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| DOI：10.13522/j.cnki.ggps.2026110 |
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| Effects of flooding on suspended-sediment characteristics and oxide transport in Longkaikou Reservoir |
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Wei Xiangxing, Shen Zhimin, Huang Yongguo, Gao Zhiguo, Li Jiayu1, Ran Ling, Du Min
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1. Huaneng Longkaikou Hydropower Co., Ltd., Dali 671505, China;
2. Yunnan Fangyuan Technology Co., Ltd., Kunming 650109, China;
3. Kunming University of Science and Technology, Faculty of Civil Engineering and Mechanics, Kunming 650500, China
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| Abstract: |
| 【Objective】Flood events can alter suspended-sediment characteristics and the transport of sediment-associated oxides, potentially affecting watershed water quality and the operation of reservoirs and hydropower facilities. Here, we studied the co-evolution of suspended-sediment morphology and oxide transport during the flood season in the Longkaikou Reservoir.【Method】The study was based on hydrological data and suspended-sediment samples collected from 2022 to 2025 at three sections of the reservoir: the outlet, upstream of the dam, and downstream of the outflow. The microstructural characteristics of suspended sediments with different particle sizes sampled at different depths under both base-flow and flood conditions were characterized using scanning electron microscopy (SEM) and X-ray fluorescence spectroscopy (XRF). Principal component analysis (PCA) and positive matrix factorization (PMF) were used to identify potential sources of SiO2, Al2O3, Fe2O3, K2O, Na2O, CaO and MgO.【Result】①The morphology of suspended sediment particles varied significantly with season and sampling depth. During the dry season, sediment particles were relatively coarse and angular, whereas during the flood season, they became finer and formed porous, flocculent aggregates. With increasing sampling depth, particle roundness decreased, while angularity increased. ②Overall, oxide concentrations were higher during the flood season than during the dry season and increased with sampling depth and particle size. Sampling depth and particle size significantly affected SiO2 and Na2O concentrations, which reached their maximum values at a depth of 1.6 m and a particle size of 14 μm. ③PCA and PMF analysis indicated that SiO2, Al2O3, Fe2O3, K2O, Na2O, CaO, and MgO were primarily associated with four potential sources, with K2O and Fe2O3 exhibiting a common source contribution in the third principal component. ④The predictive model for SiO2 and Na2O concentrations was accurate, with their R2 values being 0.85 and 0.90, respectively. Sediment particle size had a greater influence on oxide concentrations than flow rate and was the dominant factor controlling oxide transport.【Conclusion】The morphology of suspended sediment particles and oxide transport were closely coupled during the flood season, with particle size being the key factor regulating oxide concentrations and migration. These findings suggest that managing sediment particle sizes in reservoir areas and upstream of water intakes can help reduce excessive oxide transport and safeguard watershed water quality and the operation of hydropower facilities. |
| Key words: suspended matter particle morphology oxide migration synergistic mechanism PCA-PMF model |
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