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During the last four decades, around 1,500 km2 of dry croplands have been transformed, and are now irrigated in the Upper Guadiana river basin, causing hydrologic overexploitation and wetland desiccation. However, there are no estimations on how anthropogenic stressors have been changing the wetland landscape in the recent past. This chapter focuses on the understanding of how the changes on land-use land-cover (LULC), economic activities and population have driven wetland losses and habitat degradation in the basin from the 1970s. Our results show that 40.5% (2,041.6 ha) of the 5,321 ha of wetlands existing in the early 1970s had disappeared in the last 30 years (1970–2000). Most wetland losses occurred through the period 1978–1990, which registered a rate 127 ha of wetland lost per year. Most affected were floodplain wetlands (47% of total loss) and rain-fed temporary ponds (24%). During the entire period 1978–1999, the loss of wetlands could be significantly related to the loss of natural vegetation, as well as to the reduction of agricultural employment. Habitat quality of wetlands showed a clear pattern of nutrient over-enrichment, as well as a trend towards salinization, the later related to the greater disappearance of most freshwater wetlands (0–2,500 µS cm−1). LULC, economic activities and demography explained around 50% of wetland loss and habitat quality deterioration. Until 1990, the pressure of population growth, combined with the agricultural sector, explained the disappearance of most wetland area. From then on, habitat quality has been more impacted in areas where industry and building sectors had more weight in the socioeconomic development (also densely populated watersheds).

Hydrology is the key to wetland persistence and conservation. Las Tablas de Daimiel National Park is among the many freshwater wetlands around the world that experienced strong hydrological alterations since the 1970s. Wetland hydrological functioning changed from a groundwater-dependent system to one that is maintained by artificial external water diversions. Throughout this chapter, using available data from 1904 to 2008, we analyze climate trends and hydrology of the wetland in order to quantify the changes occurred in the water budget components as well as to assess the main causes of its hydrological disturbance. Finally, through a hydrological model, developed to simulate the current wetland hydrologic functioning, the hydroperiod restoration is evaluated using multiple scenarios. Both rainfall and water flow variability are the main hydrological patterns in the wetland area, whilst evapotranspiration appeared as the main hydrologic variable controlling the TDNP annual water storage. The historical analysis of the annual inundation patterns at TNDN has discriminating between four distinctive hydroperiods, showing the importance of groundwater discharges to sustain the pristine hydroperiod. While drought frequency – as measured by the Standard Precipitation Index (SPI) – did not increase in the region, groundwater pumping for irrigation appeared as the main cause of groundwater overexploitation and wetland hydrological degradation. Through a hydrological model developed to simulate wetland hydrology, it was possible to test the restoration of the wetland hydroperiod, using scenarios which promote cut-sedge recovery and open water areas. Hydrological restoration could be achieved by means of an external annual water supply of close to 54 Mm3. Future stream and groundwater flows at the Upper Guadiana basin will depend on the land use management, while climate change effects will be secondary, considering the actual hydrological situation.