Split KML Polygon in two polygons

Question

I have a country borderline KML polygon (one polygon), and I would like to split it in two regions (two polygons).

Let's say, we have German borders in KML, and I would like to split it into East and West Germany, following some regions borderlines. Or split Belgium into two regions. Or Ukraine in Russian and the rest. Or Cyprus in Greek and Turk part etc...

At least, split the polygon in two, then manually adjust the boundaries of each region, if not possible to split by a region polygon.

For Windows, I downloaded QGIS, an I have also Google Earth. I would like to create a custom MyMap (Google My Maps) based on the resulting two polygons.

Say I take Ukraine as a sample. Found the KML here, now, I have to split it in two, following the administrative divisions of some regions. As result, there should be only two polygons from one polygon.

We have the regions of Ukraine, but not really clear how to split the one country's polygon in two.

Answer 1

In QGIS:

1. Save the polygon as Geopackage file - in QGIS, editing KML files is limited. Splitting should work, still better to stick to Geopackage.

2. Select Split features icon and draw a line where the polygon should be split. Finish the line with right click and the polygon will be split. See documentation.

If Split features is not visible, activate it: Menu View > Toolbars > Advanced Digitizing Toolbar

Answer 2

If you want to do this in Google Earth, probably the best way would be to copy the polygon, and then edit one copy to be one of your new polygons, and the other copy to be the other new polygon, by adding and removing vertices as necessary. For a simple polygon, this isn't too bad. For a very complex polygon (like a large, high-resolution country boundary), this could be a lot of work. In that case, it would be better to use GIS software to draw the dividing line, and then use its analysis functionality to split the polygon by intersecting it with the new line.