Lake Evolution in the Tengger Desert, Northwestern China, during the Last 40,000 Years

1995 ◽  
Vol 44 (2) ◽  
pp. 171-180 ◽  
Author(s):  
Hans-Joachim Pachur ◽  
Bernd Wünnemann ◽  
Hucai Zhang

AbstractClimatic changes inferred from lacustrine deposits and lake-level fluctuations in northwestern and central China are mainly based on paleoclimatic records from the Tibetan Plateau, while there is still a lack of data relating to the semiarid/arid desert regions of Inner Mongolia. In the Tengger Desert, different paleolake levels at Baijian Hu are documented by six paleoshorelines and stratified lake carbonates. The highest lake level occurred ca. 39,000 14C yr B.P. and prevailed over about 16,000 km2. From sediment structure, geochemical composition, and ostracods we infer humid/cool conditions until 23,000 14C yr B.P. In the northern Badanjilin Desert at Gaxan Nur/Sogu Nur, high lake levels can be deduced from mollusc-bearing paleobeaches and lake carbonates, which have been dated to 34,000 14C yr B.P. and indicate a lake that covered some 32,000 km2. After ca. 20,000 yr B.P. the climate became dry with increased eolian activity and decreasing lake levels. Reestablishment of wet conditions occurred ca. 13,000 yr B.P. The Holocene is represented by stratified lake deposits that alternate with fluvial and eolian deposits, indicating a longterm oscillating trend toward arid conditions. The existence of widespread freshwater lakes during the late Pleistocene indicates a semihumid climate without an accompanying fall in temperature to arctic conditions.

2021 ◽  
Vol 9 ◽  
Author(s):  
Xiangjun Liu ◽  
David Madsen ◽  
Xiaojian Zhang

The Inner Tibetan Plateau (ITP), the central and western part of the Tibetan Plateau (TP), covers about one-fourth of the entire TP and contains more than 800 endorheic lakes larger than 1 km2. These lakes are important water reservoirs and sensitive to TP climate changes. They regulate regional water circulations, and further influence local ecosystems. Many lakes in ITP are surrounded by conspicuous paleoshorelines indicating much higher past lake levels. Previous studies found that lakes in the western ITP (west of ∼86°E) apparently expanded to higher levels than those to the east during the Holocene high lake level stage, however, there is no in-depth study on the reasons for the spatial differences of high lake levels within the ITP. In this study, we first identify Holocene lake level (or lake extent) changes over the ITP by combining published lake level variation data with our reconstruction of Dagze Co lake level variations. We then investigate spatial differences in the magnitude of lake expansions and explore the underlying forces driving these differences using the transient climate evolution of the last 21 ka (TraCE-21ka) and Kiel Climate Model (KCM) simulation results. We find that lakes in the ITP expanded to their highest levels during the early Holocene when the Indian summer monsoon (ISM) greatly intensified. After the mid-Holocene, lake levels fell as a result of the weakening of the ISM. The early Holocene northward shift of the westerly jet and a positive phase of the Atlantic multidecadal oscillation (AMO) resulted in the intensification of southwesterly winds on the southwest TP flank. Concurrently, westerly winds over the TP weakened, causing a differential increase in water vapor transport to the ITP with higher precipitation levels in the southwestern ITP and lower levels to the northeast. These wind-driven differential precipitation levels caused lakes in the southwestern ITP to expand to higher levels than those in the central, northern and northeastern ITP. During the early Holocene, expansion of lakes in the northwestern ITP was enhanced by an increase in glacier melt water besides the increased summer rainfall associated with the intensified ISM.


Ecohydrology ◽  
2015 ◽  
Vol 9 (2) ◽  
pp. 290-299 ◽  
Author(s):  
Yanhong Gao ◽  
Lichao Liu ◽  
Rongliang Jia ◽  
Haotian Yang ◽  
Gang Li

Soil Science ◽  
2014 ◽  
Vol 179 (9) ◽  
pp. 424-432 ◽  
Author(s):  
Haotian Yang ◽  
Lichao Liu ◽  
Xinrong Li ◽  
Yongping Wei ◽  
Xiaojun Li ◽  
...  

2021 ◽  
Vol 9 ◽  
Author(s):  
Mingzhi Sun ◽  
Jinyun Guo ◽  
Jiajia Yuan ◽  
Xin Liu ◽  
Haihong Wang ◽  
...  

Zhari Namco, a large lake in the Tibetan Plateau (TP), is sensitive to climate and environmental change. However, it is difficult to retrieve accurate and continuous lake levels for Zhari Namco. A robust strategy, including atmospheric delay correction, waveform retracking, outlier deletion, and inter-satellite adjustment, is proposed to generate a long-term series of lake levels for Zhari Namco through multi-altimeter data. Apparent biases are found in troposphere delay correction from different altimeter products and adjusted using an identical model. The threshold (20%) algorithm is employed for waveform retracking. The two-step method combining a sliding median filter and 2σ criterion is used to eliminate outliers. Tandem mission data of altimeters are used to estimate inter-satellite bias. Finally, a 27-year-long lake level time series of Zhari Namco are constructed using the TOPEX/Poseidon-Jason1/2/3 (T/P-Jason1/2/3) altimeter data from 1992 to 2019, resulting in an accuracy of 10.1 cm for T/P-Jason1/2/3. Temperature, precipitation, lake area, equivalent water height, and in situ gauge data are used for validation. The correlation coefficient more than 0.90 can be observed between this result and in situ gauge data. Compared with previous studies and existing database products, our method yields sequences with the best observational quality and the longest continuous monitoring in Zhari Namco. The time series indicates that the lake level in Zhari Namco has increased by ∼ 5.7 m, with an overall trend of 0.14 ± 0.01 m/yr, showing a fluctuating rate (1992–1999: −0.25 ± 0.05 m/yr, 2000–2008: 0.26 ± 0.04 m/yr, 2009–2016: −0.05 ± 0.03 m/yr, 2017–2019: 1.34 ± 0.34 m/yr). These findings will enhance the understanding of water budget and the effect of climate change in the TP.


Author(s):  
H. Zhao ◽  
R. Xu ◽  
G. Qiao

Abstract. There are more than 1,000 lakes (> 1 km2) on the Tibetan Plateau and lake level is an important physical feature of lake changes. Lake level change is an important indicator to reflect changes of climate and environment in a certain area. The development of satellite altimetry has provided data support for the monitoring of lake level and effectively compensated for the deficiencies of traditional water level monitoring in alpine regions. In this study, the laser altimeter of ICESat-2 and the radar altimeter of CryoSat-2 are used to provide lake level of the Nam Co lake during the period of 2010–2020. The result showed that the standard deviation (SD) of ICESat-2 (0.0895 m) was lower than the SD of CryoSat-2 (0.2556 m) and the months with higher SD values were mostly during the ice period of Nam Co lake. ICESat-2 had a considerably decreased measurement uncertainty. There are systematic differences in lake levels extracted by different altimetry satellites and the mean bias between ICESat-2 and CryoSat-2 was around 0.45 m. After removing inter-altimeter biases, the continuous lake levels from 2010 to 2020 were constructed. The inter-annual changes in lake levels were flat or even slightly decreased and the lake level has dropped by about 0.80 m in general. The water level generally reached the highest from September to October of the year in terms of intra-annual changes. Besides, temperature and precipitation changes were closely related to lake level tendency.


2007 ◽  
Vol 39 (2) ◽  
pp. 141-150 ◽  
Author(s):  
S. P. Harrison ◽  
S. E. Metcalfe

ABSTRACT Fluctuations in the extent of closed lakes provide a detailed record of regional and continental variations in mean annual water budget. The temporal sequence of hydrological fluctuations during the Holocene in North America has been reconstructed using information from the Oxford Lake-Level Data Bank. This data base includes 67 basins from the Americas north of the equator. Maps of lake status, an index of relative depth, are presented for the period 10,000 to 0 yr BP. The early Holocene was characterised by increasingly arid conditions, which led to widespread low lake levels in the mid-latitudes by 9,000 yr BP. By 6,000 yr BP this zone of low lakes extended from 32o to 51oN. Many of the features of the present day lake-level pattern, particularly high lake levels north of 46oN and along the eastern seaboard, were established by 3.000 yr BP. Four distinctive regional patterns of lake behaviour through time are apparent. Histograms of lake status from 20,000 to 0 yr BP are presented for each of these regions. They illustrate the temporal patterns of lake-level fluctuations on a time scale of 103 — 104 yr. Changes in lake status over North America are interpreted as indicating displacements in major features of the general circulation, specifically the zonal Westerlies and the Equatorial Trough, as reflected by changes in air mass trajectories and hence the position of air mass boundaries over the continent.


2017 ◽  
Vol 88 (2) ◽  
pp. 265-276 ◽  
Author(s):  
Pierre-Marc Godbout ◽  
Martin Roy ◽  
Jean J. Veillette ◽  
Joerg M. Schaefer

AbstractSurface exposure dating was applied to erosional shorelines associated with the Angliers lake level that marks an important stage of Lake Ojibway. The distribution of 1510Be ages from five sites shows a main group (10 samples) of coherent10Be ages yielding a mean age of 9.9±0.7 ka that assigns the development of this lake level to the early part of the Lake Ojibway history. A smaller group (3 samples) is part of a more scattered distribution of older10Be ages (with 2 outliers) that points to an inheritance of cosmogenic isotopes from a previous exposure, revealing an apparent mean age of 15.8±0.9 ka that is incompatible with the Ojibway inundation and the regional deglaciation. Our results provide the first direct10Be chronology on the sequence of lake levels in the Ojibway basin, which includes the lake stage presumably associated with the confluence and subsequent drainage of Lakes Agassiz and Ojibway. This study demonstrates the potential of this approach to date glacial lake shorelines and underlies the importance of obtaining additional chronological constraints on the Agassiz-Ojibway shoreline sequence to confidently assign a particular lake stage and/or lake-level drawdown to a specific time interval of the deglaciation.


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