Aa (Dieze)
| Aa | ||
 The Aa near Middelrode |
||
| Data | ||
| location | Netherlands | |
| River system | Rhine | |
| Drain over | Dieze → Maas → Hollands Diep → North Sea | |
| River basin district | Meuse | |
| source |
Nederweert 51 ° 18 ′ 48 ″ N , 5 ° 48 ′ 24 ″ E |
|
| Source height | 19.1 m | |
| muzzle | In 's-Hertogenbosch in Dieze Coordinates: 51 ° 41 ′ 46 ″ N , 5 ° 18 ′ 6 ″ E 51 ° 41 ′ 46 ″ N , 5 ° 18 ′ 6 ″ E
|
|
| length | 23.4 km (upper course), 2.8 km (Zuid-Willemsvaart), 46 km (lower course) |
|
| Catchment area | 984 km² | |
| Drain |
MQ |
11 m³ / s |
| Big cities | 's-Hertogenbosch | |
| Medium-sized cities | Helmond | |
The Aa is a small river in the east of the province of Noord-Brabant in the Netherlands . Namely, it has a length of about 72 km, but is no longer a hydrological unit. Rather, the upper course is a short tributary of the Zuid-Willemsvaart , which in turn is an artificial parallel course to the Meuse , the lower course a parallel course to the canal. However, except during high tide at the end of the common course in Helmond, as much water is allowed from the canal into the lower reaches of the Aa as has flowed into it above. The upper course rises in the municipality of Nederweert in the province of Limburg and is led into the canal in Helmond . The lower course branches off from the canal in the north of the city and joins in the center of 's-Hertogenbosch with the somewhat larger river Dommel and the old arm of the Zuid-Willemsvaart to Dieze . This flows northwest of 's-Hertogenbosch into the Meuse, 5.9 km downstream from the mouth of the canal. The straightening of the Aa did not begin until 1922. Since the turn of the millennium, efforts have been made to restore nature and replace straight sections of the river with meanders.
Emergence
The Aa was formed during the last ice age. During the Pleistocene about two million years ago, the Meuse was a tributary of the Rhine and flowed into the Rhine at the height of Cologne . After the ice had retreated, creating the terminal moraine landscape near Utrecht and the Veluwe , the rivers sought a new course. The Ardennes separated the Meuse from the Rhine, which caused it to flow much further north until it changed its direction to the west at Utrecht and the Veluwe to form the Schelde , Rhine and Mass delta . The Groote Peel in the east of Noord-Brabant with the raised bog areas at Asten and Griendsveen was created by tectonic shifts . The fluvial sediments of De Kempen and the raised bogs of Groote Peel flowed into the old Maas valley. In this way the rivers Reusel , Beerze , Dommel and the Aa were formed from west to east . Each of these rivers had and has its own side waters.
course
Source rivers and upper reaches
The Aa arises from two source rivers between 18 and 19 km long, which (like many Dutch rivers) have their origin today in ditch networks of rural drainage systems. Both arise in low-lying terrain, "Kuilen", so "Kuhlen" near the border between the Dutch provinces of Limburg and Noord-Brabant , where it runs more west-east, because here the broad southern merges into the narrow northern part of Limburg.
The Aa without Nemens addition, so probably defined as the actual upper reaches, has its origin in the Platkuil between Ospel and Ospeldijk, both districts of the municipality of Nederweert in Dutch Limburg. For the first three to four kilometers it makes an arc from west to north-north-west and is then accompanied over 10 km (mostly at a distance of over 100 m) west by the Zuid-Willemsvaart canal , whose mean discharge is 18 m³ / s is larger than that of the Aa at its mouth. At the level of Lierop , the Kleine Aa , coming from the west-south-west, is fed under the canal , which itself is only 4.7 km long, but has much longer source streams. The second long source river Astensche Aa , which comes from the Hoeks (ch) e Kuilen, flows from the right at the municipal boundary between Asten and Helmond , located in Noord-Brabant on the border of the Limburg municipality of Meijel . If necessary, water can be supplied to the source area from the Kanaal van Deurne , slowed down by several weirs and regulated by two lockable culverts (here crossings under streets). The canal gets its water from the Meuse via the upper part of the Zuid-Willemsvaart and the Noordervaart . The calcareous water of the Meuse improves the soil quality and thus the yield of the drained bog areas in the area.
800 m after this confluence, the Aa passes through a culvert under the Zuid-Willemsvaart. Afterwards it is called Nieuwe Aa , because this section was only created in the 1930s. To the north of the Helmond canal lock, the New Aa is directed into the Zuidwillemsvart, 5 km after the source rivers meet.
Part of the Zuid-Willemsvaart
In the section where the canal and the river are one, the Bakels (ch) e Aa flows north of the Helmond district of Dierdonk , which is called Oude Aa from 4.3 km above its mouth , without nowadays being further south Connection to another Aa run could be made out.
Lower course
Only 170 m after the mouth of the Bakelse Aa, the Aa, controlled by a weir, is allowed to drain from the canal to the left into its own bed, through which it flows 55 km from here to the junction with the Dommel . Soon after leaving, it is directed back to the east side of the canal through a culvert. The further course is straightened in detail, but compared to the canal it is meandering.
After the culvert at Beek en Donk , the Aa initially flows north. Shortly before the Erp , the river turns widely to the west and then flows through Erp. Veghel reaches it next to the canal, but then flows northwards along the city center. In Heeswijk-Dinther it flows northwest between the village and the canal. After the river Berlicum has passed, it is directed to the west under the Maximakanal (the new arm of the Zuid-Willemsvvart) in the 's-Hertogenbosch district of Hintham . In the north of the city center near the De Muntel district , the Aa, the old arm of the Zuid-Wilemsvvart and the Dommel merge to form the Dieze . This flows into the Meuse at the height of Crèvecoeur .
Before the first regulatory measures, the Aa partially looped around 's-Hertogenbosch, but as early as 1544 the Aa was routed in a more straightforward manner through the city, probably to improve water drainage. With the construction of the Zuid-Willemsvaart canal between 1822 and 1826, the old connection to the mainstream of the Dieze was interrupted, so that the river now forms the northeastern moat and feeds it with water. If the water level of the Meuse does not allow drainage via the Dieze, the water is drained through a drainage channel. This reverses the direction of flow of the moat and the Aa flows through the bed of the Dommel towards the north.
Economic use
The river has been used since ancient times to drain excess water from the higher sandy soils, where most of the settlement had taken place. As the population increased, the lower wet meadows and sandy soils closer to the water were settled. This happened particularly in Aarle-Rixtel , Beek en Donk, Keldonk and Heeswijk-Dinther, with the result that the residents in these communities regularly had to deal with flooding. Although the Aa used to be deeper and wider, its capacity to absorb excess water had always been too small. Especially in the winter months, the losses of livestock and fruit as a result of floods were high. The bed of the Aa was in poor condition and the millers of the water mills on the river let the water flow as they saw fit, creating large pools in various places, which in turn were responsible for flooding. The many water mills on the Aa and the arbitrary use of the water by the millers often gave rise to discord. This went so far that, in the first half of the 16th century, Emperor Charles V himself was appealed to mediate directly in this conflict. He deepened the river in 1545 and determined the amount of water that every miller was allowed to pass through. These measures were followed until the outbreak of the Eighty Years War in 1568 put an end to it. After the affected communities no longer knew what to do, they started buying up the watermills they had rejected in order to grind them. This project has been implemented almost everywhere.
1573 allowed Philip II. (Spain) in his capacity as Duke van Brabant the right by a distance of Aa to make downstream ship bahr the city Helmond. Due to the shortage of firewood in Herzogenbusch, the plan was made to further improve the Aa in its function as a traffic route. Between 1624 and 1628, the river was therefore deepened in various places and existing locks were restored. In December 1627 the first flat barge sailed from Helmond to 's-Hertogenbosch and back. The trip lasted three days. As a result of the siege of 's-Hertogenbosch by Friedrich Heinrich von Oranien in 1629, as well as the later fall of the city, these plans were not pursued any further. In 1739 and 1798, consideration was given to implementing the original plans after all. Due to disagreement between the various municipalities and the question of how much each municipality should contribute to the costs, these plans were never implemented. It became clear that the expected return would be disproportionate to the costs incurred. Until around 1840 the Aa was navigable for smaller ships and rafts from Erp to Hertogenbosch. At the height of Keldonk the river was about 7 meters wide. Several locks made it possible to moderate the difference in altitude.
River straightening
With the construction of the Zuid-Willemsvaart canal, started in 1823 and completed in 1826, the Aa lost its function as a waterway. The problems due to the regular flooding of pastures and arable land in the largely agricultural environment of the Aa remained. It was only with the establishment of the Lower Aa water association ( Waterschap de Beneden Aa ) in 1864, which merged into the larger De Aa water association ( Waterschap De Aa ) in 1924 , that it was decided to structurally solve the problems by channeling the Aa. Work began in the early 1930s. 1200 workers made sure that all branches of the Aa disappeared, so that the river lost its characteristic meander structure . Several weirs were built to prevent the water from flowing away too quickly. At first the work was only carried out with spades and wheelbarrows. Heavy equipment was only used in the 1960s and the Aa finally got its current face. The straightening of the Aa permanently changed the surrounding landscape and reduced the number of species of plants and animals. The wet meadows, the ponds and ponds surrounded by reeds with their fish population, birds and plant species disappeared to make way for agricultural land.
Renaturation measures
Since 2004 the flow area of the Aa has been part of the Aa and Maas water network ( Waterschap Aa en Maas ). At the end of the 1980s, an ecological awareness slowly began to develop. As a result, attempts are currently being made to repair the damage to the landscape to a certain extent. Old river loops, such as the one at Heeswijk Castle , are carefully maintained. The water network creates nature-friendly banks and in some places the river has regained its original meandering course, for example north of Helmond. Not all river loops can be restored, however, at the same time new loops are created in places along the course of the river where no river loops have been found.
Development projects
Dynamic Bachtal ( Dynamic Beekdal )
With this project, the water between Heeswijk-Dinther and 's-Hertogenbosch has been given more space, so that the movement of the water is now more natural, which is intended to prevent problems downstream from flooding.
Master plan Aa Veghel
This project aims to restore the course of the Aa within the municipality of Veghel. It affects the course of the river from the A50 motorway in the north to the beginning of the Erp district, a distance of around 8 km. The first phase of this project started in June 2007.
See also
Web links
Individual evidence
- ↑ 838 km² Waterschap Aa + 40 km² Limburg + 16 km² Maaskant
- ↑ a b Distributiemodel, Deel D Zuid Nederland (water distribution in the waters of the southern Netherlands)
- ↑ Drainage of the sewers in Noord-Brabant ( page no longer available , search in web archives ) Info: The link was automatically marked as defective. Please check the link according to the instructions and then remove this notice.
- ↑ http://pdokviewer.pdok.nl/→ ( Page no longer available , search in web archives ) Info: The link was automatically marked as defective. Please check the link according to the instructions and then remove this notice. TOP25raster + TOP10NL (tms), with measuring function
- ^ Rijkswaterstaat: Noordervaart
- ↑ https://www.ivn.nl/afdeling/meijel/peelkanalen
- ↑ Waterschap Aa en Maas: Dynamic Beekdal
