Not possible, no adjustable water levels.
What about lowering the platforms instead?
Not possible
Perhaps remotely possible, however nothing like a sweeper and no crank, because portcullis can literally only move about 1 meter, regardless of size. An enormous door might be able to function as a funky sweeper though.
Without trying to sound like a party pooper, making any dynamic map is extremely difficult in the Warband map maker. No levolution here guys, sorry. We literally have: movable siege towers, openable and destroyable doors, raisable portcullis and raisable ladders. Now many of these can be stretched or turned in unexpected ways which can make for some interesting maps, case and point, obitus his map Pitfalls, and I doubt all the possibilities have been exhausted. There is also falling from heights and drowning in water which can feature as environmental hazards, as I tried to do in my siege map with an underwater tunnel.
Some experimenting with this could lead to some hilarious results and I am willing to risk the respect of any serious faced player by actually implementing a bullshit, unrealistic troll map. So I encourage anyone to go ahead and actually fiddle around with this. Here's two ideas of mine that might very well be possible in Warband. They are using doors, which are probably the most moldable dynamic items, although siege towers might have some unexplored potential as well.
A tower with removable floors, eventually leading to death for everyone. Depends on whether doors can be used properly as floor surfaces and also on whether doors can be opened if someone stands on it. Fall damage, drowning, whether doors are openable or merely destructable could be interesting factors to play with.
A huge bridge or some other somewhat narrow surface, filled with doors that are stretched sideways. Depends on the same things as the first idea. When opened these doors might in theory pivot and sort of ladderpult players while simultaneously creating dangerous holes in the surface.
