An evaluation of the application of treated sewage effluents in Las Tablas de Daimiel National Park, Central Spain

At the present time there is not enough information available to develop a quantitative model on how inundation takes place in the 1490 ha area of Tablas de Daimiel National Park (Central Spain) located upstream of Morenillo Dam. Given that it is the most important area in the Park from an ecological standpoint, this is a major concern, as it has not been possible to assess the potential effectiveness of the interventions geared towards improving its current state. As a result, it is not feasible to simulate the hydrologic response to the application of treated sewage effluents, an initiative recently implemented by the Public Administration responsible for water management in the Guadiana River Basin, where the Park is located. To help solve this problem, a simplified model of the hydrologic behaviour of the system has been developed focusing on the characterisation of the main trends of the inundation process. Field data from 12 drying processes were used to identify the model parameters. Later, the evolution of the system was examined after the application of treated sewage effluents, assuming the hypothesis of a dry climate. The results show that the 10 Mm3 of available effluents is sufficient to improve from 2 ha to 60 ha the inundation condition of the areas considered to be high-priority. This therefore demonstrates that, from a hydrologic point of view, it is highly advisable to use treated sewage effluents.