Weakened hydrological oscillation period increased the frequency of river algal blooms

Qiang Hu; Yan Chen; Rui Xia; Xiaoyu Liu; Ruining Jia; Kai Zhang; Xiaoxuan Li; Chao Yan; Yao Wang; Yingze Yin; Xiang Li; Junde Ming

doi:10.1016/j.watres.2024.121496

Weakened hydrological oscillation period increased the frequency of river algal blooms

Water Res. 2024 May 15:255:121496. doi: 10.1016/j.watres.2024.121496. Epub 2024 Mar 22.

Authors

Qiang Hu¹, Yan Chen², Rui Xia³, Xiaoyu Liu¹, Ruining Jia⁴, Kai Zhang¹, Xiaoxuan Li¹, Chao Yan⁴, Yao Wang¹, Yingze Yin⁴, Xiang Li¹, Junde Ming¹

Affiliations

¹ State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, Beijing, 100012, PR China.
² 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.
³ State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, Beijing, 100012, PR China; National Joint Research Center for Ecological Conservation and High Quality Development of the Yellow River Basin, Beijing, 100012, PR China. Electronic address: xiarui@craes.org.cn.
⁴ State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, Beijing, 100012, PR China; Northwest University College of Urban and Environmental Sciences, Northwest University, Xi'an, 710127, PR China.

PMID: 38564898
DOI: 10.1016/j.watres.2024.121496

Abstract

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.

Keywords: Han River; Hydrological oscillation period; Long-term impact; Non-linear response; River algal blooms; Wavelet transform.