Excursion to the Saxon Dam Authority and Ecological Research Station Neunzenhain

Authors: Ahimbisibwe Alfred (Uganda) and Clement G Tweh (Liberia)

“Water is Life”

You wake up in the morning some minutes late and you decide to rush through your preparation to be in time for the office. You rush to the bathroom, open the tap and lo… there is no water flowing. Your mind switches to panic mode. Can you go to the office without taking a bath? Or even without brushing your teeth?

This is a disastrous situation that the Saxon Dams Authority strives to avert by ensuring that there is always sufficient supply of high quality drinking water available to households and industry at any time all year round. Participants in the 41st Postgraduate Course of Environment Management for Developing and Emerging countries held an excursion to the Saxon Dams Authority’s drinking water reservoirs in Neunzenhain on 3rd and 4th May 2018 to learn about drinking water supply.

Two staff members of the Saxon Dam’s Authority and Dr. Lothar Paul of the Ecological Station Neunzenhain conducted the excursion. The Saxon Dams Authority manages fresh water resources in the Free State of Saxony of which dams make up 20%, the rest being rivers. They are in charge of 153 reservoirs, 23 of which are for drinking water and the rest for flood control. They also supply drinking water to 40% of Saxony’s population with storage capacity of 100 million m3 of water.

Participants were informed that the Saxon dams Authority supplies drinking water to six regional contractors who distribute water in the various cities in the state. In order to balance demand and supply, some dams are interconnected through tunnel systems or open channels and that the water quality has significantly improved due to strict requirements for purification of flue gas from coal power stations and industries that were previously responsible for acid rain.

Talsperre Neunzenhain II

Neunzenhain dams were constructed to provide drinking water for the city of Chemnitz, which was growing rapidly due to industrialization in the 19th Century. The first dam was built between 1891 and 1893 while Neunzenhain II was built between 1911 and 1914 using natural stones from the region. It is gravity dam whose weight of stones holds back the water. To avoid siltation in this dam, two pre-dams built upstream reduce the sediment load of incoming water. Secondly, 25 km² of the dam’s catchment area is forested giving it the best quality of water. The rivers flowing these forests also carry little sediments. However, every 10 years the Dams Authority does a general de-silting operation to maintain the capacity of the dam.

The Neunzenhain II dam was extensively repaired between 1996 and 2000 making it more robust with more monitoring devices to ensure its life is extended. During these works, a new concrete was built behind the stone wall and a monitoring tunnel also constructed. Important parameters monitored include

  1. Pressure: Due to high pressure in the water column, water tends to escape below the wall. To mitigate this, ground water below the dam wall is sucked out and drained away.
  2. Dam displacement: Due to alternating seasons, there is dam displacement especially in summer due to temperature difference on both sides of the dam. A maximum displacement measured is 8mm.

Water can be drawn from five different layers in the reservoir and such thermo-stratification allows for continuous supply of clear water even if silted water enters the dam by drawing water from lower layers, which actually remain clear.

Ecological Research Station Neunzenhain

Participants visited the Ecological Research Station in Neunzehain which was established in 1959 focus on research on drinking water reservoirs. This was after a realization that activities in the surrounding areas of the dams affect the quality of water. It was founded as a hydro-biological field station and they have collected a lot of ecological data on reservoirs.

Dr. Lothar Paul and Ms. Henrike Beesk presented research that is going on at the station on Cyano bacteria in the drinking water reservoirs and other micro organism such as phytoplankton, zooplankton and fish. Cyanobacteria produce toxins which can cause sickness and death in severe circumstances. The team also presented ecological interventions used to maintain the quality of water such as bio-manipulation and sanitization of the catchment. Bio-manipulation involves stocking of predator fishes in the reservoirs such as pike and trout to hunt the smaller fishes thus favouring growth of zooplankton which in turn reduce the phytoplankton that degrade water quality.

Emerging Issues

  1. Per capita water demand in Saxony has reduced from 200 m3 to 85 m3 and this is attributed to increased efficiency in use and change in industry to less water intensive industry
  2. To increase forest resilience, broad leaf tree species have been introduced to the previous coniferous monoculture and this diversity improves forest productivity and resilience.
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Visiting the wastewater treatment plant Dresden-Kaditz

By Liu Haibo, China

Today we visited the wastewater treatment plant Dresden-Kaditz. Although the weather conditions were not beautiful with wind and rain, the EM40 course participants still happily visited the unit. This unit, as the only municipal sewage treatment plant in the area, has a long history but is maintained well and orderly. Although conventional sewage treatment technology is used, the plant is unique in its design / operation and management. Moreover the processing indicators can meet the management requirements.

Photos: T. Karp / Liu Haibo

Mr. Lucke, the head of the environmental analysis laboratory at the wastewater treatment plant, guided us along the treatment process, and explained the different treatment steps from inflow to coarse and fine screens to the different clarification tanks and sludge treatment. Seeing the huge groundwater pipes, we could feel our gap with Germany not only on the ground, more perhaps we can not see the place. During the visit, the participants were able to ask questions about the treatment process, the rainwater impact,and so on.

Excursion to the Ecological Station Neunzehnhain

By Louisa Chinyavu Mwenda (Kenya)

louisa_talsperre1
Reservoir at the TUD Ecological Station Neunzehnhain

On 15th September 2016, the participants of the 68th UNEP/UNESCO/BMUB International Short Course on Integrated Water Resources Management and Health set out for the ecological station in Neunzehnhain.  Along the way from Dresden to the station, I observed that land is mainly characterized as large farms, and as we approached Neunzehnhain, the area becomes hilly and forests are abundant! When we arrived at the station, we were welcomed with breath taking views of the dam with an amazing forest backdrop (I shared the above picture with my friends back home and two suggested that area looks like a good “honeymoon” location!).
We were lucky to have a chance to get in deep within the dam, 30 meters deep to be precise, where we experienced a cool 6 degrees! Unfortunately for security reasons, we were not allowed to take pictures inside the dam. When we were done with the dam, we headed back to our new “home” to settle and rest… or preferably described as catching up! At the center there is no mobile network coverage and also no wifi, which I think worked okay as it promoted group dynamics and the participants bonded more with each other, discussing various cultural differences majorly on song and dance! The area is tranquil and serene, which is good for relaxing! Dr. Paul welcomed us heartily, such a charming man he is, and an expert too in water! We had a tantalizing meal with fresh fish (my favorite!) among other varieties. We also learned that one of the participants is a talented pianist and he entertained us with one piece before we left for bed. The next morning we had an interactive session on microbiology and we had the chance to actually be hands-on at the lab, which was exciting and very interesting especially to see some of the micro-organisms in the water samples. At about midday, we then set off to the Ore Mountains, at a restaurant where we had lunch facilitated by CIPSEM; and after we proceeded to other dams within the area, guided by Dr. Paul, for another session on water reservoirs before we left for Dresden.

Visit at the Junior Research Group INOWAS

The group left Dresden upstream the river Elbe to Pirna, as there is a TU Dresden outpost of the hydro-sciences department to visit the Junior Research Group INOWAS. The project is funded by the German Federal Ministry of Education and Research and runs until 2018. The research group around our host Dr. Catalin Stefan aims at providing stakeholders with a scientifically based decision support system for planning, design and management of applications in the water sector. The focus lies on the qualitative and quantitative assessment of the managed groundwater reservoirs by means of scenario analysis, prognosis and risk assessment and with regard to the influencing climatic factors. More information on the research can be found on their website: https://tu-dresden.de/bu/umwelt/hydro/inowas

(Photos: T. Karp)

Excursion to the DREWAG Drinking Water Purification plant at Dresden Tolkewitz

By Binh Pham Doan Thanh (Vietnam)

13 September, we had the next interesting excursion to Waterworks Tolkewitz, which was  built about one hundred years ago. It is placed on the left bank of the Elbe River and uses the river water as a source for producing drinking water. At the plant we were welcomed by the former head of the Water works Tolkewitz, a very kind and experienced man. During the following hour he explained the formation and development of the drinking water supply system of Dresden. After that, we visited the drinking water treatment area. The pipe system is completely isolated from the external environment to make sure that the water will always meet all standards and norms. It was a system worth learning. Finally, I would like to thank Dr. André Lindner for his translation work during the whole excursion.

SC68 visiting the wastewater treatment plant Dresden Kaditz

Their first excursion brought the SC68 group to the wastewater treatment plant in Kaditz.  The warm and sunny weather outside set the scene for a pleasant excursion. The downside? You can smell it in the deep of the sewage system. But the expert knowledge of Mr. Lucke more than compensated. He guided the participants through the plant while explaining all the different steps of wastewater treatment from first to last.

(Photos: T. Karp)

Excursion to the air pollution measurement station Dresden Nord

Today the EM39 course met with Dr. Kath at the Dresden-Neustadt station to learn about air pollution measurements. The measurement station Dresden Nord is one of 29 stations in the air monitoring network of the state of Saxony. This network serves both the long-term monitoring of immissions, as well as the detection of briefly occurring high loads of pollutants, so that measures for prevention or remedy can be initiated if necessary.

Pollutants such as SO2, NOX, ozone, BTX as well as particulate matter PM10, PM2,5 are monitored whereas for the determination of particulate matter two measuring methods are used: The first measuring method is the continuous recording of preliminary, exploratory data  for the legally required, daily updated information of the public, the second measurement method provides final data as a basis for the determination of PM10 exceedances and the preparation of air quality plans. The filter samples are analyzed by weighing in the lab.

(Fotos: T. Karp)