In Nov of 2017 it was decided to go ahead with construction of a 10x12 raft.Two colonies were installed but they did not survive the winter.
When our 2018 packages arrived in April,the access road was flooded (gauge in Hartford was 17 ft,1 ft over flood stage).We ferried students and bees about 200 ft by canoe and hiked the rest of the way in.
During the 2018 season ,we increased hive counts through splits and swarms.We monitored mites and the two original pkgs were treated with Formic Pro in late Aug when counts reached 2.5 per 100 bees.
In Oct we noticed dead bees around the hives(after heavy rain and minor flooding) and by the end of Nov it was obvious none would last the winter.
Spring 2019 brought much rain to the Farmington and Connecticut river valleys and coupled with snow melt in New Hampshire and Vermont, the river reached about 21 ft(Hartford) in mid April and I paddled in and took a few pictures. We had tied off the raft to a tree and it had drifted about 15 ft.
Last Sun we installed 2 pkgs(in the rain),one on the raft and one at an alternative site. We floated the raft over the holes and secured with T posts.The river should be down by the end of the week and we will see how it settles in.
Frame with barrels over 2 holes.
Finished raft in position
This string has been a lot of fun. FEMA suggests floodgates that are buoyant on the bottom and rise with the water entering the pit. Sounds like what you were suggesting except it was a platform rather than a gate. If your school has flat roof area with access I would put the hives at bench height on the roof. If you roof floods you have bigger problem than beekeeping.Rooftop beekeeping is common and has the benefit of being out of reach for people who shouldn't"t be bothering the hives.
Did floating over water mess up the bees ability to orient? I know that snow can cause this, and am curious if you have seen this with hives over water.
The raft is tethered to a group of trees and is pretty conspicuous so they don't seem to have any trouble finding the hive.
If you mean " do they confuse the water for sky", no,they fly over water no problem.
The site is surrounded by water(swamp) and can be foggy/misty in cool weather.Cold air does settle in valleys
Conditions like that are problematic for bees. The question is how to make dry and warm hive? Parameters are: ventilation is only needed to replace CO2 for oxygen; and removing water from air by condensation (and internal circulation) is possible.