Analysis of long-term spring data in Austria – trends and changes

Recent groundwater data analyses show an increase of groundwater temperature related to climate warming. This trend is suspected to occur at springs as well, in particular springs draining shallow aquifer systems being affected by air temperature. Contrary, deeper circulating systems such as large karst aquifers and the related springs may not show this water temperature increase. In this study, we investigate long term spring data from all over Austria. This is done through trend analyses of long-term time series of discharge, water temperature, and electrical conductivity from 97 springs in Austria The data are provided by the Hydrographic Service of Austria  and the observation period ranges from several years up to more than 30 years. The springs drain a wide range of aquifer types, from karst areas to periglacial sediments. Importantly, the springs mainly drain mountainous regions that are less anthropogenically influenced than most of the groundwater wells in the intermontane valleys and basins.

Preliminary results show significant trends of increasing water temperatures in some springs, potentially related to climate warming and through changes in precipitation (e.g., occurring as snowfall or rainfall). However, such a trend cannot be observed for all springs and it is suggested that certain aquifer types are more prone to climate warming, others are better protected / shielded due to their extend and flow characteristics. Trend analysis is performed not only for water temperature, but also for electrical conductivity and spring discharge. There, trends are less obvious or not as consistent. Therefore, a direct impact from climate change needs to be treated cautiously, reflecting aquifer characteristics. However, a better understanding is essential to further predict future development and help in water management planning. Future work will focus on identifying changes in system characteristics over the observation period, by computing autocorrelations and master recession curves over different time periods.