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Hydropower, the global leading renewable energy source (one-sixth of worldwide electricity), is increasingly vulnerable to environmental and anthropogenic pressures. This study assesses their impacts through a systematic review and local scale studies. A systematic review carried out with a PRISMA-based screening of 1,516 Web of Science articles revealed a publication bias towards China and Brazil (24% of studies, 41% of global capacity), with a climate-focused research dominating over land use, sediment dynamics, or policy analysis. Strong correlations between precipitation or inflow variation was found, reflecting this bias. A mapping of climate, hydrology and energy model chains across structural complexity was realized. No cross-study robustness could be established. Almost no studies encompass all environmental factors. Then, to address the identified bias towards climate-focused approaches, we adopted a multi-scale, multi-factor methodology focusing on two case studies: Colombia and France, where hydropower represents approximately 68% and 20% of their total national installed capacity, respectively. In Colombia, we assessed the national-scale impact of ENSO-driven interannual climate variability on hydropower generation. Complementarily, we conducted high-resolution sediment core analyses from lakes supplying the Guatapé/El Peñol (Colombia) and Monts d’Orb (France) dams. Using a combination of fallout radionuclide dating, and multi-proxy analyses (relative density, granulometry, XRF), we reconstructed sediment dynamics to disentagle the combined effects of climate variability, land use change, and policy constrains on hydropower generation. Overall, this work reveals persistent bias and blindspots in hydropower vulnerability assessments, showing the importance of multi-scale, multi-factor approaches that integrate climate, land use, sediment dynamics, and policy constraints.