In celebration of the International Year of Caves and Karst 2021 (http://iyck2021.org/), we are organizing a Special Issue of Geosciences dedicated to the Karst Unsaturated Zone. As the guest editors, we cordially invite you to contribute (either alone or with colleagues, PhD students, post-doc, etc.) research articles, review articles, short communications, technical notes or perspectives to this Issue. This Special Issue invites contributions dealing with, but not limited to, the following topics: epikarst and transmission zone, karst geomorphology and caves topography, karst genesis, karst initiation at emersion of carbonate deposits, karst inception, palaeokarst, petrophysics, flows and storage in karst unsaturated zones, perched carbonate aquifers, karst occurrences and their impact on fluids dynamics in buried carbonate reservoirs, outcrop analogues of karstified carbonate reservoirs, and related interdisciplinary and new characterization and modelling techniques including sampling, logging, remote sensing, lidar, geophysics, groundwater monitoring, 3D modelling.

Papers can be submitted at any time up until the deadline as they will be published *on an ongoing basis*. The provisional deadline is September 30, 2021. Geosciences is an MDPI open-access journal (https://www.mdpi.com/journal/geosciences) indexed by *Scopus* (citescore 2.10) and *ESCI* (Web of Science). The Article Processing Charge (APC) is 1500 CHF (Swiss Francs) per accepted paper.

There are numerous benefits to publishing in Geosciences:

  1. one of the few interdisciplinary journals to cover all aspects of Earth and planetary sciences and aimed at a wide audience,
  2. open access and high visibility - unlimited access, broad database coverage, and various promotional activities and academic event presentations;
  3. rapid turn-around - first decision provided to authors approximately 15.5 days after submission; acceptance to publication is undertaken in 2.9 days.

For further details on the submission process, please see the instructions for authors on the journal website (http://www.mdpi.com/journal/geosciences/instructions). Please feel free to contact us or the Editorial Office (This email address is being protected from spambots. You need JavaScript enabled to view it. or This email address is being protected from spambots. You need JavaScript enabled to view it.), if you have any questions or concerns.

We very much hope that you will be interested in this invitation and will propose quality contributions. We look forward to hearing from you. Best regards, Guest-editors team: Charles Danquigny, Olivier Kaufmann, Carol Cazarin, Patricia Kambesis