Paleohydrological changes over the last 4000 years in the middle and lower reaches of the Yangtze River: Evidence from particle size and n-alkanes from Longgan Lake

We have reconstructed the history of late-Holocene paleohydrological changes in the middle and lower reaches of the Yangtze River using grain size and n-alkane data from a sediment core retrieved from Longgan Lake. We employ changes in the grain size distribution to reflect the water level in the floodplain lake, with a higher percentage of the finer fraction indicating higher water level and vice versa. The n-alkane molecular distribution, average chain length (ACL), and Paq ratio (C23+C25)/(C23+C25+C29+C31) are used to reflect mainly vegetation composition that is also sensitive to water depth. Our results reveal that the lake water level was relatively low and gradually increased from 4 to 2.7 ka. The period from 2.7 to 1.2 ka exhibited the highest late-Holocene lake water level in this region. The water level then decreased toward the present. This paleohydrological reconstruction agrees with existing paleoclimate reconstructions of the middle and lower reaches of the Yangtze River, confirming that the intensity of Asian monsoon rains is an important factor in affecting paleohydrological changes in this region.

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Mid- to- late Holocene hydroclimatic changes on the Chinese Loess Plateau: evidence from n-alkanes from the sediments of Tianchi Lake

10.5194/egusphere-egu2020-3862 ◽

2020 ◽

Author(s):

Aifeng Zhou

Keyword(s):

Water Level ◽

Loess Plateau ◽

Lake Water ◽

Late Holocene ◽

Central China ◽

Chinese Loess Plateau ◽

Average Chain Length ◽

Chinese Loess ◽

Lake Water Level ◽

The Chinese Loess Plateau

We have reconstructed the history of mid-late Holocene paleohydrological changes in the Chinese Loess Plateau using n-alkane data from a sediment core in Tianchi Lake. We used Paq (the proportion of aquatic macrophytes to the total plant community) to reflect changes in lake water level, with a higher abundance of submerged macrophytes indicating a lower water level and vice versa. The Paq -based hydrological reconstruction agrees with various other lines of evidence, including ACL (average chain length), CPI (carbon preference index), C/N ratio and the n-alkane molecular distribution of the sediments in Tianchi Lake. The results reveal that the lake water level was relatively high during 5.7 to 3.2 ka BP, and decreased gradually thereafter. Our paleohydrological reconstruction is consistent with existing paleoclimate reconstructions from the Loess Plateau, which suggest a humid mid-Holocene, but is asynchronous with paleoclimatic records from central China which indicate an arid mid-Holocene. Overall, our results confirm that the intensity of the rainfall delivered by the EASM (East Asian summer monsoon) is an important factor in affecting paleohydrological changes in the region and can be considered as further evidence for the development of a spatially asynchronous &#8220;northern China drought and southern China flood&#8221; precipitation pattern during the Holocene.

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Mid-late Holocene hydroclimate variation in the source region of the Yangtze River revealed by lake sediment records

10.5194/egusphere-egu2020-5067 ◽

2020 ◽

Author(s):

Hou Xiaohuan ◽

Liu Lina ◽

Sun Zhe ◽

Cao Xianyong ◽

Hou Juzhi

Keyword(s):

Grain Size ◽

Organic Matter ◽

Tibetan Plateau ◽

Yangtze River ◽

Late Holocene ◽

Source Region ◽

Major Constituent ◽

The Yangtze River ◽

Hydrological Change ◽

Hydrological Variation

The headwater region of the Yangtze River serves as major constituent of Chinese Water Tower and is critical in providing fresh water for hundreds of millions of people living downstream. Hydrological variation is mainly influenced by environmental changes. Therefore, a good understanding of climate changes in the source region of the Yangtze River (SRYR) is of great significance. Here, we provide a lacustrine sediment core from Saiyong Co in SRYR, northeastern Tibetan Plateau, China, to reconstruct hydrological variation and the main influencing factors based on the analysis of grain size, scanning XRF, loss on ignition (LOI), which cover the past 6 ka. It is remarkable that total organic matter (LOI-550&#8451;) exhibits opposite patterns regarding to the PC1 of XRF, which represents the allochthonous input, indicating the majority of organic matter was mainly yielded within the lake. Clustering of palaeohydrological proxies, such as the reduced PC1 and increase in median grain size, seems coincide with the weakened strength of the Indian summer monsoon, which suggest a generally dry trend in the SRYR during the mid-late Holocene. However, short pulses of outrageous period occurred at 3.8-3.2 ka BP and 1.5-1.0 ka BP. The abrupt increase in PC1 and very coarse silt indicate the lake catchment became more humid with higher surface runoff, which is consistent with weaker lake productivity. The inferred hydrological change in SRYR since 6 ka BP not only have significant environmental influence, but also agree with other sequences from Tibetan Plateau and the adjacent regions This study provides long-term records of paleoenvironmental evolution which is particularly significant to understand recent and to predict future hydrological change in SRYR.

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Investigating a complex lake-catchment-river system using artificial neural networks: Poyang Lake (China)

Hydrology Research ◽

10.2166/nh.2015.150 ◽

2015 ◽

Vol 46 (6) ◽

pp. 912-928 ◽

Cited By ~ 48

Author(s):

Y. L. Li ◽

Q. Zhang ◽

A. D. Werner ◽

J. Yao

Keyword(s):

Water Level ◽

Lake Water ◽

Yangtze River ◽

Poyang Lake ◽

Multiple Stressors ◽

Resource Planning ◽

Water Levels ◽

The Yangtze River ◽

Large Lake ◽

Lake Catchment

Lake hydrological simulations using physically based models are cumbersome due to extensive data and computational requirements. Despite an abundance of previous modeling investigations, real-time simulation tools for large lake systems subjected to multiple stressors are lacking. The back-propagation neural network (BPNN) is applied as a first attempt to simulate the water-level variations of a large lake, exemplified by the Poyang Lake (China) case study. The BPNN investigation extends previous modeling efforts by considering the Yangtze River effect and evaluating the influence of the Yangtze River on the lake water levels. Results indicate that the effects of both the lake catchment and the Yangtze River are required to produce reasonable BPNN calibration statistics. Modeling results suggest that the Yangtze River plays a significant role in modifying the lake water-level changes. Comparison of BPNN models to a 2D hydrodynamic model (MIKE 21) shows that comparable accuracies can be obtained from both modeling approaches. This implies that the BPNN approach is well suited to long-term predictions of the water-level responses of Poyang Lake. The findings of this work demonstrate that BPNN can be used as a valuable and computationally efficient tool for future water resource planning and management of the Poyang Lake.

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Link between East Asian summer monsoon and sedimentation in river-mouth sandbars since the early Holocene preserved in the Yangtze River subaqueous delta front

Quaternary Research ◽

10.1017/qua.2020.1 ◽

2020 ◽

Vol 95 ◽

pp. 84-96

Author(s):

Gang Xu ◽

Jian Liu ◽

Marcello Gugliotta ◽

Yoshiki Saito ◽

Lilei Chen ◽

...

Keyword(s):

Yangtze River ◽

Late Holocene ◽

Asian Summer Monsoon ◽

Yangtze River Basin ◽

River Mouth ◽

Early Holocene ◽

The Yangtze River ◽

Delta Front ◽

The Yangtze River Basin ◽

Asian Summer

AbstractThis paper presents geochemical and grain-size records since the early Holocene in core ECS0702 with a fine chronology frame obtained from the Yangtze River subaqueous delta front. Since ~9500 cal yr BP, the proxy records of chemical weathering from the Yangtze River basin generally exhibit a Holocene optimum in the early Holocene, a weak East Asian summer monsoon (EASM) period during the middle Holocene, and a relatively strong EASM period in the late Holocene. The ~8.2 and ~4.4 cal ka BP cooling events are recorded in core ECS0702. The flooding events reconstructed by the grain-size parameters since the early Holocene suggest that the floods mainly occurred during strong EASM periods and the Yangtze River mouth sandbar caused by the floods mainly formed in the early and late Holocene. The Yangtze River-mouth sandbars since the early Holocene shifted from north to south, affected by tidal currents and the Coriolis force, and more importantly, controlled by the EASM. Our results are of great significance for enriching both the record of Holocene climate change in the Yangtze River basin and knowledge about the formation and evolution progress of the deltas located in monsoon regions.

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Lake water level modeling using newly developed hybrid data intelligence model

Theoretical and Applied Climatology ◽

10.1007/s00704-020-03263-8 ◽

2020 ◽

Vol 141 (3-4) ◽

pp. 1285-1300 ◽

Cited By ~ 3

Author(s):

Zaher Mundher Yaseen ◽

Shabnam Naghshara ◽

Sinan Q. Salih ◽

Sungwon Kim ◽

Anurag Malik ◽

...

Keyword(s):

Water Level ◽

Lake Water ◽

Lake Water Level ◽

Hybrid Data

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Evolution characteristics and drivers of the water level at an identical discharge in the Jingjiang reaches of the Yangtze River

Journal of Geographical Sciences ◽

10.1007/s11442-020-1804-x ◽

2020 ◽

Vol 30 (10) ◽

pp. 1633-1648

Author(s):

Yuanfang Chai ◽

Yunping Yang ◽

Jinyun Deng ◽

Zhaohua Sun ◽

Yitian Li ◽

...

Keyword(s):

Water Level ◽

Yangtze River ◽

The Yangtze River ◽

Evolution Characteristics

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Fuzzy logic model of lake water level fluctuations in Lake Van, Turkey

Theoretical and Applied Climatology ◽

10.1007/s00704-006-0267-z ◽

2007 ◽

Vol 90 (3-4) ◽

pp. 227-233 ◽

Cited By ~ 30

Author(s):

A. Altunkaynak ◽

Z. Şen

Keyword(s):

Fuzzy Logic ◽

Water Level ◽

Lake Water ◽

Logic Model ◽

Water Level Fluctuations ◽

Lake Van ◽

Lake Water Level ◽

Fuzzy Logic Model

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Groundwater level assessment and prediction in the Nebraska Sand Hills using LIDAR-derived lake water level

Journal of Hydrology ◽

10.1016/j.jhydrol.2021.126582 ◽

2021 ◽

pp. 126582

Author(s):

Nawaraj Shrestha ◽

Aaron Mittelstet ◽

Aaron R. Young ◽

Troy E. Gilmore ◽

David C. Gosselin ◽

...

Keyword(s):

Water Level ◽

Lake Water ◽

Groundwater Level ◽

Lake Water Level ◽

Nebraska Sand Hills ◽

Sand Hills

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Seasonal behaviour of tidal damping and residual water level slope in the Yangtze River estuary: identifying the critical position and river discharge for maximum tidal damping

Hydrology and Earth System Sciences ◽

10.5194/hess-23-2779-2019 ◽

2019 ◽

Vol 23 (6) ◽

pp. 2779-2794 ◽

Cited By ~ 4

Author(s):

Huayang Cai ◽

Hubert H. G. Savenije ◽

Erwan Garel ◽

Xianyi Zhang ◽

Leicheng Guo ◽

...

Keyword(s):

Water Level ◽

River Discharge ◽

Yangtze River ◽

River Estuary ◽

Yangtze River Estuary ◽

Residual Water ◽

The Yangtze River ◽

The Yangtze River Estuary ◽

Seasonal Behaviour ◽

Residual Water Level

Abstract. As a tide propagates into the estuary, river discharge affects tidal damping, primarily via a friction term, attenuating tidal motion by increasing the quadratic velocity in the numerator, while reducing the effective friction by increasing the water depth in the denominator. For the first time, we demonstrate a third effect of river discharge that may lead to the weakening of the channel convergence (i.e. landward reduction of channel width and/or depth). In this study, monthly averaged tidal water levels (2003–2014) at six gauging stations along the Yangtze River estuary are used to understand the seasonal behaviour of tidal damping and residual water level slope. Observations show that there is a critical value of river discharge, beyond which the tidal damping is reduced with increasing river discharge. This phenomenon is clearly observed in the upstream part of the Yangtze River estuary (between the Maanshan and Wuhu reaches), which suggests an important cumulative effect of residual water level on tide–river dynamics. To understand the underlying mechanism, an analytical model has been used to quantify the seasonal behaviour of tide–river dynamics and the corresponding residual water level slope under various external forcing conditions. It is shown that a critical position along the estuary is where there is maximum tidal damping (approximately corresponding to a maximum residual water level slope), upstream of which tidal damping is reduced in the landward direction. Moreover, contrary to the common assumption that larger river discharge leads to heavier damping, we demonstrate that beyond a critical value tidal damping is slightly reduced with increasing river discharge, owing to the cumulative effect of the residual water level on the effective friction and channel convergence. Our contribution describes the seasonal patterns of tide–river dynamics in detail, which will, hopefully, enhance our understanding of the nonlinear tide–river interplay and guide effective and sustainable water management in the Yangtze River estuary and other estuaries with substantial freshwater discharge.

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