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The common hydrogeological concepts assume that water mostly enters and flows in fractured and karstified media through preferential pathways related to discontinuities. But it is difficult to locate discontinuities and even more to relate those to possible or effective water routes, particularly when soil or scree covers near surface features. When and where does water flow underground? How fast? Are we able to monitor the infiltration processes? A unique large scale Electrical Resistivity Tomography (ERT) surface based time-lapse experiment was carried out in fractured and karstified carbonate rock during a typical Mediterranean autumn rainy episode (230mm of rain over 17 days). 120 ERT time-lapse sections were measured over the same profile during and after this event (30 days). The gradient array was chosen for his robustness and rapidity. The site is covered by typical Mediterranean forest and is a good example of the surface conditions found in Mediterranean karst. There is no major karstification features (i.e. cave, sinkhole) or major tectonic accident (i.e. fault). In a previous paper, several commercial and research inversion software were tested on this dataset. This processing highlighted some limitations in inversion process. At the actual stage, apparent resistivity data provides insight about recharge/discharge processes that are almost valuable as the inverted resistivity results. Due to his quality, the availability of this unique dataset acquired under natural conditions will allow to the scientific and engineer community exploring advances and limits of ERT approach and to test new software or new data processing strategy., Competing Interests: The authors declare that they have no known competing financial interests or personal relationships which have or could be perceived to have influenced the work reported in this article., (© 2021 The Author(s). Published by Elsevier Inc.)

Water isotopes from plant xylem and surrounding environment are increasingly used in eco-hydrological studies. Carrière et al. [1] analyzed a dataset of water isotopes in (i) the xylem of three different tree species, (ii) the surrounding soil and drainage water and (iii) the underlying karst groundwater, to understand tree water uptake during drought in two different Mediterranean forests on karst setting. The xylem and soil water were extracted by cryogenic distillation. The full dataset was obtained with Isotope Ratio Mass Spectrometry (IRMS) and Isotope Ratio Infrared Spectrometer (IRIS), and included 219 measurements of δ 2 H and δ 18 O. Prompted by unexpected isotopic data characterized by a very negative deuterium excess, a subsample of 46 xylem samples and 9 soil water samples were double checked with both analytical techniques. IRMS and IRIS analyses yielded similar data. Therefore, the results reveal that laser spectrometry allows an accurate estimation of xylem and soil water isotopes. The dataset highlights a strong 2 H depletion in xylem water for all species. Deuterium does not seem adequate to interpret ecological processes in this dataset given the strong fractionation., (© 2020 The Author(s).)