Dhe place where the whole disaster becomes visible is inconspicuous on the second floor of a high-rise prefabricated building on the outskirts of Senftenberg in Lusatia. The “Current Situation” can be seen on a screen high above the desks: the columns in the “Precipitation” section are all in the red area. The most devastating values are provided by the Hoyerswerda measuring point, which registers a deficit of more than 50 percent. “This year alone we are already missing three months of precipitation,” says Maik Ulrich from the flood control center of the Lusatian and Central German Mining Management Company (LMBV). “Parts of the Black Elster have already dried up completely.”
Along with the Spree and Lausitzer Neisse, the Black Elster is one of the three natural water suppliers that the company, which takes care of the legacies of brown coal mining, urgently needs. In the past few years, the river had dried up several times, and this time too, helpers tried to move the fish quickly – often in vain.
Water supply is becoming increasingly difficult
The employees in the flood control center have an overview of the entire water system in Lusatia on monitors. This is where all the information about river levels, reservoir levels, rainfall and discharge comes together. And with a few clicks of the mouse, the course of the water can be controlled from these desks. Roughly speaking, they could turn off the tap here in Berlin or the Spreewald. But there are clear guidelines from the states of Saxony, Berlin and Brandenburg, with which every step you take here must be coordinated.
The top priority is the water supply, explains LMBV boss Bernd Sablotny. But it’s getting harder and harder. “The minimum outflows that the countries have imposed on us can hardly be represented anymore,” he says. “The water supply has been significantly lower for several years.” The second priority is to refill the reservoirs, followed by the task of maintaining the level of the Oder-Spree Canal. And only then, in fourth place, could the LMBV divert water from the rivers to flood the depleted opencast mines. For the latter, there was practically nothing left in recent years due to a lack of rain. So far, says Sablotny, there has been a lot of talk about flood protection.
The reservoirs created in former opencast mines were originally designed for flood regulation and special industrial standards were created for this purpose. Until recently, hardly anyone could have imagined that one day one would have to deal with the management of low water.
According to the Saxon State Office for Environment and Geology, Lusatia is particularly susceptible to drought because it is located at the transition from a maritime climate to a continental climate. Therefore, the region is “significantly less precipitation than the German average”. And there is no improvement in sight, on the contrary: climate change is also causing a shift towards a stronger influence of continental air masses. At the same time, the lack of rain also causes the groundwater levels, which feed the rivers in normal dry seasons, to drop. Due to the drought of recent years, the groundwater levels have fallen to historic lows not only in Lusatia, but in almost all of Saxony.
The office speaks of a real “groundwater drought”. 84 percent of the 250 measuring points fell below the monthly typical groundwater level by an average of 39 centimeters. This increases the risk of rivers drying up. The years 2018, 2019 and 2020 in particular were “real dry years” that “threw the entire system out of balance”, says Bernd Sablotny. Instead of the usual 100 million cubic meters of water, only a good half was available in Lusatia.
In order to be able to provide sufficient water for those “down below”, one had to fall back on reservoirs that were only half full in the summer, and 30 million cubic meters were drained annually for low-water replenishment. So far, however, the reservoirs are only running on a trial basis. In order to get back to normal operation as quickly as possible and to be able to supply water reliably, the mining remediationists now wish to lower the legal requirements for lakes left over from opencast mining, which are only used as storage and not as bathing lakes. Despite any unstable embankments or landslides, these storage facilities can be operated safely.
Lignite mining disrupts the water balance
The ministers from Brandenburg and Saxony agreed to check this. “The lack of water will be our new normal,” says Saxony’s Environment Minister Wolfram Günther (Greens). However, climate change is only one cause that exacerbates the problem. “The water balance in Lusatia has been severely damaged by lignite mining.” The drought and the increasing water demand due to structural change and the resulting new economic settlements are now added to the equation. Water management is an extremely complex issue that can only be tackled by mining remediators, local authorities and states working together. It was therefore only in May that the states of Berlin, Brandenburg and Saxony expanded their cooperation in the “River Basin Management” working group. “The water issue in Lusatia is now a top priority,” says Günther.
In the flooding center in Senftenberg, the levels at the beginning of this week show that 500 liters per second are still flowing down the Spree. “That’s no longer enough to ensure the minimum flow,” says Maik Ulrich. Normally the river would have three to four times as much water at this time, now he and his staff have to intervene. The drought started earlier this year than ever before.
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