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Quantitative identification of natural flow regimes in fish spawning seasons

Li, Fang-Fang, Liu, Cong-Min, Qiu, Jun
Ecological engineering 2019 v.138 pp. 209-218
algorithms, fish, floods, habitats, humans, rivers, spawning, water conservation, China, Yellow River
The construction and operation of water conservancy projects changes the original flow regimes of rivers, and thus disturbs the habitat conditions of aquatic organisms. As an important aquatic living resource, fish is sensitive to the flow changes of the river, especially in the important periods such as spawning seasons. Existing studies indicates that flow regimes are effective stimulus for the fish spawning. In this study, an identification algorithm composed of three times of denoising is proposed to identify those rises with a certain magnitude and duration, which are deemed to be effective for spawning stimulus. Characteristic parameters including the number of the flood processes in the spawning season, the duration of each flood, and the growth rate of rising are statistically analyzed for the identified processes. The application on the upper reaches of the Yellow River in China, where almost no human intervention occurs, indicates that there indeed are some regularity for the flow regimes in the spawning season, even in different hydrological years. 4–6 times of floods composing a flow rising process is in need, and each of them should last for about 11 days. The desired daily growth rate is around 60 m3/(s·d) for the studied case. Such results are conductive for reservoir operation and the management of the river.