Using Polygons to split landuse map and assign a value to each landuse type

Question

Hello There;

I am new to use ESRI and would appreciate your support for below :

Inputs:

*   Total of 11 land-use (*.grc format) files which represents a country
*    A Polygon (*.shp format) file which includes 600 administrative boarder polygons for all country
*    A number of population per each polygon

Demanded Output:

* Split the land-use map in to 600 administrative areas
* Read the number of land-use grids.Therefore we can get total number of grids where population can be (excluding the open area, forest, water, sea etc)
* Export the no of grids to an excel sheet where we can assign a population value for each land-use type
* Assign the calculated values to each land-use type

I would appreciate if an expert can help me to do above step by step.

many thanks in advance.

XanderBakker · Answer

Hi Gokhan NAS ,

Let's start with the input file format. The .grc files are MapInfo Classified Grid raster files and according to this blog are supported in ArcGIS: https://blogs.esri.com/esri/arcgis/2012/04/17/grd-and-grc-files-now-supported-in-arcgis-10-1/

You have 11 of these files which you could probably best mosaic together into a single raster using Mosaic To New Raster—Help | ArcGIS Desktop

If you want to use a vector analysis as Duygu Öcal described you would need to convert the resulting raster to polygons (Raster to Polygon—Help | ArcGIS Desktop ). However, below I will describe the raster approach for this analysis (Spatial Analyst license required).

First convert the polygons with the administrative units to raster using Polygon to Raster—Help | ArcGIS Desktop (use a unique ID like the ObjectID as value field in this process). The raster with the landuse (mosaic) can be combined with raster with the administrative units  Combine—Help | ArcGIS Desktop . This will create a potential large raster with a corresponding value attribute table, since it will create a record for each combination of landuse class and administrative unit. If you open and export this table to for instance DBF you can load the data into Excel for further analysis.

In case you don't have access to a Spatial Analyst license, convert the mosaic raster data to polygons and overlay it with the administrative units using Union—Help | ArcGIS Desktop . Te resulting featureclass will have information on landuse and administrative units.

GokhanNAS · Answer

Dear Duygu;

Many thanks for your quick reply to my query.

Unfortunately; I couldn't run the merge *.grc file format (the landuse map) . This is where I stuck from the beginning...

I am sure there is an alternative way and still seeking for it...

DuyguÖcal · Answer

Hello Gokhan,

Your question is very broad but I will try to help. My opinion is that, it is best for your workflow to use Modelbuilder tools. I don't know which version of ArcGIS for Desktop you use but, this tutorial will help you get familiar with Modelbuilder.

http://help.arcgis.com/en/arcgisdesktop/10.0/pdf/creating-tools-in-modelbuilder-tutorial.pdf

It seems for these steps, you need following tools or processes;

* Split the land-use map in to 600 administrative area (Merge and Clip) 
* Read the number of land-use grids.Therefore we can get total number of grids where population can be (excluding the open area, forest, water, sea etc) Spatial query and counting the selected features (Select by Location)

* Export the no of grids to an excel sheet where we can assign a population value for each land-use type (Export as Table)

* Assign the calculated values to each land-use type (Add Join to the Attribute Table)

It is important to mention that the outputs you specified can be obtained easily and quickly with the help of a modelbuilder tool.

Glad if I could help.

Duygu