Mitigation Measures Against Hydropeaking Effects
Hydropeaking consists of variations in discharge and water level due to releases of water retained in storage basin to generate electricity according to the market demand. These unnatural flow fluctuations create frequent and rapid variations in terms of flow magnitude, flow velocity, water depth, water temperature, wetted area and sediment transport which also can affect channel morphology. Such changes may lead to degradation of physical conditions and habitats in local ecosystems which directly affect biological communities in rivers. Mitigation measures can enhance the ecological state of rivers and lakes altered by hydropeaking. They are classified into 3 different types: Operational measures place constraints on the hydropower plant regime itself, fixing threshold values for amount of water released; construction measures involves construction of hydraulic structures like retention basins; and in-stream measures are renovation or maintenance works carried out inside the river. Mitigation measures are site-specific and thus local investigations must be carried out to ensure successful implementation of measures. In addition, long-term monitoring and systematic evaluation should be conducted during and after the completion of rehabilitation projects to assess the benefits of measures on local ecosystems. The literature review gathers examples of abatement measures implemented in several countries to mitigate negative impacts of hydropeaking. Examples are classified in a table and sorted by the aim of the measures.