GEO 559 Lab Assignment Jong Seo Won

Assignment part 2

Q1. Perform both the Identity and Union operations using Landuse.shp as the input and Wetlands.shp as the identity/union features.

For both operations, compare the output file to Landuse.shp. What are the differences in number of features and attributes?

By comparing two tables, it is possible to find out the difference in number of rows between “wetlands_identity” and “wetlands_union”. While the number of shape “wetlands_identity” is 499, the number of shape “wetlands_union” is 508. “Wetlands_union” shapefile has 9 more rows than “wetlands_identity” shapefile.

Describe any alterations in the output file and attribute tables. Screenshots might be helpful to include in your descriptin

“wetlands_union” attribute table (508 rows) “wetlands_identity” attribute table (499 rows)

Q2 (30 points): Please provide an accurate and insightful description of both operations in your own words :

One description for the identity operation and one for the union operation

Union is a function that combines two different polygon into one polygon, which contains all of attributes and information from two different polygon. Thus, new shaple file(result shape file) have all of attributes from both “landuse shape file” and “wetland” shapefile. Therefore, the number of rows in new shape file that are generated after “union” process of two shapefiles (“landuse” and “wetland”) in increased.

The columns of new shape file (result shape file) are same to the columns of the two shape files(“landuse” and “wetland”).

Identity function is used to combine attribute tables in the same area. Assume that there are two shape files of Erie county. While one of them only has demographic data, the other one has income data as well as demographic data. If we want to add income data from the second shape file into the first shape file, “identity” function is useful. By using “identity” function, we can add attributes that only exist in “landuse” shape file to “wetland” shape file.

Assignment part 3 Your Task: You work for the NY State Hazardous Waste Cleanup Department (NYSHWCD) as the head of GIS operations.

Q1. If a hazardous waste spill occurs on a NY state highway, the NYSHWCD must ensure that the spill does not travel farther than 500m from the road. Write down instructions to create a 500m buffer around the NY_Roads.shp.

In this case, “buffer” function is needed. The first step is click “Arc Toolbox” on the menu. (Arc Toolbox  Analysis Tools  Proximity  Buffer) (Arc Toolbox  Analysis Tools  Proximity  Buffer)

Input feature is ‘New York road’ shapefile, and name the name of output. Then, put 500 as the distance. After that, save it to my student folder. 500m distance from the road is “buffer zone”.

Q2. If a hazardous waste spill occurs within in a city, all counties located within a 10 miles radius of that city must be alerted.

Write down instructions to select all NY counties that are located within 10 miles of the cities in the NY cities layer.

In order to do this task, the necessary function is “Select by location”. First of all, click “select by location” on the “selection” menu. In the “select by location” window,

-Selection method : select features from

-Target layer : NY_counties

-Source layer : NY_cities

After these steps above, the result shows how many counties and which counties in New York state are potentially dangerous areas. The next step is creating thematic map

In order to visualize potentially dangerous areas, mapping is important. Firstly, open attribute table of NY_counties layer (New York counties). Then, click “add field” on the attribute table menu. (top left side of menu)

“add field”

Then, a new column is created (on the right side of the figure). The purpose of adding a new column (by using “add field” function) is to distinguish dangerous counties and counties that are not dangerous. I am going to put number “1” on the dangerous counties and “0” on the non-dangerous counties. In other words, “1” is “selected area” and “0” is “non-selected area”. Fill out each cells in the new column with “1” or “0”.

A new column is created (on the right side of the figure)

In order to do this process, we need to edit attribute table. On the “Editor” menu, click “Start editing”. After fill in numbers into the new column, click “Stop editing” on the “Editor” menu. Create thematic map

After finishing previous steps, we go to “Layer Properties”. Then, select “symbology” tab  “Categories”  “Unique values”. Then, choose “Select” in the “Value Field”

Finally, the thematic map that indicates “potentially dangerous counties in New York state” is created.