Estimation of minimum discharge for hydroelectric power plants

Water infrastructures, which are constructed in riverbeds within the context of water resource development projects, led to some impacts on water quantity, water quality and also water ecosystem. All of these impacts shall be taken into consideration to maintain the sustainability of water ecosystems. On this account, for the design of water infrastructures, determination of required amount of low flow in order to protect the water ecosystem in downstream of a river appears to be an important problem.Low flow calculations are mainly used for drinking and potable water supply, calculation of minimum water discharge from hydroelectric power plants, water pollution studies and determination of water quantity for sustainability of stream ecological values.In this study, it is aimed to determine the minimum discharge from a Hydroelectric Power Plant (HPP) in order to maintain the ecological balance of a stream. Various methods used by different countries exist in literature for calculation of low flow. Throughout years, some of these methods are modified according to the country conditions and later used by related countries. In this context, widely used formulas in literature are presented and sample implementation is made by using data from selected gauging stations.