Channel into aquifer + freezing
Is there anything one can do to stop dwarves jumping into a channel they have just carved? Usually it isn't all that important, but I was trying to mine through aquifer in the winter and it's just impossible. Even if you make the dwarf channel each tile one-by-one, they occasionally still jump right in there and get entombed in ice.
Normal procedure is to dig downstairs, then upstairs below, then channel the downstairs to reveal water, as detailed on https://dwarffortresswiki.org/index.php/DF2014:Aquifer#The_freezing_method
Traffic designations could also help, depending on configuration and existence of alternate paths to whereever they were going.