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How do I calculate area of LULC type for each watershed?

Hi friends,

I need some help. 
I have a map of sub-watersheds - more than thousand sub-watersheds- (in .shp file format) and a map of LULC (in .tif file format). I want to calculate area of each LULC type for every sub-watershed.
Is there any other way that I can do in ArcGIS 10? 
Thank you all in advance.



  • swolnyswolny Member, NatCap Staff
    Hi Duc -

    Have you tried the Spatial Analyst/Zonal/Tabulate Area tool?

    ~ Stacie
  • Dear Stacie,

    I run the tool and I have a table of tabulate area. It looks very nice.
    Could you please describe the result for me because I am not sure whether my interpretation is correct or not?
    - My LULC map is a raster map, coordinate system is WGS_1984_UTM_Zone_48N
    - My sub-watershed is a vector map, coordinate system is also WGS_1984_UTM_Zone_48N

    Thus, the unit in the table of tabulate area is square meter. Am I right?

    I have one more question. I would like to integrate area of each LULC type, which I got from the table of tabulate area, into the map of sub-watershed. What should I do? Do I have to enter manually or there is a tool to solve it?

    Thank you very much.
  • swolnyswolny Member, NatCap Staff
    Yes, if your projection is in UTM, the units given in Tabulate Area are square meters.

    If you want to include the LULC area information in your sub-watershed shapefile, you can do that by joining the table from Tabulate Area with the attribute table from your shapefile. For example, if you gave these parameters to Tabulate Area:

    Input raster or feature zone data: my_subwatersheds.shp
    Zone field: ws_id

    Then the resulting table will have a field called "ws_id", which you can Join to your subwatershed shapefile using the "ws_id" field in the shapefile. If you want to keep the Tabulate Area results in the shapefile without a join, you'll then either need to export the joined table to a new dataset, or create new fields within the subwatershed shapefile and copy the values from Tabulate Area to these new fields within the shapefile.

    ~ Stacie
  • I got it.

    Thank you very much and have a nice week.

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