Geoprocessing: Count Overlapping Features (or Union), but with Sum of a field

[ToddFagin]

I have hundreds of overlapping polygon layers, the features of which do not typically match. I would like to find functionality similar to Count Overlapping Features or Union, but that returns a  sum of a particular field. So, if one polygon has a value of 10 and it is spatially coincident with another layers feature that has a value of 12, and another with a value of 3, etc. The output would be the union of these features with a summed value of 25 or whatever.

Anyone know of a tool that can do this?

[DavidPike]

You could do a spatial join with a Join rule fieldmapping of 'Sum', then add anew field and calculating the original polygon value + spatial join sum value.

Are we talking 100s of individual layers, all containing different polygons?  Do the schemas match?  I think it's important to explicitly detail the nature of the data to get the right solution.

[ToddFagin]

Unfortunately, a spatial join, on its own, won't work. However, if I have an intermediate layer it will, which ultimately may be the best solution.

Essentially, I am trying to do a modified version of what John Nelson did a couple of years back to show cumulative drought intensity. I have gathered U.S. Drought Monitor weekly data from 2001 to 2020. I have then divided the data into five year increments--2001-2005; 2006-2010; 2011-2015; and 2016-2020.

I then merged all the data from the each of the five year blocks to create a composite layer.

Lastly, for visually purposes, I use U.S. Drought Monitor colors for D0 to D5 with 99% transparency to create a really cool visualization.

Works great...except there are thousands of features in each layer, it renders slows, and it takes up a lot of  storage. I am wanting to use it is a web map, so it is far from optimal.

As a work around, I create a tesselation, then can spatially join the composite layer to it, so each hexagon gets a summed value. It works, but I was hoping to get rid of that intermediate step.