This creek is an artificial one.
Well - not quite: in ancient times there already was a small river in this place, but it dried up long ago and stayed dry till last year when the national park authorities decided it was high time to do something about Lobau becoming dryer by the year.
And so they built a canal to fill this creek again - the water is supposed to help keep groundwater levels where they should be. I already have written an entry on that one last fall. The creek now is completed, and as this year is very wet it is well filled with water.