Analysis of Hydrologic Regime Changes Caused by Small Hydropower Plants in Lowland Rivers

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 environment. This study aimed to investigate hydrologic changes in Lithuanian lowland rivers caused by small plants (HPPs). Thirty-two indicators alteration (IHA) were studied 11 downstream post-impact pre-impact periods. The findings showed that HPPs reservoirs considerably disturbed primary flow river ecosystems downstream. mean IHA values found low high pulse characteristics (up 57%) number reversals 44%). Only or no deviations timing annual extreme flows found. reversals, count, fall rate fell outside their historical ranges variability often. Six (out 11) identified provoked alterations moderate degree.