Ecosystem Services in an Impacted Watershed: The Relevance of Hydrology, Human Influence, and Global Change

Abstract: Climate change previsions in the Mediterranean regions are associated with more frequent extreme climatic conditions, which could alter water availability and impact the delivery of ecosystem services. In this chapter, the vulnerability of hydrological ecosystem services to recently observed climatic extremes in the Llobregat River basin is assessed. Provisioning (water) and regulating services (erosion control and water purification) were quantified under mean climatic conditions and subsequently compared to their provision under wet and dry conditions. Results stress that in semiarid basins submitted to chronic human pressure, hydrological services are very sensitive to climatic extremes. Provisioning services are important in mean and wet climatic conditions and are the most threatened in dry conditions when their reduction can approach 100%. Conversely, water purification (regulating service) has its largest contribution to human well-being in dry conditions. These results constitute a lower boundary of the possible benefits provided by ecosystem services in the basin.