Coal phase-out = water shortage? Second Lausitz Water Conference

The Federal Environment Agency has commissioned (UBA) an investigation into how high the future water shortage in the Lausitz rivers will be. One thing is certain: The available water in the region will not be sufficient in the future to meet all needs without adjustments. We spoke to Dr. Volker Preuß from the Department of Water Technology and Sanitary Engineering.

Dr. Preuß, this is a very serious situation for Lusatia. It leaves little time for discussion. In your view, what measures need to be taken in the short, medium and long term to avert impending water deficits?

It has been known for some time that water deficits are to be expected in the future. There are also already enough hydrological analyses and forecasts. The only thing that doesn't get us anywhere is to keep calculating. This is precisely why the UBA study became necessary, in order to address the expected conflicts and options for action to overcome them in the political arena. The most important thing is to make timely decisions on the further development of water storage capacities, especially including the emerging open pit lakes and the transfer of water from neighboring river basins to the Spree. There are sufficient technical arguments for this, so in view of long planning, approval and implementation periods, decisions must be made promptly. Once these decisions have been made bindingly, the concrete measures can be taken quickly.

How can the water balance in Lusatia be controlled sustainably?

Active management of the flowing waters has long been a reality, for example through the cross-state working group on the management of the Spree and Schwarze Elster rivers, which is to have its own office in the future, or the Lausitz flood control center, which is affiliated with the LMBV. They determine, for example, the order of priority of the water users to be served on the basis of the available water volumes. This then also determines whether flooding water flows into the Cottbus Baltic Sea. This is done on a weekly basis using simulation calculations. Whether this can meet future requirements still needs to be very carefully examined. Since the task area extends beyond the borders of a single federal state, this poses special challenges. It is quite possible that a cross-state water association will be founded for this reason.

The success of structural change is also closely linked to water availability. Future company settlements will also have access to scarce water resources. Where are the opportunities and risks here?

Without sufficient water, there will be no successful structural change. The drinking water suppliers are aware of this and are facing up to this task, as the relevant expert contributions to the 2nd Lusatia Water Conference also show. For example, six water supply companies in southern Lusatia and eastern Saxony are currently in the process of expanding an existing cross-border and cross-association drinking water association in order to be able to guarantee a reliable drinking water supply for new industrial and commercial settlements as well as residential areas. In this context, a cooperation is currently developing between the ARGE Trinkwasserverbund Lausitzer Revier and the BTU's Water Technology and Sanitary Engineering department, where I work. A wide variety of factors have to be taken into account when deciding where to locate industry. One of these is water availability, but in my perception this has so far been put on the back burner. With a change in available water resources, however, more weight must be given to this issue.

The available water resources have to satisfy numerous, sometimes competing users such as industry, agriculture, tourism as well as ecological concerns. How can an optimal balance be struck between water resources and water needs, and this also in terms of water quantity and quality?

Indeed, balancing the interests becomes a balancing act. It is important that all those affected are allowed to have their say and that discussions take place at eye level. To put it briefly: everyone has to save water, and in the case of prolonged dry periods, there will sometimes have to be greater restrictions, such as on irrigation or water tourism. Rank and orders will ultimately have to be established when summer water deficits occur. However, the development of interconnected solutions in the drinking water sector or the expansion of storage systems to the point of transferring water from other river basins can also counteract the shortages of resources. Balancing the possible uses of water will therefore be an ongoing process that must be based on current possibilities.

Is the drinking water supply in Lusatia still secure in the future under the forecast conditions?

In this respect, the drinking water suppliers in Lusatia are a step ahead of many other water users. This also has to do with mining, because mining interventions have placed the water sources used today for drinking water production outside the influence of mining. This is now paying off. In Lusatia, there are secure supplies of drinking water.

How can industry and agriculture contribute to stabilizing the water balance in Lusatia, and in what time frame can effective changes be made?

Industry needs to expand its recycling management of water more strongly. Technical possibilities for this are already available in many cases. For the agricultural sector, we must assume a greater need for irrigation in the future in order to maintain self-sufficiency. Various projects are currently underway that are testing, for example, the conversion of irrigation technology to drip irrigation, the cultivation of more drought-resistant crops, modified soil cultivation techniques or the use of treated wastewater for irrigation. Existing legal hurdles must also be overcome in the process. The locally available options for water use must be constantly re-evaluated.

It is not only the phase-out of brewery coal that affects the water balance, but also climate change. What about the flooding of mining lakes in this context?

Climate change and the consequences of the coal phase-out overlap each other, and this does not make things any easier. The main purpose of flooding residual opencast mining holes is to stabilize the slopes and improve the water quality of the resulting opencast mining lake. A shortage of available water does not mean that the remaining holes will not fill with water. However, flooding in some cases will take longer than previously planned. Some target water levels will also have to be adjusted. The LMBV is currently having these effects on its mining lakes reviewed.

What research projects are you working on/planning for this topic?

As the Water Technology and Sanitary Engineering WG, we are currently involved in the BMBF-funded joint research project FLEXITILITY. It is testing concepts for decentralized intermediate drinking water storage and water reuse for agricultural irrigation. In advance, we identified the potential of existing supply systems to increase resilience to climate change risks at the level of municipal infrastructure operators. Another topic area is emerging in cooperation with the Lausitzer Revier drinking water association.

Specialist contact

Dr.-Ing. Volker Preuß
Wassertechnik
T +49 (0) 355 69-4312
Volker.Preuss(at)B-TU.De

Press contact

Wiebke Wehling
Stabsstelle Kommunikation und Marketing
T +49 (0) 355 69-3043
wiebke.wehling(at)b-tu.de
Dr. Volker Preuß, Water Technology and Sanitary Engineering