CE547 Analysis of “Greenness” of Parcels that Have Sold Off Water Rights

Back to Project Page

   

Appendix A – Steps to Create This GIS

  1. Obtain data files from various sources:
    a. Water transfer data and shapefiles from the Office of the State Engineer.
    b. Landsat7 satellite image file for July 18, 2002, bands 3 & 4. This is the “leaf on” condition.
    c. County and roads data from ESRI files.
  2. Project files to NAD 1983 UTM Zone 13 N.
  3. Using ArcMap, create a layer for each satellite band image. Use the Spatial Analyst raster calculator to calculate NDVI. Multiply by 100 to create integer values between –100 and 100. Call this new layer NDVI 2002. The formula is:
    100 * ( [Band4 - Band3]) / ( [Band4 + Band3])
  4. Create a counties layer using the ESRI US Template. Select Bernalillo, Sandoval, and Valencia counties and trim to just these 3.
  5. Trim the NDVI layer to approximately the three-county area in order to reduce its size. Set the symbology of the NDVI layer as shown below.
    Begin by using Natural breaks (jenks); however adjust so that a layer is cutoff at –10 and another at +60.
  6. According to http://www.csc.noaa.gov/crs/definitions/NDVI.html (adjusted for the range I am using) a value of –10 or less is “not very green” and a value of 60 or more is “very green”. Here are the color settings I chose:
    I originally used only five color ranges, Not green (-64 thru –10), Not very green (-10 thru 18), Slightly green (18 thru 29), Green (29 thru 60), and Very green (60+), but found that the additional breakouts were useful to determine variations when viewing parcels up close.
  7. Merge the county shapefiles. Each county’s water transfer shapefile came as a separate file. The three had to be merged using the GeoProcessing Wizard. I began by using “Merge layers together” for Bernalillo and Sandoval counties. For some reason the area covered by the Bernalillo and the Valencia county shapefiles overlapped and the two could not be merged. Instead, I had to use Union two layers to “merge” the Bernalillo-Sandoval file with the Valencia file.
  8. Create three separate layers from the water transfer data. First, open the database file in Excel. The columns “transferred” indicates what type of transfer took place. 1 = a full transfer of rights; 2 = a partial transfer of rights; other values in this field indicate that the transaction was something other than a transfer. Delete all rows that do not have a value of 1 or 2. Reopening the layer in ArcMap, use Select by Attributes to create a separate layer of just the Full Transfers; and a layer of just the Partial Transfers.
  9. In addition, some of the rights transfers included a leaseback provision. Since the water is still being used on these parcels, the greenness would not be expected to change. Leasebacks could apply to either full or partial transfers and are indicated by a date in the Lease_back field. Create a separate layer of all the leasebacks by selecting all rows where the Leaseback date is an actual date. Note that in a few cases there were default values of “12:00:00”, which I excluded from the set.
  10. In order to determine the greenness of each parcel, it was necessary to convert it to a coverage. Use the ArcInfo Shapearc command to on the full transfer, partial transfer, and leaseback files. Project to Project files to NAD 1983 UTM Zone 13 N, measured in feet.
  11. Compare the greenness of each parcel where a transfer has occurred with the greenness of the surrounding area. Since the parcels are generally some distance away from each other, this seemed like an effective way to compare greenness when considering sets of parcels. Measure the average greenness of each parcel area using zonal statistics. Then create a buffer 200 meters wide around each parcel and measure the average greenness of each buffer. See Calculating Zonal Statistics below for detailed step-by-step directions.
  12. Finally, evaluate the data from various perspectives using Excel graphing tools as presented in the main body of the paper.


Calculating Zonal Statistics

Do the following for both PartialTransfers.shp and FullTransfers.shp.

  1. Create zonal stats on PartialTransfer.shp over NDVI2002 3C(14) raster using the ID_ field. Result is PartXfers.dbf.
  2. Join PartialTransfers.shp with PartXfers.dbf. Result is PartXferWMean.shp.
  3. Using Buffer wizard, create 200m buffers around each parcel. Do not dissolve boundaries. Select Buffers outside polygons. Result is PartXferWMeanBufferCopy.shp.
  4. Manually cross-identify each buffer with its corresponding shape. Assign the parcel FID to each PartXferWmeanBufferCopy.ID field. Note that 3 of the parcels mysteriously didn’t get buffers.
  5. Create zonal statistics on PartXferWmeanBufferCopy.shp over NDVI2002 3C(14). Result is PartXferWBufferMean.dbf.
  6. Join PartXferWBufferMean to PartialXfersWMean. Result is PartXferWBuffMean.shp.
  7. In ArcCatalog, add a new field
    MeanDiff (Double, 10,5) to PartXferWBuffMean.shp.
  8. Open the PartXferWBuffMean.dbf file in Excel and populate MeanDiff using:
    Mean_1 (the buffer area mean) – MEAN (the parcel area mean) = MEANDIFF
  9. Repeat steps for the FullTransfers.shp file.