GIS 4048: Week 6 - Prepare MEDS

The minimal essential data sets (MEDS) is a standards-based geospatial model used by local, state and federal governments for the collection, discovery, storing and sharing of data for large urban areas.  The MEDS provide the foundation necessary for Homeland Security to carry out the key national security strategy objectives: preventing terrorist attacks within the U.S., reducing the country's vulnerability to terrorism, and minimizing damage and accelerating recovery from natural or man-made disasters.

The analysis of MEDS allow for identification of features that maybe vulnerable and shows possible means to protect them.  The data sets could also be used following an incident to provide information on certain areas, such as the best route in and out of an area to provide a response to thee incident. 

MEDS consists of: hydrography, orthoimagery, land cover, elevation, geographic names, transportation, boundaries, and structures. 

The National Hydrography Data (NHD) provides data regarding lakes, ponds, streams, rivers, springs and wells.  The data set also includes the location of dam spillovers weirs to control the direction and flow of floodwater.  The structure data set identifies structures of importance that may be targets for terrorist attacks such as: areas of large congregation of people, government buildings, office buildings, research centers, large sports venues, churches, military installations and historical structures. 

Orthoimagery is a data set of aerial photographs that have been corrected to remove distortion and relief displacement so that direct measurements of locations, distances, and directions can be made.  Ortho corrected images also provide a realistic view of the landscapes. 

The land cover data set provides information of tree canopy, percent impervious surface and 16 classifications of land cover shown at 30 meter resolution.  This allows homeland security personnel to get a layout of the land. 

The elevation data set consists of digital elevation models (DEM) generated by the USGS. DEMs contain information regarding the elevation and terrain of a certain area.  The data can be used to generate 3D models of the terrain.

The geographic names data set contains the federally recognized names for physical and cultural geographic features in U.S. both current and historical locations.

Finally, the transportation data set classifies roads as local, primary, and secondary roads. They are defined using the Census Feature Classification Code (CFCC), which ranges from A00 to A75. The classification allows security analysts to identify roads for evacuations and the security risks if compromised. 

To prepare the MEDS for the Boston Metropolitan Statistical Area (BMSA), the data was organized into group layers according to the type of data.  Prior to grouping the transportation layers together, the road classifications had to be identified and were selected from the original file of Massachusetts Roads.  The roads were then symbolized and set to be shown at a scale of 1:24,000 or larger so the roads could easily be seen, while still making the map readable.  The land cover data was extracted as a mask to lie within the BMSA boundary and converted and shown as a color map.  The symbology was labeled with descriptions.  The geographic names were projected to the appropriate state plane for Massachusetts and then the features were named according to the Feature_Name.  The names were set to appear at a scale of 1:24,000 or larger.  Lastly, the group layers were saved as layer files (as shown below), which preserves the symbologies, labels zoom settings, and other manipulations of the data.  The layer files allow for the sharing of data especially in a crisis situation.