This study aims to evaluate the potential impact of climate and land use change on seasonal dynamics of surface runoff within the Upper Tarlung watershed of 71.62 km². Using the Soil and Water Assessment Tool (SWAT), we simulated the surface runoff under the projections from four global and regional combination models for two representative concentration pathways (RCP4.5 and RCP8.5) and three land use change scenarios. In addition, short (2020–2039), mid (2040–2069), and long-term model simulations (2070–2100) were analyzed compared with a ten-year baseline period (1979–1988). Ensemble SWAT outputs showed that, in spring, surface runoff could decrease by up to 28% or increase by up to 86%, in summer can decrease by up to 69%, while in autumn and winter, increases of approximately two to five times fold are expected. The decreasing tendency is more pronounced under climate conditions, while the sharpest increases are estimated in the comprehensive scenario of climate and land use change by 50%. Those results serve as a support for local water, forest, and land managers in anticipating possible threats and conceiving adaptive strategies to manage the studied watershed efficiently.

This study aims to build and test the adaptability and reliability of the Soil and Water Assessment Tool hydrological model in a small mountain forested watershed. This ungauged watershed covers 184 km² and supplies 90% of blue water for the Brașov metropolitan area, the second largest metropolitan area of Romania. After building a custom database at the forest management compartment level, the SWAT model was run. Further, using the SWAT-CUP software under the SUFI2 algorithm, we identified the most sensitive parameters required in the calibration and validation stage. Moreover, the sensitivity analysis revealed that the surface runoff is mainly influenced by soil, groundwater and vegetation condition parameters. The calibration was carried out for 2001–2010, while the 1996–1999 period was used for model validation. Both procedures have indicated satisfactory performance and a lower uncertainty of model results in replicating river discharge compared with observed discharge. This research demonstrates that the SWAT model can be applied in small ungauged watersheds after an appropriate parameterisation of its databases. Furthermore, this tool is appropriate to support decision-makers in conceiving sustainable watershed management. It also guides prioritising the most suitable measures to increase the river basin resilience and ensure the water demand under climate change.

Mountain areas are prone to the occurrence of extreme events, especially torrential floods, amplified by climatic and environmental changes. In this context, it is mandatory to increase resilience and guide decision-makers toward more effective measures. Life cycle assessment (LCA) is considered as a decision support tool that can provide the qualitative and quantitative criteria required by the Do No Significant Harm, thus contributing to a more accurate assessment of environmental impacts of the torrent control structures. This study aimed to investigate the current state of the LCA applications in the torrent control to provide practitioners perspectives for new research and a pathway for optimized LCA analysis. Our analysis reveals that in the torrent control area, these studies are still limited. Most of the papers considered Ecoinvent as the main database source and cradle to grave as the main system boundary. This study suggests that restoring the functional capacity of dams and other torrent control structures instead of demolition or decommissioning from the end-of-life stage will ensure an orientation towards more sustainable and circular strategies. Although strong partnerships and consistent efforts are needed, general findings reveal that LCA is a useful tool for moving towards more sustainable construction practices.