WIP Adding SWAMP to colorized textured GIMP Tutorial fantasy Map

[Jason Sutton]

Several years ago I created a map for my world basically using the clone stamp tool in photoshop and google earth. I'll post a picture. This had several problems lack of control aesthetics etc. A couple of days ago I found a tutorial by GMBean a member here at cartographers' guild and tried to recreate this terrian. Though I have limited artistic ability I am happy with my results so far. However now that I'm involved I may make changes for instance the rainforest in the east doesn't "pop" probably because of my over use of the tree brush in that tutorial. Also While I painted the mountains by hand I did a pretty terrible job with that brush and there is jittery overlay where I clicked twice next to each other trying to get them darker because I didnt understand pen flow and opacity yet. so I may delete the mountains and redo them or more likely follow a different tutorial to create the mountain layer with a a noise difference hieght map (seemed very interesting but a little complicated). Anyway I have been stuck for a full day trying to figure out a way to add marshlands to the southern border of the eastern river. There are a couple of tutorials here for how to hand draw some lines to give a marsh like impression but I couldnt get the color behind it or the scale to satisfy me. Also it wont match the style of the map so well especially if I replace the mountains as I suggested. I did find one post from 2008 that looked pretty good and used a stipple brush (no idea what that is or how to use it). In any case any help would be very appreciated. Besides most of these seem to be traditional river fed swamps almost deltas where as the area I envision is a basically a muddy boggy terrible marshland created by rainforest levels of precipitation and deforestation. I looked at deforesttion in brazil but that soil is much more red than I envision. Imagine that muddy pig farmer village in the movie dragon heart and show me how to add an area like that to the bottom of the forest widening toward the sea and narrowing toward the mountains. That would be amazing. Also sorry for length new to asking for help and want to make sure I give as much information as possible.

As an aside I am particularly proud of the transition between the lowlands and the arid land in the south. I didnt know anything about blending and just played with cloud brushes and shadows till I got a nice lookign ridge and a more or less gradual fade if there is a better way to do this I'm interested but I like the "ridge" it made it seemed a logical extension of the mountains and such.

Also any general feedback is appreciated.
I'm incredibly new I'm 2 days in and eagerly looking to learn more about gimp in particular.

I forgot I did find a single post from a guy completing the sept 2008 challenge to make swamps where he used something called a stipple brush and had some good effects. I know nothing about this but will google more.
There has probably been a better way to do this discovered in the last 10 years though.