Study On Joint Operation Of Feeding Reservoir Group For River Ecosystem Health

In recent years, more attention has been paid on the effects of reservoir operation on eco-environment. The ecological operation of reservoir and reservoir group has become the focus of water resources science and ecology research. Compared with the situation abroad, research on ecological operation started late in China. There are still many theories and technologies need to be further improved, although some research has been done already. This paper focuses on the theory and technology of ecological operation, with the purpose to solve the problem on ecological operation of reservoir group in downstream of Luan River. It also has reference value for ecological operation research of other water-scarce regions in northern China. Researches about river physical habitat simulation, assessment of regional ecological water demand and optimization of operation rules for reservoir group have been done in the paper based on river ecohydrology, river ecohydraulics and optimal operation theory of reservoir group. The downstream reaches of Luan River and Panjiakou reservoir, Daheiting reservoir, and Taolinkou reservoir were taken as an example. The study content and results are as follows:(1) A pattern of joint operation for reservoir group for river ecosystem health was proposed. Based on the related research both at home and abroad, this paper discussed the connotation and measures of ecological operation of reservoir and reservoir group. According to the runoff characteristics of Luan River and the actual demand of the reservoir group operation, a pattern of joint operation for reservoir group to maintain river health has been proposed in the paper. It can provide theoretical support for ecological operation research in water-scarce regions.(2) Taking the deficiencies of river physical habitat simulation model into account, this paper proposed an integrated modeling method to simulate and assess river habitat area under different discharge. The1-dimensional hydrodynamic model MIKE11and Physical Habitat Simulation Model (PHABSIM) were coupled in this paper to simulate the Q-WUA relationship of the reaches in Luan River downstream. The study river is firstly divided into10separate reaches; Then, MIKE11was used to simulate the hydraulics process for all reaches, and PHABSIM was used to get the Q-WUA relationship of each reach. The boundary conditions of PHABSIM were given by MIKE11simulation results. The results of field surveys were used to verify the habitat simulation. It shows that the simulation results were reliable for the Q-WUA relationships basically consistent to the habitat characteristics of Luan River downstream.(3) A classification assessment and integration pattern for ecological water demand of watershed/regional complex ecosystem has been proposed, and the method and model has been build. Nowadays, people pay more attention on the downstream river ecosystem near dam(s) in ecological operation study. However, the river ecosystem with further distance, estuaries ecosystem and the riparian ecosystem with hydraulic connection to the river were ignored. Thus, an integration pattern and model for ecological water demand of watershed/regional complex ecosystem have been proposed according to the water demand of each ecosystem in the downstream effect region. In order to support ecological operation decisions, the ecological water demand of different ecosystems is integrated to discharge process of dam(s) through a reverse passing loop algorithm. The downstream reaches of the Luan River have been taken as an example based on the pattern and model.(4) An ecological operation optimization model for feeding reservoir group has been built and its solving algorithm was given. According to the runoff characteristics of the Luan River and the actual demand of the reservoir group, this paper proposed a pattern of joint operation for reservoir group based on classification of ecological water demand. Ecological water demand was divided into two levels, minimum ecological water demand and suitable ecological water demand. During dry season, the discharge of reservoir group should meet the minimum ecological water demand so that the downstream ecosystem is non-degenerate, while the discharge should meet the suitable ecological water demand in wet season in order to provide a nice habitat conditions. Based on the pattern, an ecological operation optimization model for feeding reservoir group has been built according to the large system decomposition-coordination theory, which takes the operation chart of polymerization reservoir and the decomposition coefficients of water supply amount as measurement tools. Adaptive Genetic Algorithms (AGA) and Progressive Optimality Algorithm (POA) were used as solver tools and the reservoir group in the downstream of Luan River was taken as an example. The result shows that the guaranteed rates of minimum and suitable ecological water demand were increasing while the social-economic benefits were reduced. The research could provide theory and technical support to ecological operation of reservoir group in downstream of the Luan River, and also has reference value for other similar region.