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I am using QGIS and looking at multiple businesses (purple dots), and water levels (the grey behind them).

Data in QGIS

I am trying to calculate the average water level within x feet of each business (purple dot). I have looked through some guides and found that I need to do a Spatial Join. As part of this, I would have to join the layers by a specific attribute, and I get this window when I do Vector > Data Management Tools > Join Attributes By Location:

Action window for join

However, my water level data (grey) is not an option on either of the menus. How would I best approach a spatial join for this data - or, am I approaching this completely wrong and missing an easier way to calculate the average water level around each point?

If it is relevant, the water level data was loaded from *.tif files and the businesses were pulled from a *.csv.

Vince
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shrey_shankar
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1 Answers1

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Your water level data is raster data? If so, buffer your points to the relevant 'x' distance. Use the resulting polygons and the zonal statistics plugin to get the average water depth for each business.

Keep in mind that vector-raster operation, like zonal statistics, require that the raster and vector data share the same coordinate reference system. Look around GIS SE for more information on projecting data if that is required.

GBG
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  • I have figured out buffering and am working on the zonal statistics - however, I am not sure how to export the data to a normal .csv or similar where I just have: Firm, Lat, Long, Avg. Water Level As columns with values for each firm's circle. How do you obtain a proper output from zonal statistics? – shrey_shankar Sep 22 '23 at 06:01
  • See here for exporting an attribute tables: https://gis.stackexchange.com/questions/135801/exporting-attribute-table-to-excel-from-qgis – GBG Sep 22 '23 at 15:11