Water for admin level 4
I like the "water" version of file which make spatial join to not miss feature near the water. But seems to me that it is available only for admin level 2. Is there any way to have "water" version of other admin levels? Assuming that it is not available, how can i come up with my own version...? Is there algorithm/implementation released? I can think of buffer with a certain distance from land/water boundary, but then i dont know how to draw polytical boundary over the water.