Environmental flow assessment of Kayan River: Managing sustainability indicator of hydropower project

Nowadays, constructing a new hydropower plant is one of the most attractive solutions to overcome energy requirements. The Kayan Hydroelectric, built in the Kayan River, is projected to generate electricity of nine hundred megawatts. However, the dams have to be managed appropriately since alteration of river discharge will have a significant impact on the environment. This paper proposes an environmental flow assessment as an appropriate indicator to manage sustainability. Three environmental flow assessment methods were used: Flow Duration Curve Analysis (FDCA), Tennant method, and Building Block method. The environmental flow pattern was used as a benchmark to evaluate whether the operation rule of the dams fulfilled the sustainable requirement, particularly on the hydrological pattern of the river. Regarding the Tennant and FDCA method, the minimum discharge that has to be maintained for the minimum environmental flow of the river is about twenty-five cms (corresponds to ten percent of AFF) and thirty-five cms, respectively. Meanwhile, the Building block method informs a range of discharge from a hundred cms to twenty thousand cms during the flood. The environmental flow should be managed to guarantee that the river's ecosystem and carrying capacity can be preserved.