Operation of a hydropower system considering environmental flow requirements: A case study in La Nga river basin, Vietnam

A reservoir operation simulation study is carried out to analyze the impact of alternative scenarios of a hydropower system operation on energy production and natural flow regime in the La Nga river basin in Vietnam. The current operation policy causes severe hydrologic alteration in the natural flow regime represented by 32 parameters of the Range of Variability Approach (RVA). In the cases of the hydropower system operating at its full generation capacity and under a specified RVA target range at a downstream location, the power production can be increased by eight and four percent while reducing the overall degree of hydrologic alterations by 24 and 27 percent respectively compared to the existing rule-curve based operation. Results indicate that the system operation can be improved with increased power production while maintaining the environmental flow requirements for downstream ecosystems.

► Study obtains a tradeoff between hydropower production and environmental flow.
► Range of Variability Approach is suitable to indicate the hydrologic alterations.
► Current operating policy resulted in severe alterations in the natural flow regime.
► Proposed system operation improves both power production and ecological conditions.