Eco-Hydrogeology and Engineering for the Conservation of Mediterranean Peatlands in Karst: An Interdisciplinary Case Study

Peatlands in mid-latitudes are critical and rare ecosystems, acting as important carbon sinks and hydrological regulators. This study presents an interdisciplinary investigation (geological, hydrogeological and palaeoecological) of the Calatañazor peat bog (Soria, Spain). Through geological mapping, geophysical prospecting, soundings and C14 dating, the evolution of the karst lagoon system is reconstructed. The results reveal a genesis linked to the closure of the valley by a barrier of calcareous tuffs during the Upper Pleistocene, and the sedimentation of lacustrine organic clays during the last glaciation, followed by a phase of active peat formation in the early Holocene (7590–5800 BP). Hydrochemical analysis and piezometric monitoring demonstrate that the peat bog functions as a regional discharge point for the Utrillas Facies aquifer, maintaining critical water table levels (0–1 m) and exerting a self-purifying effect (denitrification). Following decades of degradation caused by agricultural drainage, the research provides a scientific basis for its restoration through an analysis of its structure and hydrological functioning. It concludes that restoring the original water body is technically and hydrologically feasible, as the system exhibits an outflow character downstream, ensuring the conservation of the ecosystem without compromising local water resources. The engineering intervention, carried out between 2025 and 2026, consisted of creating a shallow lagoon and plugging strategic drains. The project demonstrates that the integration of palaeoecology and active management is key to the resilience of Mediterranean wetlands in the face of climate change.