三峡水库1990—2021年洪峰沙峰异步特性分析
Asynchrony of flood peaks and sediment peaks in the Three Gorges Reservoir from 1990 to 2021
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摘要: 泥沙淤积问题是水库能否长期运行的关键, 根据洪峰沙峰异步特性进行沙峰排沙调度是减少水库淤积、保持水库库容的有效手段, 研究水库洪峰沙峰异步特性具有重要意义。针对现有分析异步特性的方法存在不能反映整体水沙过程异步情况、异步类型分类不明确等局限性, 本文基于动态时间规整(DTW)算法, 将洪峰沙峰过程图形特征数值化, 进而计算异步时长并判断异步类型, 以三峡水库1990—2021年的洪水过程为研究对象分析其洪峰沙峰异步特性。研究结果表明: 三峡水库与金沙江下游梯级水库修建后, 三峡水库坝前沿程各站的沙峰滞后比例增加, 且距坝里程越近异步时长减小越多; 与传统方法相比, DTW算法考虑了完整的场次洪水水沙变化过程, 能有效处理复杂洪水过程, 适用性良好, 在水库运行管理与排沙调度方面具有应用潜力与发展前景。Abstract: Sediment deposition is a critical issue for the long-term operation and maintenance of reservoirs.Implementing sediment peak discharge regulations based on the asynchronous characteristics of flood and sediment peaks is an effective measure for reducing sediment deposition and maintaining the reservoir capacity.However, existing methods for analyzing asynchronous characteristics, such as peak appearance time subtraction and SSC-Q loop analysis, are still limited in reflecting the overall asynchronous characteristics of the water-sediment process and accurately classifying asynchronous types.Here, we employ the dynamic time warping (DTW) algorithm to characterize flood event processes.We calculate the duration of asynchrony and determine the type of asynchrony by quantifying the graphical features of flood and sediment peaks.By examining flood events that occurred in the Three Gorges Reservoir (TGR) from 1990 to 2021, we analyze the asynchronous characteristics of flood and sediment peaks in the reservoir and obtain their spatiotemporal variations.In this study, we reveal that after the construction of the TGR and the Lower Jinsha River terrace reservoirs, the proportion of the sediment peak lagging at each station along the front range of the TGR before the dam increases, and the duration of asynchrony decreases with decreasing distance from the dam.Compared to traditional methods, the entire water-sediment change process during individual flood events can be considered in the DTW method, which can be used to effectively manage complex flood processes, demonstrating wide applicability.The DTW method exhibits notable potential and prospects in reservoir operation management and scheduling.