Hydrological response of Mediterranean headwaters to climate oscillations and land-cover changes: The mountains of Duero River basin (Central Spain)

Water resources in Mediterranean mountains are not only facing the effects of a changing climate, higher temperature and lower precipitation, but also the consequences of a socioeconomic process with the abandonment of rural activities and the resulting changes in land-use/land-cover. In the present work we analyze the evolution of runoff and fluvial regimes in a selection of catchments located in the surrounding mountains of Duero River basin, Central Spain. Furthermore, evolution of the main climatic variables (precipitation and temperature) and land-use changes have been studied in order to understand their interaction with the changes observed in runoff. Environmental conditions are representative of Mediterranean mountains and the studied rivers are not regulated, hence presenting a natural regime. Results show a generalized negative trend in annual runoff, due to losses in winter and spring flow. Decreasing precipitation and increasing temperature during winter and spring months are the main processes responsible for such changes, by reducing water and snow available for runoff generation. Forest and shrub area has increased within the catchments due to abandonment of agricultural and traditional practices. Effects of land-cover expansion over runoff evolution could be only partially demonstrated, which confirms the difficulty achieving a profound understanding of the interaction between hydrology and land-use at a catchment scale in Mediterranean environments.