The Lobau (German pronunciation: [loˈbaʊ̯] ⓘ) is a Vienna floodplain on the northern side of the Danube in Donaustadt and partly in Großenzersdorf, Lower Austria.

In addition to the water coming from the Alps through the Wiener Hochquellenwasserleitung, the Lobau is a source of groundwater for Vienna.

The Lobau also has a big impact on tapwater in Vienna itself, since it is one of the sources to provide water to its population.

As said before this park is known for its wide variety of flora and fauna and one typical example is the reed bed surrounding the Josefsteg covering a large part of the area.

The common reed (Phragmites australis) is a cosmopolite[clarification needed] species of perennial plant that belongs to the Poaceae, which is a sub-family of the Arundinoideae.