Rain brings only slow relief to Upper Austria drought

Rainfall over recent days has eased the drought in Upper Austria only slightly, ORF reported. Between 20 and 70 litres of rain per square metre fell in the region, but the precipitation deficit built up over months and low groundwater levels remain.

Rainfall was unevenly distributed across the federal state, said Thomas Peneder of the Upper Austrian Hydrological Service. The Mühlviertel received relatively little, while somewhat more rain fell in the central region.

Much of the water has already evaporated, and groundwater levels in many parts of Upper Austria remain well below the usual level for this time of year. Heavy rain is of limited benefit because much of it runs off the surface instead of entering the soil and replenishing groundwater. In the Hausruck area, 40 to 50 litres per square metre fell within a short period.

For groundwater replenishment, Peneder said, steady rain over a longer period would be more effective because it gives the soil time to absorb the water. The soil itself is also a factor: after the prolonged dry spell, near-surface layers are severely dried out. Water needs suitable pathways to reach deeper layers and eventually the groundwater.

Geologist Peter Baumgartner said this process can take months where thick, heavily dried clay layers are present. Sealed surfaces such as asphalt and concrete further reduce groundwater replenishment because they prevent water from penetrating the soil and cause it to drain away quickly.

The drought is also affecting vegetation and forests. Some trees are already turning brown, which Baumgartner said was not normal seasonal discolouration but a sign that their location had become completely dry.

Further showers are expected at times in the coming days. Experts said a significant improvement in groundwater levels would require rain that is longer-lasting and evenly distributed.