Diversity in reservoir surface morphology and climate limits ability to compare and upscale estimates of greenhouse gas emissions

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Abstract

Greenhouse gas (GHG) emissions from reservoirs are influenced by many factors, including the reservoir's morphology, watershed, and local climate. Failure to account for diversity in waterbody characteristics contributes to uncertainties in estimates of total waterbody GHG emissions and limits the ability to extrapolate patterns from one set of reservoirs to another. Hydropower reservoirs are of particular interest given recent studies that show variable – and sometimes very high – measurements and estimates of emissions. This study uses characteristics describing reservoir surface morphology and location within the watershed to identify US hydropower reservoir archetypes that represent the diversity of reservoir features relevant to GHG emissions. The majority of reservoirs are characterized by smaller watersheds, smaller surface areas, and lower elevations. Downscaled climate projections of temperature and precipitation mapped onto the archetypes show large variability in hydroclimate stresses (i.e., changes in precipitation and air temperature) within and across different reservoir types. Average air temperatures are projected to increase for all reservoirs by the end of the century, relative to historical conditions, while projected precipitation is much more variable across all archetypes. Variability in projected climate suggests that despite similar morphology-related traits, reservoirs may experience different shifts in climate, potentially resulting in a divergence in carbon processing and GHG emissions from historical conditions. Low representation in published GHG emission measurements among several reservoir archetypes (roughly 14 % of the population of hydropower reservoirs), highlights a potential limit to the generalization of current measurements and models. This multi-dimensional analysis of waterbodies and their local hydroclimate provides valuable context for the growing body of GHG accounting literature and ongoing empirical and modeling studies.

Original languageEnglish
Article number164851
JournalScience of the Total Environment
Volume893
DOIs
StatePublished - Oct 1 2023

Funding

The authors would like to thank Ganesh Ghimire for his thorough review and suggestions for improving this manuscript. This material is based upon work supported by the U.S. Department of Energy Water Power Technology Office under contract number DE- AC05-00OR22725 .

FundersFunder number
Water Power Technologies OfficeDE- AC05-00OR22725
Water Power Technologies Office

    Keywords

    • Archetype analysis
    • Climate projections
    • Hydropower reservoirs

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