22-27 September 2019
Trade Fairs and Congress Center (FYCMA)
Europe/Madrid timezone

Drivers of changes in Austrian groundwater levels – climate vs. water use

23 Sep 2019, 11:45
15m
Multiuse room 2 ()

Multiuse room 2

Oral Topic 2 - Groundwater and climate change Parallel

Speaker

Prof. Steffen Birk (University of Graz, Institute of Earth Sciences, NAWI Graz Geocenter)

Description

Groundwater is an important resource for public, industrial, and agricultural water use. Climate change alters the hydrological cycle and thus also the replenishment of groundwater resources by infiltrating precipitation or surface waters. In Austria, renewable freshwater resources overall exceed by far water use, but in the eastern part of the country considerably lower precipitation and thus lower groundwater recharge prevails. Warming in the Alpine region since the late 19th century was twice as high as the northern hemispheric and global average. Thus, potential impacts of climate change on Austria’s water resources warrant attention. Future changes in water or land use (which may or may not be induced by climate change) can aggravate or mitigate adverse climate change impacts on groundwater. To improve our understanding and identify potential drivers of long-term trends and short-term responses of groundwater levels, we analyze standardized time series of groundwater levels, stream stages, and precipitation in Austria. As we have recently shown (Haas and Birk, J. Hydrol.: Reg. Stud., 2019) countrywide and regional averages of groundwater levels trend downwards until the 1980s, from whereon they recover. As compared to the distinct falling trend, the subsequent rise is less pronounced. Precipitation follows this track, but the downward trend is less severe. River stages lack data for the downward trending period, but follow the upward trend too. We hypothesize that the increasing water use before the 1980s accounts for the discrepancy between average precipitation and average groundwater level in this period, especially since Austria meets its water demand mostly from groundwater and the observation wells cluster around areas with high water demand. Although Austria has a diverse and differing geography, the observed trends hold for almost all regional subsets. However, since most groundwater observation wells follow human use, large parts of the country (mainly the mountainous regions) lack long-term groundwater data. Thus, the findings of this work are representative for Austria’s populated lowland and valleys rather than for the Alpine peaks and ranges.

Primary authors

Prof. Steffen Birk (University of Graz, Institute of Earth Sciences, NAWI Graz Geocenter) Mr Johannes C. Haas (University of Graz, Institute of Earth Sciences, NAWI Graz Geocenter)

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