Groundwater storage in the Euro-Mediterranean karst region has been detected to be decreasing across approximately 60–80% of its area, yet only a few studies have attempted to quantify this phenomenon. This study conducts a spatio-temporal characterization of karst aquifer dynamics on a continental scale using Gravity Recovery and Climate Experiment (GRACE) measurements. The groundwater storage anomaly (GWSA) and subsurface water storage anomaly (SWSA) were computed from GRACE data, with GWSA representing water storage in the saturated zone and SWSA encompassing storage in both unsaturated and saturated zones. We systematically analyzed and compared GWSA and SWSA to explore groundwater recharge and storage dynamics. The analysis was complemented by VarKarst model simulations, which represent potential groundwater recharge in karst terrain, and validated using spring discharge observations from selected karst catchments. Trend analysis of both GWSA and the simulated potential karst groundwater recharge for the period 2002–2019 revealed the steepest decline in groundwater recharge and storage in the Alpine region’s polar climate zone. In temperate climate zones, a strong correlation was found between SWSA and the simulated potential karst groundwater recharge when recharge values were timely shifted. The results highlight the significant role of soil and epikarst in influencing karst aquifer recharge, particularly in temperate climates, and demonstrate the spatial suitability of GRACE satellite data for large-scale karst system characterization. The observed declining trends in GWSA underscore the importance of sustainable groundwater management in the Euro-Mediterranean karst region. Spatial variations in GWSA reflect the impacts of climate, water use, and characteristic karst properties on groundwater storage dynamics. This study emphasizes the need to consider the effects of the epikarst when relating GRACE data to recharge processes in karst systems. Overall, the integrated approach combining GRACE measurements, karst groundwater recharge modeling, climate data, spring discharge observations, and water use information provides a robust methodology for characterizing continental-scale karst hydrogeology.

中文翻译：

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探索 GRACE 测量在大陆尺度上表征岩溶系统的效用


据检测，欧洲-地中海喀斯特地区的地下水储量在其大约 60-80% 的面积上正在减少，但只有少数研究试图量化这一现象。本研究使用重力恢复和气候实验 （GRACE） 测量在大陆尺度上对喀斯特含水层动力学进行了时空表征。地下水储量异常 （GWSA） 和地下水储量异常 （SWSA） 是根据 GRACE 数据计算得出的，其中 GWSA 代表饱和区的储水量，SWSA 包括非饱和区和饱和区的储水量。我们系统地分析和比较了 GWSA 和 SWSA，以探索地下水补给和储存动力学。该分析得到了 VarKarst 模型模拟的补充，该模型模拟代表了喀斯特地形中潜在的地下水补给，并使用来自选定喀斯特集水区的泉水流量观测进行了验证。对 2002-2019 年期间 GWSA 和模拟的潜在喀斯特地下水补给的趋势分析表明，阿尔卑斯地区极地气候区地下水补给和储存的下降幅度最大。在温带气候区，当补给值及时变化时，SWSA 与模拟的潜在喀斯特地下水补给之间存在很强的相关性。结果突出了土壤和表层岩溶在影响岩溶含水层补给中的重要作用，尤其是在温带气候中，并证明了 GRACE 卫星数据对大规模岩溶系统表征的空间适用性。观察到的 GWSA 下降趋势凸显了欧洲-地中海喀斯特地区可持续地下水管理的重要性。 GWSA 的空间变化反映了气候、水利用和特征喀斯特特性对地下水储量动态的影响。本研究强调在将 GRACE 数据与岩溶系统的补给过程相关联时，需要考虑表层岩溶的影响。总体而言，结合 GRACE 测量、岩溶地下水补给建模、气候数据、春季流量观测和水资源利用信息的综合方法为表征大陆尺度的岩溶水文地质提供了一种强大的方法。