INTEGRATED ASSESSMENT OF EVAPORATION REDUCTION AND ENERGY GENERATION FROM FLOATING PHOTOVOLTAICS ON HYDROPOWER RESERVOIRS: CASE STUDY IN LAKE POWELL

Author

• Aashish Subedi, University of Rhode IslandFollow

Date of Award

2026

Degree Type

Thesis

Degree Name

Master of Science in Civil and Environmental Engineering

Department

Civil and Environmental Engineering

First Advisor

Leon Thiem

Abstract

The Colorado River Basin, which supports 40 million people across seven U.S. states, is facing a critical water storage crisis driven by a severe drought, a decline in runoff, and open-water evaporation. Lake Powell, the second-largest reservoir in the United States, has experienced a persistent decline in water level and risks falling below the minimum pool elevation, which will have drastic effects on hydropower generation and water release. This study presents a comprehensive assessment of the use of floating photovoltaics (FPV) on Lake Powell to understand its dual water-energy benefits through saving evaporation loss and generating solar and additional hydropower. Monthly surface area time series were obtained from the JRC Monthly Water History Dataset, which shows reservoir extent from 270km² to 570km², with a decline in area from 2000 to the present. Open-water evaporation was modeled using the physically based Penman- Monteith equation, which incorporates heat storage in the reservoir with meteorological input from the TerraClimate dataset. The model was validated against in-situ Eddy Covariance measurements collected by the Bureau of Reclamation, achieving a Nash-Sutcliffe Efficiency of 0.7 and a Kling-Gupta Efficiency of 0.8. Monthly evaporation rates ranged from 2.2 - 2.5mm/day in winter and 5 - 5.7mm/day in summer months, with an average evaporation loss of 80 Mm³ in August. FPV coverage of 20%, 40%, and 50% reduced evaporation by 38.4%, 53.8%, and 61.5%, respectively. With 50% coverage in August, water saving ranged from 15.8 - 50 Mm3 with a normalized rate of 112000m³/km², hydropower generation ranged from 6 - 19 GWh with a normalized rate of 42600 KWh/km², and FPV solar energy ranged from 2.9 - 8.4 TWh with a normalized rate of 15.3 GWh/km². These findings demonstrate that FPV usage on hydropower reservoirs represents a technically viable, multi-benefit strategy for integrated water conservation and renewable energy generation.

Recommended Citation

Subedi, Aashish, "INTEGRATED ASSESSMENT OF EVAPORATION REDUCTION AND ENERGY GENERATION FROM FLOATING PHOTOVOLTAICS ON HYDROPOWER RESERVOIRS: CASE STUDY IN LAKE POWELL" (2026). Open Access Master's Theses. Paper 2738.
https://digitalcommons.uri.edu/theses/2738