Wuhlebecken
| Wuhlebecken | ||
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| Map of the Wuhlebeck | ||
| Geographical location | Central Europe , Germany , Berlin | |
| Tributaries | Wuhle | |
| Drain | Wuhle | |
| Places on the shore | Biesdorf -Süd, Kaulsdorf -Süd | |
| Data | ||
| Coordinates | 52 ° 28 '55 " N , 13 ° 33' 44" E | |
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| Altitude above sea level | 33 m | |
| surface | 6 ha | |
| Maximum depth | 5 m | |
The Wuhlebecken is a lake in the Berlin district of Marzahn-Hellersdorf . It is also known as the Wuhlesee . It is located in the southern course of the Wuhle and, with a size of almost 6 hectares, is one of the largest lakes that the Wuhle forms. At its widest point, it measures 110 meters and is over 520 meters long. At 5 meters, it is quite deep and thus includes a large volume of fresh water.
description
At its beginning and at its end, the lake is dammed by two locks and the Wuhle is led around the lake in a side arm to the west. This creates an inaccessible, protected bank strip between the basin and the tributary that is between 5 and 10 meters wide.
In terms of landscape, the Wuhle basin and its surroundings represent a varied area that invites visitors to take a walk. On the east bank of the basin, the only unspoilt water edge of the Wuhle, there are large reed and reed beds and some groups of trees. On the bank of the tributary to the west, there is a newly planted row of weeping willows. In large areas, the Wuhle is characterized by dense bushes and shrubs on its embankment and thus, in addition to its large plant species diversity, offers protection for numerous animal species and thus forms a distinctive biotope . The variety of vegetation, especially near the bank, clearly stands out from other stretches of water. Water birds find the peace they need to breed on the cordoned-off dam and the fish population in the Wuhle basin is connected to the Spree .
History of origin and source area
The Wuhle, as a tributary of the Spree, arose at the end of the last Ice Age , the Weichsel Ice Age , around 18,000 years ago as a drain for the meltwater from the glaciers and lies on the edge of the Berlin glacial valley . It rises near Ahrensfelde .
Since the glacier ice mountains melted, the Wuhle has been fed by groundwater and seepage water. Their visible beginning is a narrow ditch near the Ahrensfelde Friedhof train station . From here to where it flows into the Spree, the Wuhle covers 16.4 kilometers and overcomes a difference in altitude of around 30 meters. The Wuhle and thus also the Wuhle basin are located above large young moraine landscapes which, when they were formed, produced layers of soil rich in lime and minerals, which represent coveted arable land.
At first there was an elongated sand ridge at the current location of the Wuhle basin, around which the Wuhle flowed on the western side. In the 1950s, the Wuhle and the Wuhle basin were rebuilt. The newly created lake served to lower the groundwater and, moreover, the sludge carried along by the Wuhle was supposed to settle when it flowed through the lake.
At the end of the 80s, the Wuhle had to be expanded again. The Falkenberg sewage treatment plant had meanwhile taken over the function of the sewage fields , and the clarified water was discharged via the Wuhle. Since ever larger amounts of dirty water had to be disposed of, the runoff of clear water also increased. The passage capacity of the Wuhle should therefore be increased from 9 to 15 m³ / s. At the same time, the Wuhlesee was dredged to a depth of 5 m and bordered by a dam on the western side, so that the Wuhle now flows around the lake. The aim was to use a dam to regulate the water flow and the groundwater level and to improve the water quality of the lake.
climate
The climate is arguably one of the most important density-independent abiotic factors. It affects all species in a biotope equally because it has a large area. The various climate elements, such as the amount of precipitation, temperature mean, maximum and minimum, influence the viability and spread of a species; on the other hand, certain species can be used as bio-indicators for certain climatic conditions.
Due to the homogeneity of the climate in larger areas, average climate values for the Berlin region were used in order to make general, longer-lasting statements.
Berlin and thus also the Wuhle basin biotope is located, with an annual average temperature of 8.4 ° C and an average rainfall of 587 mm, in the temperate climate zone, which allows clear seasons in spring, summer, autumn and winter. The mild and rainy climate values typical for Berlin and Central Europe, as well as the small difference (19 ° C) between temperature minimum (−1 ° C) and maximum (18 ° C), are due to the influence of the Gulf Stream . The climate diagram for Berlin shows that the average rainfall in each month is above the temperature mean. This is a prerequisite for growth to take place. Thus there is a growing season in the Wuhlebecken area all year round, although the preferred time for the development of the plants varies from species to species.
The climate enables a statement to be made about the distribution of species. Looking at the mandarin duck , it can be seen that the average climate values in China, one of the regions of origin of the mandarin duck, with an average temperature of 11.9 ° C and an average precipitation of 593 mm, differ only slightly from those of Berlin. This is one reason why the mandarin duck is also widespread here, as the local climate values cover their tolerance range.
water
After the closure of the Falkenberg sewage treatment plant, the water of the Wuhle is almost exclusively derived from the groundwater and seepage water of the 21.3 km² catchment area. Around 6.4 km² of this catchment area is sealed, with the degree of sealing of 31% well below the Berlin average of 40%. The water has a pH value of 7 and, at 8.4 ° dH, reflects the water hardness characteristic of Berlin's waters. During today's inspection of the Wuhle basin, a strong green coloration of the water can be seen, which indicates a high concentration of algae. This eutrophication can have various reasons, such as an excessively high concentration of nutrients in the water or stagnant or slowly flowing water.
With the shutdown of the sewage treatment plant in February 2003, the annual runoff decreased from 2.6 million m³ in 2001 to around 0.9 million m³ in 2005. Since the Wuhle was expanded for a discharge rate of 15 m³ / s at that time, it decreased Now the flow speed in the wide ditch and the runoff even comes to a complete standstill in particularly hot and dry weather. Therefore, the water circulation and with it the oxygen concentration has decreased drastically, which reduces the fish populations and even causes individual fish species to become extinct, but also damages other aquatic animals. On the other hand, the pollutant levels of the water have continued to improve since the closure, especially the sodium and phosphorus levels.
Although the low oxygen concentration and the slow flow rate make the water and aquatic animals difficult to cope with, the water values can generally be described as good. All pollutant concentrations are below the permissible limit values for lowland waters, but do not come close to drinking water quality. In the course of a water analysis of the Wuhle basin, the nitrate concentration of the water was measured, which plays a major role in eutrophication, as nitrate is an important nutrient for the algae. The value was 6 mg / l and is thus well below the limit value of 50 mg / l. The nitrite value of 0.1 mg / l is also still within the tolerance range. The ammonium concentration was so low that it could no longer be detected, but in the report of the Senate Administration it is given as 0.002 mg / l with a permissible limit value of 0.5 mg / l.
Furthermore, exposure to heavy metals has decreased significantly in recent years. Large proportion of this was the construction of the largest filter plant in Biesdorfer Stretch , in which the rain water catchment area is Bundesstraße 1 /5 and commercial area Märkische Allee collected and the sludge settles. Most of the heavy metals are adsorbed in this sludge. This reduced the concentration of the nutrient phosphorus, which is highly responsible for eutrophication, by 79%.
The low nutrient load of the water is not the trigger for the eutrophication of the Wuhlewasser, but the criteria described above, such as insufficient oxygen and low flow rate. Thus, better water quality can only be achieved through increased flow speeds. Some projects for the renaturation of the Wuhle are aimed at this problem point.
Projects for the renaturation of the Wuhle basin
requirements
It must be mentioned in detail that the projects on the Wuhle and the Wuhle basin cannot be viewed completely separately, as they are directly related. Since it became known in 1994 that the Falkenberg sewage treatment plant was to be closed, there have been many plans and studies for the renaturation of the Wuhle. Here, the river is divided into two sections according to the requirements for comprehensive renaturation: the part north of the federal road 1/5, which offers numerous opportunities for recultivation measures, and the southern section, which also includes the Wuhle basin. In the north there is a lot of free space with little urban development pressure , so that one could remeander the Wuhle without major problems , i.e. reverse the straightening of the course and thus not only create a natural floodplain again, but rather reduce the flow speed of the Wuhle and thus the Reduce nutrient input into the subsequent waters, which at the same time prevents eutrophication. Another crucial condition is the relatively good water quality in terms of pollutants. South of Bundesstrasse 1/5, the Wuhle, which has been continuously straightened towards the Spree, was built, which does not permit any major measures to increase retention .
Previous projects / current projects
In addition to the various "maintenance measures" of the water, such as desludging and external filtering of the water, the first step was taken in 2004 with the construction of the filter system in the Biesdorf Baggersee to further improve the water quality. In mid-April of this year, a program to rehabilitate the Wuhletal began to run until 2008 . In addition to raising the water level by backfilling the river bed and replacing the soil in areas that are even more contaminated with soil pollutants (heavy metals), these projects also include the dismantling of some weirs in order to create a continuous biotope for aquatic animals such as fish.
Criticism / reflection
However, the potential that the Wuhle offers with regard to renaturation has not been fully exploited. The measures are almost exclusively aimed at improving the water quality in order to relieve the relatively highly polluted downstream waters such as the Spree and Havel , rather than revitalizing the Wuhle with its adjacent biotopes. The area of the Wuhletal is not used for an actually obvious and in other cases practiced remeandering (extension of the course) and there are no concepts for the areas south of the B1 / 5. On the contrary, the Biesdorf- Süd area bordering the Wuhle was even provided for in the zoning plan for development with apartments, which increases the sealing on the left of the Wuhle and disrupts retention efforts (striving for a lower flow rate). Furthermore, the Wuhle is still paved with gravel from the Wuhle basin, instead of using natural measures such as willow planting. In summary, it has to be said that a rethinking of short-term maintenance measures towards sustainable renaturation is necessary.
Web links
- mahe.berlin - Pictures , videos and information about the Wuhlebecken
- Water management in the Wuhletal
- Berlin water