Hydrogeological characteristics of the Trebeshinë-Dhëmbel-Nëmërçkë (TDN) karst massif and groundwater drainage through the Këlcyra Gorge, Albania

This study focuses on the Trebeshina-Dhëmbel-Nemërçkë (TDN) karst massif, one of Albania’s largest karst regions. The study integrates field investigations, geological and hydrogeological mapping and observations, groundwater balance calculations, and hydrochemical and stable-isotope evidence. The main contribution of this study is explaining the karst massif's functioning by identifying the recharge area, calculating renewable groundwater resources, and determining groundwater discharge. The value of the study also lies in identifying the dominant hydrochemical processes and the role of the Permian evaporite formation underlying the Mesozoic carbonate rock in the hydrogeochemistry of karst water in the TDN massif. A better understanding of the massif, especially the Këlcyra Gorge (canyon), where many important karst springs emerge, is valuable because the Vjosa River catchment basin was designated a National Park in 2024 and holds international significance. In this context, knowing the quantity and quality of karst waters draining into the Këlcyra Gorge is essential, as they affect the overall quality of the Vjosa River. The TDN massif is a transboundary karst massif shared with Greece (UNECE, 2007), but no coordinated investigations have been conducted by either country to date. The massif's total renewable karst water resources are nearly 12.0 m³/s, most of which drain into the Këlcyra Gorge, with the remainder flowing into Greece. The results provide the first comprehensive hydrogeological synthesis of the TDN karst massif and establish a scientific basis for future sustainable management of the Vjosa National Park in general, which is also a transboundary aquifer shared between Albania and Greece. The study finds that the TDN massif is a typical Mediterranean karst area characterized by large hypsometric differences, which favor the formation of significant karst flows that recharge large karst springs with highly variable regimes.