三峡水库下游宜昌-城陵矶河段地形多样性变化评价及其成因分析  

Evaluation and causes analysis of changes in morphological diversity in Yichang-Chenglingji reach downstream of the Three Gorges Dam

作　　者：陈立[1] 余博闻 杨成刚 袁晶 CHEN Li;YU Bowen;YANG Chenggang;YUAN Jing(State Key Laboratory of Water Resources Engineering and Management,Wuhan University,Wuhan 430072,China;Bureau of Hydrology,Changjiang Water Resources Commission,Wuhan 430010,China)

机构地区：[1]水资源工程与调度全国重点实验室,武汉大学,湖北武汉430072 [2]长江水利委员会水文局,湖北武汉430010

出　　处：《水利学报》2024年第12期1428-1438,共11页Journal of Hydraulic Engineering

基　　金：三峡工程泥沙重大问题研究项目(12610100000018J129-03);国家自然科学基金项目(U2340217)。

摘　　要：河道地形的多样性决定了河流栖息地物理生境的多样性,对水生生物物种丰度、多样性程度有重要影响。三峡水库蓄水后,下游河道河床发生显著冲淤调整,河道地形多样性也随之变化。使用2003、2018年长江三峡水库下游宜昌-城陵矶河段固定断面实测地形数据,基于河道纵向多样性、横向多样性、水深方向生境完整性指标,构建多样性综合指标,分析三峡水库蓄水后不同河型、不同河段栖息地地形多样性变化差异性及成因。结果表明:不同河型地形多样性不同,不同河段地形多样性也相应的存在差异,弯曲河型峰度系数低,低滩占比大,多样性高于其他河型,由弯曲河型为主构成的下荆江河段多样性也最高。水库蓄水后,下游河段地形多样性总体降低,但不同河型、不同河段地形多样性变化不同:顺直河型平滩水位、枯水位下峰度系数均增加,分汊河型枯水位峰度系数整体增加,而弯曲河型平滩水位下峰度系数减小,以弯曲河型为主的下荆江河段峰度系数减小。蓄水后不同河型冲淤调整的差异性是导致多样性变化趋势不同的内在机制。研究成果可为认识人类活动影响下河流栖息地变化提供支持。The diversity of river channel morphology largely determines the diversity of physical habitats for riverine organisms,playing an important role in shaping the abundance and diversity of aquatic biological species.After the impoundment of the Three Gorges Dam,downstream riverbed underwent severe erosion and deposition adjustments,leading to changes in river channel diversity.Using field-measured fixed cross section morphology data from Yichang to Chenglingji in the downstream reach of the Three Gorges Dam during the years 2003 and 2018,the composite diversity index of the river channel was constructed based on indexes of longitudinal diversity,lateral diversity and bathymetric habitat integrity.These indexes were employed to analyze the differences in diversity between different river patterns and reaches after the impoundment of the Three Gorges Dam,and the causes of the changes.The results revealed that,morphological diversity varied across different river patterns,with corresponding differences in morphological diversity among different reaches.Meandering river patterns exhibited a lower kurtosis coefficient and a higher proportion of low bars,resulting in higher diversity compared to other river patterns.Consequently,the Lower Jingjiang River,primarily characterized by meandering river pattern,exhibited greater diversity than other reaches.Following reservoir impoundment,overall morphological diversity in the downstream reaches generally decreased.However,changes in morphological diversity varied among different river patterns and reaches.Kurtosis coefficients increased significantly in straight river patterns under both low and bankful water levels,and was increasing in bifurcated river patterns under low water level,but decreased for meandering patterns under bankful water level.Accordingly,the kurtosis coefficient of the Lower Jingjiang Reach,dominated by meandering patterns,decreased.The difference in post-dam erosion and deposition adjustment patterns between different river patterns was the intrinsic me

关 键 词：河流栖息地 多样性 三峡水库 河道冲刷 

分 类 号：TV147[水利工程—水力学及河流动力学]