You can symbolize the new landuse_poly.shp to match with lu_reclass grid or leave it unchanged. Confirm the Input raster is lu_reclass, the Field is Value, output geometry type is Polygon, and save the Output features as landuse_poly.shp in your working directory (this output is saved only as a shapefile without any other options). In ArcToolbox, Click on Conversion Tools->From Raster->Raster to Polygon. The final step in processing land use data is converting the reclassified land use grid into a polygon feature class which will be merged with soil data later.
A new grid named lu_reclass will be added to the map as shown below (if you get different colors in symbology is absolutely fine). Save the output raster as lu_reclass in your working folder, and click OK. In the reclassification window, confirm the Input raster is cedar_lu, Reclass field is Value, and then manually assign the new numbers based on the above table as shown below (leave NoData unchanged). Click on Spatial Analyst Tools->Reclass->Reclassify, and then double-click on Reclassify tool. To implement the above re-classification, use the Spatial Analyst Tools in Arc Toolbox. The following table shows how we will accomplish the reclassification of cedar_lu. As these represent the four major classes, we will adequately reclassify cedar_lu. By opening the attribute table of cedar_lu, you will notice that majority of cells represent grass/crops, followed by forest, developed land, and then water. The cedar_lu grid has 15 different categories which you can leave unchanged, or reclassify the grid to reduce the number of land use classes to make the task easier. The SCS CN table gives CN for different combinations of land use and soil group. Perform the re-classification of classesĮventually, we are going to use these land use classes and soil group type, in conjunction with runoff curve numbers (CN), to create the curve number grid. A description of some of the land classes and their associated numbers can be found here.ġ.2. These numbers represent a land use class defined according to the USGS land cover institute (LCI).
The grid is added with a unique symbology assigned to cells having identical numbers as you can see below: Add Spatial Analyst extension and activate it by clicking on Customize -> Extensions…, and checking the box next to Spatial Analyst.ġ.1. Create a new empty map, and save it as cngrid.mxd (or any other name). Workflow for the Creation of CN Grid in ArcMap
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