Massachusetts Institute of Technology Department of Urban Studies and Planning 11.520: A Workshop on Geographic Information Systems 11.188: Urban Planning and Social Science Laboratory Homework 2 Extracting Census Data, Simple Queries, and Suitability Maps Lecture 5 class/lab) Lecture 9 - Question #1 Lab 8 - Question #2 Distributed: Due: (at start of BEFORE STARTING ARCMAP, PLEASE PAUSE AND SKIM THROUGH THE WHOLE ASSIGNMENT FIRST. Getting the 'big picture' first will help you develop a better GIS strategy and will reduce time and energy wasted. A local non-profit group is interested in locating a site for building a senior center in Cambridge. Given your expertise in GIS, you are hired as a GIS analyst by this company to help them locate the best site. After a long meeting with the organization and the community you agree to run some numbers in order to get a handle on the locations and characteristics of potentially suitable Cambridge sites. You settle on the following criteria to get rolling with your site selection process: 1. The minimum area of land needed for the project is 1 contiguous hectares (1 hectare = 10,000 square meters = 2.471 acres, and 1 acre = 43,560 square feet). 2. Ideally, the site should be located near, but not in, a residential neighborhood.  The 1999 land use data is available from MassGIS or from class data folder (M:\data\camb_area_lu_1999.shp) to classify landuse. Recall from Lab #2 that you can refer to MassGIS Datalayer Descriptions and Guide to User Services and, specifically, the documentation for the land use datalayer on the web for further discussion of land use codes. The non-profit organization has been promised financial assistance from a number of wealthy philanthropists and has the support of the Cambridge City Council and Mayor. Thus they are capable of buying any land even if it is already developed. (In other words, don't worry about whether or not the land is vacant or about how much it would cost to acquire the land.) You decide to consider any land that:  Was classified as open (excluding urban public space and cemeteries), commercial, or industrial in 1999. (Hint: Read the land use code definitions carefully -- all of them.)  Abuts, but is not actually in, a residential area. (Hint: Using "Select by Location" with "Are Within Distance Of" is a way to accomplish this.) 3. Accessibility to the project is a major concern for the organization, especially given the often limited mobility of seniors. You determine that the project should be located within 200 meters of a major road.  MassGIS major road layer, majmhda1.shp.is available to assist you in determining which places meet this accessibility requirement. The shapefile is located in the class data directory (M:\data\). (Consult the MassGIS metadata for this layer for the correct set of attribute information.) 4. The organization is also worried about health risks. They decide that they want the site to be far (more than 300 meters away) from Toxic Release Inventory (TRI) sites as identified by the Environmental Protection Agency (EPA) data from their toxic release inventory databases.  Data from the Envirofacts database are available to identify relevant TRI site locations. A shapefile of TRI facilities for Massachusetts, mass_tri_facilities.shp, is stored in the M:\data directory. Note that this constraint applies to all TRIfacilities, not just those located in Cambridge or the abutting towns north of the Charles River (i.e., TRI facilities in Brookline or the Boston neighborhoods of Allston and Brighton count too).  We use the EPA Toxic Release Inventory database for illustrative purposes only -- to show how well-documented external databases can be incorporated into our own local analysis. In reality, not all TRI sites are health risks to nearby residents and case by case analysis (based on the specific nature of a site's toxic releases) is warranted before rejecting locations proximate to a site.  The TRI facilities shapefile includes all the TRI facilities for Massachusetts in the EPA's database (as of October 26, 2000 and for which a latitude-longitude location was provided) that fell within the borders of Massachusetts. Not all of the facilities in the EPA's database included latitude-longitude locations, and some of those with location data did not map to locations within Massachusetts (as determined by intersecting the points with a theme circumscribed by the Massachusetts border). 5. Accessibility by seniors with limited financial means for joining private clubs is deemed especially important. Therefore, you decide to narrow the criteria to census block groups where:  The percentage of the below-poverty-level senior (aged 65 or over) in the senior population with known poverty status is high. For the purpose of this assignment, a block group is considered to have a high percentage of below-poverty-level senior if the percentage of below-poverty-level seniors is at least 10 % above the average for the five towns including Cambridge, Arlington, Belmont, Somervillle and Watertown. For example, if you found that the overall five-town percentage of impoverished seniors was 15%, then you would be looking for block groups with at least 15% * (1+ 10%) = 16.5% impoverished seniors.  Use the Massachusetts Block Groups 2000 layer from MIT Geodata Repository as we used in lab 5. Set the coordinate system of the coverages to Massachusetts State Plane, NAD 1983 meters and set the 'map units' to be meters.  Use the ma_towns00.shp layer in M:\data directory as the town boundary.  As a tip, you may want to select a sub set of features in both the Block groups layer and the ma_towns00.shp layer that are relevant to this problem, export them to your own working directory, and add them to ArcMAP. In this way, the operation in ArcMAP isfaster and at the same time, you get the writing permission on these files so that you can modify them when needed. More importantly, you will be able notice the "sliver" problem. The graph above shows the selected five town and the block groups that are selected using "Select by Location" function with "intersect" specified as the topological relation between two layers. Many block group outside the five town boundary are also selected. If you zoom into a small area across town boundary as shown below, you will see why those block groups are selected. The two themes have different levels of