In the past few days it has rained a lot in large parts of Bavaria, the soil is looking better again. But only viewed from above, says a hydrogeologist and explains how it would have to rain to get the drought under control in the long term.
Nuremberg (dpa / lby) – After the rainy days in Bavaria, the soil is wetter again – but only in the upper layers. “It’s nice that there’s finally precipitation, but that’s just not enough to replenish deeper layers of soil and the groundwater in the long term. But these are enormously important for water use and also for forests,” said hydrogeologist Johannes Barth from the Friedrich- Alexander University of Erlangen-Nuremberg (FAU).
An expert from the German Weather Service (DWD) reported that the heavy rainfall over the past few weeks has filled at least the top 30 centimeters of the ground with water. “Due to the current weather situation with falling temperatures and additional precipitation”, little water will continue to evaporate and the water reserves in the ground will continue to be replenished, added the DWD meteorologist.
“Soil moisture near the surface recovers faster, but is then used up again more quickly,” said Johannes Barth from FAU in explanation. You have to look deeper and consider longer periods of time. At greater depths, the drought is far from over – “and hasn’t been for years”.
In order to get the drought under control, not only does enough rain have to fall, it also has to be the “right” one, said the head of the Chair of Applied Geology. “That means we would need weeks of drizzle or, in the winter, finally a snow cover followed by melting. This allows the water to penetrate the ground much more efficiently and slowly, and also get deeper.” The background: Dry floors can have a water-repellent effect and then absorb water only very poorly or not at all. Accordingly, continuous light rain would be better to counteract the dry soil – in contrast to individual heavy rain events.
In the future, scientists assume that Bavaria will also have to adapt to drier soils as a result of climate change. “Drought and extreme weather conditions are an even more urgent problem this year, for example in large parts of southern Europe, and we can already see them as a pre-warning,” said Barth. He recommends learning from other countries – for example Israel. Among other things, drip irrigation is used very efficiently in agriculture there. With the technology, the water reaches the plants directly via pipes – a lot of water can be saved accordingly.
