Adv. Manipulation - Adding geography

I'm trying to convert a nude photograph into a landscape. I've played around

with the saturation levels to increase the sense of distance and light, added a

skyline and later will be adding a few trees, etc. Right now, I want to add a

river or a series of steps along the shadow line on her stomach leading to her

armpit.

I thought that I could paint an appropriate color, add a Layer Style/Texture to

it and then set the blending mode to Color. But rather than subtly alter the

coloration, it adds texture, regardless of blending modes.

Even if that works, there's still the question of how to adjust the edges of the

river to meld with the skin.

Any advice, suggestions, etc would be greatly appreciated.<div></div>