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ArcGIS II: Intermediate Map Making for the Social Sciences

Tutorial Goal: This workshop is a continuation of ArcGIS I. The emphasis is on creating and editing data. Topic

covered include tagging, joining tables, buffering, selecting, editing, making new features, merging shapefiles,

using the field calculator, and creating new data. Tools and toolboxes are explored.

First, lets review the important parts of GIS and spatial data that we learned in the last tutorial.

GIS (Geographic Information Systems)

In this lesson, we will learn more uses of a GIS (Geographic Information System). This is a software

package that allows you store, manipulate, analyze and display geographic data. We will be usingArcGIS 9.2, which is produced by ESRI(http://www.esri.com/). This software is available in many labsthroughout Brown, including the CIS computers in the Rockefeller Library.

Layers Tables

GIS in a nutshell: layersand tables. Layers and tables are the building blocks in your use of a GIS, andeverything you do will extend from these two things.

A layeris an overlay that represents a feature. A feature is a group of similar objects. For example, towncan be one feature and roads can be another feature. So, one layer contains towns. Another contains roads

Yet another represents vegetation. Each one is laid one atop another to make the final map.

A tableis the information that is attached to each layer. The information is data in the form of aspreadsheet, where rows represent the cases and the columns represent the variables. So, for the towns

layer, we have a table and each row is a town. The columns are the variables for the towns. They could bsize, location, population, etc. These data about the feature are called an attribute.
http://www.esri.com/http://www.esri.com/


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Projection:A method by which the curved surface of the earth is portrayed on a flat surface (GISDictionary).

Basically, as you see in the picture, you are putting a light under the surface of the Earth and

projectingthe surface of the sphere onto a flat surface.

(http://www.geog.ucsb.edu/~dylan/mtpe/geosphere/topics/map/map1.html)

Every shapefile has a projection, and if you want to work with different ones in the same view, you

have to make sure all the projections are the same.

If you want to learn more about map projections, go to:

http://en.wikipedia.org/wiki/Map_projection http://www.progonos.com/furuti/MapProj/Normal/TOC/cartTOC.html

Now, lets set up our tutorial for today. We are part of the State of Rhode Islands GIS task force in charge ofprotection against terrorist attacks. Our job is to map out and analyze possible threats and our responses to those

threats. We will specifically do the following:

Import location data about special teams and map outwhere they are located in RI.
http://www.geog.ucsb.edu/~dylan/mtpe/geosphere/topics/map/map1.htmlhttp://en.wikipedia.org/wiki/Map_projectionhttp://en.wikipedia.org/wiki/Map_projectionhttp://www.progonos.com/furuti/MapProj/Normal/TOC/cartTOC.htmlhttp://www.progonos.com/furuti/MapProj/Normal/TOC/cartTOC.htmlhttp://www.progonos.com/furuti/MapProj/Normal/TOC/cartTOC.htmlhttp://en.wikipedia.org/wiki/Map_projectionhttp://www.geog.ucsb.edu/~dylan/mtpe/geosphere/topics/map/map1.html


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Using the teams as center points,draw 3-mile circles around each

one and calculate how many

people fall within these circles

and are consequently covered bytheir services.

Import addresses and match them with street

files to create a new layer

First, we need to map out two first responder teams in RI:

Hazard Material Teams (Hazmat)provide assistance in identification and control of hazardous material. Forexample, if some sort of chemical or biological weapon were discovered, they would be called to analyze what so

of bomb it is and how to handle it.

Mass Victim Decontamination Teams (VictimDecon)have trained personnel and equipment to set updecontamination shelter units, showers, water heaters and even a conveyor system for non-ambulatory patients.

Their goal is to clean off victims of chemical or biological weapons so they can be sent to hospitals for propertreatment.


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Lets start by finding all the fire stations in Rhode Island that contain Hazmat Teams. We can do this by taggingallthe cases in the fire station shapefile that have these teams. Tagging is where you create a new field (column)in the table and set a value for those cases that have the item and those that dont. Please unzip and store in your

storage device the data (GISData2)

Ok, lets now do our tagging.

1. In our ArcGIS, 1) click on the add data icon and navigate to your storage device. 2) Add the shapefilestowns(towns.shp in the towns folder), fire stations (firestations.shp in the firestations folder).

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We now have in our view the fire stations and towns of road island.
http://dl.lib.brown.edu/gateway/ssds/GISData2.ziphttp://dl.lib.brown.edu/gateway/ssds/GISData2.zip


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Lets save our project first. Remember, save often so you wont lose work if the system crashes. In the File menuleft-click Save. Name the project Terrorism.

Lets open up the text document with the fire stations that have the list of the Mass Victim Decon teams in Rhode

Island.

1. In your GISData2 folder, open up the Hazmat Team Locations in Rhode Island file. You can see that itcontains the name of each fire department and station if there is more than one station in the department.


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2. Now lets open the attribute table of the shapefile we are going to tag. In ArcGIS, right-click on the firestatioshapefile in the TOC and then left-click the Open Attribute Table.

3. In the Attributes of Firestationstable, right-click on field label Fire-Compa. This field contains the names oall the fire stations. In the pop-up menu, right-click on Sort Ascendingto put the list of names in alphabetical

order A-Z.


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4. In the Attributes table, scroll down to Hope Valley Fire Departmentand select it. You can select it byclicking on the gray block at the very left of the row. Bring up the Hazmat Team Locations text file and have itshowing with the attributes table. You see that these two attributes are the same. So, we have to make a new fiel

for hazmat teams and tag it for Hope Valley to show it has a team.

5. In the Attributes table, left-click the Optionsbutton on the bottom. Left-click on Add Field.


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6. In the Add Fielddialog, type in the new name of the field Hazmat. We can keep theTypeas Short Integersince we are populating the field with numbers. You have other choices, such as Text, to type in words. Click

OK. If you scroll to the right of the table, you see the new field Hazmat has been added.

7. Now we want to show which stations have the Hazmat teams. In the field, we will type a 1 for the stations thahave teams and keep a 0 for those that dont. In order to enter data into the field, we have to Start Editing. 1In the ArcGIS interface, left-clickEditor and then left-click Start Editing. 2) In the Start Editing dialog, youneed to select the shapefile that you are editing. Please select firestations and then click on OK.

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Remember, if a toolbar is

not in the interface, youneed to activate it. Go to

View, select Toolbars andthen left-click Editor.


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8. You now see the title bars of the fields turn white. This signifies that the table is active for editing. But, as yocan see, tables can be awkward to work with if there are many fields. The new field has been added at the very

right of the table, far away from the names of the records. In this case, we need to use the Freeze/UnfreezeColumnfunction, which will hold the field in one set position as you scroll to different ends of the table. 1) Righclick on the Hazmat title bar and then left-click on Freeze/Unfreeze Column. 2) The Hazmat field has been frozeon the left side of the table. You can now scroll to the left and this new field will be stationed next to the

Fire_Compan, so you can easily tag the stations. Using the Hazmat Teams document, type in a 1at each stationthat has a team.

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9. When youre done, close the word document. In ArcGIS, left-click on Editorand then left-click on StopEditing. You will be prompted to save your edits. Click OK. You see the Attribute table turn gray again,signifying that the editor is not active. Close the Attributes table.

So, now we know which fire stations have Hazmat Teams. Also, for our project, we need to know which firestations have Mass Victim Decontamination Teams. These teams decontaminate victims of biohazards, so theycan be brought to medical facilities without risking others with contamination. Each team has a trailer which

contains equipment such as tents and showers for decontamination.

For this, we canjoindata tables. This means that we want to join two separate data tables into one using one fieldin both that is exactly the same, or a common field. So, for example, both tables have a field of fire departmentnames and each case is named exactly the same. Remember, if the cases arent exactly the same, those cases will

not be joined. When you join, the function recognizes the names in the common field as being the same and adds

the data from one table into the case in the other table.

The fire stations that have the Victim Decon teams are stored in an Excel Worksheet in our GISData2 folder.With the new 9.2 version, ArcMap can directly import the Excel spreadsheet into the program. Then we can add

this data file and join it to our fire stations shapefile.


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1. In ArcGIS, click on the add data icon . You see VictimDecon.xls. Double left-click onto the file to see thfile.

2. An Excel file might have several spreadsheets. We wantSheet1$. Double-left click to add it.

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You now see that the TOC switch to theSource tab and that VictimDecon is present. Since this is a data file andnot a shapefile, it can not be listed in the Display tab.

3. Ok, as mentioned before, in order to join two data tables, you need two fields that are exactly the same. In theTOC, open up the attribute table of firestations and Sheet1$. You see there is one field in each, Fire_Compaifirestations and Fire_Departin VictimDecon, with the same identifiers. So, we can use them as common fields.

Close the tables.

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6. Open up the attribute table for firestations and scroll to the right and down. You see the fields from

VictimDecon have now been added. Close the table.

Ok, we now have added new data to our table. We have in the shapefile the fire stations that contain Hazmat and

Mass Victim Decon teams. So, we want to query our data to find exactly which fire stations these are and make aseparate layer for each set of teams. We can use the Select by Attributesfunction to select the fire stations thathave the teams and then Create Layers from Selected Featuresto make a new layer.

First, lets select the Hazmat teams and create a layer for them.

1. In the Selectionmenu, left-click onto Select By Attributes.

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2. In the Select By Attributesdialog, 1) make sure firestationsis selected inLayer. In Methodmake sureCreate a new selectionis selected. 2) Scroll down in your attribute menu and double left-click onfirestations.Hazmatwhich makes it appear in the statement box below. Were going to have to write out ourselection statement.

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3. Now we have to write our query. 1) Click on Get Unique Values. You see 0 and 1. Remember, we setHazmats at 1. 2) Click on the equal sign and then click on 1 to write our query. 3) Click on OK.

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4. Click on the display tab in the TOC. Open up the attributes tables and click on Selected. As you can see in thview and the table, all the fire stations with Hazmat teams have been selected. You can close the table.

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Once you have selected certain cases from one layer, for example fire stations housing Hazmat teams, you can

make them a new and separate layer. So, lets turn these Hazmat fire stations into a different layer.

1. Right-click on the firestations layer in the TOC, and select Selection in the pop-up menu. In the new pop-upmenu, left-click on Create Layer from Selected Features.

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2. You can clear the selected features. As you can see, a new layer firestations selectionhas been added.

3. Its a good idea to label your new layers. 1) Double left-click on the new layer in the TOC and bring up theLayer Propertiesdialog. 2) Click on the General tab, and in Layer Name, name the new layerHazmat Teams3) Click OK.

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We have a layer for the Hazmat teams, but we also need a layer for the Victim Decon teams.

1. In the Selectionmenu, left-click onto Select By Attributes.

2. In the Select By Attributesdialog, delete the former statement. 1) scroll down and selectSheet1$.Fire_Depart, which has the values for this attribute. 2) Click on Get Unique Values. You see that therare NULL, which mean there is no teams there, andnames of each team. So, we need to select each team. 3) Inthe statement box, you form the statement Sheet1$.Fire_Depart = departments name. Before anotherstatement can be entered, you need OR. This allows maybe values to be added. Please form the statement witheach number for each VictimDecon team as seen below. 4) Click OK.

In this case, there is an easier way to selectseven features we want. We have the

names of each and also we have NULL.

So, we can select whatever is not NULL,which would be Sheet1$.Fire_DepartIS NOT NULL.

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3. This time create a shapefile from your selection. 1) Right click on the firestations and select Datain the pop-umenu. 2) Left click on Export Datain the new pop-up menu.

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4. In the Export Data dialog, 1) make sure the Export:reads Selected features, and 2) you are saving your data tfolder. Name it something appropriate, in this case Victim Decon.shp. Select OK. 3) When prompted to add thexported data, choose Yes. The layer appears in the TOC. Please deselect features.

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Now that we have the locations of the teams mapped out, we want to see how many residents of Rhode Island arebeing protected. We specifically want to buffer. Buffering is when you draw concentric circles around a featureto show a spatial relationship among features or objects. For our example, we suppose that these teams can

effectively protect people within a 3-mile radius from each station. So, we want to bring up census data. Then, bdrawing a circle with a 3-mile radius, we can calculate how many people are within that circle. However, there ar

two different layers, the buffer for Hazmat teams and the buffer for the Victim Decon. So, using the Mergefunction, we can merge the features of the two separate layers into one layer and do only once calculation instead

of two.

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1. 1) Double left-click open the toolbox Data Management Tools. 2) Double left-click open on the Generaltoolset. 3) Double left-click the Mergetool.

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2. In theMerge wizard, 1) select Hazmat Teams and Victim Deconin theInput Features dropdown. 2) InOutput Features, name the new layer Merge. 3) Click OK.

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3. Now you see a Merge dialog which runs a script. When the script ends, click Close. There is a new layerMergehas been added. Close the Data Management Tools toolbox.

We can now add the census data and perform the buffering.

1. Add the censusf1 shapefilefrom the GISData2 folder.

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2. Now we need to work with ArcToolbox, which is a platform that contains toolboxes with most of the function

used for spatial data. In the ArcMap interface, 1) click on Show/Hide ArcToolbox Window and 2) you see anew table of contents for the ArcToolboxes opens.

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3) Double left-click open the toolbox Analysis Tools. This contains a number of toolsets which contain

similar functions. 2) Double left-click open on the Proximitytoolset. In the toolset, you see the tools whichare the functions. 3) Double left-click the Buffertool.

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4. In the Buffer dialog, 1) select the Merge layer from the Input Featuresfield. 2) In the Output Feature Classyou have the name of the new layer and where its being stored. Change the name of the layer to Buffer. 3) InDistance, you can choose the how long the radius of the buffer should be. Type in 3in the Linear unit field andthen choose Milesfrom the dropdown. So far, this will merely draw a circle around each point. There will beoverlap among the points. We want all the buffer circles to be treated as one feature, so we need to dissolve. Thifunction takes all the features and combines them into one. 4) In the Dissolve Typefield, select ALLfordissolving all the features. 5) Click OK.

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After the message of the completion of the function, you see a new layer has been added with the buffer of the

teams.

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3. Open up the attributes table of censusf1. 1) Click on Selected so we can calculate only those blocks that areselected. 2) Scroll down to POPTOT which is the field with the population of each block. 3) On the title baright-click on then left-click on Statistics.

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4. In the Selection Statistics of census1, you see in Sumthat the population count for the selected blocks is

635319. So, over half of RIs population is within the buffers. You can close this window and the attributeswindow and clear the selections. Also, deselect the selected features by going to the Selection menu and left-click

Clear Selected Features .

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But, we have a problem. Zoom into a border area where the merged buffers end. The block groups that areintersected are crossing over the border. If even a sliver of block group is in the buffer, then its selected and its

whole population is counted. Our numbers will be off. You can close the attribute table and deselect all features.

There are ways around this problem. What we need to do is calculate the area of the part falling into the buffer an

then use that as a ratio for how many people fall within the buffer. For example, if 20% of the block group fell

into the buffer, then we estimate that 20% of the population did as well. For this we need to use the FieldCalculator, which is a calculator for the fields in the attribute table. You can perform a number of proceduressuch as addition and subtraction for numeric characters and other procedures for text, such as trimming letters.

First, using the Intersecttool, we want to calculate how much of the censusf1layer falls into the mergelayerwithout any overlap.

1. 1) Double left click on the Analysis Toolstoolbox. 2) Double left click on the Overlay toolbox. 3) Double leclick on the Intersect tool.

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2. We now need to select the two layers that we want to intersect. 1) In the Input Features, select Mergeandcensus1 and you will see them listed in the Featureslist. 2) In the Output Feature Class, change the name toIntersect.shp. 3) Click OK.

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Close the executive window when its complete. You see a new layer, Intersect, has been added. It has featuresthat correspond to the block groups that only fall into the Merge layer. If you open up its attributes table, you see

attributes from both layers are there. Scroll to the right and you see the AREAfield from the censusf1 layer.Thats the original area measurement of the block group. We now need to make a new field and calculate what thnew area measurement is. You can deselect the features.

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1. In the attribute table for Intersect, left click onto Optionsand then left click on Add Field.

2. In the Add Field dialog, 1) call the new field newareain the Name field. 2) Chose Doublein Typeto allowdecimals. 3) Press OK.

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3. Open up Field Calculator. 1) Right click on the title barof the newarea field. 2) Left click on CalculateGeometry. 3) You now receive a warning that you cant undo the calculations. For our purposes, this is fine.Click Yesin Field Calculator.

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2. 1) Right click on the newpoptitle bar and then left click on Statistics. 2) You can see in the Statistics ofInterestthat the new estimate is now 603,421. There was an approximate 30,000 people difference.

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Some interesting research using GIS:

Colwell-Chanthaphonh, C.; Brett, H. (June, 2004). Mapping History: Cartography and the Construction of the SanPedro Valley.History & Anthropology. Vol. 15 Issue 2, p175-200. Article retrieved October 4, 2005, from

Academic Search Premier.

Sassaman, K. E.; Russell, J. C.; Endonino, J. C. (Winter 2003). Archaeological Consequences of Urban Land-Use

Conversion in Northeast Florida, 1970-1995. Southeastern Archaeology. Vol. 22 Issue 2, p196-209. Articleretrieved October 4, 2005, from Academic Search Premier.

Stewart, D. J.; Zhi-Yong Y.; Dona J.; Bullard, S. M.; MacLachlan, J. T.; (Jan 2004). Assessing the SpatialStructure of Urban and Population Growth in the Greater Cairo Area, Egypt: A GIS and Imagery Analysis

Approach. UrbanStudies. Vol. 41 Issue 1, p95-116. Article retrieved October 4, 2005, from Academic Search

Premier.

Entwisle, B.; Rindfuss, R. R.; Walsh, S. J.; Evans, T. P.; Curran, S. R.; (May, 1997). Geographic Information

Systems, Spatial Network Analysis, and Contraceptive Choice.Demography. Vol. 34, No. 2, pp 177- 187. Articl

retrieved October 4, 2005, from JSTOR.

Pavlovskaya, M. (June, 2004). Other Transitions: Multiple Economies of Moscow Households in the 1990s.

Annals of the Association of American Geographers. Vol. 94 Issue 2, p329-351. Article retrieved October 4,2005, from Academic Search Premier.

Please feel free to contact me with any questions or for further assistance.

Thomas Stieve

[email protected](401) 863-7978
http://www.jstor.org/view/00703370/di973894/97p0067w/0?currentResult=00703370%2bdi973894%2b97p0067w%2b0%2c3EF001&searchUrl=http%3A%2F%2Fwww.jstor.org%2Fsearch%2FAdvancedResults%3Fhp%3D25%26si%3D1%26All%3Dgis%26Exact%3D%26One%3D%26None%3D%26sd%3D%26ed%3D%26jt%3D%26dc%3DPolitical+Science%26dc%3DPopulation+Studieshttp://www.jstor.org/view/00703370/di973894/97p0067w/0?currentResult=00703370%2bdi973894%2b97p0067w%2b0%2c3EF001&searchUrl=http%3A%2F%2Fwww.jstor.org%2Fsearch%2FAdvancedResults%3Fhp%3D25%26si%3D1%26All%3Dgis%26Exact%3D%26One%3D%26None%3D%26sd%3D%26ed%3D%26jt%3D%26dc%3DPolitical+Science%26dc%3DPopulation+Studiesmailto:[email protected]:[email protected]:[email protected]://www.jstor.org/view/00703370/di973894/97p0067w/0?currentResult=00703370%2bdi973894%2b97p0067w%2b0%2c3EF001&searchUrl=http%3A%2F%2Fwww.jstor.org%2Fsearch%2FAdvancedResults%3Fhp%3D25%26si%3D1%26All%3Dgis%26Exact%3D%26One%3D%26None%3D%26sd%3D%26ed%3D%26jt%3D%26dc%3DPolitical+Science%26dc%3DPopulation+Studieshttp://www.jstor.org/view/00703370/di973894/97p0067w/0?currentResult=00703370%2bdi973894%2b97p0067w%2b0%2c3EF001&searchUrl=http%3A%2F%2Fwww.jstor.org%2Fsearch%2FAdvancedResults%3Fhp%3D25%26si%3D1%26All%3Dgis%26Exact%3D%26One%3D%26None%3D%26sd%3D%26ed%3D%26jt%3D%26dc%3DPolitical+Science%26dc%3DPopulation+Studies

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