Shoreline in DW

[Polak2]

Anyone can shed some light on the subject how to make the shoreline brighter than the rest of the land? Like so in this thread:
http://www.subsim.com/radioroom/showthread.php?p=2522546#post2522546

[p7p8]

Open editor and... draw lines manually.

Here is link (https://drive.google.com/open?id=1U_4v93cOHBSzqwoP5SOcGlWEW8eTe4UE) to some of my "lined" maps.

[Polak2]

... draw lines manually.
I was hoping for something else. But Thanks anyway.