i have an aquifer settled in a human town
i decided to use reveal to see where some solid unwet rocks were
finally i found them and began to dig towards them
i discovered a way to make it to safe locations without drowning (with lots of teleport saves)
dig a 1x1 tunnel about 6 squares toward the safe dry rock
surround that with a channel AFTER the dwarves dug out the 1x6 rock
the aquifer will flow down into the channel before hitting the 1x6 in the center
continue slowly and watch for drowning dwarves and save them
the water on the 1x6 toward the dry rock will eventually dry up since the water is bypassing into the channel below
i am very close to my destination where i can dig down into completely dry rocks
this is useful also for stairwells if you can convince a dwarf to go down there and dig
or have a dry place to begin from with another dry place on the same level to end at
diagram as follows:
-------------------
#####
#___#
#_<_#
#_:_#
#_:_#
#_:_#
#_:_#
#_:_#
#_#_#
#####
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the only difficult part is at the end of the tunnel connected to the damp rock where water flows sometimes 5/7 or easy 3/7 to dig deeper
continue the pattern in a generally straight line untill you can reach completely dry rock
once there dig down and surround your stairwell with a channel to collect any water and build a bridge over that to proceed
make sure to leave yourself a nice 6x6 to land on and bridge toward the desired direction
as it is on my current human map i have it surrounded by a channel 4 levels deep
and level 3 is 1/2 dug out (attempting to collapse the entire fort) and the dry rock is below level 6 with 2 spots of dry rock on 5 and 6 allowing me to go into dry areas
not all aquifers can work with this idea
and dont attempt a 3x3 surrounded by water, this will cause too heavy flowing water to move forward