Adapt water reserves to climate change: study case Romania.

At the regional level, hydrological factors, catchment properties, as well as the way water reserves are utilized, represent major determining factors of the reactions of lake ecosystems to climate change (CC). In this context, lakes also have a negative impact related to the large amounts of water they can consume through evaporation. This paper quantifies the effects of a small artificial lake-Dridu from Romania (with complex usage) on the environment in the context of CC, estimating the blue water footprint (WF) and carbon footprint (CF) under different use scenarios. Thus, an analysis of the evolution of CF and WF is conducted until 2100, considering forecasts of changes in average temperatures, as well as a partial coverage of the lake's surface with floating photovoltaic systems (FPV). During the study period from 2017 to 2021, the average WF was 0.054 million m³, and the carbon intensity was 120.23 kg CO₂e/MWh. By covering 2 ha of the reservoir's surface with FPV, the production and release of CO₂ and CH₄ into the atmosphere decrease, on average, by 30% for WF and 28.13% for CF. For the CC scenarios, it is observed that WF will increase by an average of 10.4%, while the carbon footprint shows no significant variations. It is worth mentioning that this type of approach, e.g., impact of FPV on WF and CF, as well as the use of FPV as a measure of coping with CC, has not been studied yet in any region of Eastern Europe. This study, given that it deals with relatively new technologies (FPV), has some gaps, since the CF is computed based on estimates, not on measured data. However, the results and the methodology currently presented can be used by various stakeholders to identify the best coping mechanism for preserving the water quantity and for generating clean energy. Also, these types of studies can be a good stimulus for the authorities to develop and permit the placement of FPV on small reservoirs and to investigate the effects of such projects in terms of energy, FPV efficiency, water quantity, and quality, as it will allow the actual quantification of different effects and benefits brought by this technology (water quality indicators, GHG emission, reduction of evaporation, FPV energy output).