Estimation of Lake Level Using Tiangong-2 InIRA Data

Rock varnish is a manganiferous dark coating accreted on subaerially exposed rocks in drylands. It often contains a layered microstratigraphy that records past wetness variations. Varnish samples from latest Pleistocene and Holocene geomorphic features in the Lake Turkana basin, East Africa display a regionally replicable microstratigraphy record of Holocene millennial-scale wetness variability and a broad interval of wetter conditions during the African Humid Period (AHP). Three major wet pulses in the varnish record occurred during the generally wet interval of the early Holocene (11.5–8.5 ka) when the lake attained its maximum high stand (MHS) at 455–460 m. A >23 m drop from the MHS occurred between 8.5 and 8 ka. Subsequently two additional wet pulses occurred during the early to middle Holocene (8–5 ka) when the lake occupied its secondary high stand at 445 m. Collectively, these five wet phases represent an extended wet interval coincident with the AHP in the region. One moderate wet phase occurred during the subsequent climatic transition from the humid to arid regime (5–4.3 ka) after the lake level dropped rapidly from 445 m to <405 m. Five minor wet phases took place during the overall arid period of the late Holocene (4.3–0 ka) when the lake level oscillated below 405 m. These findings indicate that the AHP terminated rapidly around 5 ka in the Turkana basin in terms of lake level drop, but the regional shift in relative humidity from the AHP mode to its present-day condition lagged for about 700 years until 4.3 ka, hinting at a gradual phasing out in terms of moisture condition. These findings further suggest that Lake Turkana overflowed intermittently into the Nile drainage system through its topographic sill at 455–460 m during the early Holocene and has become a closed-basin lake thereafter for the past 8 ky.

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Managing Lake Urmia, Iran for diverse restoration objectives: Moving beyond a uniform target lake level

Journal of Hydrology Regional Studies ◽

10.1016/j.ejrh.2021.100812 ◽

2021 ◽

Vol 35 ◽

pp. 100812

Author(s):

Somayeh Sima ◽

David E. Rosenberg ◽

Wayne A. Wurtsbaugh ◽

Sarah E. Null ◽

Karin M. Kettenring

Keyword(s):

Lake Level ◽

Lake Urmia

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Late Quaternary tectonic activity and lake level change in the Rukwa Rift Basin

Journal of African Earth Sciences ◽

10.1016/s0899-5362(98)00023-2 ◽

1998 ◽

Vol 26 (3) ◽

pp. 397-421 ◽

Cited By ~ 43

Author(s):

D. Delvaux ◽

F. Kervyn ◽

E. Vittori ◽

R.S.A. Kajara ◽

E. Kilembe

Keyword(s):

Lake Level ◽

Late Quaternary ◽

Tectonic Activity ◽

Rift Basin ◽

Lake Level Change ◽

Level Change

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Late Pleistocene and Holocene Paleoenvironments of Chalco Lake, Central Mexico

Quaternary Research ◽

10.1006/qres.1993.1086 ◽

1993 ◽

Vol 40 (3) ◽

pp. 332-342 ◽

Cited By ~ 111

Author(s):

Maria Socorro Lozano-Garcı́a ◽

Beatriz Ortega-Guerrero ◽

Margarita Caballero-Miranda ◽

Jaime Urrutia-Fucugauchi

Keyword(s):

Volcanic Activity ◽

Lake Level ◽

Environmental Changes ◽

Late Quaternary ◽

Cold Climate ◽

Central Mexico ◽

Pollen Record ◽

Loss On Ignition ◽

Southeastern Part ◽

Saline Marsh

AbstractIn order to establish paleoenvironmental conditions during the late Quaternary, four cores from the Basin of Mexico (central Mexico) were drilled in Chalco Lake, located in the southeastern part of the basin. The upper 8 m of two parallel cores were studied, using paleomagnetic, loss-on-ignition, pollen, and diatom analyses. Based on 11 14C ages, the analyzed record spans the last 19,000 14C yr B.P. Volcanic activity has affected microfossil abundances, both directly and indirectly, resulting in absence or reduction of pollen and diatom assemblages. Important volcanic activity took place between 19,000 and 15,000 yr B.P. when the lake was a shallow alkaline marsh and an increase of grassland pollen suggests a dry, cold climate. During this interval, abrupt environmental changes with increasing moisture occurred. From 15,000 until 12,500 yr B.P. the lake level increased and the pollen indicates wetter conditions. The highest lake level is registered from 12,500 to ca. 9000 yr B.P. The end of the Pleistocene is characterized by an increase in humidity. From 9000 until ca. 3000 yr B.P. Chalco Lake was a saline marsh and the pollen record indicates warmer conditions. After 3000 yr B.P. the lake level increased and human disturbance dominates the lacustrine record.

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Variations in Lake Levels during the Holocene in North America: An Indicator of Changes in Atmospheric Circulation Patterns

Géographie physique et Quaternaire ◽

10.7202/032598ar ◽

2007 ◽

Vol 39 (2) ◽

pp. 141-150 ◽

Cited By ~ 38

Author(s):

S. P. Harrison ◽

S. E. Metcalfe

Keyword(s):

North America ◽

General Circulation ◽

Lake Level ◽

Data Bank ◽

Relative Depth ◽

Lake Levels ◽

Regional Patterns ◽

Air Mass ◽

The Holocene ◽

Lake Status

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.

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Late Quaternary Lake-level fluctuations and environments of the northern Rift valley and Afar region (Ethiopia and Djibouti)

Palaeogeography Palaeoclimatology Palaeoecology ◽

10.1016/0031-0182(78)90011-1 ◽

1978 ◽

Vol 24 (4) ◽

pp. 279-325 ◽

Cited By ~ 137

Author(s):

E. Gasse ◽

F.A. Street

Keyword(s):

Rift Valley ◽

Lake Level ◽

Late Quaternary ◽

Lake Level Fluctuations ◽

Afar Region

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Cosmogenic10Be dating of raised shorelines constrains the timing of lake levels in the eastern Lake Agassiz-Ojibway basin

Quaternary Research ◽

10.1017/qua.2017.40 ◽

2017 ◽

Vol 88 (2) ◽

pp. 265-276 ◽

Cited By ~ 7

Author(s):

Pierre-Marc Godbout ◽

Martin Roy ◽

Jean J. Veillette ◽

Joerg M. Schaefer

Keyword(s):

Lake Level ◽

Time Interval ◽

Lake Levels ◽

Lake Agassiz ◽

Cosmogenic Isotopes ◽

Exposure Dating ◽

Group 3 ◽

Lake Stage ◽

Lake Ojibway

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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Eddy covariance flux measurements confirm extreme CH<sub>4</sub> emissions from a Swiss hydropower reservoir and resolve their short-term variability

Biogeosciences ◽

10.5194/bg-8-2815-2011 ◽

2011 ◽

Vol 8 (9) ◽

pp. 2815-2831 ◽

Cited By ~ 50

Author(s):

W. Eugster ◽

T. DelSontro ◽

S. Sobek

Keyword(s):

Greenhouse Gas ◽

Eddy Covariance ◽

Land Surface ◽

Lake Level ◽

Driving Forces ◽

Open Water ◽

Short Term ◽

Flux Measurements ◽

Floating Chamber ◽

Hydropower Reservoir

Abstract. Greenhouse gas budgets quantified via land-surface eddy covariance (EC) flux sites differ significantly from those obtained via inverse modeling. A possible reason for the discrepancy between methods may be our gap in quantitative knowledge of methane (CH4) fluxes. In this study we carried out EC flux measurements during two intensive campaigns in summer 2008 to quantify methane flux from a hydropower reservoir and link its temporal variability to environmental driving forces: water temperature and pressure changes (atmospheric and due to changes in lake level). Methane fluxes were extremely high and highly variable, but consistently showed gas efflux from the lake when the wind was approaching the EC sensors across the open water, as confirmed by floating chamber flux measurements. The average flux was 3.8 ± 0.4 μg C m−2 s−1 (mean ± SE) with a median of 1.4 μg C m−2 s−1, which is quite high even compared to tropical reservoirs. Floating chamber fluxes from four selected days confirmed such high fluxes with 7.4 ± 1.3 μg C m−2 s−1. Fluxes increased exponentially with increasing temperatures, but were decreasing exponentially with increasing atmospheric and/or lake level pressure. A multiple regression using lake surface temperatures (0.1 m depth), temperature at depth (10 m deep in front of the dam), atmospheric pressure, and lake level was able to explain 35.4% of the overall variance. This best fit included each variable averaged over a 9-h moving window, plus the respective short-term residuals thereof. We estimate that an annual average of 3% of the particulate organic matter (POM) input via the river is sufficient to sustain these large CH4 fluxes. To compensate the global warming potential associated with the CH4 effluxes from this hydropower reservoir a 1.3 to 3.7 times larger terrestrial area with net carbon dioxide uptake is needed if a European-scale compilation of grasslands, croplands and forests is taken as reference. This indicates the potential relevance of temperate reservoirs and lakes in local and regional greenhouse gas budgets.

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