Las Tablas de Daimiel National Park (TDNP), recognized as both Biosphere reserve by UNESCO and Ramsar site, is one of the last representatives in the Iberian Peninsula of Mediterranean wetlands linked to groundwater dynamics. It constitutes an outstanding flora and fauna reserve. The inappropriate agricultural management of the groundwater resources that support the system has caused the drying up of the wetland from 2004 to 2009. As a consequence, a smouldering peat fire started inside the TDNP in August 2009. This fire poses an enormous risk for both the physical structure supporting the ecosystem and the quality of groundwater beneath it. The situation got worse in September when a surface fire in the eastern limit of the Park, 3.5 km away from the first underground seat, transmitted to the subsoil giving rise to a second smouldering peat fire outside the Park. The analysis of key parameters monitored in several locations of the TDNP at different depths, such as soil moisture, temperature and organic matter content, shows there was enough previous evidence to foresee the peat self-combustion and the risk that any surface fire could be transmitted to the subsoil. The relatively small size of the Park, the knowledge of the spatial distribution of peat masses, together with the detailed knowledge about soil and vadose zone structure, have allowed to design and execute an emergency plan to hold the fire back. The experience has allowed to check for strong and weak points in the vigilance and alert system implemented, to confirm the effectiveness of the measures applied for the fire control and to propose short and long term actions for preventing fires from starting in the future.

Las Tablas de Daimiel National Park (TDNP) in Spain is one of the most important semiarid wetlands of the Mediterranean area. The inversion of the regional groundwater flow, primarily due to overexploitation and inadequate aquifer management, has led to degradation. The system has turned from a groundwater discharge zone into a recharge zone, and has remained mostly dry since the 1980s. High heterogeneity and complexity, enhanced by anthropogenic management action, hampers prediction of the surface-groundwater system response to flooding events. This study analyses these interactions and provides empirical evidence to define a conceptual model of flooding-infiltration-groundwater dynamics through the application of a few simple analysis tools to basic hydrological data. Relevant surface water-groundwater interactions are mainly localized in the left (west) margin of TDNP, as confirmed by the fast responses to flooding observed in the hydrochemic, hydrodynamic and isotopic data. During drying periods, small artificial and/or lowflow natural floods are followed by infiltration of evaporated poor-quality ponding water into saline lowpermeability layers. The results allow an improved understanding of the hydrological behaviour essential to support efficient management practices. The relative simplicity of the methodology allows for its application in other similar complex groundwater-linked wetlands where detailed knowledge of local geology is still absent.

Las Tablas de Daimiel National Park is one of Spain's most representative groundwater‐dependent ecosystems. Under natural conditions, water inflows combined brackish surface water from River Gigüela with freshwater inputs from River Guadiana and the underlying aquifer. Since the mid‐1970s, aquifer overexploitation caused the desiccation of the wetlands and neighbouring springs. The National Park remained in precarious hydrological conditions for three decades, with the only exception of rapid floods due to extreme rainfall events and sporadic water transfers from other basins. In the late 2000s, a decrease in groundwater abstraction and an extraordinarily wet period reversed the trend. The aquifer experienced an unexpected recovery of groundwater levels (over 20 m in some areas), thus restoring groundwater discharge to springs and wetlands. The complex historical evolution of the water balance in this site has resulted in substantial changes in surface and groundwater quality. This becomes evident when comparing the pre‐1980 groundwater quality and the hydrochemical status in the wetland in two different periods, under “dry” and “wet” conditions. Although the system is close to full recovery from the groundwater‐level viewpoint, bouncing back in the major hydrochemical constituents has not yet been obtained. These still appear to evolve in response to the previous overexploitation state. Moreover, in some sectors, there are groundwater‐dependent ecosystems that remain different to those found in preoverexploitation times. The experience of Las Tablas de Damiel provides an observatory of long‐term changes in wetland water quality, demonstrating that the effects of aquifer overexploitation on aquatic ecosystems are more than a mere alteration of the water balance and that groundwater quality is the key to aquifer and aquatic ecosystem sustainability.

No abstract

No abstract