Water Quality Monitoring Strategy for Sustainable Hydropower Use: SWOT-Based Framework for Identification of Key Drivers in Environmental Management of Small Hydropower Cascades

The current environment and climate scenario sound worrying for the future. Serious mitigation measures are needed to reduce the impact of global threats and achieve decarbonization goals. Diversifying the energy portfolio and prioritizing renewable energy projects are at the forefront of these efforts. Hydropower is a critical source, providing 71% of renewable energy globally, but the construction and operation of hydropower plants, including small ones, often lead to changes in river morphology, water quality, sediment transport, and biodiversity. These impacts necessitate the development of a comprehensive environmental monitoring strategy to ensure sustainable operation. The study introduces a framework based on a SWOT analysis (Strengths, Weaknesses, Opportunities, and Threats) to identify the key drivers and assess the environmental impacts of small hydropower plants (SHPs), focusing on water quality. The methodology is applied to a case study of the Middle Iskar cascade, where five SHPs are located in one of the most anthropogenically affected river sectors of the Iskar River (Bulgaria). The identified strengths include improved water quality downstream due to the retention of nutrients and pollutants in impoundments created by SHPs. However, the weaknesses of SHP operation, including rapid sedimentation in impoundments, leading to the accumulation of hazardous pollutants and organic matter, are emphasized. The identified SWOT elements are a base for a detailed monitoring strategy for assessing SHP’s impact on water quality. The case study of the Middle Iskar cascade demonstrates the feasibility of the proposed monitoring strategy, showing positive outcomes in terms of improved water quality and ecological state.