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middle-late Holocene environment change induced by climate and human based on multi-proxy records from the middle and lower reaches of yangtze river,eastern China

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Science China Earth Sciences 2023年第7期66卷 1450-1467页

作者： Rui KE Xiayun XIAO Changting CHI Aubrey HILLMAN Baoyan JIA &Xiangdong YANG State Key Laboratory of Lake Science and Environment Nanjing Institute of Geography and LimnologyChinese Academy of SciencesNanjing 210008China University of Chinese Academy of Sciences Beijing 100049China Department of Atmospheric and Environmental Sciences University at AlbanyState University of New YorkAlbany 12222USA

Our knowledge about the interaction between human activities and the environment in the middle-late Holocene remains *** C1 in Lake Chaohu from the middle and lower reaches of yangtze river (MLYR),eastern China,provides an opportunity to investigate vegetation and climate changes,human activities,and East Asian summer monsoon(EASM) evolution since 5100 *** *** variables are assessed based on radiocarbon dating,pollen and charcoal records,and magnetic susceptibility (χ_(lf)),median grain size and *** reveal a hiatus in sedimentation between 2080 and 730 *** BP in the western part of Lake Chaohu,which is common in most lakes in the *** and deciduous broadleaved mixed forest retreated gradually after 3650 *** BP,and was replaced by secondary Pinus forest after at least 730 *** *** agricultural activities and vegetation clearance are first detected at 2520 *** *** settlements expanded from the lake front wetlands (during the period 2520–2080 *** BP) to remote high-altitude areas(2080–400 *** BP),and then returned to the lake front to reclaim the wetlands and lake (after 400 *** BP).A gradual trend of recessional EASM strength from 4300 *** BP and centennial-scale variations of EASM during the period5100–3650 *** BP are *** reduction of summer insolation,southward shift of the ITCZ,and El Ni?o Southern Oscillation may control the intensity of EASM and climate on a large regional scale.

关键词： Pollen Environment change Human activity Lake sediment middle-late Holocene middle and lower reaches of yangtze river

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Diagnosing anomalous characteristics of atmospheric water cycle structure during seasonal-scale drought events:A case study in middle and lower reaches of yangtze river

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Water Science and Engineering 2022年第2期15卷 103-113页

作者： Hai He Rui Cao Zhi-yong Wu Yuan Li Hao Yin Fei Yuan College of Hydrology and Water Resources Hohai UniversityNanjing 210098China

Anomalous characteristics of the atmospheric water cycle structure are highly significant to the mechanisms of seasonal-scale meteorological *** also play an important role in the identification of indicative predictors of *** better understand the causes of seasonal meteorological droughts in the middle and lower reaches of the yangtze river(MLRYR),characteristics of the atmospheric water cycle structure at different drought stages were determined using standardized *** results showed that the total column water vapor(TCWV)was anomalously low during drought occurrence *** contrast,there were no anomalous signals at the drought persistence and recovery stages in the ***,there was no significant temporal correlation between the TCWV anomaly and seasonal-scale drought index(the 3-month standardized precipitation index(SPI_(3))).During drought events,water vapor that mainly originated from the Bay of Bengal was transported southwest of the ***,the anomalous signal of water vapor transport was negative at the drought appearance *** the drought persistence stage,the negative anomalous signal was the most *** vapor flux divergence in the MLRYR showed significant positive anomalous signals during drought events,and the signal intensity shifted from an increasing to a decreasing trend at different drought *** addition,a significant positive correlation existed between the anomaly of water vapor flux divergence and regional SPI_(3).Overall,water vapor flux divergence is more predictive of droughts in the MLRYR.

关键词： Water vapor transport Water vapor flux divergence Standardized anomalies Seasonal-scale drought process middle and lower reaches of yangtze river

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Analysis of Precipitation in the middle and lower reaches of yangtze river in the Summer of 2000-2007

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Meteorological and Environmental Research 2011年第2期2卷 58-62页

作者： WANG Xue-qiang College of Atmospheric Sciences of Lanzhou University Lanzhou 730000China Xilinguole Union Bureau of Meteorology of Inner Mongolia Xilinhaote 026000China

Based upon the summer (June-August) precipitation data from 30 stations in the middle and lower reaches of yangtze river in China, the spatial and temporal distribution of summer precipitation in the yangtze river Basin was analyzed. As was shown in the results, the distribution of summer precipitation in the middle and lower reaches of yangtze river was mainly composed of four types: northern type (2005 and 2007), southern type (2001 and 2003), intermediate type (2000, 2004 and 2006) and integral type (2002). According to the correlation analysis of summer precipitation and atmospheric circulation in East Asia, the precipitation in the yangtze river Basin and high-low level circulation anomalies were significantly related. In other words,with the increase of the meridional degree of circulation at mid-high latitudes in the middle and upper troposphere as well as anomaly by south of subtropical high at low latitudes,the center or ridge line remained steady in the south of 30° N,thus the precipitation in the yangtze river Basin was obviously on the high side. The study could provide better guidance for the diagnosis and forecasting of precipitation in the yangtze river Basin in the future.

关键词： middle and lower reaches of yangtze river Summer rainfall China

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Coarse and fine sediment transportation patterns and causes downstream of the Three Gorges Dam

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Frontiers of Earth Science 2018年第4期12卷 750-764页

作者： Songzhe LI Yunping YANG Mingjin ZHANG Zhaohua SUN Lingling ZHU Xingying YOU Kanyu LI State Key Laboratory of Hydraulic Engineering Simulation and Safety Tianjin UniversityTianjin 300072China Key Laboratory of Engineering Sediment Tianjin Resear_ch Institute for Water Transport EngineeringMinistry of TransportTianjin 300456China State Key Laboratory of Water Resources and Hydropower Engineering Science Wuhan UniversityWuhan 430072China Bureau of Hydrology Changjiang Water Resources CommissionWuhan 430010China Hubei Provincial Water Resources and Hydropower Planning Survey and Design Institute Wuhan 430064China Changjiang Waterway Bureau Wuhan 430010China

Reservoir construction within a basin affects the process of water and sediment transport downstream of the dam. The Three Gorges Reservoir (TGR) affects the sediment transport downstream of the dam. The impoundment of the TGR reduced total downstream sediment. The sediment group dae0.125 mm (fine particle) increased along the path, but the average was still below what existed before the reservoir impoundment. The sediments group d > 0.125 mm (coarse particle) was recharged in the Yichang to Jianli reach, but showed a deposition trend downstream of Jianli. The coarse sediment in the Yichang to Jianli section in 2003 to 2007 was above the value before the TGR impoundment. However, the increase of both coarse and fine sediments in 2008 to 2014 was less than that in 2003 to 2007. The sediment retained in the dam is the major reason for the sediment reduction downstream. However, the retention in different river reaches is affected by riverbed coarsening, discharge, flow process, and conditions of lake functioning and recharging from the tributaries. The main conclusions derived from our study are as follows: 1) The riverbed in the Yichang to Shashi section was relatively coarse, thereby limiting the supply of fine and coarse sediments. The fine sediment supply was mainly controlled by TGR discharge, whereas the coarse sediment supply was controlled by the duration of high flow and its magnitude. 2) The supply of both coarse and fine sediments in the Shashi to Jianli section was controlled by the amount of total discharge. The sediment supply from the riverbed was higher in flood years than that in the dry years. The coarse sediment tended to deposit, and the deposition in the dry years was larger than that in the flood years. 3) The feeding of the fine sediment in the Luoshan to Hankou section was mainly from the riverbed. The supply in 2008 to 2014 was more than that in 2003 to 2007. Around 2010, the coarse sediments transited from depositing to sco

关键词： grouped sediments genetic analysis Three Gorges reservoir transportation characteristics middle and lower reaches of yangtze river fine fine yangtze Three Gorges Downstream scour Aminopyrine sediment supply genetic analysis Deposits High Flow TXNRD3 gene river bed Dams

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AN EAST ASIAN SUBTROPICAL SUMMER MONSOON INDEX DEFINED BY MOISTURE TRANSPORT

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Journal of Tropical Meteorology 2008年第1期14卷 61-64页

作者：梁萍汤绪何金海陈隆勋 Shanghai Climate Center Shanghai Meteorological Bureau Nanjing University of Information Science & Technology Chinese Academy of Meteorological Sciences

Using daily NCEP/NCAR reanalysis dataset and observation rainfall data in China for the 1971-2000 period, a subtropical summer monsoon index has been defined by meridional moisture transport of the total atmosphere column. Results show that the subtropical summer monsoon index defined by the difference of meridional moisture transport between South China and North China can be used to describe the intensity of the subtropical summer monsoon. High (low) index is corresponding to strong (weak) subtropical summer monsoon. And the new index is well related to the summer rainfall over the middle and lower reaches of yangtze river. In addition, the convergence of moisture transport from the west Pacific via the South China Sea and that from the North China may be responsible for the anomalously excessive summer rainfall over the middle and lower reaches of yangtze river.

关键词： moisture transport index subtropical monsoon middle and lower reaches of yangtze river precipitation

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Improving Conservation of Cranes by Modeling Potential Wintering Distributions in China

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Journal of Resources and Ecology 2016年第1期7卷 44-50页

作者：焦盛武曾晴孙工棋雷光春北京林业大学自然保护区学院北京100083

Habitat management is essential for the conservation of wildlife, especially cranes. Here, we collected occurrence data at wintering grounds for four cranes （Leucogeranus leucogeranus, Grus monacha, Antigone vipio and G. grus） and analyzed associated environmental variables to model and project overall potential wintering habitat using Maxent. ENMTools was used to calculate the degree of niche overlap among cranes. Results showed that lakes in the middle and lower reaches of the yangtze river are main habitats for the four focal species. Inland water and coastal wetlands in Jiangsu are also potential wintering areas. G. grus spreads over central and eastern China. The four cranes show tight niche overlap in the middle and lower reaches of the yangtze river. Poyang Lake is one of the most important habitat sites for all four cranes, according to modeling and niche overlap results. Poyang Lake is cut into a dozen nature reserves, but a bigger nature reserve or system would be more effective for cranes. The conservation of these four crane species will be improved on the basis of this study.

关键词： cranes middle and lower reaches of yangtze river habitat Maxent ENMTools

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