Abstract
Hydropower plants produce renewable and sustainable energy but affect the river’s physico-chemical characteristics and change the abundance and composition of the aquatic organisms. The impact of large HPPs on the ecological conditions of surface water bodies have been extensively studied, but less attention has been paid to environmental impact studies of small hydropower plants (SHPs). The impact of hydropeaking on both the river flow regime and ecosystems has been well-studied for peaking mode plants, mainly medium to large-sized ones. However, for small hydroelectric power plants, and especially for those in lowland rivers, the available information on water quality, benthic macroinvertebrates communities and fish abundance, and biomass is not sufficient. Ten small hydropower plants were selected, and the ecological status of water bodies was assessed in different parts of Lithuania. The studies were performed at the riverbed upstream from the SHPs, where the hydrological regime has not changed, and downstream from the SHPs. It was found that the small hydropower plants do not affect the physico-chemical values of the water quality indicators. This study demonstrated that the total number of benthic macroinvertebrates taxa (TS) is influenced by the concentration of nitrogen and suspended solids, the water flow, the river area, and the current speed; the number of EPT (Ephemeroptera (mayflies), Plecoptera (stoneflies), and Trichoptera (caddisflies)) taxa is influenced by the concentration of nitrogen and suspended solids. The studied indicators do not have a significant impact on biomass. The SHPs affect the fish abundance and biomass. The Lithuanian fish index (LFI) is influenced by the average depth and area of the river. Some SHPs operating in lowland areas may yield somewhat significant hydrograph ramping but more detailed investigation is needed to support the significance of this impact on the biological indices.
Highlights
In many parts of the world, much attention is paid to the development of hydropower as one of the cheapest traditional, clean, and renewable energy sources [1,2,3,4]
By evaluating the values of water indicators below and above the small hydropower plants, it was found that the values above the hydropower plants are higher than those below the hydropower plants, Student’s t value, which shows the differences between the values, was found to be insignificant (p > 0.05)
This shows that hydropower plants do not have a negative impact on the physico-chemical values of water quality indicators
Summary
In many parts of the world, much attention is paid to the development of hydropower as one of the cheapest traditional, clean, and renewable energy sources [1,2,3,4]. The construction capacity of large hydropower plants (HPPs) is currently limited, but the construction of small hydropower plants (SHPs) is considered a renewable and sustainable energy supply alternative [5,6] with a minimal impact on the environment [7,8,9,10]. The environmental impact of hydropower plants can be reduced by using modern technologies [11]. Disruption of the natural regime of a river affects the river’s ecological conditions, hydrochemical characteristics, and changes in the abundance and composition of organisms in the water body [12,13,14,15,16,17]. The nature of HPP operation varies depending on the demand for the energy produced, which affects habitat diversity, abundance, biodiversity, and productivity [24,25,26]
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