LAND  DEVELOPMENT  PROJECT

The acquisition of a land parcel consisting of 25 to 30 acres, located in the north/central Phoenix vicinity was the basis for this project.  The requirements for the project included select parcels with less than 3,000 meters in proximity to the Phoenix Deer Valley Municipal Airport.  Elevation specifications for the site stipulated that any difference in grade was not to exceed 5 meters.  Assumptions were made that all current city zoning ordinances were satisfied and the project site was available for sale on the open market.  The purpose of acquiring this site was to develop an industrial plaza to accommodate several office/warehouse structures, site adds and open space features.  A search area was placed around the Phoenix Deer Valley Municipal Airport land parcels to initiate the site search process.   

The project required several layers of image data furnished by the U.S. Geological Survey to be integrated with the base map of Maricopa County Parcels (parcels.shp). The image data used for spatial analysis were: hypsographic, hydrographic and digital photographic topographic maps.  Data research on the USGS Web site was crucial in the identification and acquisition of the specific Digital Raster Graphic (DRG), Digital Orthophoto Quarter-Quadrangle (DOQQ) and Digital Elevation Model (DEM) required for the project.  Each of the graphics were downloaded and converted to Spatial Analyst grids for analysis.  

The digital graphics used in this project were originated in 1 :24,000 scale.  The DRG and DEM  graphics were produced in 7.5 minute quadrangles.  The base map and the USGS digital graphics were projected in NAD27, Universal Transverse Mercator (UTM), Zone12N horizontal datum.

A link to Metadata for the spatial images can be activated by clicking inside the frame of each image.  All graphics were developed by the use of ESRI ArcView/ ArcGIS/ Spatial Analyst software, and samplings of these images are provided below.  Access to the graphics can be achieved by using the browser vertical scroll bar.

The 8 highlighted polygonal shapes feature Maricopa County Assessor Books that appeared within a search area for possible candidate sites.  Using a geoprocessing clip operation, the assessor parcel numbers (APN) included in these books were clipped from a database of 227 records.  This procedure was used again to extrapolate 44,272 parcel records from a database containing 464,491 records.  The purpose of the clip operation was to produce a more manageable and efficient spatial database.

This DRG overlay features hypsographic, hydrographic and digital topographic data, which were essential elements in identifying the airport location and surrounding terrain.  The Image Warp registration process  was implemented to register the DRG to the Parcels base map.   The DRG image was "rubber sheeted" to the landmark points on the base map. Then ground control points (GCP)  were established.  This operation corrected an offset of 80 meters, which was discovered when a transparent DRG image was overlaid with the base map.  The same GCP database was used to register the DOQQ image to the base map.

Flood prone areas and terrain variations from the southeast region of the airport property can be seen in this image.  Other relevant data will eventually be spatial analyzed when elevation contours are applied to the graphic as an overlay.  The DOQQ view represents the same area, and  scale as shown in the DRG.  The aerial photograph has be rectified so that geometric distortions caused by relief displacement have been removed.  DOQQ and DRG graphics are produced by the USGS in Tag Image File Format (TIFF), both graphics share the same GCP database.       

This view shows the elevation change by color.  Dark lavender areas are higher in elevation.  For analyzing relationships between elevations and potential sites, the DEM layer has been placed over the parcels base map vector theme.  

USGS Digital Elevation Model images are produced in batch files for use with the DLG 32 Viewer.  In order to view the DEM in ArcView/ ArcGIS/ Spatial Analyst software, the files had to be reconfigured with SDTS grid support.  The Warp Environment extension was used for the registration process in spatial raster grids.  The last view shows a DEM conversion to contour intervals in a layout presentation.  

The candidate parcels shown in yellow meet the distance, size and open space criteria for the project site. Close analysis of APN 21305002B (smaller parcel) reveals that a portion of the land is located in a low-laying area near the Cave Creek Wash.   Portions of the larger site is beset with hillside terrain which renders most of the land unsuitable for this project. 

This view features a spatial combination of the two land parcels.  By combining these two parcels, a suitable site can be development in a spatial split.  For analysis purposes, the Cave Creek wash delineation has been digitized on this theme from the DRG overlay.    

The results of the spatial parcel split is shown in this view.  The attributes are displayed in the view of the Site.shp database.  This parcel meets the given criteria for the land requirements of the project .

Critical data needed for the project are illustrated in this layout, which features five meter contour intervals to describe variations in elevation.  The contour intervals were developed in a Spatial Analyst grid overlay, and originated from the Digital Elevation Model using the Surface menu option.  The spatial combined parcel and the potential project site are shown with hydrographic data and parcel dimensions.

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