In 's-Hertogenbosch, at the confluence of the Aa and the Dommel, the river Dieze is formed, which flows into the Meuse (Dutch: Maas) a few km further.

[2] 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.

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.

[3] 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.

In 1625 plans were made to make the Aa navigable from the Stipdonk mill at Lierop, south of Helmond to 's-Hertogenbosch.

In 1626 agreements were made with municipalities along the river, and in 1627 and 1628 locks were updated, and the Aa was brought to depth in some places.

After the Zuid-Willemsvaart had been dug, a more industrial approach to extract peat started in the raised bog of the Peel in 1853.

As a consequence, the precipitation that was previously retained by the raised bog began to flow downstream with steadily less delay.

Therefore, in 1927-1929 two canals were dug around Helmond, and connected to the Zuid-Willemsvaart, so the water situation in the Peel could be improved.

One of the causes was a policy which had centered on getting rid of excess water as soon as possible, and to trust in technical measures to solve any problems.

The events of 1995 changed this policy, and created focus for spillover areas, meandering, and restoration of streams and brooks.

[8] The aim is to prevent flooding by slowing drainage, and by temporarily storing excess water in spill over areas.

For the Aa it meant that many improvements for navigability, or to increase the speed with which it drains water downstream, had to be reverted.

It is currently under development to create an ecological connection zone, and to restore the river Aa.

The stretch of the Aa downstream from Heeswijk Castle till the Maxima Canal is characterized by the effects of the Dynamisch Beekdal project.

Further to the east the Hinthamereinde has the city side of the lunettes of the Muntelbolwerk, and a very decorative nineteenth-century water tower.

Environmental processes that were typical for brooks, like shore-erosion, shoal-forming and local fast currents had been eliminated by the canalization.

For marine life, the project created fish ladders in some places where the natural situation could not be restored.

This was important because typical brook fishes had decreased and even disappeared, and had been replaced by the european perch and common roach.

[11] With regard to birds there is hope that the Common Kingfisher, Sand martin, Marsh warbler, and Nightingale will profit.