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VandyDataScience / land-trust2

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Download updated dataset and run land cover change analysis #3

Open chenkh1 opened 1 year ago

chenkh1 commented 1 year ago

Luke has provided us with an updated zip files containing all the raster datasets within our area of interest. Open these in QGIS and try running some sort of land cover change analysis using some of the sample datasets contained in the zip.

chenkh1 commented 1 year ago

Try using MOLUSCE plugin, SCP tab → post-processing → land cover change.

chenkh1 commented 1 year ago

  1. Open QGIS and add your raster datasets for the years of interest using the "Add Layer" button in the Layers panel.

  2. In the Processing Toolbox, search for the "Raster calculator" tool and open it.

  3. In the Raster calculator tool, set the output layer name and select the input raster layers for the two years you want to compare. Then, enter the formula to subtract the raster values of the two layers to calculate the difference. For example, if you have layers for the year 2010 and 2020, the formula would be: "2010_raster - 2020_raster". Make sure to select the appropriate data type for the output raster.

  4. Click "Run" to perform the calculation. The output raster will show positive values for areas that have decreased in land cover and negative values for areas that have increased in land cover.

  5. To calculate the area of each land cover type in each year, use the "Zonal statistics" tool. First, create a polygon layer that covers the extent of your raster layer. You can use the "Create grid" tool to create a grid of polygons that covers your area of interest. Then, select the Zonal statistics tool and set the input raster to the land cover layer for the year of interest and the zone layer to the polygon layer you just created. Select the appropriate statistics you want to calculate, such as sum or mean. Repeat this process for each year.

  6. The output of the Zonal statistics tool will be a table that shows the area of each land cover type in each polygon for the year of interest. You can export this table to a CSV file or other format for further analysis.