History of the Oker in Braunschweig
| Oker in Braunschweig | |
|---|---|
| length | 33.8 km |
| Entry into the urban area | Stöckheim-Leiferde |
| Entry fee | 74 m above sea level NHN |
| Leaving the urban area | Veltenhof / Watenbüttel |
| Height exit | 63 m above sea level NHN |
| Left tributaries | Thiedebach , Fuhse Canal , Schölke , Aue-Oker Canal |
| Right tributaries | Springbach |
| Still waters | South Seas , Kennel , Oil Lake |
| Water body NLWKN | 15001 |
The Oker in Braunschweig consists of the Okerum flood and the watercourses in the historic city center, the so-called city ditches. The Okerum flood divides into two artificially created water ditches , which are called flood ditches and were created as part of the city fortifications . They form the boundary of the historic city center of Braunschweig . This article mainly deals with the Oker course in the historic city center and refers to further entries about the Oker in the city area. The main article Oker provides information on the entire river .
The Oker in the medieval city
Historical course
The original course of the Oker up to the settlement and founding of the city was multi-armed and characterized by a swampy meadow landscape. Between elevations called the Klint , the river branched, meandered and formed so-called Werder as island-like inclusions. Today's street names like Klint point to the elevations and Werder on islands.
The historical level of the Oker lowlands is around 68 m above sea level. NN assumed. In the area of today's Bürgerpark, the river divided into two main arms and a large number of side arms. A wide, marshy floodplain was created, which extended over the unpopulated break area and only narrowed to about 300 m in the area of today's inner city. An east-facing headland with 70 m above sea level. NN constricted this floodplain and was advantageous as a location for the Dankwarderode Castle, which was built later . An early oker ford is suspected there. On one of the highest elevations with over 76 m above sea level. The Aegidienkloster was founded in 1115 , other areas higher than 73 m above sea level. NN were favorable for the first historical settlements attested since the 9th century (Kohlmarkt and old town) as well as the settlement of the eastern bank of the Oker in the area of Altewiek (Nikolaikirche) dated around 1000. The Cyriakus pen was built on a hill outside of what will later be the urban area .
Design in the 12th century
During the reign of Henry the Lion , the city was expanded and all of the soft areas were fortified with the city wall, rampart and moat. The Hagens area was drained with the help of naturalized Frisians . The street name Friesenstraße indicates where she lives. During this time, new trenches were dug and existing parts of the river were laid, e.g. B. the archaeologically proven source stream from Rennelberg , which ran in the area of the Neustadt . Braunschweig's inner city received its present form in the 13th century and was delimited for centuries by the outer arms of the Oker. The fracture area south of the city was excluded from the fortification belt and unpopulated for centuries.
The map shows the defensive ring built up to then with the outer flood ditches, as they are assumed around the year 1400. In the inner-city area, the branching course of the Oker and the artificially created city moats can be seen:
- The Burgmühlengraben, originally the left arm of the Oker, ran between the southwestern city wall in the rupture area to the Nickelnkulk completely within the city, presumably following the natural course of the river.
- The Münzgraben, originally an eastern Oker arm, formed the city limits in the Bruch area and flowed from the Ottilienteil until it met the Burgmühlengraben within the city.
- The trench served as a branch from the western Okerarm of the southern city limits and the drainage in the rupture area, where other smaller trenches were available.
- Steingraben and Wendengraben branched off from the Münzgraben and drained the Hagens area. Their course indicates an artificial system.
- The moat branched off from the Burgmühlengraben, enclosed the castle district and delimited it from the sack . It should also have arisen in the course of the burger direction.
- The drifts branched off from the Burgmühlengraben in the northern part of the city and encompassed the Werder .
The demarcation trenches and early defensive trenches are listed:
- The Neustadtmühlengraben, which branches off from the western Okerarm in the Gieseler area and represents the outer boundary of the old and new town. It runs to the Neustadtmühle and still branches off into the Oker as underwater of the mill , during the
- Bosselgraben absorbed the water overflowing in front of the Neustadtmühle on the weir and leads to the confluence of the trenches at Nickelnkulk.
- NN, branching off from the eastern Okerarm and surrounding the Altewiek . This ditch was no longer recorded in the 17th century.
- The Wendenmühlengraben, branching off in the Ottilienteil from the Münzgraben to the east, formed the border between Hagen and Altewiek and, from the Steintor to the Wendentor, the outer city limits.
The inner-city trenches still meet today as open trenches on the former Nickelnkulk near today's Schubertstrasse near the Gaußdenkmal. At Neustadtmühlengraben, an impressive remnant of the city wall is visible on Echternstrasse , in the area of the Bosselgraben a meter-thick remnant of the city wall was only drilled through in 2007 in the course of horizontal drilling between Inselwall and Wendenmühlengraben.
Separately from the outer ditches, the flood ditches are clearly recognizable as broad and largely straight lines of the Oker. They also meet in the area of today's Bammelsburger Strasse.
Mills in the historic city center
The names Burg-, Neustadt- and Wendenmühlengraben indicate mills within the historic city. Six locations are shown on the map, whereby the mills were assigned to the Weichbildern or other independent districts.
- Aegidienmühle immediately west of the Aegidienkirche at the junction of the Wendenmühlengraben from the Münzgraben, for example at the location of the New Apostolic Church near the consumer association , probably since the 12th century and equipped with four grinding aisles in the 18th century,
- Südmühlen at the entrance of the Burgmühlengraben through the Südmühlentor into the fortified old town, today around Friedrich-Wilhelm-Platz, from the 18th century only one mill with six grinding courses,
- Dammmühle with five grinding courses, within the city, today western development on Münzstraße opposite the C&A department store
- Burgmühle directly opposite the castle, today next to the location of the sculpture 2000 Years of Christianity on Ruhfäutchenplatz, equipped with four grinding courses,
- Neustadtmühle am Neustadtmühlengraben, initially two mills and in the 18th century a mill with six grinding courses, renewed in the 19th century in the shape that still exists today,
- Wendenmühle at Wendentor with five grinding aisles, today the location of the administrative court
In order to regulate the water balance and the inflow of a mill, an additional mill ditch with appropriate weirs is necessary. There is an extensive trench in the maps for the Dammmühle, the Neustadtmühle and the Wendenmühle.
Water supply from the 16th century
In the 16th century, water art was built to supply selected town houses with drinking water from the Oker, from the Säcker water art under the construction management of Barward Tafelmaker :
- Aegidia water art (1525) at the Aegidia mill
- Säcker Wasserkunst (1527) opposite the castle mill
- Neustädter Wasserkunst (1529) at the Neustadtmühle
- Hägener Wasserkunst (1540) at the castle mill
- Vordere Südkunst (1541) in the old town near the Südmühle at the Bruchtor (also called Reichskunst)
- Rear southern art (1561) also at the southern mill
- Gieseler art (from 1560) in front of the old town on Gieseler, completed after Tafelmaker's death (1565).
The water arts were dissolved in the 19th century after the laying of central water pipes from the Bürgerpark pumping station .
shipping
Harbors for supra-local freight traffic are already assumed to have existed for the early settlement period, whereby simple berths for barges have to be imagined, see also Okerschifffahrt . The mills in the urban area made it extremely difficult to navigate the Oker continuously, so that two locations are assumed for traffic: A port in the southern area is assumed at the confluence of Bruchgraben and Münzgraben. There the existence of a Nikolaikirche has been handed down, the namesake of which is the patron saint of seafarers. A landing stage in the northern area has not yet been proven, but is suspected in the Großer Hof area near the former Nickelnkulk. Another mooring point was available in the Hagen city area near Werder, but it may only be relevant for inner-city traffic.
Long-distance trade routes and city gates
Braunschweig was on several important long-distance trade routes. In the late Middle Ages, the Okerum flood and the southern Oker courses were the outer boundary of the entire city and the trade routes crossed the Okerum flood at the city gates:
- The Aegidientor, later called Auguststor, in the area of today's John-F.-Kennedy-Platz, through which the road to Wolfenbüttel and Leipzig led to the right of the Oker.
- The Magnitor at today's street of the same name, but this gate was closed later, the traffic in the direction of Magdeburg only continued
- the stone gate, the location of which can be assumed at Georg-Eckert-Straße. The customs houses on Helmstedter Strasse that still exist today are from the time of the fortification of the bastions.
- The Fallersleber Tor at the location of Fallersleber Straße and the wall of the same name for the street to the east, later Berliner Straße.
- The turning gate at the intersection of the street of the same name and the gate wall on Gaußberg for the street towards Hamburg, i.e. right of the Oker.
- The Neustadttor at the Neustadtmühle, the way led into the Masch , the gate was closed later.
- The Petritor at today's Petritorwall and the street of the same name. The names "Am Neuen Petritor" and "Am Alten Petritor" indicate that the gate passage has been relocated. Along here the road led via Celle to Bremen, so left the Oker.
- "Das Hohe Tor" with the road connection directly to the old town market suggests a very old and stately use. The floor plan of the historic city gate is embedded in Sonnenstrasse . The external road led to Hildesheim, but also branched south.
- The Michaelistor at the bridge on today's Prinzenweg over the Neustadtmühlengraben with the arterial road to Goslar, so heading south on the left of the Oker. This gate was replaced by the later Wilhelmitor.
In addition to the east-west connection, there were various north-south connections for which there was the possibility of crossing the Oker in Braunschweig and the choice of the further route to the right or left of the Oker. The directions refer to looking in the direction of flow.
There were three gates in the rupture area that had no regional significance:
- The Südmühlentor with a bridge connection between the Südstraße and the Bruchgebiet, the later Wallstraße.
- The Bruchtor in the area of the Long Bridge , which provided a road connection between the Kattreppeln and the path later called Leopoldstraße.
- The water gate at the entrance of the Münzgraben into the city area, today at the beginning of the Bruchtorwall at Lessingplatz . This gate was only later a bridge to the rupture area and previously probably served as a watchtower.
Oker course in the inner city area
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The Long Bridge around 1750 with the Aegidien Church in the background
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The Oker course on Ruhfäutchenplatz ,
painting by Domenico Quaglio , 1832 |
Overbuilding of the Oker from the 19th century
Hygienic grievances
The appearance of the city center until the end of the 19th century was characterized by the arms of the Oker and a large number of bridges . In particular, the long bridge in the area behind Liebfrauen and Kattreppeln as well as the Oker course at Ruhfäutchenplatz have been handed down as idyllic locations in old views. In fact, all of the wastewater in the city center was discharged via the Okerarme, which led to odor and hygiene problems. In the 19th century, the Braunschweig magistrate decided to backfill and pipeline the arms of the Oker and carry it out for the entire inner city area from 1871 under the direction of Louis Mitgau until 1905. At the same time, the planning of a newly structured city center around the castle began. The town hall as well as the administrative buildings of the state government (Dankwardstraße, Ruhfäutchenplatz), court and police buildings were built and new streets like Münzstraße and Casparistraße were created after the canalization of the Burgmühlengraben. The oker arms were largely given their shape that still exists today.
Burgmühlengraben
It was completely laid in a predominantly rectangular underground channel about 1.80 m high. It begins under the Bruchtorwall at the main building of the Landessparkasse, where its beginning can be seen as a mouth hole under favorable conditions. It follows Friedrich-Wilhelm-Straße and passes the former main post office on its west side. From there it crosses under the built-up area to the beginning of the castle passage, where it is accessible through shafts in the hat filter area . In the southern area of the district court building it meets the also canalised Münzgraben.
At Dankwarderode Castle, which was newly built at the end of the 19th century, it was made close to the original course as a historical quote and gives today's viewer an idea of the earlier townscape. It also runs under the houses on the west side of Casparistraße. At the passage between Stecherstraße and Hagenbrücke, the former Hagenbrücke is still there under the pavement. The route between Hagenbrücke and Kaiserstraße is entered by name on the city map from 1938, today Litolffweg along the former market hall and Großer Hof. From the Kaiserstraße bunker, the canal crosses Geiershagen street. Its exit in the Schubertstrasse area has only been an artifact since 2009, as the canal was previously branched off underground and fed to a pumping station on Inselwall. The functionless mouth hole was rebuilt for reasons of monument protection so as not to change the overall impression of the complex.
In describes that a historical access from the Kohlmarkt to the former open moat can still be guessed today, which has been handed down as Amestieg .
Coin pit
Its beginning is still visible today as a barred concrete pipe at the Bürgerpark public baths. Furthermore, it runs east of Leopoldstrasse and west of Lessingplatz. At the garrison school and in the school yard of the Lessing school, the former course of the open ditch is clearly recognizable as the edge of the terrain. He leaves the former large orphanage BMV on the right and follows Münzstraße, which is named after him, where he meets the Burgmühlengraben Canal at the level of the Regional Court.
Neustadtmühlengraben
At the Gieseler it branches off from the western flood ditch, where it was built over about 100 meters in length after 1945. There it used to be spanned by a bridge in the area of Güldenstrasse . It begins today directly under the rest of the historic city wall on the Gieseler. Another piece of history can be found behind the house at Echternstraße 16 ( Stobwasserhaus ), where an old battlement leads from the backyard to the moat under the historic city fortifications.
At the bridge on Prinzenweg , the town gate situation of the Michaelistor is still easy to understand today through the narrow buildings. In the further course of the ditch in the area of Sonnenstrasse and the Petritor, parts of it were covered.
The MTV Braunschweig climbing wall is erected on Güldenstrasse directly above the moat. Earlier bridges were removed or built over, as on the old Petritor. The two-arched bridge on the New Petritor (nowadays rather Radeklint) is still completely preserved, but overbuilt on one side. On the other half-side, its historical shape and especially the bend in the street can be seen. In the Neuer Weg area, smaller pedestrian bridges cross the open, green ditch reinforced with natural stone masonry. At the Neustadtmühle, the existing bridge to the Inselwall is also still recognizable as a two-arched bridge. The second arch is partially covered. This moat and the adjacent Bosselgraben are the only city moats that have been almost completely preserved as open moats.
Bosselgraben
The Bosselgraben is the continuation of the Neustadtmühlengraben between the Neustadtmühle and the Gaußberg. Its bank area is completely green. Remnants of historical walls and a historical bridge are still there. Towards the Gaußberg, the right bank is determined by the Johannes-Selenka-Schule (vocational school) before the ditch meets the other inner-city ditches.
Wendenmühlengraben
It is only partially visible in the area of Neue Kniehauerstraße and is otherwise piped. At the consumer association (see Ottilienteil ) there is a channel as a quote from the former course of the ditch. The further course behind the former castle along the Mauernstrasse is no longer recognizable.
Wendengraben
The Wendengraben was canalized as early as 1826. It ran in the middle of the street similar to a canal with paths on both sides and 17 bridges, which was the reason for the width of Wilhelmstraße , which was noticeable even before the destruction of the inner city . As part of the reorganization of the inner city drainage from 2007 (see below), the Wendengraben will be led through a new pipeline from around the Wilhelmstrasse / Wendenstrasse intersection to the former Nickelnkulk , where it will be routed together with the Burgmühlengraben to a new pumping station.
Today's importance of the city moats
Urban drainage
The entire surface drainage of the inner city is still carried out today via the old Oker arms and inner city canals, which are monitored and maintained by the city drainage of Braunschweig. In addition, they partly serve to relieve mixed water by absorbing excess mixed water from the mixed water sewer network that is still predominantly in the city center during heavy rain events. During heavy rain events this regularly led to pollution of the Oker trenches with mixed water and thus also with faeces. To avoid this, the Burgmühlengraben, into which the Wendengraben also flows, should not be led any further as open water to the island wall. In 2007/08, a further pumping station was installed at the site of the existing Inselwall waste water pumping station at the Gaußdenkmal, to which the water from Burgmühlen- and Wendengraben is led via new drilled sewer lines. The pumping station is equipped with a mechanical cleaning system for the waste water that occurs, which transports the faecal residues to the Bammelsburger Strasse pumping station and thus into the sewage system. The remaining water is pumped into the castle mill moat on the island wall and ultimately into the eastern flood ditch. Burgmühlengraben and Wendengraben therefore continue to function as mixed water relief channels.
At the level of the Gaußdenkmal, only the Bosselgraben and Wendenmühlengraben flow together over the remainder of the Burgmühlengraben along the pumping station. The former exit of the castle mill moat is now walled up and is only used for aesthetic purposes, see above .
Recreation
In the area of the Inselwallpark , the Burgmühlengraben flows into the eastern flood, which shortly thereafter also includes the Neustadtmühlengraben. Further downstream at Pestalozzistraße, the western and eastern flood ditches meet. This area is a popular resort in the city center and offers an impression of the earlier structure of the Oker course.
There are various concepts for using the Neustadtmühlengraben in particular for educational and leisure activities. The problem is the heavy pollution of the ocher sediments with heavy metals such as cadmium, copper and zinc. When evaluating the Bosselgraben as a possible canoe route for children, the sediment was examined in 2008 and classified as hazardous waste . The values for arsenic were 380 mg / kg of tested dry matter, the test value according to the Federal Soil Protection Act is 125 mg / kg for leisure facilities. Damage to health through direct skin contact or swallowing cannot be ruled out, especially for smaller children. Removal of this contaminated sludge is extremely time-consuming and prevents systematic use.
Design of the Okerum flood
Development up to the 17th century
The outer flood ditches run relatively straight in the historical views. Over the centuries, the moats and defensive walls were gradually redesigned. The city model in the old town hall shows the state around 1671. The outer ramparts are heavily fortified and reinforced around bastions, so that the result is a polygonal city plan with the flood ditches as edges.
Fortification in the 17th century
After Duke Rudolf August took over the bourgeois town in 1671, the outer defensive ring was expanded into a bastionary fortification from 1692 onwards . The ramparts were transformed into 16 bastions, between which so-called ravelins were surrounded by water . The basic triangular shape of both types of bulwark gave the flood ditches their zigzag shape to this day, as they continued to flow around them after bastions and ravelins had been razed and only a few sections were filled.
The bastions were given local names and given names that were common in the ducal family and are listed counterclockwise from the south together with the still recognizable ravelins:
- "Aegidien" or "Christine" - today remains of the windmill mountain.
- "Wilhelm" - Löwenwall , recognizable as a steep slope towards the Oker.
- "Magni" - stone gate wall, triangle at the level of the former bridge cultural center ,
- in front of the next bastion in the middle is a ravelin, the triangular shape of which can be seen in the museum park right next to the Herzog-Anton-Ulrich-Museum.
- "Ulrich" - recognizable as a hill in the museum park near the State Theater. The height of the eastern fortifications is due to the Giersberg opposite .
- "Anton" - Theater Park , clearly perceptible as a triangle and today at over 83 meters above sea level. NN the highest point within the flood ditches.
- "Fallersleber" - opposite the Botanical Garden at the AOK,
- in front of the next there is a ravelin, which can be seen east of the Oker bridge Pockelsstraße in the triangular course of the Oker.
- "August" - Wendentorwall, hardly noticeable today because of the straight Oker course.
- "Rudolf", the first bulwark with the Wenden weir that already existed at the time - today the Gaußberg , now referred to as the Anatomy Mountain .
- "Ludwig" - Löbbeckes garden , the area with the fountain,
- upstream a ravelin, which is today Löbbeckes Insel .
- "Kaiser" - on the Inselwall near the Wehrstraße directly on the Petri weir, which already existed at that time.
- "Elisabeth" - near Radeklint / Petritor; the Heerstraße to Celle led between No. 10 and 11 over a Ravelin as Neues Petritor ,
- in front of the next bastion is a ravelin, which today determines the course of the Oker behind the Holwedestrasse hospital.
- "Carl" - Hohetorwall / Petritorwall north of the Sidonia Bridge,
- upstream a ravelin, over which the street of the Hohetor led, which is barely noticeable today.
- "Ferdinand" - south of the bridge Am Hohen Tor / Madamenweg at Pawelstrasse and not, as one might assume, at Ferdinandstrasse.
- "Eugenius" - south of the Ferdinandstrasse bridge, on the former Buchler site there is a clear Okerkink,
- the ravelin to the next bastion is still clearly recognizable in depictions from 1826, i.e. after the start of the razing , today the area of the Europaplatz stop at Artmax .
- "Detachiert" - a bastion at Kalenwall, which, like a ravelin, was completely surrounded by the Oker and the branching Neustadtmühlengraben, later the location of the former main station , today the Landessparkasse. Between this and the next bastion in the rupture area, the rampart in the Wallstrasse area was made wider.
- "Luise" - viewing hill in Hollandtsgarten (Salve Hospes and outdoor area of the public baths Bürgerpark).
The rough course of the flood ditches was not changed because of the surrounding hills of Giersberg and Rennelberg, so that the heart-shaped structure of the city center was preserved. The medieval river courses in the inner area of the city were not changed by the new fortification, but the break area with its branched river arms has been fully included in the fortification.
Design of the ramparts in the 19th century
The military value of the fortress was already worthless when it was completed, so that from 1803 a wall demolition commission was set up and the demolition began under the direction of Peter Joseph Krahe . The conversion of the ramparts into promenades at the beginning of the 19th century gave the ramparts their park-like shape, between which the flood ditches meander deeply. The map layout typical for the city center was created. With these promenades and the simultaneous expansion of the city outside the flood, the medieval city limits were finally lifted.
Remodeling in the 20th century
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A significant change in the ramparts took place from 1950 as part of the reconstruction of the city center and the new construction of the main train station until 1960. The Petritor / Radeklint and Löwenwall / Windmühlenberg areas were completely redesigned, old crossings removed and new, wide bridges built. The partly winding character of the streets, which originated from the bastionary times, was destroyed in these areas and replaced by a traffic-friendly design. In the Am Hohen Tore area , on the other hand, the earlier structure is still clearly visible.
Use of the Okerum flood
Water management
The water level of the Oker is regulated above the city at the Eisenbütteler weir and below the Ölper weir .
In between are the two weirs of the flood ditches and the historical damming of the Neustadtmühlengraben near the Neustadtmühle. The regulating weir of the western flood ditch is the Petri weir ( Maschwehr ), that of the eastern flood ditch is the Wenden weir . Both represented an obstacle for the boat trip and for migratory fish. Currently, after the reconstruction of the Wenden weir, the construction of a fish passage at the Petri weir is being started.
Bathing operation
Until 1951 there was a regular bathing operation in the Oker, which was given up because of the water pollution. From 1813 on, a swimming facility for the educated estates is mentioned at Am Magnitor . In 1821 the city opened a civil bathing establishment for men, which was called the "Gellertshoffsche" after its tenant. The Badetwete, which is still known today, led to this from Wolfenbütteler Strasse. In 1828 a military bathing establishment followed in front of the Augusttor and from 1854 a bathing area for railway workers in front of the Wilhelmtor. This moved to the Bürgerpark and was accessible to all citizens under the name Bahnbade from 1874 until it ceased operations in 1951.
After the First World War, there were not only single-sex pools in the city, but also family pools. Close to the Oker near Melverode, the swimming club Delphin, founded in 1897, opened a swimming area on what is now the area of the Friends of Nature on the South Sea . After the cessation of bathing in the Oker, the Kennelbad as well as the gravel ponds and the Rafteich are still used by the Braunschweig residents .
Recreational value
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Together with the ramparts, the flood ditches represent a relaxing green area within the city. Several boat rental companies have established themselves who offer successfully guided excursions and readings on the Oker as well as other adventure tours. The gastronomy along the Oker has also discovered this tourist area, so a beach café is operated in the Bürgerpark in the summer months, from which excursions are possible.
The view of the city from the Oker offers tourists as well as locals new perspectives on the city and is offered as an attraction by the city marketing of Braunschweig. Motorized boat traffic is normally not permitted on the Oker, but electrically operated and therefore low-noise drives are exceptionally permitted for tourist trips.
The green area along the Oker has already been used several times as a cultural location for music and other events, for example jazz on the Oker . In 2000 on the occasion of the Expo , the Oker was illuminated, in 2010 and 2016 there were further light installations as part of the light course .
Western flood ditch
The Western Umflutgraben is viewed in the official waterways as a continuous arm of the Oker with a length of 3.7 kilometers. The most important water management structure is the Petri weir, which is a listed building.
Distinctive points on the course of the western flood ditch (from south to north):
Eastern flood ditch
The eastern flood ditch is 4.1 kilometers in length, slightly longer than the western one and is regulated in the northern area by the Wenden weir. Distinctive points on the course of the eastern flood ditch (from south to north):
- Bürgerpark
- Lion wall
- Duke Anton Ulrich Museum
- Museum park
- State Theater Braunschweig
- Theater park
- Botanical garden of the Technical University of Braunschweig
- Technical University of Braunschweig
- Wendenwehr
- Löbbeckes garden
- Löbbeckes Island
bridges
Oker in the rest of the city
South of downtown
The Oker near Stöckheim and Leiferde from neighboring Wolfenbüttel enters the present-day urban area of Braunschweig . Distinctive places are the Rüninger weir at the Rüningen mill and subsequently the South Pacific in the district of Rüningen and Melverode . The South Pacific serves to regulate the water level and to protect against floods and is a popular local recreation area for walkers, sailors and anglers.
The Rüningen waterworks existed in this groundwater-rich area until the 1950s. A building of this plant still exists at the intersection of the railway line to Bad Harzburg and the A 39 near the Spielmann pond. The ponds created in the kennel area served as settling basins for the drinking water, which was pre-cleaned in this way and pumped into the city's supply lines by the Bürgerpark pumping station .
The weir near Eisenbüttel has been regulating the water level in front of the Braunschweig city center for centuries and is the beginning of the Bürgerpark. There the oker arms branch off at the portico to the flood.
North of downtown
To the north of the Inselwallpark , the Oker runs along the Uferstrasse power station to the district of Ölper . Another local recreation area has existed there since the 1970s with the artificially created oil lake. The lake relieves the Oker, which used to regularly flood the meadows.
The weir in Ölper at the site of the former mill regulates the water level for the cooling water extraction of the central heating power station and the amount of water discharged into the lake. Furthermore, the Oker runs in the now sandy subsoil, meandering along the higher bank at Veltenhof through a wide meadow landscape to Watenbüttel . There it is ducked under the Mittelland Canal and leaves the Braunschweig urban area at the A 2 motorway bridge towards Rothemühle in the Gifhorn district . The area from the Ölpersee to the city limits is under nature protection as the " Braunschweiger Okeraue ".
Water quality
The water quality especially of the Oker in the Braunschweig urban area was investigated on behalf of the city of Braunschweig in 2012.
Water structure quality
Overall, the Oker is rated as the second worst quality class VI and also classified as Heavily Modified WaterBody in the Braunschweig area . This affects the two flood ditches and the Oker course in front of and behind the city center. The inner city trenches are not taken into account in this assessment, but are classified as sewers. The course of the flood ditches is completely remote from the nature of the history of their origins. In addition, in the bank areas they are fixed in sections with stone fillings and fascines in order to avoid demolition and to preserve the property boundaries. This hinders both the species-rich vegetation and the fauna.
In the 1960s, significant interventions were made in the course of the river between Leiferde and Rüningen and in the construction of the oil lake between the city center and the Ölper weir. Originally meandering and thus natural sections were replaced by straightening with edge fortifications.
Another problem are the weirs in Rüningen, Eisenbüttel and Ölper as well as the Petri and Wenden weirs. In the Braunschweiger Oker course there is a height difference of 11 meters, 6 meters of which at the weir falls. The backwater partially extends as far as the weir in front of it, so that the water level is practically free of slopes. The weir on the Rothemühle also backs up into the Braunschweig urban area. The low gradient leads to a lower flow velocity in the river bed and to high sedimentation, i.e. silting up of the bottom. This phenomenon is observed in both flood ditches and south of the city center. In addition, the weirs hinder the natural transport of stones, dead wood and gravel and inhibit the migration of organisms.
To the north of the Ölper weir, on the other hand, there is an extensive section with symptoms of deep erosion in the form of erosion in the bank area and trees sliding into the river. A possible cause could be the lack of transport of sediments from the upper river.
Biological quality
As in the rest of the Oker course, the Oker is classified in quality class II-III, i.e. as "critically loaded". The section on the city ditches has already dealt with the extraordinarily strong exposure to heavy metals for historical reasons.
The existence of some aquatic plants such as the Mummel in the section above the Rüninger weir is rated positively, on the other hand the flood ditches and the further course to the Ölper weir are noticeably poor in vegetation. The fish population with roach and perch as well as eels from artificial stock does not meet the expectations of lowland water and is rated as unsatisfactory.
Central heating plant
The thermal output of the thermal power station is 330 MW and is used for the district heating supply . The unused heat is discharged into the river via the cooling water taken from the Oker, which can lead to a considerable increase in the water temperature, especially in summer. According to the water law permit, this is limited to 28 ° C. According to the C report from 2004, this does not lead to any damage to the communities in the river. However, salmon that are supposed to return to the Oker stop migrating from 25 ° C.
literature
- Wilhelm Appelt, Theodor Müller: Water arts and waterworks of the city of Braunschweig. In: Braunschweiger workpieces. Vol. 33 Braunschweig 1964.
- Wolfgang Ernst: Braunschweig's underworld. Canals and vaults under the city.
- Volume 1: The Burgmühlengraben through the ages. Appelhans Verlag, Braunschweig 2011, ISBN 978-3-941737-40-2 .
- Volume 2: Wendenmühlengraben and Neustadtmühlengraben through the ages. Appelhans Verlag, Braunschweig 2014, ISBN 9783944939094 .
- Theodor Müller: Shipping and rafting in the river area of the Oker. In: Braunschweiger workpieces. Vol. 39 Braunschweig 1968.
- Harold Hammer-Schenk : Castle and castle area. A new city center for Braunschweig. In: Old City - Modern Times. , Ed. Cord Meckseper on the state exhibition Stadt im Wandel, Braunschweig 1985, ISBN 3-88746-120-7
- Water . In: City of Braunschweig (ed.): Environmental Atlas . Braunschweig December 2007, Chapter 8, p. 4 (see "Fig. 8/1: Oker and artificial trenches in medieval Braunschweig").
Web links
Individual evidence
- ↑ a b c d City of Braunschweig (client), Aland: Concept of measures according to EC WFD for the water body Oker in Braunschweig , Braunschweig March 2012, source website of the city of Braunschweig on April 8, 2013
- ↑ Henry W. Schupp: The medieval town to the loss of independence in 1671 Braunschweig. In: The image of the city in 900 years, Volume 2: Braunschweig's city history. Braunschweig 1985, published by the Städtisches Museum Braunschweig
- ↑ Wolfgang Ernst: Braunschweig's underworld. Canals and vaults under the city. Vol. 1: The Burgmühlengraben through the ages. Braunschweig p. 31 and the maps on p. 14.
- ↑ Construction description of the Inselwall pumping station ( memento of the original from March 4, 2016 in the Internet Archive ) Info: The archive link has been inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice. (PDF; 1.6 MB)
- ↑ Wolfgang Ernst: Braunschweig's underworld. Canals and vaults under the city. Vol. 1: The Burgmühlengraben through the ages. Braunschweig, p. 17
- ↑ See also the map from 1826 in Wolfgang Ernst: Braunschweigs Unterwelt. Canals and vaults under the city. Vol. 1: The Burgmühlengraben through the ages. Braunschweig 2011, p. 22.
- ↑ Wolfgang Ernst: Braunschweig's underworld. Canals and vaults under the city. Vol. 1: The Burgmühlengraben through the ages. Braunschweig, p. 52
- ↑ Udo Gebauhr: 1938/2010 Historical-Synoptic Map of the Braunschweig inner city. Richard Borek Foundation / City of Braunschweig, 2010, ISBN 978-3-00-029747-2
- ↑ See Wolfgang Ernst: Braunschweigs Unterwelt. Canals and vaults under the city. Vol. 1: The Burgmühlengraben through the ages. Braunschweig 2011, p. 78.
- ↑ Wolfgang Ernst: Braunschweig's underworld. Canals and vaults under the city. Vol. 1: The Burgmühlengraben through the ages. Braunschweig, p. 34
- ↑ Wolfgang Ernst: Braunschweig's underworld. Canals and vaults under the city. Vol. 1: The Burgmühlengraben through the ages. Braunschweig, p. 23
- ↑ See Wolfgang Ernst: Braunschweigs Unterwelt. Canals and vaults under the city. Vol. 1: The Burgmühlengraben through the ages. Braunschweig 2011, p. 63 f. and 81.
- ↑ Construction description of the Inselwall pumping station ( memento of the original from March 4, 2016 in the Internet Archive ) Info: The archive link has been inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice. (PDF; 1.6 MB); Wolfgang Ernst: Braunschweig's underworld. Canals and vaults under the city. Vol. 1: The Burgmühlengraben through the ages. Braunschweig 2011, pp. 73-79.
- ↑ Wolfgang Ernst: Braunschweig's underworld. Canals and vaults under the city. Vol. 1: The Burgmühlengraben through the ages, Braunschweig. P. 64.
- ↑ Children's parkour on the old city moat ( memento of the original from March 4, 2016 in the Internet Archive ) Info: The archive link was automatically inserted and not yet checked. Please check the original and archive link according to the instructions and then remove this notice.
- ↑ Braun, Christian: Renovation and hydraulic engineering redesign of the Bosselgraben in Braunschweig as a canoe route for children , study draft at the Leichtweiß Institute for Hydraulic Engineering at the Technical University of Braunschweig, July 2009.
- ^ Richard Moderhack: Braunschweig around 1671 in the city model. Working reports from the Städtisches Museum Braunschweig, Braunschweig 1978.
- ↑ Henry Schupp: The ducal city until the onset of industrialization. In: Braunschweig - the image of the city in 900 years. Braunschweig Municipal Museum, 1985.
- ^ Planning approval for the city of Braunschweig
- ↑ Margot Ruhlender in Brunswick Stadtlexikon , 1992, Braunschweig, keyword baths
- ↑ BS-Energy: Heizkraftwerk Mitte , website website BS-Energy , accessed on September 7, 2016
- ↑ Water law permit of the NLWKN of July 10, 2009, quoted in the Oker action plan in Braunschweig, p. 21.
