Strong sources of CO2 in upper estuaries become sinks of CO2 in large river plumes

2012 ◽  
Vol 4 (2) ◽  
pp. 179-185 ◽  
Author(s):  
Chen-Tung Arthur Chen ◽  
Ting-Hsuan Huang ◽  
Yu-Han Fu ◽  
Yan Bai ◽  
Xianqiang He
Keyword(s):  
Large River ◽  
River Plumes ◽  
Sources Of Co2

scholarly journals Influence of Estuarine Tidal Mixing on Structure and Spatial Scales of Large River Plumes

2019 ◽  
Author(s):  
Alexander Osadchiev ◽  
Sergey Shchuka ◽  
Eduard Spivak ◽  
Maria Pisareva ◽  
Igor Semiletov
Keyword(s):  
Discharge Rate ◽  
Spatial Scales ◽  
Large River ◽  
Tidal Mixing ◽  
The Arctic ◽  
Large Area ◽  
River Plumes ◽  
Climate Conditions ◽  
Tidal Forcing ◽  
Discharge Rates

Abstract. The Yenisei and Khatanga rivers are among the largest estuarine rivers that inflow to the Arctic Ocean. Discharge of the Yenisei River is one order of magnitude larger than that of the Khatanga River. However, spatial scales of buoyant plumes formed by freshwater runoffs from the Yenisei and Khatanga gulfs are similar. This feature is caused by different tidal forcing in these estuaries, which have similar sizes, climate conditions, and geomorphology. The Khatanga discharge exhibits strong tidal forcing that causes formation of a diluted bottom-advected plume in the Khatanga Gulf. This anomalously deep and weakly-stratified plume has a small freshwater fraction and, therefore, occupies a large area on the shelf. The Yenisei Gulf, on the other hand, is a salt-wedge estuary that receives a large freshwater discharge and is less affected by tidal mixing due to low tidal velocities. As a result, the low-salinity and strongly-stratified Yenisei plume has a large freshwater fraction and its horizontal size is relatively small. The obtained results show that estuarine tidal mixing determines freshwater fraction in these river plumes, which governs their depth and area after they spread from estuaries to coastal sea. Therefore, influence of estuarine mixing on spatial scales of a large river plume can be of the same importance as the roles of river discharge rate and wind forcing. In particular, rivers with similar discharge rates can form plumes with significantly different areas, while plumes with similar areas can be formed by rivers with significantly different discharge rates.

scholarly journals Influence of estuarine tidal mixing on structure and spatial scales of large river plumes

Ocean Science ◽  
2020 ◽  
Vol 16 (4) ◽  
pp. 781-798 ◽  
Author(s):  
Alexander Osadchiev ◽  
Igor Medvedev ◽  
Sergey Shchuka ◽  
Mikhail Kulikov ◽  
Eduard Spivak ◽  
...  
Keyword(s):  
Discharge Rate ◽  
Spatial Scales ◽  
Large River ◽  
Tidal Mixing ◽  
The Arctic ◽  
Large Area ◽  
River Plumes ◽  
Climate Conditions ◽  
Tidal Forcing ◽  
Estuarine Mixing

Abstract. The Yenisei and Khatanga rivers are among the largest estuarine rivers that inflow to the Arctic Ocean. Discharge of the Yenisei River is 1 order of magnitude larger than that of the Khatanga River. However, spatial scales of buoyant plumes formed by freshwater runoff from the Yenisei and Khatanga gulfs are similar. This feature is caused by different tidal forcing in these estuaries, which have similar sizes, climate conditions, and geomorphology. The Khatanga discharge experiences strong tidal forcing that causes formation of a diluted bottom-advected plume in the Khatanga Gulf. This deep and weakly stratified plume has a small freshwater fraction and therefore occupies a large area on the shelf. The Yenisei Gulf, on the other hand, is a salt-wedge estuary that receives a large freshwater discharge and is less affected by tidal mixing due to low tidal velocities. As a result, the low-salinity and strongly stratified Yenisei plume has a large freshwater fraction and its horizontal size is relatively small. The results show that estuarine tidal mixing determines freshwater fraction in these river plumes, which governs their depth and area after they spread from estuaries to coastal sea. Therefore, the influence of estuarine mixing on spatial scales of a large river plume can be of the same importance as the roles of river discharge rate and wind forcing. In particular, plumes with similar areas can be formed by rivers with significantly different discharge rates, as illustrated by the Yenisei and Khatanga plumes.

scholarly journals Large River Plumes Detection by Satellite Altimetry: Case Study of the Ob–Yenisei Plume

2021 ◽  
Vol 13 (24) ◽  
pp. 5014
Author(s):  
Dmitry Frey ◽  
Alexander Osadchiev
Keyword(s):  
Satellite Altimetry ◽  
Outer Boundary ◽  
World Ocean ◽  
Large River ◽  
Statistical Correlation ◽  
Surface Salinity ◽  
River Plumes ◽  
In Situ Data ◽  
The World

Satellite altimetry is an efficient instrument for detection dynamical processes in the World Ocean, including reconstruction of geostrophic currents and tracking of mesoscale eddies. Satellite altimetry has the potential to detect large river plumes, which have reduced salinity and, therefore, elevated surface level as compared to surrounding saline sea. In this study, we analyze applicability of satellite altimetry for detection of the Ob–Yenisei plume in the Kara Sea, which is among the largest river plumes in the World Ocean. Based on the extensive in situ data collected at the study area during oceanographic surveys in 2007–2019, we analyze the accuracy and efficiency of satellite altimetry in reproducing, first, the outer boundary of the plume and, second, the internal structure of the plume. We reveal that the value of positive level anomaly within the Ob–Yenisei plume strongly depends on the vertical plume structure and is prone to significant synoptic and seasonal variability due to wind forcing and mixing of the plume with subjacent sea. As a result, despite generally high statistical correlation between the ADT and surface salinity, straightforward usage of ADT for detection of the river plume is incorrect and produces misleading results. Satellite altimetry could provide correct information about spatial extents and shape of the Ob–Yenisei plume only if it is validated by synchronous in situ measurements.

Key Construction Technologies for Large River-Crossing Slurry Shield Tunnel: Case Study

2021 ◽  
Vol 34 (2) ◽  
pp. 04020118
Author(s):  
Song Zhou ◽  
Guan-Lin Ye ◽  
Lei Han ◽  
Wang Jian-Hua
Keyword(s):  
Large River ◽  
Shield Tunnel ◽  
Slurry Shield

DRAINAGE BASIN AS A COMPLEX SOCIO-NATURAL HIERARCHICAL SYSTEM

2020 ◽  
Vol 42 (3) ◽  
pp. 293-303
Author(s):  
VALERIY BONDAREV
Keyword(s):  
Drainage Basin ◽  
Temporal Analysis ◽  
Large River ◽  
Hierarchical Level ◽  
Effective Management ◽  
Drainage Basins ◽  
Time Intervals ◽  
Natural Systems ◽  
Spatial And Temporal Analysis ◽  
Entire Complex

The theoretical and methodological basis of the systems hierarchical spatial and temporal analysis of a drainage basin, which addresses the problems of effective management in socio-natural systems of different ranks, is considered. It is proposed to distinguish 9 orders of forms that are relevant to the analysis of drainage basins, where the first level is represented by individual aggregates and particles, and the last - by basins of large and the largest rivers. As part of the allocation of geological, historical and modern time intervals, the specificity of the implementation of processes in basins of different scales from changing states, through functioning to evolution is demonstrated. The interrelation of conditions and factors that determine the processes occurring within the drainage basins is revealed. It is shown that a specific combination of conditions and factors that determine processes in the drainage basin is associated with the hierarchy of the objects under consideration, i.e. the choice of a spatial-temporal hierarchical level is crucial for the organization of study within drainage basins. At one hierarchical level, some phenomenon can be considered as a factor, and at another - as a condition. For example, tectonic processes can be considered as an active factor in the evolution of large river basins in the geological perspective, but for small drainage basin, this is already a conservative background condition. It is shown that at the historical time the anthropogenic factor often comes to the fore, with the appearance of which in the functioning of the drainage basin, there is a need to take into account the entire complex of socio-environmental problems that can affect the sustainable state of various territories, especially in the field of water and land use. Hierarchical levels of managing subjects are identified, which are primarily responsible for effective management at the appropriate hierarchical level of the organization of the socio-natural system within the catchment area, starting from an individual to humankind as a whole.

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