VALUTAZIONE DEGLI IMPATTI DEL CAMBIAMENTO CLIMATICO SULLA PERFORMANCE DELL’INVASO DI RIDRACOLI

Climate change represents one of the most discussed challenges at the centre of the scientific, political and socio‐cultural debate today. In Italy, in recent years, the perception of the increase in temperatures and variation in precipitation, both in frequency and intensity, foreshadow a risk scenario feared by the stakeholders in the water services, as any period of prolonged water scarcity could put water supply systems out of service. The tools implemented in this work, developed in collaboration with Romagna Acque ‐ Società delle Fonti S.p.A., are capable of assessing the availability of the water resource over the future period, according to 7 different chains of climate models and two different climate change scenarios. The first one is considered more optimistic as it results from the implementation of controlling policies to reduce greenhouse gases emission rates (RCP4.5), whereas the second one represents the no‐policy baseline approach (RCP8.5). Thus, scenario‐based modelling allows us to estimate the impact of future climatic variations on the water supply system of Romagna, in Italy. Moreover, a theoretical‐statistical analysis is first conducted in order to improve climate models’ outputs, which otherwise cannot be used at local‐scale applications, due to the presence of non‐negligible biases in the original signals. The technique adopted, known as Quantile Mapping, considering only the gap between the frequency distributions of climatic variables, observed and simulated, on the same historical reference period, allowed to obtain the same corrected climatic forcings in the future period. These series have constituted the necessary input, together with evaporation, of an accurate modelling chain, consisting of a rainfall‐runoff model that continuously feeds the management model of the Ridracoli reservoir. In this way, it was possible to obtain an estimate of the future surface runoff at the dam closure section and in correspondence with the weirs placed on the rivers connected to the Ridracoli reservoir and consequently a sufficiently reliable and realistic forecast of future drinking water supply, up to the year 2100, for both climatic scenarios considered. The study presented illustrates an analysis path that can be extended to other regulation reservoirs located in the Euro‐Mediterranean area, configuring itself as a useful approach for the definition of the tools required in a decision support system. In fact, with such tools, water system managers are capable of evaluating the effects of possible adaptation strategies to the expected climate scenarios, with the final aim of limiting as much as possible periods of future deficits in the water supply systems.