Abstract
Hydropower remains the most important and largest source of renewable energy. However, besides many additional benefits, such as dams for water supply, irrigation, flood control, recreation, navigation, etc., hydropower generation has a negative impact on the environment. This study aimed to investigate the hydrologic changes in Lithuanian lowland rivers caused by small hydropower plants (HPPs). Thirty-two indicators of hydrologic alteration (IHA) were studied in 11 rivers downstream of hydropower plants in the post-impact and pre-impact periods. The findings showed that HPPs and reservoirs considerably disturbed the primary flow of river ecosystems downstream. The largest changes in mean IHA values were found for low and high pulse characteristics (up to 57%) and the number of reversals (up to 44%). Only small or no deviations of the timing of annual extreme flows were found. The number of reversals, a low pulse count, and a fall rate were the flow characteristics that fell outside their historical ranges of variability most often. Six (out of 11) hydropower plants were identified that provoked hydrologic alterations of a moderate degree.
Highlights
No statistically significant changes in the average discharges were identified. This confirms that the small hydropower plants (HPPs) reservoirs, which were studied, are mostly daily regulated and do not considerably affect average annual flows
The turbines installed in this HPP leak a large amount of water range
To the best of our knowledge, this is the first study in Lithuania and the Baltic States to examine the full range of natural hydrologic regime variables, including size, time, frequency, duration, and change rates that play a key role in maintaining the aquatic ecosystem
Summary
Hydropower (or hydroelectric power) is one of the oldest sources of energy used by humans. To date, it remains the most important and largest source of renewable energy. Hydropower dams are useful for water supply, irrigation, flood control, recreation, navigation, and more. Besides the aforementioned benefits, hydropower production has a negative impact on the environment. Frequent and sudden changes in water level and temperature, disturbed sediment transport, and blockage of fish migration routes are just a few of the many consequences that threaten the river ecosystem after constructing a dam. The use of rivers for energy production is a topic that does not lose relevance among politicians, environmental NGOs, hydropower professionals, hydrologists, ecologists, ichthyologists, and many others
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
