Optimizing reservoir operation considering downstream ecological demands of water quantity and fluctuation based on IHA parameters

Abstract

The construction and operation of reservoirs arise the problems in downstream river of hydrological regime alteration and threat to freshwater biodiversity. Currently, most researches on reservoir operation model considering downstream ecology just quantify single ecological objective, which is difficult to reflect the downstream ecological demands comprehensively. To address the challenges above, this paper divides the parameters in Indicators of Hydrological Alteration (IHA), a widely used tool reflecting flow regime from multiple perspectives but seldom applied to guide practice reservoir operation, into two categories to reflect ecological demands of water quantity and fluctuation respectively. Then, two ecological objectives of Water Quantity Level (WQL) and Hydrological Alteration (HA) are defined to be incorporated into reservoir operation model with the economic objective of Hydropower Production (HP) for generating optimal operation strategy coordinating economic and ecological benefits. The case study of a typical reservoir in Hunan Province, China shows that: 1) two ecological objectives defined can reflect the alteration of hydrological regime from the perspective of water quantity and fluctuation accurately; and 2) compared with historical operation strategy and optimal operation strategies in the other two scenarios, the optimal operation strategy in scenario C is proved an excellent strategy to guide operation practice reconciling the economic benefits of hydropower plant with the ecological benefits of downstream river, which can balance two objectives of WQL and HA well with high level HP and make the released flow maintain more regime of natural flow.