Author(s): Tomasz Kolerski; Sarah Burgess; Ayurzana Badarch; Khishigbat Batdelger; Nasanbayar Narantsogt
Linked Author(s): Ayurzana Badarch, Tomasz Kolerski
Keywords: Thermal pollution; Hydropower operation; Winter river temperature; Numerical modeling; River ice formation
Abstract: This study evaluates the thermal impact of heated water discharged from a planned hydroelectric power plant on the winter temperature regime of the Selenge River. The power plant would be located on the Eg River, approximately 3 km upstream of its confluence with the Selenge River. Numerical simulations were conducted to assess the downstream extent of thermal influence and to determine the distance at which river water temperature reaches 0°C. The numerical simulations considered air temperature under mild (−10°C) and severe (−30°C) winter conditions, discharge from the power plant reservoir at temperatures ranging from +1°C to +4°C, and different modes of power plant operations. Plant operational modes included peak-load operation and operation moderated by a re-regulation reservoir designed to attenuate short-term discharge fluctuations. The modeled results were then analyzed to determine the effect of different variables on the thermal conditions downstream of the plant. Results indicate that warmer discharge (+3°C and +4°C) without re-regulation significantly extends the downstream thermal influence of the plant, while inclusion of the re-regulation reservoir substantially reduces its effect. With the re-regulation reservoir, water temperatures reach 0°C approximately 15 km downstream in the severe winter scenario (−30°C), whereas in the mild winter scenario (−10°C) the distance extends to 40–45 km. The study demonstrates that a re-regulation reservoir effectively mitigates thermal impacts of heated water discharge, limiting potential disturbances to river ice formation and preserving the winter thermal regime in the Eg–Selenge River system.
Year: 2026