GIMP - Layer/background transparency issues and help with channels

[The Noobilator]

Hi all,

I am a first-time cartographer and generally not a very artistically minded person, so I apologise in advance for any foolish mistakes I make/have made!

I am currently working on converting a map drawn in AutoREALM to a more visually appealing map using GIMP. However, as I am a first time GIMP user, I have followed a guide posted on the Cartographers' Guild (link: https://www.cartographersguild.com/s...ad.php?t=10655). In doing so I have stumbled on some more general problems with GIMP, likely caused by my own ineptitude in following the aforementioned guide. However, as I cannot find any information online or posts by people with the same problems as me, I hope I can find some help here!

Firstly, I have noticed rather a long way in to the process that my terrain layers appear to have some issue with transparency, or being bound in some regard to the background layer. When toggling the background layer off, all of my terrain layers disappear (please see attached screenshots). I was wondering if anyone had any ideas for remedying this, and hopefully an explanation as to what I have done wrong so I can avoid doing it again in the future!

Secondly, while following the guide, I used a sketch of the coastline to generate a channel (see attached screenshots) to denote the location of the sea and other bodies of water. However, following the generation of this channel, the tutorial indicated that I should delete the coastline sketch, and I dutifully complied. I must have made some mistake in my process however, as my coastline no longer has a stroke defining it. So my question is: is it possible to generate an outline for a channel, in much the same way the Stroke Selection tool works? Or have I condemned myself to re-drawing my coastline?

Finally, my river layer, despite being below all of my other terrain layers, is for some reason drawing over the top of everything else (see attached screenshots). Could this be something to do with the terrain layers being associated with the background layer in some way as suggested above? I am certainly going to re-do my rivers (as I am very unhappy with how they look), it's just that this subverts my entire (limited) understanding of how layers work!

Thanks in advance for any help you can give!

-Matt

P.S - I am aware that there are likely many problems with the design of the map itself! Although it is not the purpose of this post, I will gladly accept any advice on how to improve my cartography prowess!