闽江流域典型河道型水库溶解氧时空分异特征及影响因子

Spatiotemporal heterogeneity characteristics of dissolved oxygen and their influencing factors in typical channel-type reservoir of the Minjiang River Basin

摘要

【目的】河道型水库水动力兼具河流与湖泊的双重特性,对水环境要素纵向梯度分布产生重要影响。闽江是我国东南沿海第一大河,但其干流水库的DO时空分异特征及其影响因子目前尚不清晰。【方法】基于2020—2024年闽江水口水库上游支流及库区逐小时监测数据,有机结合STL时间序列分解、改进Mann-Kendall趋势检验、Pettitt突变点检测及皮尔逊相关性分析方法,以数据处理、特征剖析、趋势检验、归因分析为递进研究思路,建立了适用于河道型水库的综合分析方法,系统解析了水口水库溶解氧的时空演化规律。【结果】研究表明:水口水库表层DO呈现显著的纵向异质性,其浓度沿河流区(6.5~7.3 mg/L)、过渡区(5.6~6.8 mg/L)、湖泊区(5.2~6.2 mg/L)逐渐递减,低氧风险相应升高,具体表现为河流区低氧概率为0.7%~16.9%,过渡区为16.1%~38.3%,湖泊区为27.6%~46.1%;不同分区的DO主导驱动机制存在显著差异,且各驱动因子的影响程度随时间发生动态变化。此外,同一外部事件在不同分区中表现出明显的时间滞后效应,响应时差可达1~4个月。【结论】结果显示,所建综合分析方法可充分挖掘高频监测数据的深层信息,阐释其DO时空分异特征及其驱动机制,为进一步采取河流区外源管理、过渡区水动力-污染调控、湖泊区内源治理与生态调控等系统性改善措施提供依据。

Abstract

[Objective] The hydrodynamics in channel-type reservoirs exhibit dual characteristics of both rivers and lakes, significantly influencing the longitudinal gradient distribution of water environmental factors. The Minjiang River is the largest river in the coastal region of southeastern China, but the spatiotemporal heterogeneity characteristics of dissolved oxygen(DO) and its influencing factors in mainstream reservoirs remain unclear. [Methods] Based on the hourly monitoring data from 2020 to 2024 in the upstream tributaries and reservoir area of the Shuikou Reservoir in the Minjiang River, an integrated analytical method suitable for channel-type reservoirs was developed by combining STL time series decomposition, modified Mann-Kendall trend testing, Pettitt' s test for change-point detection, and Pearson correlation analysis. This method followed a progressive research framework of data processing, feature characterization, trend assessment, and attribution analysis, thereby systematically elucidating the spatiotemporal evolution patterns of DO in the Shuikou Reservoir. [Results] The result showed that the surfacelayer DO in Shuikou Reservoir exhibited significant longitudinal heterogeneity, with DO concentrations gradually decreasing from the riverine zone(6. 5~7. 3 mg/L), through the transition zone(5. 6~6. 8 mg/L), to the lacustrine zone(5. 2~6. 2 mg/L). Consequently, the risk of hypoxia increased correspondingly, specifically manifested as hypoxia probabilities of 0. 7% ~16. 9% in the riverine zone, 16. 1%~38. 3% in the transition zone, and 27. 6% ~ 46. 1% in the lacustrine zone. The dominant driving mechanisms of DO exhibited significant differences among these zones, and the influence degree of each driving factor dynamically changed over time. Furthermore, the same external events demonstrated significant temporal lag effects across different zones, with response delays ranging from 1 to 4 months. [Conclusion] It is evident that the established integrated analytical method can fully extract deep information from high-frequency monitoring data, elucidating the spatiotemporal heterogeneity characteristics of DO and their driving mechanisms. This provides a basis for further implementing systematic improvement measures, such as external source management in the riverine zone, hydrodynamic-pollution regulation in the transition zone, and internal source control and ecological regulation in the lacustrine zone.

关键词

河道型水库 / 溶解氧 / 时空分异 / 纵向分异 / 低氧风险 / 分区治理 / 闽江流域 / 影响因素

Key words

channel-type reservoir / dissolved oxygen / spatiotemporal differentiation / longitudinal heterogeneity / hypoxia risk / zonal management / Minjiang River Basin / influencing factors

基金资助

国家自然科学基金(52279013)