Polygon aggregation

[Anonymous User]

I have polygon data for water bodies in a watershed generated from Google Earth Engine for years 1984-2015. I have one shapefile for each year. (I also have 1 shapefile that has them all combined, attributed with the year, if that helps.) Basically, in the data is showing how the water bodies have changed over time, thus, there are new polygons in later years.

I am looking for a way to aggregate all of the polygons into 1 shapefile but only retain the polygon with the earliest date. So if a polygon has been there since the 1984 data, it will be attributed 1984 but then everything else that overlaps with it will be deleted. 

Thanks for any help!

[DanPatterson_Retired]

Not quite clear from your description, but are there instances of the same polygon each with their own date?  Or what was done with the individual year data to create the combined?  Was it a Union of the files? a Merge?  How they were 'combined' will limit or narrow down the options you can choose from

[Anonymous User]

Using Google Earth Engine a tiff was created from landsat for each year. Each tiff was then converted to a polygon shapefile - 1 shapefile for each year with a bunch of water body polygons in each. So, there are instances where the polygons are the same, but most of the time they have shifted a little - due to differences in the imagery, I assume. But there is overlap for each year.