Aa (Meuse)

The Aa (Dutch pronunciation: [aː]) is a small river in the Netherlands. It rises near Nederweert in the southeastern province of Limburg, in the Peel region. It flows northwest through the province of North Brabant towards 's-Hertogenbosch, roughly along the Zuid-Willemsvaart canal. In 's-Hertogenbosch, at the confluence of the Aa and the Dommel, the river Dieze is formed, which flows into the Meuse (Maas) a few km further. The main cities and towns along the Aa's course are Asten, Helmond, Veghel and 's-Hertogenbosch.

The current Aa is not as important as the former river. This is due to the Zuid-Willemsvaart, which has been dug in the drainage basin of the Aa from 1823 to 1826. The canal absorbs much of the water that would otherwise flow to the Aa. The Zuid-Willemsvaart was initially dug to be much wider than the Aa, but since then its width and depth accelerated, taking ever more water from the Aa. The role of the Aa in history can only be understood by considering its former state. In the 1760s the Aa was navigable till the bridge of Erp, about 25 km from 's-Hertogenbosch. In 1839 it was still navigable till the lock of Erp. There are also reports that barges moved by poles and small boats could navigate the river till Koks, just north of Gemert, about 30 km from 's-Hertogenbosch. All this might actually point to the same place. Anyway, near the Koksehoeve in Koks, Gemert there was a harbor for barges to and from 's-Hertogenbosch, and this activity only ended after the Zuid-Willemsvaart was dug. It explains why Heeswijk Castle on the Aa, about 10 km from 's-Hertogenbosch, was such a strategic position for defending 's-Hertogenbosch against the Dutch Republic.

Flows through: Netherlands.

River data from Wikidata (CC0); lengths normalised to a common unit.