Hu Qiang, Chen Yan, Xia Rui, Liu Xiaoyu, Jia Ruining, Zhang Kai, Li Xiaoxuan, Yan Chao, Wang Yao, Yin Yingze, Li Xiang, Ming Junde
State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, Beijing, 100012, PR China.
State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, Beijing, 100012, PR China; Chongqing Institute of Green and Intelligent Technology, Chinese Academy of Sciences, Chongqing, 400714, PR China.
Water Res. 2024 May 15;255:121496. doi: 10.1016/j.watres.2024.121496. Epub 2024 Mar 22.
The evolution of riverine aquatic ecosystems typically exhibits notable characteristic with cumulative, enduring, and hysteresis. Exploring the non-linear response of riverine ecology to long-term hydrological fluctuations become a major challenge in contemporary interdisciplinary research. In response to the critical issue of frequent river algal blooms in the lower Han River, which is impacted by Asian largest inter-basin water diversion project. We identified the non-linear response of eco-hydrology across various time scales through the integration of Continuous Wavelet Transform (CWT) and Inverse Wavelet Transform (IWT). Our study revealed that: 1) Over the past half century, the hydrological regime in the lower Han river showed a significant downward trend, and existed three significant hydrological oscillation periods (HOPs), including the short-scale Intra-AC (180 days), the medium-scale AC (365 days, the first major period), and the long-scale Inter-AC (2500 days), the variation of Inter-AC changed most dramatically. 2) We further found that the Inter-AC variation of hydrology is more closely related to the formation of river algal blooms in the Han River, and when the hydrological Inter-AC shows steady state or downward trend, the frequency of algal blooms in the lower Han River increases significantly. 3) The river algal blooms in the lower Han River is a cumulative consequence to the long-term hydrological influences. Weakened hydrological Inter-AC is more likely to increase the frequency of river algal blooms, and 10-years Inter-AC cumulation increased the frequency by 60%. Therefore, the weaken of long-scale HOP will significantly increase the frequency of river algal blooms in the future. This study received a critical scientific insight and aimed at provide guidance for the optimization of ecological management within the framework of national large-scale water conservation.
河流生态系统的演变通常呈现出累积性、持续性和滞后性等显著特征。探索河流生态对长期水文波动的非线性响应已成为当代跨学科研究中的一项重大挑战。针对受亚洲最大的跨流域调水工程影响的汉江下游频繁发生的河流水华这一关键问题，我们通过连续小波变换（CWT）和逆小波变换（IWT）的结合，确定了不同时间尺度上生态水文的非线性响应。我们的研究表明：1）在过去半个世纪中，汉江下游的水文情势呈显著下降趋势，存在三个显著的水文振荡周期（HOPs），包括短尺度的年内周期（180天）、中尺度的年周期（365天，第一个主要周期）和长尺度的年际周期（2500天），其中年际周期的变化最为剧烈。2）我们进一步发现，水文的年际周期变化与汉江河水华的形成更为密切相关，当水文年际周期呈稳定状态或下降趋势时，汉江下游水华发生频率显著增加。3）汉江下游的河流水华是长期水文影响的累积结果。水文年际周期减弱更有可能增加河流水华发生频率，10年的年际周期累积使频率增加了60%。因此，长期尺度的水文振荡周期减弱将在未来显著增加河流水华发生频率。本研究获得了关键的科学见解，旨在为国家大规模水资源保护框架内的生态管理优化提供指导。
