The water-level fluctuation zone of Three Gorges Reservoir — A unique geomorphological unit

Bao, Yuhai; Gao, Peng; He, Xingyuan

doi:10.1016/j.earscirev.2015.07.005

Cited by 240 publications

(106 citation statements)

References 66 publications

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“…The upper-middle section above Fengjie County is dominated by hilly landscape and underlain by purple and red rocks comprised of sandstone and mudstone. The lower section below Fengjie County is mountainous landscape with high mountains and deep-incised channels, and carbonate rocks comprised of limestone and dolomite (Bao et al, 2015a).…”

Section: Site Descriptionmentioning

confidence: 99%

“…On a hydrological year basis (i.e., October-September), the reservoir water level fluctuates between the base level of 145 m during the wet season (i.e., May-September) for flood control and the peak level of 175 m during the dry season (i.e., October-April) for hydropower generation . Seasonal water level fluctuation has created a reservoir fluctuation zone, which refers to all geomorphological features that fall into the elevation ranges between the base and peak levels (Bao et al, 2015a). The reservoir fluctuation zone, commonly also referred to as water-level fluctuation zone (Schreiber et al, 2011;Ye et al, 2011), littoral zone (Li et al, 2011a;Yuan et al, 2013), transitional area, drawdown zone Su et al, 2012), or disturbance zone (Bao et al, 2015a), represents a unique artificial landscape that was originally composed of terrestrial uplands with diverse land use and which was transformed to a transitional area undergoing seasonal flooding and exposure.…”

Section: Introductionmentioning

confidence: 99%

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Flow regulation manipulates contemporary seasonal sedimentary dynamics in the reservoir fluctuation zone of the Three Gorges Reservoir, China

Tang

Bao

et al. 2016

Science of The Total Environment

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101

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• Hydrological regime in the reservoir fluctuation zone has been significantly altered.• Grain-size variations are diagnostic for sedimentary stratigraphy differentiation.• Post-dam sedimentation processes were reproduced by chronology determination.• Regular flow regulation controls contemporary seasonal sedimentary dynamics. Since the launch of the Three Gorges Dam on the Yangtze River, a distinctive reservoir fluctuation zone has been created and significantly modified by regular dam operations. Sediment redistribution within this artificial landscape differs substantially from that in natural fluvial riparian zones, due to a specific hydrological regime comprising steps of water impoundment with increasing magnitudes and seasonal water level fluctuation holding a range of sediment fluxes. This study reinterpreted post-dam sedimentary dynamics in the reservoir fluctuation zone by stratigraphy determination of a 345-cm long sediment core, and related it to impact of the hydrological regime. Seasonality in absolute grain-size composition of suspended sediment was applied as a methodological basis for stratigraphic differentiation. Sedimentary laminations with relatively higher proportions of sandy fractions were ascribed to sedimentation during the dry season when proximal subsurface bank erosion dominates source contributions, while stratigraphy with a lower proportion of sandy fractions is possibly contributed by sedimentation during the wet season when distal upstream surface erosion prevails. Chronology determination revealed non-linear and high annual sedimentation rates ranging from 21.7 to 152.1 cm/yr. Although channel geomorphology may primarily determine the spatial extent of sedimentation, seasonal sedimentary dynamics was predominantly governed by the frequency, magnitude, and duration of flooding. Summer inundation by G R A P H I C A L A B S T R A C T a b s t r a c t a r t i c l e i n f o Contents lists available at ScienceDirectScience of the Total Environment j o u r n a l h o m e p a g e : w w w . e l s e v i e r . c o m / l o c a t e / s c i t o t e n v natural floods with enhanced sediment loads produced from upstream basins induced higher sedimentation rates than water impoundment during the dry season when distal sediment supply was limited. We thus conclude that flow regulation manipulates contemporary seasonal sedimentary dynamics in the reservoir fluctuation zone, though little impact on total sediment retention rate was detected. Ongoing reductions in flow and sediment supply under human disturbance may have profound implications in affecting sedimentary equilibrium in the reservoir fluctuation zone. The results herein provide insights of how big dams have disrupted the sediment conveyance processes of large scale fluvial systems.

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Section: Site Descriptionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Flow regulation manipulates contemporary seasonal sedimentary dynamics in the reservoir fluctuation zone of the Three Gorges Reservoir, China

Tang

Bao

et al. 2016

Science of The Total Environment

Self Cite

101

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“…Compared with the saturated water content in flooded wet samples, the presence of the soil moisture gradient and unfilled pores in the dry samples usually led to a heterogeneous environments with both anaerobic and aerobic micro niches (Puertolas et al 2013), which would support higher microbial diversities (Walsh et al 2005;Crump et al 2012). As a carrier of nutrients, the soil water also regulates the soil nutrients (Bao et al 2015), which were considered to be the best predictors of microbial diversity (Nielsen et al 2010;Wessén et al 2010). Therefore, the inhomogeneous soil water condition in the dry samples might be a key factor for the higher diversity of archaea.…”

Section: Archaeal Diversity Related To Water Floodingmentioning

confidence: 99%

“…The Three Gorges Reservoir (TGR)-triggered ecological issues draw wide attention globally (Stone 2008;Qiu 2009) and make the dam one of the most controversial hydraulic projects in China (Xu et al 2013;Bao et al 2015). Many of these issues pertain to the reservoir's riparian zone, which is also referred to as the water-level fluctuation zone (WLFZ) (Bao et al 2015). The water level rises to the highest level of 175 m in winter and drops to 145 m in summer, which is reverse to the fluctuation of natural water bodies ( Fig.…”

Section: Introductionmentioning

confidence: 99%

Shifts of archaeal community structure in soil along an elevation gradient in a reservoir water level fluctuation zone

Jiang

et al. 2016

J Soils Sediments

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Purpose Although archaea play an important role in nutrients cycling, the archaeal community in a reservoir water-level fluctuation zone (WLFZ) remains unclear. An elucidation of archaeal community responding to the environmental variables is essential to understand the nutrients dynamics in WLFZ. This study focused on the response of the archaeal community structure and abundance to the periodic water flooding along an elevation gradient in the WLFZ of the Three Gorges Reservoir. Materials and methods Along the elevation gradient (152-175 m) of the study area, soil samples in the beginning and late stages of water flooding were collected to investigate the influence of water flooding on the archaeal community in soil, using quantitative PCR and Illumina high-throughput sequencing approaches.Results and discussion An increase of archaeal abundance from 3.8 × 10 8 to 3.8 × 10 9 copies (g d.w.s) −1 on average was observed after water flooding. The archaeal abundance was positively correlated with the contents of ammonium, organic matter, and moisture in soil and with the accumulated flooding time. Higher diversity was observed in dry samples (non-flooded soil samples) rather than wet samples (flooded soil samples). The Thaumarchaeota were predominant in most of the dry samples. Interestingly, high proportions of Candidatus Nitrososphaera were observed in the transition zone, while euryarchaeotal methanogens dominated the wet samples. The proportion of methanogens decreased dramatically in the dry samples at higher elevations, which was associated with the decrease of the moisture content and the probably increase of available oxygen in soil.Conclusions Archaeal abundance, diversity, and community composition shifted along an elevation gradient and were influenced by water flooding. The increased archaea abundance after water flooding and elevation related community composition and diversity indicated that water flooding was a key dynamic environmental variable in the WLFZ.

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“…水库消落带是因水库周期性蓄洪、行洪或其他原因引起水库水位周期性变动而在水库上缘形成的一段水陆交替区，是水库特有的一种现象 [1][2][3] 。由于人为控制或自然降雨在时间尺度上的不均匀，水库水位会发生季节性和时间性的波动，进而导致消落带土壤出现周期性淹水和出露，并在植物、动物、微生物多度、土壤地球化学元素形态组成及其生物有效性等方面较邻近水陆生态系统具有明显差异 [2,4] 。三峡大坝修建及"蓄清排浑" 水位调度节律在三峡水库消落带形成系列生态水文格局及沉积学特征 [3,5] ，进而导致生源要素 C、N、P 及重金属在水土界面作用时间、作用方式发生变化。Cu、Zn、Cr、Pb、 As 等重金属元素更在环境条件如氧化还原电位、含水量发生改变时从土壤中以溶解、离子交换、解吸等方式进入水库水体，但水库水体中水溶性重金属也会通过乳状物吸附、螯合、沉淀等方式滞留于水体沉积物中 [5][6][7] ，并在汛期出露。目前关于三峡水库消落带土壤重金属含量研究主要有：135、175 m 土壤淹水后 Cu、 Pb、Zn、Cd、Cr、Hg、As 大尺度或面上分布 [5,[8][9] ，不同淹水深度含量变化 [10][11][12][13] ，覆水与出露期间赋存形态及其含量变化 [11,[14][15] 、动植物生物富集 [16][17] …”

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三峡水库蓄水对消落带土壤Cu、Zn、Cr、Cd含量的影响

杨丹¹,

Yang²,

谢宗强³

et al. 2018

JOURNAL OF NATURAL RESOURCES

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The water-level fluctuation zone of Three Gorges Reservoir — A unique geomorphological unit

Cited by 240 publications

References 66 publications

Flow regulation manipulates contemporary seasonal sedimentary dynamics in the reservoir fluctuation zone of the Three Gorges Reservoir, China

Flow regulation manipulates contemporary seasonal sedimentary dynamics in the reservoir fluctuation zone of the Three Gorges Reservoir, China

Shifts of archaeal community structure in soil along an elevation gradient in a reservoir water level fluctuation zone

三峡水库蓄水对消落带土壤Cu、Zn、Cr、Cd含量的影响

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