Climate Change

Where does the water go during a drought? Germany researchers try to find out

Researchers examined how the process of evaporation and groundwater recharge differed under various kinds of soils and land uses

By DTE Staff
Published: Monday 20 July 2020

Where does the water go in a drought? How does it get distributed during low-precipitation periods and what are the ways to improve water retention in such a situation?

Vegetation can geavily influence the underground water distribution, according to Dörthe Tetzlaff, a researcher at the Leibniz-Institute of Freshwater Ecology and Inland Fisheries (IGB), Berlin.

The team of researchers investigated how the process of evaporation and groundwater recharge differed under various kinds of soils and land uses. They examined the storage, distribution and quality of water within the landscape.

In drought-sensitive Demnitizer Mühlenflierb, Brandenburg, Germany, said to be a sub-catchment area of the Spree, they measured the visible and invisible water flows during and shortly after the drought of 2018.

Brandenburg has the lowest rainfall in the region. The annual rainfall there is 560 liters per square metre. In 2018, there was about 390 litres of water per square meter, which is 40 per cent less precipitation than normal.

Under the grassland, the water continuously recharged the groundwater. The soil could store more water. As the plants only took water from the upper soil, this led to “older” soil water.

Even under normal climatic conditions, about 90 per cent of the precipitation is said to be released back into the atmosphere; it does not flow into rivers or groundwater.

The researchers have been working together with the forestry as well as the agricultural sectors to bring their research results into practice.

According to Dörthe Tetzlaff:

We saw that groundwater levels continued to in 2020. The vegetation has still not been able to recover due to the low rainfall in the winter months. Unfortunately, we are far from ‘normal’ conditions. To improve the resistance of Brandenburg’s ecosystems to droughts and other climate changes, measures must be implemented that promote groundwater recharge and create soils that can store more water. Our results underline the central role of vegetation in the development of such strategies.

The question arises, in times of low precipitation, where and how is the limited available water distributed, and what are the possibilities available for soil retention and the landscape?

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