Study On Ecological Flow Accounting Assessment And Assurance Of Typical Small Hydropower Steps Development Rivers

River-lake ecological flow is an important condition in maintaining the stability of the structures and ecological functions of rivers,lakes,wetlands and other ecosystems.With the development of social economy and the increase of production and living water,the exploration and utilization of water resources in rivers and lakes has gradually been accelerated,the phenomenon of ecological water being occupied has also emerged.In addition,a small hydropower station is an important water conservancy infrastructure in China,which plays an important role in improving the energy structure and promoting the development of the rural economy.Due to the historical limitations in the knowledge of river and lake ecological protection,most small hydropower projects in the past did not install ecological flow guarantee facilities,which had a certainly negative impact on the ecological balance of the rivers.Therefore,the protection of river-lake ecological flow has become one of the hot issues of concern in the world.It is vital to carry out researches on the ecological flow accounting,evaluation and guarantee of typical small hydropower terrace development rivers to promote the construction of water-ecological civilization.In this study,the relevant studies on the calculation methods and accounting cases of river ecological flow at home and abroad were summarized.And the ecological flow and cascade small hydropower profiles in the typical small hydropower terrace development river were analyzed.Simultaneously,the technical requirements of the ecological flow of rivers were summarized in terms of legal policies,water resources demonstration,engineering layout design,environmental impact assessment and other aspects.Besides,the main accounting methods of ecological flow at home and abroad and their scope of the application were classified and analyzed in this study.Based on the hydrology and data studies of a typical small hydropower terrace development river(Dongjiang River Basin),the minimum ecological flow at the control hydrological station(Boluo Station)in the Dongjiang River Basin were estimated using the empirical and frequency methods.Subsequently,the results and values of the minimum ecological flow scheme at the Boluo Station were evaluated by the Tennant method.The results of the evaluation showed that the empirical method and the frequency method were more suitable for calculating the minimum ecological flow in small hydropower terrace development rivers than the existing scheme.And the best range of the minimum ecological flow calculation values for Boluo Station in the Dongjiang River Basin was 226m3/s～233m3/s.Finally,some suggestions were made in this study for securing the ecological discharge of small hydropower steps development rivers in this study.The results of this study can help to improve the minimum ecological flow accounting and evaluation methods and support the measures to ensure the ecological flow of small hydropower terrace development rivers in China.Meanwhile,the minimum ecological flow accounting methods adopted and safeguarding measures proposed in this study can be used as a model for other rivers.