Climate services for sustainable resource management: The water-energy-land nexus in the Tarlung river basin (Romania)

Decision-makers need tailored information regarding future climate, land use, forest management and societal scenarios for sustainable watershed management. Such information can be attained by integrating the water-energy-land nexus approach with climate services. To support decision-makers from Brasov metropolitan area (Romania), we co-developed land use, forest management and societal scenarios and analysed their impact on the water-energy-land nexus under climate change. We applied the Soil and Water Assessment Tool (SWAT) to the Sacele reservoir from the Tarlung river basin in order to spot the interrelations between nexus components under different climate and societal scenarios. In particular, we applied four bias-corrected GCM & RCM model combinations for two climate scenarios RCP4.5 and RCP8.5, nine land use and forest management scenarios, and twelve societal scenarios. Modelling results were analysed between 2020 and 2099. The results for the study area indicate that the projected average annual precipitation is close to historical averages in most climate scenarios explored, while the projected average annual temperature is increasing. Furthermore, the analysed data suggest an increase in severe dry intervals from approximately 6% (for the period 1961-2013) to 12% by the end of the 21st century, indicating that precipitation variability may change considerably. The SWAT model results show no significant changes in the water flow under different forest management scenarios. In contrast, model results for scenarios that imply forests' clearcutting and their replacement with pastures or meadows indicate that water quality is affected by increased sediment flow. Regarding the number of months with water scarcity in the Sacele reservoir (i.e. water demand exceeds water supply), we found an increase from 0.4 months in 2020 to 1.5 months in 2099. The model results also revealed that climate change significantly influences the water supply in the reservoir. To conclude, the regional stakeholders highly value the model results for the co-developed scenarios, which have been already used to promote sustainable resource management.