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Region

I have a file geodatabase feature class, type polygon, of land use type. SEQ LU Update X project clip in the attached.

I have a districts shapefile (shapefile feature class polygon). All_Brisbane in the attached.

I need to know, by district, the percentage of the area of each district that is irrigated. There are six land use types beginning with Irrigated (see attached).

I'd like to generate a table (CSV etc) that has each district name/id in one column and the percent of the total district area that is irrigated (i.e. the sum total of all six Irrigation types divided by the total of all types in the district) in another column.

How can I do this?

  • What GIS software are you using? – PolyGeo Dec 6 '19 at 0:37
  • Start with tabulate area tool. – FelixIP Dec 6 '19 at 3:22
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I think you can:

  • 1) In the district shapefile, create a new column "area" in the attribute table and calculate geometry in km². It will calculates area per district.
  • 2) Select by attribute your six classes of irrigated lands.
  • 3) Create a new layer of this selection.
  • 4) Export the layer and re-import it in Arcmap. Dissolve the new layer to delete borders of each class (data management tools --> general --> dissolve).
  • 5) Make a union (geoprocessing) of the new dissolved shapefile and the district shapefile.
  • 6) In the union shapefile, select the irrigated lands and create a new layer with selection.
  • 7) Export the layer and re-import it in Arcmap. Create a new column "area" in the attribute table and calculate geometry in km². It will calculates area per irrigated class for each district.
  • 8) Do a table join (right click on the district shapefile) with the irrigated lands shapefile using FID as common field.
  • 9) Export the layer and re-import it in Arcmap. Create a new column percentage in the attribute layer and enter the formula to calculate percentage using field calculator.
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  • Hi - this was very helpful and I'd like to thank you! The only difference was that I had to project everything into the Australian national grid GDA2020 MGA Zone 55 so units were in metres. Then it worked. – DHG Dec 28 '19 at 23:11
  • Why wouldn't you use Intersect at step 5 instead of Union? Then you could skip step 6 and step 8. You already have the area of the districts in your intersected shapefile, so then you just need to add an irrigated area and percentage field, and calculate them. – Baltok May 7 at 13:27

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