Water on Strategy map

I've found the textures under terrain/aerial_map/sea, but does anybody know where to specify and define the location of these files in a .txt? can only find for ground terrain. as I've understood, rtw looks in the pack first, and since I haven't renamed it in any txt file it just pick the default one...

if you want to change the colour of the water, I believe you need to edit water_surface.tga in your campaignmap folder (ex: data\world\maps\campaign\imperial_campaign).