Enhancing run-of-river hydropower capacity assessment through integrated time series flow regime modeling and continuous wavelet transform analysis
Journal
Journal of Environmental Management
Journal Volume
404
Start Page
129363
ISSN
03014797
Date Issued
2026-04-15
Author(s)
Abstract
Run-of-river hydropower (RoR HP) systems are gaining prominence as sustainable energy alternatives because of their reduced ecological footprint compared with that of reservoir-based installations. However, in some regions, seasonal flow variability poses challenges for consistent energy generation and operational efficiency. This study introduces a novel framework that integrates continuous wavelet transform (CWT) and flow duration curve (FDC) analyses to evaluate hydropower potential by quantifying functional flow rates (FFRs) while accounting for flow regime continuity, which is a critical factor often overlooked in conventional assessments. Using a 22-year hourly discharge dataset from a subtropical watershed, we applied the CWT with a Morlet wavelet basis to decompose flow time series data, identifying dominant temporal scales via the global wavelet power spectrum. The results revealed primary (1 year) and secondary (3.5 years) hydrological cycles, reflecting the seasonal and interannual flow variabilities that directly impact hydropower feasibility. FFR thresholds were derived via continuous exceedance probability (CEP), which incorporates temporal flow continuity, and compared with traditional discrete exceedance probability (DEP) methods. Key findings indicate that the conventional DEP-based FDC approach systematically overestimates useable hydropower potential because it aggregates flow magnitudes without considering temporal sequencing and continuity, and this bias becomes more pronounced under strong seasonal variability. Across the evaluated continuity thresholds (3–24 h), CEP yields consistently lower and more operationally realistic energy and capacity-factor estimates than DEP. The dry-season flows consistently exceeded the CEP thresholds, whereas the wet-season flows exhibited high variability, necessitating adaptive operational strategies. Contrary to conventional insight, the dry season typically maintains a more continuous and available flow within a moderate discharge range. By prioritizing temporal continuity, the CEP framework provides a robust tool for policymakers and developers to mitigate financial risk, enhance climate resilience, and safeguard aquatic ecosystems. RoR systems can optimize energy output while minimizing risks from overestimated capacity factors by aligning installed capacity with CEP-derived thresholds. The proposed methodology reduces operational uncertainties and enhances the viability of RoR systems as low-impact renewable energy solutions, supporting climate resilience and environmental management goals.
Subjects
Capacity factor
Flow regime continuity
Run-of-river hydropower
Subtropical hydrology
Sustainable energy planning
Wavelet analysis
Publisher
Academic Press
Type
journal article