Application of Multiple Environmental Flow Methods to Optimize Cascade Dams Operation in the Lower Jinsha River

Abstract:

To mitigate possible negative impacts of cascade dams in the Lower Jinsha River and maintain the natural flow regime of national natural reserve areas of rare and special fishes of the upper Yangtze River, environmental flow (e-flow) demands need to be considered in the cascade dams operation. Due to lack of regular ecological observation data, multiple hydrology-based e-flow methods including Tennant, minimum monthly flow, 7Q10 and Q₉₀ are applied to provide specific e-flow prescripts to guide the reservoir release. A joint operation optimization model is developed for the cascade dams in the Lower Jinsha River for maximal hydropower generation under various e-flow constraints. The economic and ecological performances of cascade dams operation are evaluated by total hydropower outputs and hydrological alteration degree of downstream river individually. The operation results are analyzed and discussed, and some questions on the tradeoff relationship between ecology and hydropower generation, inherent relationship between ecological constrains and hydrological alteration, and rationality criteria of e-flow are further addressed. The conclusions indicate : (1) optimal operation for ecological considerations under e-flow constrains only reduce hydropower outputs slightly, no more than 2.4%; (2) e-flow constrains help lower hydrological alteration induced by hydropower dams, among the four e-flow methodologies Tennant is best in term of ecology; (3) there is a limitation for hydrology-based e-flow methodologies, and it is necessary to stress ecological foundation and ecological relevance for e-flow methodology. The paper will provide technical references for future ecological re-operation of the cascade dams.

• Periodical: Advanced Materials Research (Volumes 955-959)
• Pages: 3057-3064
• DOI: https://doi.org/10.4028/www.scientific.net/AMR.955-959.3057
• Online since: June 2014
• Authors: Zheng Jie Yin*, Jin Chen, Ji Jun Xu
• Keywords: Dam Operation, Environmental Flow, Flow Regime, Hydrologic Alteration

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