Effects of Climate Change on Hydrology and Hydropower Systems in the Italian Alps

1 I N T R O D U C T I O N 1.1 setting the context Climate change is considered to be a key factor in the availability of water resources during the XXI century [IPCC, 2014]. The rise of temperature and the shift in the distribution of precipitation at the global scale will affect the hydrological cycle and thus the water re- lated human activities. The hydrology of the Alpine regions is likely to be affected more then others since they are characterized by a high presence of snow and glaciers and are more sensitive to climate con- ditions [Zierl and Bugmann, 2005; Beniston, 2003]. The temperature increase will cause an earlier snowmelt and a shift in temporal and spatial precipitation patterns will considerably change water avail- ability. Furthermore, the impact of climate change on hydrology will be accentuated by the glaciers retreat [Haeberli and Beniston, 1998]. The hydropower plants installed in the Alps play a key role in the sup- ply of electricity and, due to their flexibility compared to other elec- tricity sources, they also provide a certain stability in the international network [Gaudard et al., 2014]. Moreover, their importance as a key resource is growing with the increase of power installed in intermit- tent renewable energy sources such as wind and solar power. Since the patterns of production of wind and solar power are very irreg- ular, and other traditional sources of electricity (e.g., nuclear power and fossil fuel) are less flexible, hydropower is a strategic source for the future. Hydropower in a mountainous country like Switzerland represents 59.7% of electricity generation [Energiebundesamt, 2012], while in Italy this value decreases to 13.2% [Terna, 2012], mantaining anyhow a considerable share of the national production. The changes currently taking place in the electricity market due to the increasing share of renewable energies and the implementation of an energy stock exchange are leading to several transformations in which hy- dropower will be one of the main players. In such a context, it is important to investigate the complex relation- ship occurring among climate, water availability, and hydropower production. When dealing with climate change, the uncertainty related to future projection can not be neglected. Climate change impact studies are the result of a complex modelling chain, which comprises the defi- nition of the Representative Concentration Pathway (RCP), the Gen- eral Circulation Model (GCM), Regional Circulation Model (RCM), the downscaling procedure, the hydrological modelling, and the mod- 1