Fairfax County, Virginia school location

Finding a suitable location for a new elementary school in Fairfax County based on the DEM/NED and Land cover map


Indela.Vanaja Parimala Rani,Distance learning student of Geospatial Analysis


April 22nd, 2010


ES 551 Computer Mapping Systems


To find a suitable location for a new elementary school in Fairfax County based on the DEM and Land Cover map of Fairfax County


Fairfax County has more than 1 million residents and 580,000 plus jobs. It is 395 square miles or 252,828 acres in area. The inflow of the people age one and older to the county is 7.6% in the last year 2008. The present schools are overcrowded and many kids are going to the private schools because of the lack of the space in public schools. So there is always a requirement for the new elementary schools. The county is always regularly in search of the new location. This study limits only to the elementary schools.


Many of the criteria will be assumed as it is not a real project and due to the lack of the data.

Criteria for the new elementary school location of the site:

It is assumed to be
1) The site should be from 297-427 feet or 90 130 meters in elevation
2) The area should be at least minimum 5 acres to maximum 10 acres enough for playground and parking
3) The main highway road should be at least 2 miles away from the school to avoid disturbance to the school and at the same time it should be accessible in emergency


The Digital elevation model and Land cover maps of Fairfax county are downloaded from the National Map seamless server of USGS in Arc grid and Geotiff format respectively. Then both the images are imported into IDRISI Taiga software for analysis. The DEM is extracted from (NED) National elevation 1/3 arc dataset that was taken by satellite on February 2010.

The land cover map downloaded does not have the legend. So the legend has been assigned to the land cover map from the attribute values.

The elevation for a location of a school is assumed to be 90 to 130 meters because the average elevation of the cities in the Fairfax County is 106 meters.The DEM (digital elevation model) is projected from latlong referencing system to US27TM19 and is further reclassified according to the average elevation and it is overlaid with reclassified image of LULC (land cover data).

The land cover map used was classified in 2001. Based on the Fairfax county general land use category there is only 16 acres of vacant natural land left and 32 acres of parks and recreational area. And some area left is not included in this table due to the lack of zoning and development. Land cover map is also projected from ALBERS83 to US27TM19 and then it is reclassified for the vacant area like vegetation, grasses and forest.

Both the LULC and DEM reclassified images are overlaid and the overlaid image is grouped. The area of the grouped map is converted to the units of acres and it is further reclassified for at least 5- 10 acres of area that is enough and suitable location for elementary schools. The third criteria of the highway will be analyzed physically when the county is ready for the new school.


In this study the location for a new elementary schools is derived from the DEM/NED and land cover maps by reclassification and overlaid concepts. The suitable location for the new elementary school is the red color area in the final map.


http://eros.usgs.gov/ For DEM and LULC map
http://www.fairfaxcounty.gov/demogrph/demrpts/report/popfgrw.pdf For population and its growth data by 2030
http://www.fairfaxcounty.gov/demogrph/demrpts/landuse/existinglanduse.xls For land use category
http://www.fairfaxcounty.gov/maps/gallery.htm For all the maps of Fairfax County
https://lpdaac.usgs.gov/lpdaac/get_data/glovis For the land use data
http://www.idcide.com/citydata/va/fairfax.htm For mean sea level
http://veloroutes.org/elevation/?location=fairfax%2C+fairfax%2Cvirginia&units=m For conversion of an address to the elevation