Long-term trend and fluctuations of karst spring discharge in a Mediterranean area (central-southern Italy)

Times and currently feed some tens of millions inhabitants with tap water of high quality. Unlike otherkarst springs, they are characterized by a steady rate during the year with modest seasonal variability.However, the effects of climate changes are being strongly perceived in central and southern Italy as in therest of the Mediterranean basin, and groundwater is obviously also affected. In this paper, we analyze thedischarge time series of some important karst springs in the region, evaluating the trends and fluctuationsin relation to rainfall regime, on a yearly time scale. The aim is to evaluate the response of these large karstaquifers in the Mediterranean area to the recharge input variation. The role of the North AtlanticOscillation has also been considered. Trends and fluctuations have been highlighted by n-years movingaverage and transforming the time series by the Rescaled Adjusted Partial Sum. The results show that adrop in the discharge has occurred since 1987, with reductions ranging from 15 up to 30 %, although thisnegative trend is now possibly attenuating or even reversing. As a final remark, the spring discharge of thelarge karst aquifers in central-southern Italy can be assumed as a robust indicator for climate changes as itintegrates the effects of precipitation and temperature variation in time and space.

Karst springs in central-southern Italy are largelyexploited for the human consumption since the RomanTimes and currently feed some tens of millions inhabitantswith tap water of high quality. Unlike other karst springs,they are characterized by a steady rate during the year withmodest seasonal variability. However, the effects of climatechanges are being strongly perceived in central andsouthern Italy as in the rest of the Mediterranean basin, andgroundwater is obviously also affected. In this paper, weanalyze the discharge time series of some important karstsprings in the region, evaluating the trends and fluctuationsin relation to rainfall regime, on a yearly time scale. Theaim is to evaluate the response of these large karst aquifersin the Mediterranean area to the recharge input variation.The role of the North Atlantic Oscillation has also beenconsidered. Trends and fluctuations have been highlightedby n-years moving average and transforming the timeseries by the Rescaled Adjusted Partial Sum. The resultsshow that a drop in the discharge has occurred since 1987,with reductions ranging from 15 up to 30 %, although thisnegative trend is now possibly attenuating or even reversing.As a final remark, the spring discharge of the largekarst aquifers in central-southern Italy can be assumed as arobust indicator for climate changes as it integrates theeffects of precipitation and temperature variation in timeand space.