Hi,
Nothing of the kind. They were constructed by the Kaiserliche Marine which is for certain or by the IV Army.
No river, no waterway in the area, the coast is still a few miles away, as are any villages.
They were made early in the war, and didn't survive the war very long. All wooden hangars and barracks were as good as immediately stripped by local population for the wood which was used for all possible purposes, but in first instance for heating !
Also furniture etc was taken away by the locals. I have for example one of these, an old desk from the Jabbeke aerodrome, it's over 120 years old and I'm sitting behind it writing this answer
I know that the hangar's at Nieuwmunster didn't survive the twenties.
Curious thing is that I know almost all there is to know on the construction of the very first hangars on the early aerordromes in the northern part of West-Flanders, but nothing at all on the ones at Nieuwmunster...
Thanks and best from Johan