Climate change would also be affecting quality of drinking water

Drinking water is also being affected by climate change. A recent study focused on analyzing the effects of climate-induced deforestation on the water quality of the Rappbode reservoir, the largest drinking water reservoir in Germany.

The team of researchers from the Helmholtz Center for Environmental Research (UFZ) analyzed the effects of climate-induced deforestation on the water quality of the Rappbode reservoir, the largest drinking water reservoir in Germany.

In the Harz region, where this reservoir is located, the extensive periods of drought that occurred between 2015 and 2020 caused the region's tree population to weaken, causing them to be damaged at a faster rate and die faster.

Michael Rode, the lead author of the study and hydrologist at the Helmholtz Center for Environmental Research (UFZ), explained in a statement, caused "in the last four years, the Rappbode catchment area lost more than 50% of its forest."

Rode warned that the mass die-off of the forest continues to advance rapidly and will have dire consequences for the reservoir and drinking water. Why? The main reason is that forests play a transcendental role in the water cycle since they filter it and fix the nutrients. "In other words, forests are necessary for good water quality," said the hydrologist.

To study this reservoir, the researchers used data collected over 10 years by the TERENO network of environmental observatories. Then, with the international ISIMIP project, they predicted future climate changes with cross-sectoral impact models.

Xiangzhen Kong, an environmental scientist at UFZ and co-author of the study, explained that to accomplish this, "we first fed this data into a model to estimate climate-related effects on nutrient balance in the catchment area." Then, they studied separately two of the three hydrographic basins of this reservoir.

One of them is Hassel, which is characterized by agriculture, and the other is predominantly forestry. “Before the water from the two basins flows into the large Rappbode Reservoir, it is first held back by a previous dam upstream. Agricultural influence results in significantly higher nutrient content in the Hassel Dam water,” Kong added.

The Rappbode Reservoir is the largest drinking water reservoir in Germany, supplies around a million people, and has suffered from severe drought between 2015 and 2020, which has weakened the tree population.

The catchment area is believed to have lost more than 50% of its forest due to tree damage, which is of grave concern to the reservoir and waterworks operators. Two different catchment areas supplying Rappbode Reservoir were studied, one of which is more agricultural and the other predominantly forestry.

"We were able to show that, for up to 80% anticipated deforestation, the former Rappbode Dam will experience an 85% increase in dissolved phosphorus concentration and more than 120% increase in nitrogen concentration in just 15 years," said the lead author. of the study, Dr. Xiangzhen Kong. "The previous Rappbode dam will achieve almost the same nutrient levels as the previous Hassel dam."

The team expects this to lead to a more than 80% increase in diatoms and a more than 200% increase in green algae before the dam, highlighting the need for adaptations in drinking water management.

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In results published in Water Research, the researchers noted that they "demonstrated that, with up to 80% anticipated deforestation, Rappbode Dam will experience an 85% increase in dissolved phosphorus concentration and a greater than 120% increase in dissolved phosphorus concentration. nitrogen concentration in just 15 years.” The results from the Rappbode Reservoir can be applied to other reservoir basins in similar regions, they said.

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