Organic matter geochemical signatures of sediments of Lake Ngoring (Qinghai-Tibetan Plateau): A record of environmental and climatic changes in the source area of the Yellow River for the last 1500 years

The Wufo Basin at the margin of the northeastern Tibet Plateau connects the upstream reaches of the Yellow River with the lowland catchment downstream, and the fluvial terrace sequence in this basin provides crucial clues to understand the evolution history of the Yellow River drainage system in relation to the uplift and outgrowth of the Tibetan Plateau. Using field survey and analysis of Digital Elevation Model/Google Earth imagery, we found at least eight Yellow River terraces in this area. The overlying loess of the highest terrace was dated at 1.2 Ma based on paleomagnetic stratigraphy (two normal and two reversal polarities) and the loess-paleosol sequence (12 loess-paleosol cycles). This terrace shows the connections of drainage parts in and outside the Tibetan Plateau through its NE margin. In addition, we review the previously published data on the Yellow River terraces and ancient large lakes in the basins. Based on our new data and previous researches, we conclude that the modern Yellow River, with headwaters in the Tibet Plateau and debouching in the Bohai Sea, should date from at least 1.2 Ma. Ancient large lakes (such as the Hetao and Sanmen Lakes) developed as exorheic systems and flowed through the modern Yellow River at that time.

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Source, sink and preservation of organic matter from a machine learning approach of polar lipid tracers in sediments and soils from the Yellow River and Bohai Sea, eastern China

Chemical Geology ◽

10.1016/j.chemgeo.2021.120441 ◽

2021 ◽

pp. 120441

Author(s):

Keyu Tao ◽

Yunping Xu ◽

Yinghui Wang ◽

Yuntao Wang ◽

Ding He

Keyword(s):

Machine Learning ◽

Organic Matter ◽

Polar Lipid ◽

Bohai Sea ◽

Yellow River ◽

Eastern China ◽

The Yellow River ◽

Learning Approach ◽

Machine Learning Approach ◽

Source Sink

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Impacts of climate change on runoff in the source area of the Yellow River

10.22541/au.162738549.99991610/v1 ◽

2021 ◽

Author(s):

Dongying Yi ◽

Yue Xu ◽

Nan Wang ◽

Xiaoyi Ma

Keyword(s):

General Circulation ◽

Yellow River ◽

Swat Model ◽

Circulation Model ◽

Source Area ◽

Annual Runoff ◽

The Yellow River ◽

Runoff Simulation ◽

Climate System Model ◽

Average Annual Runoff

The primary approach to realizing long-term runoff prediction involves combining a hydrological model with general circulation model. Previous studies on the Source area of the Yellow River were all based on the Coupled Model Intercomparison Project Phase 5 (CMIP5) data sets with defects in physical mechanisms. In this paper, the Beijing Climate Center Climate System Model (BCC-CSM2-MR) of CMIP6, which proved to perform well in arid and semi-arid regions, will be used to drive the Soil & Water Assessment Tool (SWAT) model and evaluate its applicability in runoff simulation at Tang Nahai Hydrological Station from 2011 to 2019. The occurrence of the extreme value of runoff, its change trend, and the year of abrupt change of runoff in the four Shared Socio-economic Pathway (SSP) scenarios (SSP1-2.6, 2-4.5, 3-7.0, and 5-8.5) during 2021-2100 were analyzed. The results show that: (1) the runoff simulation evaluation index of SWAT driven by BCC-CSM2-MR in the research area from 2011 to 2019 is excellent, and the runoff simulation in the future is reliable and effective. (2) only the average annual runoff in scenario 5-8.5 (708.5m /s) from 2021 to 2100 was significantly higher than that in 2011-2019. Other scenarios are close to or less than the annual runoff observed. Most importantly, the maximum and minimum annual runoff values under the four scenarios all occurred during 2060-2080, so the attribution analysis of runoff extremum during 2060-2080 is worth further study. (3) it is necessary to evaluate whether the existing reservoirs and hydropower stations in the Yellow River basin can reasonably regulate and utilize the annual runoff under scenario 5-8.5.

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