcMap before, your interface may be arranged differently.
Next, you'll find the study area for this project: Rondônia, Brazil. Rondônia is located in the Amazon rainforest, so adding a layer of the Amazon is a good start. You'll add a layer from ArcGIS Online.
- On the Standard toolbar, click the arrow next to the Add Data button and choose Add Data From ArcGIS Online.
The ArcGIS Online dialog box opens.
- In the search box, type Amazon Ecoregion and press Enter.
- In the list of results, find the result titled Amazon Ecoregion by Learn_ArcGIS and click Add.
The layer appears on the map as a large orange shape. These are the boundaries of the Amazon ecoregion, but it's not clear where in the world the boundaries are located. Next, you'll add a basemap. A basemap depicts background reference information such as landforms and political boundaries. It can help show your data's location in the context of the world.
- On the Standard toolbar, click the arrow next to the Add Data button and choose Add Basemap.
- In the Add Basemap dialog box, click Imagery and click Add. Close the Geographic Coordinate Systems warning.
If the Hardware Acceleration dialog box opens, click Yes. This will allow your basemap to draw faster.
The Imagery basemap is added to the map and the Table Of Contents under the Amazon Ecoregion layer. It uses satellite imagery as reference information. With the basemap, you can see the Amazon's location in South America. The area inside the Amazon is much greener than the area outside. Most of the Amazon rainforest is dominated by dense tree canopy.
You still don't have enough data to find Rondônia on the map. You'll add another layer showing the states of Brazil.
- Click the arrow next to the Add Data button and choose Add Data From ArcGIS Online.
- Type Brazilian States in the search box and press Enter.
- Find the result titled Brazilian States by Learn_ArcGIS and click Add.
The layer appears on top of the Amazon Ecoregion layer. However, some of the layer extends beyond the current map extent, or zoom level. To see the whole layer, you'll zoom out.
- On the Tools toolbar, click the Zoom Out tool.
When you move the pointer over the map, it becomes a magnifying glass.
- Click anywhere on the map. Click the map again.
The map zooms out and centers on the location you clicked. You're zoomed out far enough to see the entire layer, but the layer may not be centered in the map frame.
You can also zoom using the mouse's scroll wheel. Depending on your screen resolution and monitor size, you may need to zoom more to see the entire layer.
- On the Tools toolbar, click the Pan tool.
When you move the pointer over the map, it becomes a hand.
- Drag the map until the Brazilian States layer is in the center.
Unlike the Amazon Ecoregion layer, which has only one feature, the Brazilian States layer has twenty-seven features. Features are discrete representations of a real-world object on a map. In this instance, each state is a feature. Features also contain attribute data, which describes the feature's characteristics.
- On the Tools toolbar, click the Identify tool.
- Click any state on the map.
The state flashes green and the Identify dialog box opens.
The Identify dialog box shows the attribute data, or information, for the feature you clicked. Although you can identify states until you find Rondônia (if you were lucky, it may have been the state you clicked), you can use a quicker method to find a feature with a specific attribute.
- Close the Identify dialog box.
- On the Tools toolbar, click the Find tool.
The Find dialog box opens.
- In the Find dialog box, on the Features tab, type Rondonia in the Find box. Click Find.
At the bottom of the Find dialog box, a list of matching values appears. The list contains one item called Rondonia.
- Right-click the Rondonia value and choose Zoom To.
The map zooms to the Rondônia feature in the Brazilian States layer, highlighted in the following image:
- Close the Find dialog box.
Organize and symbolize the data
Currently, you can't see the basemap under the Brazilian States layer. You'll change the layer's symbology to better see your layers. You'll also organize the layers in the Table Of Contents.
- In the Table Of Contents, locate the Brazilian States layer.
The Table Of Contents lists all layers in the map. It also shows the layer's symbology and any groups that organize the layers. In this case, the Brazilian States layer is in a group also titled Brazilian States. Layers added from ArcGIS Online are placed into groups by default, but a single layer doesn't need to be grouped.
- Right-click the Brazilian States group and choose Ungroup.
The layer is ungrouped, which changes only how the layer is organized in the Table Of Contents.
- Right-click the Amazon Ecoregion group and choose Ungroup.
Because the Imagery layer is a basemap, it can stay in the Basemap group. Next, you'll change the symbology of the Brazilian States layer.
- In the Table Of Contents, click the symbol for the Brazilian States layer.
The Symbol Selector dialog box opens. It includes a list of preset symbols and some symbology options. You'll give the Brazilian States layer a symbol with only an outline, similar to the Amazon Ecoregion layer.
- For Fill Color, choose No Color.
- For Outline Width, highlight the existing value of 0.40 and type 1.50.
- For Outline Color, choose Arctic White.
On the color palette, you can see the name of a color by pointing to it.
- Click OK.
The symbology changes. The Brazilian States layer now has only a white outline.
The Amazon Ecoregion layer (the orange line) is beneath the Brazilian States layer (the white lines). Layers are drawn on the map in their order in the Table Of Contents.
- In the Table Of Contents, drag the Amazon Ecoregion layer above the Brazilian States layer.
The Amazon Ecoregion layer appears above the Brazilian States layer.
- Examine the map.
When the map was zoomed to South America, the area inside the Amazon Ecoregion layer appeared greener than the area outside. In Rondônia, however, a large portion of the land is grayish-brown terrain, with the green regions mostly in the northern and western parts of the state. The large, barren-looking area is deforested.
Although the land looks barren, it is actually not. While deforestation in the Amazon does occur for extractive purposes, such as acquiring lumber, a lot of deforestation clears land for cattle grazing or perennial agriculture. Most of the seemingly barren terrain is actually pasture or farmland.
The soil quality in the region is poor and quickly depleted of nutrients. As such, it is difficult to regrow Amazon rainforest after it has been deforested. To protect the rainforest, prevention of future deforestation is key.
Add and symbolize the Cities layer
You've found your study area. Now, you'll add a layer showing cities in Rondônia and symbolize it to show the largest cities by population.
- On the Standard toolbar, click the arrow next to the Add Data button and choose Add Data From ArcGIS Online.
- Type Rondonia Cities in the search box and press Enter.
- Find the result titled Rondonia Cities by Learn_ArcGIS and click Add.
The layer is added to the map above the other layers. It contains points of various colors, each representing a city in Rondônia. Most cities are in deforested areas.
- Locate the Cities layer in the Table Of Contents.
Like the Amazon Ecoregion and Brazilian States layers, the Cities layer is in a group by default (the group is called Rondonia Cities).
- In the Table Of Contents, right-click the Rondonia Cities group and choose Ungroup.
Unlike the other layers, the Cities layer has four symbols instead of one. Layers can be symbolized based on attribute data. In this case, the attribute is Population_2014. The labels next to each symbol indicate the range of population each symbol represents. The lighter red symbols are for cities with lower populations, while the darker red symbols are for cities with larger populations. You can find the population of each feature using the Identify tool, or you can see the attributes of all features with the layer's Attribute Table.
- In the Table Of Contents, right-click the Cities layer and choose Open Attribute Table.
In the Attribute Table, attributes are organized into columns, or fields, and features are organized into rows.
The fields give the name of each city, its 2014 population, its latitude, and its longitude. The OBJECTID and Shape fields are managed by the software. The populations of the 52 cities in Rondônia range between 2,000 and 500,000.
- Close the table.
Symbolizing the cities by color is okay, but it would be more intuitive if the cities were symbolized by size, with larger symbols indicating larger populations.
- In the Table Of Contents, right-click the Cities layer and choose Properties.
The Layer Properties dialog box opens. This dialog box includes more symbology options than the Symbol Selector you used earlier.
- At the top of the Layer Properties dialog box, click the Symbology tab.
The symbols are set by Quantities, which classifies attribute values into ranges and gives each range a unique symbol. Currently, those symbols have graduated colors, but they can be given graduated symbol sizes instead.
- Under Quantities, click Graduated symbols.
The symbols retain their ranges and labels, but now have random default graduated symbols. Next, you'll change the size and color of the symbols.
- Click the Template button.
The Symbol Selector opens.
- In the list of preset symbols, click Circle 2.
- Change the color to Arctic White.
- Click OK.
The four circles range in size from 4 to 18 points. The smallest symbol is difficult to see.
- Above the list of symbols and ranges, change the Symbol Size range to be from 8 to 20.
- At the bottom of the Layer Properties dialog box, click OK.
On the map, the largest cities tend to be in the middle of the deforested area, although they range in distribution from north to south. Smaller cities tend to be closer to the edge of the deforestation.
Lastly, you'll change the Population_2014 attribute in the Table Of Contents. Your eventual goal is to share your data as part of a finished map, so renaming the attribute to something more presentable is important.
- In the Table Of Contents, under Cities, click Population_2014 once to select it. Click it a second time to make it editable.
- Type Population (2014) and press Enter.
The attribute is renamed in the Table Of Contents. Its name in the Attribute Table remains unchanged.
Download additional data
You've added reference data to your map. Next, you'll add data to be used in your analysis of the relationship between roads and deforestation. Rather than add this data directly from ArcGIS Online, you'll download it to your computer.
- Go to the Get Started with ArcMap group.
The Get Started with ArcMap group contains one item: a file geodatabase called Rondonia. A geodatabase is a spatial data format that stores geographic data.
- Click the thumbnail of the Rondonia item to download it.
The item downloads as a compressed file folder.
- When the download finishes, find the compressed folder and extract its contents to a location you can easily find.
- In ArcMap, to the right of the map, click the Catalog tab.
The Catalog window opens. The Catalog is a directory of files, tools, servers, and services associated with ArcMap. It allows you to organize and access files for your map. To add geographic data from your computer to a map, you need to connect to the folder where the data is stored.
To keep the Catalog docked to the right of your map, click the Auto Hide button (the pin icon) on the title bar of the Catalog window.
- On the Catalog window toolbar, click the Connect to Folder button.
- Browse to the location of your Rondônia folder. Click the Rondônia folder (not the geodatabase) and click OK.
Depending on where you extracted the data, your path will be different than the example images.
The folder is added to the Catalog under Folder Connections.
- Click the plus sign next to the folder connection to expand it. Then, expand Rondônia.gdb.
The extension .gdb stands for geodatabase. In the Catalog, geodatabases have a gray cylinder icon.
The geodatabase contains four feature classes and one raster dataset, which can be added to the map as layers. You'll learn more about raster datasets later. Feature classes are groups of features sharing similar attributes and geometry, like the Brazilian States layer. The term layer refers to a map representation of data, while feature class refers to the file-based data itself. Feature classes come in three main types: point, line, and polygon.
Before you add the data to your map, you'll set the Rondônia geodatabase as the default geodatabase for your map document. The default geodatabase is the location where new datasets are saved by default.
- In the Catalog window, right-click Rondônia.gdb and choose Make Default Geodatabase.
Next, you'll add some data to the map.
Add and symbolize the Roads layer
Next, you'll add a layer of roads. There are two main types of roads in Rondônia: Official roads, built by or with the permission of the government, and unofficial roads, built independently of the government. Because your ultimate goal is to determine the potential deforestation caused by a proposed road, looking at existing roads is vital to your final analysis.
- In the Catalog window, drag the Roads feature class to the Table Of Contents, below the Brazilian States layer.
When you add a layer from your computer it has random default symbology. Your symbology may vary from the example images.
The Roads layer contains a dense network of roads that covers most of the state. The layer doesn't extend past the Amazon Ecoregion boundary.
- In the Table Of Contents, right-click the Roads layer and choose Open Attribute Table.
Among the fields are Name and Status. Status shows whether a road is official or unofficial. Unofficial roads do not have names, although official roads might. The number at the bottom of the table reports the total number of features: 27,662. Which roads on the map are official and which are unofficial? You could use graduated symbology options to give each type of a road a unique appearance, or you could use an attribute query to select all features in a layer with a certain attribute.
- On the ArcMap main menu, click Selection and choose Select By Attributes.
The Select By Attributes dialog box opens. It has many options and can look complicated at first. You'll become familiar with its interface before you use it.
In this dialog box, you build a logical expression to determine the attribute by which features will be selected. In the topmost box are the field names in the selected layer. Below it are the logical operators, which define the relationship between two things. To the right of the logical operators is a box that displays the unique values of a field you select, and the bottom box contains the expression.
Using these options, you'll create an expression to find roads where Status = Official.
- For Layer, choose Roads from the list.
- In the list of fields, double-click Status.
The word Status appears in the box at the bottom of the dialog box.
- In the list of logical operators, click the equal sign (=) button.
An equal sign appears next to the word Status. Next, you'll add the unique value of Official.
- Next to the list of logical operators, click Get Unique Values. Double-click 'Official' to add it to the query.
The word Official in single quotation marks appears in the box at the bottom. Your query should look like the following image:
- At the bottom of the Select By Attributes dialog box, click OK.
Official roads are selected (highlighted in blue) on the map.
Official roads appear to connect municipalities and facilitate travel between population centers. Although they mostly appear in deforested areas, deforestation does not solely occur in places where there are official roads. There appear to be significantly fewer official roads than unofficial roads.
The ability to see official roads independent of the total road network is useful reference information. However, a selection is not permanent and will be erased if you make another selection or deselect the features. To prevent this, you'll make a new layer based on the selection.
- In the Table Of Contents, right-click the Roads layer, point to Selection, and choose Create Layer From Selected Features.
The Roads selection layer is created and added to the top of the Table Of Contents.
- On the Tools toolbar, click the Clear Selected Features button.
The original selection is cleared. It may have the same symbology as the original Roads layer, so you may not be able to see it in the map.
- In the Table of Contents, click the symbol for the Roads selection layer to open the Symbol Selector. Scroll through the preset symbols and click the Stacked Multi Roadway symbol.
- Change the color to Seville Orange.
- Click OK.
The official roads cover up the cities. Also, the Roads selection layer should be renamed to better reflect what it shows.
- In the Table of Contents, click the name of the Roads selection layer to edit it. Change the name to Official Roads.
- Drag the Roads selection layer below the Brazilian States layer and above the original Roads layer.
Lastly, you'll change the symbology of the original Roads layer.
- In the Table Of Contents, click the symbol for the Roads layer to open the Symbol Selector. In the list of symbols, click the Arterial Street symbol.
- Change the color to Raw Umber.
- Click OK.
The difference between official and unofficial roads is clear. Unfortunately, the unofficial roads still clutter the map. Because the official and unofficial roads are now in separate layers, you can turn off the Roads layer to temporarily hide it while keeping the Official Roads layer visible.
- In the Table Of Contents, uncheck the box next to the Roads layer.
You can turn the layer back on at any time by checking the box again. For now, you'll leave it off.
Save the map
Next, you'll save your map so you can return to it at any time.
- On the Standard toolbar, click the Save button.
The Save As dialog box opens.
- Name the map Amazon Deforestation and save it in the same location as the Rondônia folder that you downloaded.
The map document is saved with the extension .mxd, which is the standard extension for ArcMap map documents.
You've started a new map and added boundary layers to locate your study area. You added layers of infrastructure that will be important for analysis and general map information. Next, you'll take a closer look at the relationship between deforestation and roads to find a pattern you can apply to the proposed road.
Compare roads and deforestation
Now that you've familiarized yourself with the study area, you'll take your analysis a step farther. First, you'll add a layer showing the extent of deforestation. Then, you'll quantify the percentage of land that is deforested within a certain distance from roads. By finding the relationship between existing roads and deforestation, you'll later be able to estimate the deforestation prevented by the proposed road's prohibition.
Although you looked at deforestation in the last lesson, now you'll begin a more thorough exploration in order to understand existing deforestation patterns in Rondônia. You'll start by adding a layer that shows deforestation in the state.
- If necessary, open your Amazon Deforestation map document in ArcMap.
- In the Catalog window, drag the Deforested_Area layer to the Table of Contents, below the Roads layer.
- In the Table Of Contents, click the symbol for the Deforested Area layer. In the Symbol Selector, change the symbol's Fill Color to Lime Dust.
- Change the Outline Color to No Color.
- Click OK.
The layer has only one feature. This is a multipart feature: a feature composed of many noncontiguous elements. Deforestation typically occurs in small parcels, not large unbroken swaths. At this map scale, it's difficult to see deforestation in much detail. You'll zoom in to look closer, but first you'll bookmark the current map extent. With a bookmark, you can quickly navigate to specific map extents.
- On the ArcMap main menu, click Bookmarks and choose Create Bookmark.
The Create Bookmark dialog box opens.
- Change the bookmark name to Rondonia and click OK.
- On the Tools toolbar, click the Zoom In tool.
When you move the pointer over the map, it becomes a magnifying glass.
- Draw a rectangle around the area of deforestation in northwestern Rondônia.
The map zooms to the extent of the rectangle. Once zoomed in, you can see the deforestation in more detail. Deforestation is often patchy, like in the following image:
Typically, small strips of forest are deforested through a process called slash-and-burn agriculture. In slash-and-burn-agriculture, small farmers cut and burn plots of forest to create fields. The burned biomass serves as fertilizer for agriculture on the cleared land. This agricultural technique has been practiced for centuries throughout the world, including the Amazon. In small amount, slash-and-burn agriculture can be sustainable. But when widespread, massive areas are cleared in a small amount of time, it can drastically affect an ecosystem.
Next, you'll compare the Deforested Area layer to the visible deforestation on the Imagery basemap. To see both the layer and the basemap at the same time, you'll use transparency.
- In the Table Of Contents, double-click the Deforested Area layer.
- In the Layer Properties dialog box, on the Display tab, change the Transparent setting to 50 percent.
The higher the percentage, the more transparent the layer will be.
- Click OK.
If you have difficulty seeing the basemap through the transparent layer, you can also turn the Deforested Area layer on and off to compare.
You can see where visible deforestation overlaps with areas in the Deforested Area layer. However, some parts of the layer do not seem to coincide with deforestation visible on the basemap, especially areas close to untouched rainforest. Deforestation is a constantly changing process and the basemap may not have been updated to show its most recent occurrences.
If you want to know the last time the basemap or the Deforested Area layer was updated, you can view the layer's metadata. Metadata explains when data was collected and by whom it was collected, among other things. To see the metadata of a part of the basemap, use the Identify tool to click the map (make sure you are identifying from the World_Imagery layer by choosing it at the top of the Identify dialog box). The SRC_DATE2 field gives the date of the imagery for that portion of the basemap. To see the metadata for the Deforested Area layer or any other feature layer on your map, right-click the layer in the Table of Contents and choose Data > View Item Description.
Another noticeable pattern is that deforestation sometimes ends abruptly with fairly sharp boundaries, as in the following image:
In the above example, the boundaries are defined by protected areas, which either prohibit or greatly restrict deforestation. Protected areas come in two types: protected forests and indigenous territory. Feature classes for both categories are in the Project Data geodatabase. You are welcome to add them both to explore, but for this project you only need the data on protected forests.
- On the ArcMap main menu, click Bookmarks and click Rondonia.
- In the Catalog window, add the Protected_Forests layer to the Table Of Contents, below the Roads layer.
The Protected Forests layer covers the layers under it. You'll change the symbology and make it transparent.
- In the Table Of Contents, click the symbol for the Protected Forests layer. In the Symbol Selector, scroll through the list of symbols and click the Pink symbol.
- Click OK. Open the Layer Properties dialog box of the Protected Forests layer.
- Change the transparency to 60 percent and click OK.
The protected areas seem to be an effective deterrent of deforestation. Now that you can see one of the preventative measures against deforestation, you'll investigate its causes. In the previous lesson, you turned off the Roads layer because the dense road network obscured other layers on your map. Now, you'll take a closer look at those roads to see how they relate to deforestation.
- In the Table Of Contents, check the Roads layer to turn it on.
- Zoom back to the area in the northwest part of the state.
If you have not navigated anywhere else or closed ArcMap since the last time you zoomed in, you can use the Go Back To Previous Extent button on the Tools toolbar.
- Pan and zoom around the map, paying attention to the distribution of roads and deforestation.
There is a strong relationship between roads and deforestation. In fact, 95 percent of deforestation in the Amazon rainforest occurs within 5.5 kilometers of a road. Roads allow access to the otherwise impenetrable rainforest and facilitate the transportation of lumber. Unlike official roads, which connect cities, unofficial roads access deeper areas of the rainforest and connect rural properties.
Your goal is to estimate how much deforestation a proposed road would cause if its construction were allowed. To make this estimate, you'll first find how much deforestation is associated with existing roads.
- Return to the Rondonia bookmark.
Select a sample area to analyze
Before you begin your analysis, you'll select a sample area of the existing road network. The road network is massive, with over 20,000 features. Performing analysis on the entire thing would take a lot of time. Selecting a sample area may affect your results slightly, but not much.
- In the Table Of Contents, turn off all layers except the Roads layer and the Imagery basemap.
To quickly turn off all layers, right-click Layers at the top of the Table Of Contents and choose Turn All Layers Off. Then, turn on the Roads layer and the basemap.
To select a sample of the Roads layer, you'll use the Select tool. The Select tool selects features from all selectable layers. Turning off the other layers makes them unable to be selected, ensuring that only features in the Roads layer will be selected. The basemap has no features, so it has nothing to select.
- On the Tools toolbar, click the Select Features tool.
If you click the arrow next to the Select Features tool, you can choose from several selection methods. Clicking the Select Features tool will use the Select by Rectangle method by default.
- On the map, draw a box around the northwest portion of the state.
Your selection does not have to match the above image exactly.
The features within the box are selected in the map.
Some roads that extend outside the selection area are selected. If part of a feature is in the selection area, the entire feature is selected.
- On the ArcMap main menu, click Selection and choose Zoom To Selected Features.
The map zooms to the extent of your selection. Some of the selected roads, particularly on the northern end of your selection, are not near visible deforestation (you can turn on the Deforested Area layer to confirm). Other roads are inside very dense deforestation. Overall, your selection gives a general representation of the roads in this area.
Find deforestation near existing roads
Next, you'll begin your analysis. To estimate the impact of the proposed road, you'll first determine the impact of existing roads. You'll measure this impact by the percentage of area around roads that is deforested. To find this percentage, you'll create a buffer around your roads selection and compare the buffer's area to the area of deforestation inside the buffer.
- On the ArcMap main menu, click Geoprocessing.
The Geoprocessing menu expands. This menu contains six of the most commonly used geoprocessing tools, as well as options to find and use tools. Geoprocessing tools are operations that manipulate geographic data. Typically, they take an existing dataset as their input and run a process to transform it into a new output.
- In the Geoprocessing menu, click Buffer.
The Buffer dialog box opens. In this dialog box, you'll set your input dataset and a few parameters needed to run the tool. One of those parameters sets the distance of your buffer, or how far away from the input features the buffer area will extend. You already know that 95 percent of deforestation in the Amazon occurs within 5.5 kilometers of roads. This is a good distance for your buffer, as relatively little deforestation occurs beyond this distance.
For an explanation of either the tool or a parameter in the tool, click the Show Help button in the lower right of the tool window.
- In the Buffer dialog box, for Input Features, choose Roads.
When you choose a layer as your Input Features, only selected features are used as the input. If no features are selected, all features are used.
If you want to use a layer that is not in your Table Of Contents as your input, use the Browse button and browse to the location of the data.
- For Output Feature Class, confirm that the output location is the Rondônia geodatabase.
The name of the output feature class is at the end of the text string. In this case, it is Roads_Buffer. You can change the default name by replacing it in the text box, but this name is fine.
- For Distance, in the Linear unit text box, type 5500.
The default measurement unit is meters; 5,500 meters equals 5.5 kilometers. Alternatively, change the measurement unit to kilometers and type 5.5 in the box.
The only other parameter you need to change is the Dissolve Type. By default, the Buffer tool creates a buffer for each feature in the input layer. Because your Roads layer selection has many features and those features are very close together, the Buffer tool would create a large number of overlapping buffer features. By changing the Dissolve Type parameter, the Buffer tool will create a single feature as its output.
- For Dissolve Type, choose All.
- At the bottom of the Buffer dialog box, click OK.
The Buffer tool runs. When the process finishes, the result layer is added to the map.
When the output of a geoprocessing tool is added to the map, it has random default symbology. Your symbology may be different than that in the example images.
Next, you'll find how much deforestation falls within this buffer zone.
- In the Table Of Contents, drag the Roads_Buffer layer below the Deforested Area layer. Turn on the Deforested Area layer.
- On the Tools toolbar, click the Clear Selected Features button to deselect all features.
- Compare the Deforested Area and Roads_Buffer layers.
If the default symbology of the Roads_Buffer layer makes the Deforested Area layer difficult to see, change the symbology of the buffer layer.
A significant portion of the buffer overlaps with the Deforested Area layer, although not uniformly. The northwestern part of the buffer has many areas that are near roads but have relatively little deforestation.
To calculate the percentage of the buffer that is deforested, you'll need a layer of deforestation within the buffer. You can create this layer using a geoprocessing tool called Clip. The Clip tool clips the extent of one layer to the extent of another.
- On the ArcMap main menu, click Geoprocessing and choose Clip.
The Clip dialog box opens.
- For Input Features, choose Deforested Area.
- For Clip Features, choose Roads_Buffer.
- For Output Feature Class, confirm that the output will be saved to the Rondônia geodatabase with the name Deforested_Area_Clip.
- Click OK.
After the tool finishes, the layer is added to the map.
Calculate the percentage of deforested area near roads
You've created two layers. One shows the area within 5.5 kilometers of the roads in your sample area. The other shows deforestation within that buffer. Your next goal is to calculate the percentage of the buffer that is deforested. To find the percentage, you'll calculate a new attribute field.
- In the Table Of Contents, right-click the Deforested_Area_Clip layer and choose Open Attribute Table.
The layer has two fields of geometry that are automatically created for all polygon feature classes: Shape_Length (perimeter) and Shape_Area.
- Examine the Shape_Area field.
Because the area is based on the sample roads you selected, your area values (and all subsequent values you calculate from them) will probably differ from the example images.
The unit of measurement is not given in the table, but specified in the layer's coordinate system information.
- Leave the attribute table open and open the Layer Properties dialog box of the Deforested_Area_Clip layer.
- On the Source tab, under Data Source, scroll down to the projection information.
The projection of the data is South America Albers Equal Area. Output layers made from geoprocessing tools use the same projection as their input. Below the projection name is technical information about the projection, including its linear unit (the unit of measurement used by the projection). For the South America Albers projection, the linear unit is meter. Thus, the Shape_Area field in the attribute table is in square meters.
- Close the Layer Properties dialog box and return to the attribute table.
- Right-click the Shape_Area value and choose Copy.
Copying the area will allow you to use it while you look at the Roads_Buffer table.
- In the Table of Contents, right-click the Roads_Buffer layer and choose Open Attribute Table.
The table opens in a new tab on the table that is already open. Like the Deforested Area Clip layer, the Roads Buffer layer has a Shape_Area attribute. You'll add a new field and use both area values to find the percentage.
- On the table's toolbar, click the Table Options button and choose Add Field.
- In the Add Field dialog box, for Name, type Percent_Deforested. For Type, choose Double.
The field type determines what kind of values the field can have. The Double type allows numerals with decimals.
Field names can only have text, numerals, and underscores. You can create a field alias that contains other characters. The field alias is displayed in the table, while the actual name is stored in the data.
- Under Field Properties, click the box next to Alias and type Percent Deforested, with no underscore.
- Click OK.
The Percent Deforested field is added to the end of the attribute table. It has <Null> as its value. <Null> is the default value for new fields and is equivalent to having no value. To add a value, you can edit a table cell directly or create an equation to calculate values.
- Right-click the Percent Deforested field and choose Field Calculator.
A warning explains that you are about to calculate outside of an edit session.
- Click Yes to ignore the warning.
The Field Calculator opens. The Field Calculator is similar to the Select By Attributes dialog box in that it prompts you to build an expression. It gives you standard mathematical operators and functions as well as existing fields in the attribute table to help build your expression. To find the percentage, you'll divide the area of the Deforested_Area_Clip layer by the area of the Roads_Buffer layer and multiply the result by 100.
- In the Field Calculator, in the text box at the bottom of the window, paste the area value that you copied from the Deforested_Area_Clip attribute table.
- In the list of mathematical operations, click the division button.
- Under Fields, double-click Shape_Area.
The Shape_Area field is added to the equation after the division symbol. To express the value as a percentage, you'll multiply it by 100.
- In the list of operations, click the multiplication button to add it to the equation.
- In the equation, after the multiplication symbol, type 100.
The initial area value in your expression may be different than the example.
- At the bottom of the Field Calculator, click OK.
The Percent Deforested field is calculated. Based on the example area values, the value returned was about 46 percent. Your value may differ, but probably not by more than a couple of percentage points.
You now know the percentage of land within 5.5 kilometers of roads that is deforested. If a new road were built in this sample area, you could predict that a similar percentage of land within 5.5 kilometers of that road would become deforested.
Now that you have this value, the Deforested_Area_Clip layer is no longer necessary. You'll remove it from your map. You'll keep the Roads_Buffer layer because it has the percentage value in its attributes, but you'll turn off the layer.
- Close the attribute table. In the Table Of Contents, turn off the Roads_Buffer layer. Right-click the Deforested_Area_Clip layer and choose Remove.
The layer is removed from the map. The feature class still exists in the Rondônia geodatabase.
- Return to the Rondonia bookmark and save the map.
You've looked at deforestation in Rondônia and determined its relationship to roads. Ultimately, you determined the percentage of land around roads that is deforested. Next, you'll apply that percentage to the proposed road to estimate how much deforestation was prevented by the road's prohibition.
Predict the impact of the proposed road
Now that you've calculated the percentage of deforested area within 5.5 kilometers of roads, you'll use that percentage to estimate the area in square kilometers that would have been deforested if a proposed road were built. You'll first digitize, or draw, the proposed road as a new feature class based on an image of the road. Then, you'll buffer the road and calculate the predicted deforestation area using its attribute table.
Add an image of the proposed road to the map
The proposed road is in neither roads layer, because those layers only show existing roads. You'll add an image of the proposed road to the map and create your own feature based on the image. This image came as a raster dataset in the Rondônia geodatabase. A raster dataset is an image composed of a grid of pixels. The Imagery basemap in your map is also a raster image. Your other data is called vector data.
- If necessary, open your Amazon Deforestation map document.
- Drag the Proposed_Road layer from the Rondônia geodatabase to the Table Of Contents, placing it below the Deforested Area layer.
Instead of a symbol, the Proposed_Road layer has three color bands. These bands determine the color of each pixel in the image's raster grid.
- Turn off all layers except the Proposed_Road layer and the basemap. In the Table Of Contents, right-click the Proposed_Road layer and choose Zoom To Layer.
The map zooms to the extent of the layer.
The image shows a topographic view of the area, with features such as national boundaries, some existing roads, mountainous terrain, and rivers. The proposed road is a thick line in the middle of the image.
- Turn on the following layers: Cities, Official Roads, and Protected Forests.
The proposed road connects two official roads, with cities near both endpoints of the road. You can use the Identify tool to find out the names of each city, or you can temporarily turn on labels.
- In the Table Of Contents, right-click the Cities layer and choose Label Features.
Each city on the map is labeled with its name. The labels indicate that the cities the road will connect are Guajará-Mirim to the west and Campo Novo de Rondônia to the east. The proposed road also crosses two protected areas: the Guajará-Mirim state park and the Rio Ouro Preto Extractive Reserve. The road was prohibited because it would have gone through these areas.
- Right-click the Cities layer again and choose Label Features to turn off labels.
- Turn on the Roads layer.
Some portions of the proposed road, especially at the ends of the road, coincide with existing unofficial roads. As you draw the proposed road feature, you'll trace these existing roads where appropriate.
- On the ArcMap main menu, click Bookmarks. Create a bookmark called Proposed Road.
Create a new feature class
Using the image as a guide, you'll digitize the proposed road as a feature. You could digitize the proposed road as part of one of your roads layers, but that would alter reliable data with a feature representing a road that does not actually exist. Instead, you'll create a new feature class.
- In the Catalog, right-click the Rondônia geodatabase, point to New, and choose Feature Class.
The New Feature Class dialog box opens.
- For Name, type Planned_Road (with the underscore). For Alias, type Planned Road (with no underscore).
The name cannot be the same as any other item in the Rondônia geodatabase, so you'll go with Planned Road instead of Proposed Road.
- For Type, choose Line Features.
- At the bottom of the New Feature Class window, click Next.
Next, you'll choose the feature class's coordinate system. A coordinate system defines positions and measurement values of geographic features on a map. You'll learn more about coordinate systems later in the project. For now, you'll use the coordinate system used by the layers already on your map, which you can quickly choose from the list.
- In the list of coordinate systems, expand the Layers folder. Click South America Albers Equal Area Conic.
You can check which layers use which projection by clicking the plus sign next to the projection's name. The South America Albers Equal Area Conic projection is used by all your layers except the basemap, which uses the WGS 1984 Web Mercator (Auxiliary Sphere) projection.
- Click Next.
The next part of the New Feature Class dialog box allows you to specify XY tolerance. XY tolerance defines how close two coordinates must be to be considered the same coordinate. The default value is fine.
- Click Next.
The next parameter is for database storage configuration. You don't have to worry about this parameter.
- Click Next.
Lastly, you'll add the attribute fields. The Planned_Road feature class should have attribute fields like the existing Roads feature class. Although you can manually create fields by entering names and data types, you can also import attributes from an existing feature class.
- Click the Import button.
- In the Browse dialog box, browse to the Rondônia geodatabase. Click the Roads feature class and click Add.
The list of fields populates with the fields of the Roads feature class: Name and Status.
- Click Finish.
The Planned_Road feature class is created in the Rondônia geodatabase and added to the map as a layer. It currently has no features.
Digitize the proposed road
To add a feature of the proposed road, you'll use the image as a reference and trace the unofficial roads that coincide with the road's location. To start digitizing a feature, you'll begin an editing session.
- In the Table Of Contents, right-click the Planned Road layer, point to Edit Features, and choose Start Editing.
An editing session begins and the Editor toolbar is turned on, showing several options for editing. The Edit tool is active by default. The Edit tool selects or moves features from any editable layer. This tool is useful for modifying existing features, but doesn't create new features.
Any toolbar can be moved by dragging it around the ArcMap window. If moved to the top of the window, the toolbar will dock.
- On the Editor toolbar, click the Create Features tool.
- In the Create Features window, click the Planned Road template.
The pointer changes to crosshairs, allowing you to draw features. Before you begin, you'll explore some drawing behavior.
- Point to some of the features on the map (don't click anything yet).
The pointer is pulled toward features. This behavior is called snapping. Snapping makes it easy to connect new features to other features. However, it makes it difficult to create features that are close to other features but don't touch exactly. Because the planned road connects to the Official Roads, Roads, and Cities layers, snapping will be useful. However, you'll turn off other feature layers so you don't accidentally snap to them while digitizing.
If snapping is not enabled by default, turn on the Snapping toolbar by clicking Customize, pointing to Toolbars, and choosing Snapping. On the Snapping toolbar, click Snapping and choose Use Snapping.
- Turn off the Protected Forests layer.
The only visible layers are the basemap, the image, the Cities layer, and all three roads layers.
- On the Editor toolbar, click the Trace tool.
The Trace tool traces an existing feature, making it useful for the portions of the proposed road that overlap sections of existing roads.
- Use the scroll wheel on your mouse to zoom to the left endpoint of the proposed road.
If you use the Zoom In tool, you'll have to reselect both the Planned Road feature template and the Trace tool after you zoom in. Alternatively, use keyboard shortcuts to make certain tools active without changing the selected tool on the toolbar. Hold the C key to make the Pan tool active. While holding the C key, hold the Shift key to make the Zoom In tool active, allowing you to draw a box on the map to zoom in. When you release the C and Shift keys, the Trace tool will become active again.
- Confirm that Trace is the active tool and click the left endpoint of the proposed road, snapping to where it touches the nearby official road.
Once you click the endpoint, the pointer immediately starts tracing any existing features you hover over.
- Trace the unofficial road that coincides with the proposed road on the image.
If you reach the edge of the map extent, hold the C key to make the Pan tool active, pan to the right, and release the C key to resume tracing.
- When you reach the end of the unofficial road that overlaps with the proposed road, click the endpoint to finish tracing.
After you click, a feature with the current symbology of the Planned Road layer appears on the map. Green squares on the line indicate vertices and the red square indicates the endpoint.
The next section of the road doesn't coincide with existing features. You'll draw the next section with the Straight Segment tool.
- On the Editor toolbar, click the Straight Segment tool.
The pointer changes to crosshairs and is connected to the endpoint by a line.
- At the next bend in the proposed road, click to add a vertex.
If the cursor snaps to the nearby unofficial road when you place your vertex, temporarily disable snapping by holding the spacebar.
A new segment is added and the endpoint (the red square) moves to the location you clicked.
- Use the Straight Segment tool to draw the next section of the proposed road, placing a vertex at each bend in the road. Place the last vertex where the proposed road joins up with an unofficial road again.
For the final section of the proposed road, you'll trace another existing feature.
- Click the Trace tool. On the map, click the last vertex you added and trace until you reach the right endpoint of the proposed road, where it connects to an official road.
- Double-click the endpoint to finish the feature.
The proposed road feature is selected and the vertices disappear.
- Return to the Proposed Road bookmark and confirm the entire length of the proposed road is digitized.
If you're satisfied with your road, you'll save your edits. Until you save your edits, all of your edits can be undone by ending the editing session or exiting ArcMap. Even if you save the map document, your edits will remain unsaved.
If you don't like how your road turned out, you can either discard the edits by ending the editing session and redoing the drawing, or edit individual vertices in the road with the Edit Vertices tool on the Editor toolbar.
- On the Editor toolbar, click Editor and choose Save Edits.
Don't stop editing yet. You'll make more edits in the next section.
- Close the Create Features window. In the Table Of Contents, remove the Proposed_Road layer.
- On the Tools toolbar, click Clear Selected Features.
Symbolize and add attribute data to the proposed road
The proposed road has been digitized, but it uses the default symbology of the Planned Road layer, which is thin and difficult to see on the map. Also, while you added attribute fields when you created the feature class, those fields have no attribute data.
- In the Table Of Contents, drag the Planned Road layer below the Official Roads layer.
- Double-click the Planned Road layer to open its Layer Properties. Click the Symbology tab.
You'll give the proposed road symbology similar to that of the existing roads, but it should also be distinct and attention-grabbing. You'll import the symbology from the Official Roads layer and alter it to make it stand out.
- At the upper right of the Symbology tab, click Import.
- In the Import Symbology dialog box, confirm that Official Roads is chosen and click OK.
The orange line appears on the Symbol button. The only change you'll make to the symbol is its color.
- Click the Symbol button.
- In the Symbol Selector, for Current Symbol, change the color to Cherry Cola.
- Click OK. In the Layer Properties dialog box, click OK.
Next, you'll add attribute data to the proposed road feature.
- In the Table Of Contents, right-click the Planned Road layer and choose Open Attribute Table.
The digitized feature is the layer's only feature. Apart from the OBJECTID, SHAPE, and SHAPE_Length fields, the layer has attribute fields for Name and Status. Neither field has attribute data.
If you are in an editing session, you can directly edit attribute tables. You should be in an editing session from the previous section. If not, start an editing session using the Editor toolbar.
- In the attribute table, double-click the <Null> value in the Name field to edit it. Type BR 421 and press Enter.
BR 421 is actually the name of an existing highway that connects the major municipality of Ariquemes to Campo Novo de Rondônia. The proposed road would have extended the highway to the western part of the state.
- In the Status field, double-click the <Null> value and type Proposed. Press Enter.
- On the Editor toolbar, click Editor and choose Save Edits.
- Click Editor again and choose Stop Editing.
- Close the attribute table.
Find the potential deforestation of the road
Next, you'll estimate the deforestation the road would have caused. In the previous lesson, you determined the percentage of land that was deforested 5.5 kilometers from a selection of existing roads. To find a total area (not a percentage) of potential deforestation around the proposed road, you'll buffer the Planned Road layer to the same 5.5-kilometer distance and multiply the buffer area by the percentage of deforestation observed around existing roads. You'll also remove areas of existing deforestation so they won't be included in your total.
- On the ArcMap main menu, click Geoprocessing and choose Buffer.
- For Input Features, choose Planned Road. Confirm that the Output Feature Class will be saved to the Rondônia geodatabase with the name Planned_Road_Buffer.
- For Distance, type either 5500 (for meters) or 5.5 (for kilometers).
- Click OK.
The tool runs and the buffer is added to the map.
The Planned_Road_Buffer layer covers some areas that already have roads and deforestation, although it's difficult to tell because of the layer's order on the map.
- In the Table Of Contents, move the Planned_Road_Buffer layer below the Deforested Area layer.
- Turn on the Deforested Area layer and compare existing deforestation to the buffer.
If the Deforested Area layer is difficult to see on top of the buffer, change the buffer's symbology to a darker color.
There are some areas where deforestation has already occurred. You don't want to include already deforested areas in your analysis. You'll remove existing deforestation from the buffer with the Erase tool. The Erase tool subtracts parts of one layer that overlap another layer.
The Erase tool is not one of the tools that can be accessed from the Geoprocessing menu. Instead, you'll search for the tool.
- On the ArcMap main menu, click Geoprocessing and choose Search For Tools.
The Search window opens.
If you haven't used the Search window before, it will open on top of the Catalog. You can return to the Catalog by closing the Search window or using the tabs at the bottom of the window. Like the Catalog and Create Features windows, the Search window can be moved and docked anywhere in the ArcMap application window.
- In the search box at the top of the Search window, type Erase and press Enter. Click the result called Erase (Analysis).
The Erase dialog box opens.
- For Input Features, choose Planned_Road_Buffer. For Erase Features, choose Deforested Area.
The tool will take the Input Features and subtract from them areas that overlap with the Erase Features. In this case, it will remove areas of deforestation from the buffer.
- Confirm that the Output Feature Class will be saved to the Rondônia geodatabase. Replace the default output name of Planned_Road_Buffer_Erase with Erased_Buffer.
- Click OK.
The tool runs and the layer is added to the map.
The Erased_Buffer layer is a single multipart feature. To find out how much of this area would have been deforested, you'll multiply the area by the percentage value you obtained earlier. This value is stored in the attribute table of the Roads_Buffer layer.
- In the Table Of Contents, right-click the Roads_Buffer layer and choose Open Attribute Table.
- Right-click the value in the Percent Deforested field and choose Copy.
- Open the attribute table for the Erased Buffer layer.
You'll add a new field to estimate the deforestation of the buffer around the proposed road. You'll then multiply the total area by the percentage value you just copied. You'll also convert the area from square meters to square kilometers so the value is appropriate for what it measures.
- On the table's toolbar, click the Table Options button and choose Add Field.
- In the Add Field dialog box, for Name, type Potential_Deforestation. For Type, choose Double. For Alias, type Potential Deforestation (sq. km).
- Click OK.
The field is added to the attribute table. Next, you'll use the Field Calculator to find the estimated deforested area in square kilometers.
- Right-click the Potential Deforestation (sq. km) field name and choose Field Calculator. When the edit session warning opens, click Yes to continue.
The Field Calculator opens. The expression for this field is more complicated than the last equation because you also want to convert the square meters of the SHAPE_Area field to square kilometers. One kilometer equals 1,000 meters, which means that one square kilometer equals 1 million meters.
- Under Fields, double-click SHAPE_Area to add it to the expression box at the bottom of the Field Calculator. Click the division button and type 1000000.
- Add parentheses around the equation. After the closing parenthesis, add a multiplication symbol and paste the percentage value.
Your value is still expressed as a percentage, so you'll divide the percentage by 100.
- After the percentage value, add a division symbol and type 100. Add parentheses around this part of the expression as well.
- Click OK.
According to this analysis, approximately 623 square kilometers were saved by the cancelling of the proposed road. Your value may be slightly different.
- Close the attribute table, return to the Rondônia bookmark, and save your map.
Although your value may vary from the example, the overall story remains unchanged. If the proposed road had been constructed, several hundred square kilometers of land would have become deforested, much of that land in untouched rainforest. In addition to the deforestation that would occur directly as a result of the road, even more natural forest may be lost due to unofficial roads branching from the road or the conversion of surrounding land to private holdings.
This analysis predicted the impact of a road that was never built. The process used for the analysis could be adapted to other locations in the Amazon in order to predict the impact of future roads. Not all proposed roads end up being prohibited, so understanding the deforestation a road may cause can be a key piece of information for balancing economic and ecologic concerns.
Additional questions could guide an impact analysis. For instance, is there a difference between the deforestation caused by official and unofficial roads? Are there additional factors, such as terrain and the protection status of the land, that affect deforestation? How does changing the sample area of existing roads affect the ultimate outcome of the analysis? You can use ArcMap to explore these questions on your own.
You've predicted the amount of deforestation caused by a proposed road. Next, you'll present your findings with a print map that can be saved and shared.
Finish and print the map
Now that you've estimated the amount of deforested area that would have occurred if a proposed road had been built, you'll present your results as part of a finished map layout that you can print or export to a shareable file format. Because you intend to share your finished map with others, it should be presentable and clear. In addition to the map of Rondônia itself, you'll add the following:
- A map legend
- A title and description
- An inset map that shows Rondônia's location in the world
Finally, you'll print or export your map to share your findings with the world.
Prepare the map layout
So far, you've worked in Data View, a map view that allows you to best explore the data layers on your map. To prepare your print map, you'll switch to Layout View, which allows you to see the arrangement of map elements such as legends, scale bars, or titles. Before you switch views, you'll turn on certain layers so that important reference information is visible on your map.
- If necessary, open your Amazon Deforestation map document.
- In the Table Of Contents, turn layers on and off so only the following layers are turned on:
- Amazon Ecoregion
- Brazilian States
- Official Roads
- Planned Road
- Protected Forests
- Deforested Area
- World Imagery Basemap
- Rename the Planned_Road_Buffer layer At-Risk Area and move it below the Planned Road layer.
- In the Table Of Contents, click the At-Risk Area symbol. In the Symbol Selector, change Fill Color to Solar Yellow and Outline Color to No Color.
- Click OK.
The bright yellow color draws attention to this key part of the map. Next, you'll switch to Layout View and design your map for the printed page.
- On the ArcMap main menu, click View and choose Layout View.
You can also switch between Data View and Layout View by clicking the buttons at the lower left of the map.
The map changes to include a frame and rulers that show the dimensions of the layout. The dimensions are in the default measurement units of your software and may be different than those in the following images.
The default layout isn't very appealing. For starters, the layout is vertical, although the extent of your data is horizontal. Furthermore, the layout has no map elements other than some text in the lower right corner that provides the sources for the basemap. You can navigate the layout using the tools on the Layout toolbar, which opened when you switched to Layout View.
Most of the tools on the Layout toolbar are navigation tools with similar functions as the navigation tools with which you are already familiar, such as Zoom Out and Pan. You can still use the tools on the Tools toolbar to navigate the map within the layout.
- On the Layout toolbar, click the Change Layout button.
The Select Template dialog box opens, showing a list of layout templates. You'll use a template that includes a place for a legend, a title, and an inset map.
- In the Select Template dialog box, click the Traditional Layouts tab. Click the LandscapeModernInset.mxd template and click Next.
The window changes to the Data Frame Order dialog box. A data frame is another name for a map. The template you chose has two data frames, one in the main square and one in the smaller square in the lower right. This dialog box allows you to choose which data frame will be displayed in which square. Currently, you only have one data frame: the Layers data frame, where you have placed all your layers so far. You'll learn more about data frames when you create an inset map later in the lesson. For now, you'll ignore this window.
- Click Finish.
The layout changes to reflect the new template.
Besides the main data frame, which contains your map, the layout has spaces for a title, a legend, a text description, and an inset map.
- On the Layout toolbar, click the Zoom Whole Page button.
The layout zooms to cover the entire page. Take note of the rulers above and to the left of the map. When you applied the new template, the dimensions of the layout changed to 16 by 21 inches (the values may be different if you are using another unit of measurement). These are the default dimensions of the template, but they are much larger than a standard printer paper page.
- On the ArcMap main menu, click File and choose Page and Print Setup.
The Page and Print Setup dialog box opens. You'll change the page dimensions to a standard 8.5 by 11 inches (or 215.9 by 279.4 millimeters).
Before you change the page settings, confirm your printer is set to print pages of these dimensions.
- In the Paper section, for Orientation, click Landscape.
- For Map Page Size, check Use Printer Paper Settings and confirm that the page dimensions change to 8.5 by 11 inches (or equivalent units).
- At the bottom of the window, check Scale Map Elements proportionally to changes in Page Size.
This option ensures the existing map elements are automatically resized to fit the new page dimensions.
- Click OK.
The rulers change to reflect the new dimensions. When the map elements were resized, they moved a little and no longer line up with the layout.
- Right-click any blank space in the Layout View and choose Select All Elements.
Every map element is highlighted with a dashed line and selection handles. If you move any element, all selected elements will move with it.
- Drag the map elements to the center of the page.
Try to keep all map elements (with the exception of the legend, which you'll change in the next section) within the dotted line near the border of the page. This dotted line represents the printer margins.
- When you're satisfied with the position of the map elements, click any blank space in the Layout View to clear the selection.
You've prepared the layout of your final map. Next, you'll change the default map elements, beginning with the legend.
Format the legend
A legend shows what the map's symbols represent. Your default legend is so long it sticks out over the top of the layout. In this section, you'll format the legend so it fits on the layout and conveys information as clearly as possible.
- On the map layout, double-click the Legend. At the top of the Legend Properties dialog box, click the General tab.
The General tab allows you to choose which map layers appear in the legend and in what order. By default, the Legend Items list includes every layer on the map, even layers that are turned off. The left and right arrows add or remove items, while the up and down arrows reorder them.
- In the Legend Items list, click Roads and click the arrow button that points left.
The Roads item is removed from the list and will no longer appear in the legend.
- Remove the following items from the legend:
- World Imagery
- Low Resolution 15m Imagery
- High Resolution 60cm Imagery
- High Resolution 30cm Imagery
Select multiple items at once by holding Ctrl and clicking the items.
After they are removed, the list has the following items:
These items reflect the visible layers. You'll reorder the list so the key elements of your analysis appear at the top and the reference layers appear at the bottom.
- In the Legend Items list, click Cities and click the Move to bottom button (the underlined arrow).
The Cities item is moved to the bottom of the list. You can use these arrow buttons to move legend items up and down or to the top or bottom of the list.
- Rearrange the items in the following order:
- Official Roads
- Planned Road
- Deforested Area
- At-Risk Area
- Amazon Ecoregion
- Brazillian States
- Protected Forests
- At the bottom of the Legend Properties dialog box, click Apply. Move the dialog box so you can see the changes on the legend.
The legend is still too tall. You don't want to remove any more list items, but you can break the legend into two columns. Additionally, the layer name and heading of the Cities item are too large compared to the rest of the text.
- In the Legend Properties dialog box, click the Items tab.
- In the list of legend items on the left side of the tab, click Cities to highlight it. In the Item Columns section, check Place item(s) in a new column.
This setting adds a second column that includes the Cities item. Because the Cities item is larger than the others, organizing your columns this way should give you two similarly sized columns.
- In the list of legend items, right-click Cities and choose Properties.
The Legend Item Properties dialog box opens. In this dialog box, you can change the text symbols used by the legend item. Most of your legend items have only one type of text: the label next to the map symbol. The Cities item has a layer name, an attribute heading, and labels that show the values for each symbol.
- In the Legend Item Properties dialog box, click the General tab. Click Layer Name Symbol.
- In the Symbol Selector, change the font size to 7 and remove the bold style.
- Click OK. In the Legend Item Properties dialog box, click Heading Symbol.
- Change the font size to 6, remove the bold style, and click OK.
- In the Legend Item Properties dialog box, click OK. In the Legend Properties dialog box, click OK.
Next, you'll resize the legend and move it to the middle box in the right column of the layout.
- In the middle box, click the Double-click here to enter text string to select it. Right-click it and choose Delete.
- Click the legend to select it. Drag it to the middle box. Click and drag the selection handles around the legend to resize it to fit the box.
Improve the map's clarity
Next, you'll change details of the map and layout to increase clarity. First, you'll add a title. Then, you'll change the color scheme of the rectangles in the layout to match the map. After that, you'll add a description that explains your analysis and cites your sources. Lastly, you'll change the map's scale and add a scale bar so your audience will understand the size of the area your map represents.
- Double-click the text in the title bar.
The Properties dialog box opens.
- In the Text box, type Deforestation in Rondônia, Brazil and click OK.
To include the circumflex accent mark above the second O in Rondônia, copy the title from the step instruction.
Next, you'll change the colors of the rectangles to match your map.
- Double-click the title bar at the top of the layout (but don't click the title text).
The Properties dialog box opens, with options for the rectangle's appearance.
- Change Fill Color to Lotus Pond Green and click OK.
You'll change the other rectangles to a lighter shade of green.
- Double-click the first rectangle to the right of the map.
The rectangle's Properties dialog box opens.
- On the Frame tab, in the Background section, for Color choose Sage Dust. Click OK.
- Change the color of the second rectangle, which contains the legend, to Sage Dust as well.
If you find it difficult to click the rectangle without clicking the legend, move the legend out of the way, change the rectangle's color, and move the legend back.
Next, you'll add a description to explain the purpose of your map and the results of your analysis. You'll also use it to show the sources of your data.
- Click the top light green rectangle to select it. Click and drag the central bottom selection handle to increase the rectangle's size.
Next, you'll draw a text box in the empty rectangle and type your description.
- On the ArcMap main menu, click Customize, point to Toolbars, and choose Draw.
The Draw toolbar opens. This toolbar has options to draw lines, shapes, and text boxes on your map or layout.
- On the Draw toolbar, click the arrow next to the Text tool and choose Rectangle Text.
- In the green box on the layout, draw a text box that uses most of the available area.
The box has the word Text as its default text.
- Double-click the text box to open its Properties dialog box and click the Text tab. Replace the default text with the following description (or write your own):
This map shows the extent of deforestation in Rondônia, Brazil, and the area that would be at risk of deforestation if a proposed road were built. About 46 percent of the area within 5.5 km of existing roads is deforested. Assuming a similar rate of deforestation, the proposed road would lead to about 623 sq. km of new deforestation.
This description uses the example results, which may differ from your results. Replace the percentage of area near roads and the area of new deforestation values with your own values.
- After the description, press Enter twice to create a line break. Add the following citation:
Data sources: Brazilian Institute of Geography and Statistics, Brazilian National Institute for Space Research, World Wildlife Fund, Imazon, HERE.
- Click Change Symbol. Change the font to Times New Roman and click OK.
- Change the paragraph style from Justify to Align Left.
You'll also remove the default black frame that appears around the text box.
- In the Properties dialog box, click the Frame tab. In the Border section, change the border style to None.
- Click OK.
If your text does not completely fit, your text box may be too small. Either resize the text box or change the font size until all text is visible.
Next, you'll change the map scale and add a scale bar. A map's scale is the relationship between a distance on the map and a distance on the ground. Scale is typically expressed as a fraction or ratio. For instance, in a map with a 1:400 scale, one unit of distance on the map is equal to 400 of the same units of distance in the real world. The scale of your map can be found on the Standard toolbar.
- On the Standard toolbar, click the box that contains the map scale to edit it. Type 4,000,000 and press Enter.
The map zooms to the new scale.
When you rescale the map, your data may become off-center or parts of it may fall outside of the data frame. You can reposition the map in the data frame with the Pan tool on the Tools toolbar.
- On the ArcMap main menu, click Insert and choose Scale Bar.
- In the Scale Bar Selector dialog box, scroll through the list and click Alternating Scale Bar 1 Metric.
Because your analysis was done in metric measurements, you'll use a metric scale bar.
- Click OK.
The scale bar is added to the layout.
- Drag the scale bar to the lower left corner of the map.
The scale bar overlaps with the basemap sources. Resizing the scale bar will change the values it displays.
- Click the central right selection handle and resize the scale bar until the largest value is 200.
The color of the scale bar doesn't show up well on top of the basemap.
- Double-click the scale bar to open the Alternating Scale Bar Properties dialog box. On the Format tab, change both the Text and Bar color to Arctic White.
The scale bar also has a black outline.
- In the Bar section, click Symbol. In the Symbol Selector, change Outline Color to Arctic White and click OK.
- Click Symbol 2. Change Outline Color to Arctic White, and click OK. In the Alternating Scale Bar Properties dialog box, click OK.
Create an inset map
Next, you'll create an inset map. An inset or locator map is a smaller map that shows the geographic location of the main map. Because most people don't know the location of Rondônia, Brazil, an inset map will give your map important geographic context. Your inset map will go in the empty data frame of your layout
To have multiple maps in one layout, each map needs its own data frame. Map documents have only one data frame by default, but you added a second data frame when you applied the layout template. The text in the lower right rectangle gives the name of the new data frame: Layers 2.
- At the bottom of the Table Of Contents, right-click Layers 2 and choose Activate.
Only one data frame can be active at a time.
In the Table Of Contents, the active data frame is in boldface. On the layout, the active data frame is surrounded by a dashed gray line. Now that you've activated the Layers 2 data frame, you can add data to it. The Layers 2 data frame will contain an inset map showing the location of Rondônia. You'll use a reference basemap from ArcGIS Online.
- On the Standard toolbar, click the arrow next to the Add Data tool and choose Add Data From ArcGIS Online.
- In the ArcGIS Online window, type World Physical Map in the search box and press Enter.
- Find the result titled World Physical Map and click Add.
The layer is added to the Table Of Contents under the Layers 2 data frame. In the layout, it appears in the empty data frame.
You want your inset map to locate Rondônia with respect to South America. You'll accomplish this by changing and customizing the map projection. Every data frame has a projection, which is a mathematical method for representing the round earth on a flat surface. Projections differ with respect to what parts of the world they show, which aspect or point of view they present, and the types of spatial distortion they impose on geography.
- In the Table Of Contents, double-click Layers 2 to open the Data Frame Properties dialog box. On the Coordinate System tab, type South Pole Orthographic in the search box and press Enter.
Inside the Polar folder is the single result: South Pole Orthographic.
- Click the South Pole Orthographic projection and click Apply to see how the projection looks in the layout.
When the projection is applied, the map becomes small, round, and focused on Antarctica. The South Pole Orthographic projection gives the world a circular appearance, distorting everything except the location on which the projection is centered. You'll change where the projection is centered.
- In the Data Frame Properties dialog box, right-click the South Pole Orthographic projection and choose Copy and Modify.
The Projected Coordinate System Properties dialog box opens. You'll use this dialog box to create a custom copy of the South Pole Orthographic projection centered on South America.
- In the Projected Coordinate System Properties dialog box, change the name to South_America_Orthographic. Change the Longitude Of Center parameter to -60 and the Latitude Of Center parameter to -15.
The coordinates specify a point just to the south of the state of Rondônia.
- Click OK. In the Data Frame Properties dialog box, click OK.
The projection is centered on South America, but you need to zoom in on the map.
- On the Standard toolbar, change the scale to 205,000,000.
The inset map zooms to the new scale.
- Use the Pan tool on the Tools toolbar to center the map in the data frame.
The inset map is focused on South America, but it doesn't show anything else.
- In the Table Of Contents, drag the Amazon Ecoregion layer from the Layers data frame to the Layers 2 data frame, placing it above the World Physical Map layer. Close the Geographic Coordinate Systems warning.
When you drag a layer from one data frame to another, the layer is copied instead of moved. The Amazon Ecoregion layer now appears in both maps.
Next, you'll add an extent indicator to the inset map. An extent indicator shows the extent of one data frame as an object on another data frame. In this case, you'll show the extent of your Rondônia map on your inset map.
- In the Table Of Contents, double-click the Layers 2 data frame. In the Data Frame Properties dialog box, click the Extent Indicators tab.
- Under Other data frames, click Layers. Click the arrow button that points to the right to add the Layers data frame to the list of data frames that have extent indicators.
- Click Apply. If necessary, click Yes to close the coordinate system warning and add the changes to the inset map.
The extent indicator shows Rondônia's location in South America. Its default appearance is too thick, however.
- In the Data Frame Properties dialog box, under Options - Layers, click the Frame button.
The Extent Indicator Frame Properties dialog box opens.
- In the Border section, click the Style properties button.
The Border dialog box opens.
- Change Color to Black and Width to 2. Click OK.
- In the Extent Indicator Frame Properties window, click OK. In the Data Frame Properties window, click OK. If necessary, click Yes to close the warning.
Next, you'll remove the blue background of the inset map.
- Open the Data Frame Properties dialog box and click the Frame tab. Change the Border and the Background to None.
- Click OK.
Your map is finished.
- Save the map document.
Export the map
Your map is ready to share. You have many options for sharing and distributing a print map: You can print physical copies of the map or you can export the map and distribute the file electronically.
- On the ArcMap main menu, click File and choose Print.
The Print dialog box opens. This dialog box allows you to choose the printer from which to print the document, the output image quality, and the number of copies to print. Make sure you are using a printer using 8.5 by 11 inch paper (or the metric equivalent).
- If you choose to print your map, click OK. If you do not want to print your map, click Cancel.
- Click File again and choose Export Map.
The Export Map dialog box opens. This dialog box allows you to choose an export file type, such as PDF or PNG, and specify an output location. At the bottom of the window, under Options, you can adjust image quality and other settings.
- If you choose to export your map, choose an output location and file type, give the file a new name, and click Save. If you do not want to export your map, click Cancel.
This concludes the lesson Get Started with ArcMap. In this project, you created a map and added data to it, symbolized and modified the data, performed analysis to answer a geographic question, and shared your results in the form of a printable map. This project has been only a taste of the functionality and capabilities of ArcMap. If you're interested in learning more about ArcMap, try the projects Homeless in the Badlands and Mapping the Public Garden.
You can find more lessons in the Learn ArcGIS Lesson Gallery.