Streamflow components and climate change: Lessons learnt and energy implications after hydrological modeling experiences in catchments with a Mediterranean climate

Sustainable water management should consider climate change effects to ensure its future availability. Hydrological modeling is a supportive tool for this analysis, which has been used in this work to assess the climate change impacts on the water resources of three basins under Mediterranean climate (Ompólveda and Salado River basins, in Spain, and Guadalupe River basin, in Mexico).The outcomes of previous climate change scenarios simulation addressed with the Soil and Water Assessment Tool (SWAT) have been compiled, evaluating the impacts on the water balance, and focusing on the streamflow components. The potential implications of these effects on energy production have been discussed.The results point to a streamflow reduction by the end of the century around 50%–60% in the worst scenarios, with varying effects for each of the streamflow components. In the Spanish catchments, where groundwater contribution dominates in baseline conditions, a noticeable decrease of this component is expected (up to -74%), becoming lateral flow the main streamflow component. In the Mexican basin, lateral flow, which is already predominant (69%), will experience the largest absolute decrease, but the highest relative decrease might be experienced by groundwater flow, up to -92%. Absolute variations in the surface component are small and the different ways to simulate the climate change scenarios might hinder their interpretation.This work shows that water resources will be even more scarce in these regions, being especially worrying the groundwater component reduction, which currently maintains the streamflow during dry periods. This situation would limit energy production both from sources that directly use water, such as hydropower, and others that require water for cooling. Higher atmospheric and water temperatures will increase demands for irrigation and for cooling systems. Therefore, competition for water will rise among key sectors, and an accurate planning considering these factors must be a priority.