Impacts of the Kapulukaya Dam on the Hydrological Health of the Kızılırmak River

This study analyzes the hydrological conditions of the downstream of Kapulukaya Dam on the Kızılırmak River, comparing the pre-construction natural period (1970–1989) with the post-operation-controlled period (1989–2013). Using the Flow Health Software, the nine different hydrological sub-indicators, such as High Flow, Low Flow, and Seasonal Flow Shift were employed to determine the ecological and functional integrity of the river on a scale of 0 to 1. The results show a moderate deviation from natural processes; the most significant changes were observed in the Flood Flow Interval (FFI) and Seasonal Flow Shift (SFS) indices, indicating the suppression of natural flood cycles. Even during periods of extreme drought between 2006 and 2008, the Kapulukaya Dam has a high Persistently Very Low (PVL) rating of 0.95, preventing the complete drying up of the riverbed. However, the facility failed to reach its design energy production target of 190 GWh annually due to climatic pressures and upstream water conditioning. Furthermore, factors such as increase in drinking water demand in Kırıkkale and the lack of a central irrigation union negatively affected operational efficiency. The results obtained demonstrate that the dam achieved its flood control objective but experienced increased seasonal pressures on the river flow. In conclusion, the study highlights the need for an efficient water management strategy in the Kızılırmak Basin, encompassing climate change and water demand scenarios to achieve long-term sustainability.