三峡蓄水以来葛洲坝下中华鲟产卵场河床质特征变化规律

VARIATION REGULARITY OF BOTTOM SUBSTRATE CHARACTERISTICS IN SPAWNING GROUND OF CHINESE STURGEON DOWNSTREAM THE GEZHOUBA DAM FROM IMPOUNDING OF THE THREE GORGE RESERVOIR

  • 摘要: 为探究葛洲坝下中华鲟(Acipenser sinensis)产卵场的河床质特征变化规律, 研究基于水声学和水下视频影像分析三峡蓄水以来现有数据(2004—2020年), 研究底质表观特征与水声学特征的相关性, 分析产卵场底质特征变化及其原因。结果表明: (1)硬度、粗糙度和分形维数分别与河床质充塞度、粒径和主要组成相关; (2)葛洲坝下中华鲟产卵场河床底质特征参数在2004—2020年发生了明显的变化, 硬度、粗糙度和分形维数三种特征均值在2004—2012年均呈现先增加后减少的趋势(P<0.01), 在2012—2019年均显著增加(P<0.01), 在2019—2020年显著减少(P<0.01); (3)产卵场含沙的底质比例在2004—2008年减少33.08%, 在2008—2012年增加12.69%, 在2012—2015年减少33.83%, 此后其持续减少至2019年, 在2019—2020年增加39.37%, 期间的底质变化可能与三峡蓄水、泥沙调度、新修水坝的蓄水运行及期间发生的洪水有较大关联, 且中华鲟的自然繁殖活动明显受河床质变化影响。研究结果为葛洲坝下中华鲟产卵场河床质的推演和产卵场的恢复与重建提供基础数据。

     

    Abstract: In order to investigate the changes of riverbed texture characteristics of Chinese sturgeon (Acipenser sinensis) spawning grounds under the Gezhouba Dam, we analyzed the correlation between the apparent characteristics of substrate and hydroacoustic characteristics. The analysis was based on hydroacoustic data and underwater video images collected from 2004 to 2020, covering the period since the Three Gorges water storage. The study aimed to analyze the changes of substrate characteristics and their causes. The results showed that (1) hardness, roughness and fractal dimension were found to be correlated with riverbed mass congestion, grain size and major composition, respectively; (2) the characteristic parameters of riverbed substrate at the spawning ground of Chinese sturgeon under the Gezhouba Dam showed significantly changes from 2004 to 2020. The mean values of hardness, roughness and fractal dimension showed an increasing trend followed by a decreasing trend from 2004 to 2012 (P<0.01). The three acoustic parameters also showed an increasing trend followed by a decreasing trend from 2012 to 2019. Between 2019 and 2020, all three acoustic characteristics mean values exhibited a significantly increase (P<0.01), followed by a significantly decrease (P<0.01); (3) the proportion of substrate containing sand in spawning grounds decreased by 33.08% between 2004 and 2008, increased by 12.69% between 2008 and 2012, and decreased 33.83% between 2012 and 2015. Subsequently, it continued to decrease until 2019 and increased by 39.37% during the period of 2019—2020. The substrate changes during this period were likely influenced by the Three Gorges water storage, sediment scheduling, water storage operation of newly constructed dams, floods, and the natural reproductive activities of Chinese sturgeon, which were obviously affected by the changes in riverbed substrate. The results of the study provide basic data for the extrapolation of the riverbed substrate of the Chinese sturgeon spawning grounds under Gezhouba Dam and the restoration and reconstruction of the spawning grounds.

     

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