As an experiment in reducing water in a flooded level, our group has recently installed a syphon. The purpose is to gradually lower the water by assisting any natural drainage, and is intended to act over weeks and months rather than be a quick solution.
You will need an appropriate length of 25mm or 32mm blue alkathene water pipe, a 1100GPH bilge pump and a 12V motorcycle battery preferably the sealed gel-pac type. An assortment of hose clamps, cable ties and bicycle inner tube, hacksaw and Leatherman are also essential.
Now you've got a de-watering kit which is portable and inexpensive.
Run the pipe from as low down in the water as you can get it, with the exit pipe at least a metre below the inlet. If it is in the open, you will need to camouflage the pipe or bury it.
Attach the pump to the wet end of the pipe using inner tube and cable ties, submerge pump and apply power, this should fill the syphon in no time provided the maximum head is no more than about 2m. You may have to cut a slit trench to lower the pipe apex.
When suction is achieved, keeping the inlet submerged, remove the pump (it should just pull off) and attach a strainer made from a pierced drinks bottle to keep the inlet clear of sediment. You may also find that a reducer on the outlet will help keep the syphon full and running if the flow low.
I hope this helps
MARK