scholarly journals Greater Water Surface Variability Revealed by New Congo River Field Data: Implications for Satellite Altimetry Measurements of Large Rivers

2019 ◽  
Vol 46 (14) ◽  
pp. 8093-8101 ◽  
Author(s):  
Andrew B. Carr ◽  
Mark A. Trigg ◽  
Raphael M. Tshimanga ◽  
Duncan J. Borman ◽  
Mark W. Smith
Keyword(s):  
Water Surface ◽  
Satellite Altimetry ◽  
Field Data ◽  
Large Rivers ◽  
Congo River ◽  
Surface Variability

Comparison of field data with theories on ice cover progression in large rivers

1984 ◽  
Vol 11 (4) ◽  
pp. 798-814 ◽  
Author(s):  
Bernard Michel
Keyword(s):  
Quantitative Determination ◽  
Key Words ◽  
Field Data ◽  
Ice Cover ◽  
Large Rivers ◽  
Ice Dynamics ◽  
Physical Mechanisms ◽  
Flow Parameters ◽  
Existing Data ◽  
St Lawrence River

There are many theories pertaining to the progression of ice covers in rivers fed by frazil slush and floes but very few have been examined critically by comparing them with field data. In this paper the existing theories on dynamic ice cover progression are reviewed, an additional one is proposed, and they are classified according to the physical mechanisms that are involved. Finally, they are compared with some existing field data for large rivers. The data are extremely scarce and difficult to obtain because of the costs involved and the dangers in traveling over thin ice when the ice cover is being formed.It is usually easier to get only the critical values of parameters giving the limits of ice cover progression. In this paper, complete data were taken from the St. Lawrence River, the Beauharnois Canal, and the La Grande Rivière where the ice thicknesses along with the flow parameters have been measured.In these cases the existing data are adequate, so they could be grouped to explain the various mechanisms involved and to obtain numerical values for their quantitative determination. Key words: glaciology, river ice, ice dynamics, fluvial processes, ice hydraulics.

Investigations of the Tasman Sea by satellite altimetry

1984 ◽  
Vol 35 (6) ◽  
pp. 619 ◽  
Author(s):  
R Coleman
Keyword(s):  
Spatial Distribution ◽  
Satellite Data ◽  
Satellite Altimetry ◽  
Sea Surface ◽  
Altimeter Data ◽  
Winter Period ◽  
East Australian Current ◽  
Tasman Sea ◽  
Topographic Influence ◽  
Surface Variability

Altimeter data obtained over a period of 3.6 years (from April 1975 to November 1978) and over the winter period July-September 1978 from the GEOS-3 and SEASAT satellites were used to study the spatial distribution of mesoscale sea-surface variability in the Tasman Sea. Satellite data generally agreed with existing hydrographic measurements. Patterns of higher sea-surface variability were shown to be associated with the East Australian Current and eddy areas. Though the Tasman Front is known to be present at certain times of the year, it is concluded that it is not a permanent feature across the Tasman Sea. Low variability levels in the mid-Tasman Sea are seemingly dictated by the Lord Howe Rise, thus suggesting some sort of topographic influence.

Wind-induced turbulent heat and mass transfer over large bodies of water

1976 ◽  
Vol 77 (4) ◽  
pp. 645-664 ◽  
Author(s):  
C. Y. Shaw ◽  
Y. Lee
Keyword(s):  
Mass Transfer ◽  
Heat And Mass Transfer ◽  
Satisfactory Agreement ◽  
Water Surface ◽  
Field Data ◽  
Theoretical Study ◽  
Field Conditions ◽  
Turbulent Heat ◽  
Bodies Of Water ◽  
Principle Of Similarity

A semi-theoretical study has been made of the problem of stable turbulent heat and mass transfer between a water surface and surrounding atmosphere under the influence of wind. The equations derived are based on the principle of similarity and are therefore expected to be valid under both laboratory and field conditions. The predicted heat- and mass-transfer Stanton numbers appear to be in satisfactory agreement with the available field data.

Ensemble learning regression for estimating river discharges using satellite altimetry data: Central Congo River as a Test-bed

2019 ◽  
Vol 221 ◽  
pp. 741-755 ◽  
Author(s):  
Donghwan Kim ◽  
Hanwen Yu ◽  
Hyongki Lee ◽  
Edward Beighley ◽  
Michael Durand ◽  
...  
Keyword(s):  
Ensemble Learning ◽  
Satellite Altimetry ◽  
Altimetry Data ◽  
Test Bed ◽  
Congo River ◽  
Satellite Altimetry Data

scholarly journals AN ORIGINAL PROCESSING METHOD OF SATELLITE ALTIMETRY FOR ESTIMATING WATER LEVELS AND VOLUME FLUCTUATIONS IN A SERIES OF SMALL LAKES OF THE PANTANAL WETLAND COMPLEX IN BRAZIL

2016 ◽  
Vol XLI-B8 ◽  
pp. 327-334 ◽  
Author(s):  
Paulo Henrique Costa ◽  
Eric Oliveira Pereira ◽  
Philippe Maillard
Keyword(s):  
Water Level ◽  
Water Surface ◽  
Satellite Altimetry ◽  
Water Levels ◽  
Small Lakes ◽  
Water Surface Area ◽  
Volume Fluctuations ◽  
Calm Water ◽  
Gauging Station

Satellite altimetry is becoming a major tool for measuring water levels in rivers and lakes offering accuracies compatible with many hydrological applications, especially in uninhabited regions of difficult access. The Pantanal is considered the largest tropical wetland in the world and the sparsity of <i>in situ</i> gauging station make remote methods of water level measurements an attractive alternative. This article describes how satellites altimetry data from Envisat and Saral was used to determine water level in two small lakes in the Pantanal. By combining the water level with the water surface area extracted from satellite imagery, water volume fluctuations were also estimated for a few periods. The available algorithms (retrackers) that compute a range solution from the raw waveforms do not always produce reliable measurements in small lakes. This is because the return signal gets often “contaminated” by the surrounding land. To try to solve this, we created a “lake” retracker that rejects waveforms that cannot be attributed to “calm water” and convert them to altitude. Elevation data are stored in a database along with the water surface area to compute the volume fluctuations. Satellite water level time series were also produced and compared with the only nearby <i>in situ</i> gauging station. Although the “lake” retracker worked well with calm water, the presence of waves and other factors was such that the standard “ice1” retracker performed better on the overall. We estimate our water level accuracy to be around 75 cm. Although the return time of both satellites is only 35 days, the next few years promise to bring new altimetry satellite missions that will significantly increase this frequency.

scholarly journals Satellite Technologies in Monitoring of Ecosystems

2015 ◽  
Vol 2 ◽  
pp. 60
Author(s):  
Nikolay Belyaev ◽  
Vasily Krupin ◽  
Evgeny Mikhalenko ◽  
Aleksandr Smirnov ◽  
Valentin Vilkevich ◽  
...  
Keyword(s):  
Water Surface ◽  
Field Data ◽  
Hydraulic Engineering ◽  
Relative Accuracy ◽  
Drainage Area ◽  
Area Measurement ◽  
Theoretical Base ◽  
Land Plot ◽  
Practical Research ◽  
Plot Area

<p class="R-AbstractKeywords"><span lang="EN-US">The article provides a description of modern geodetic devices, which are used to solve several problems connected with environmental and hydraulic engineering. In particular, a non-conventional method of area measurement for ecosystems monitoring, which involves the usage of satellite navigation devices, is considered. </span></p><p class="TTPParagraphothers"><span lang="EN-US">Nowadays electronic tachymeters, digital levelling instruments, laser scanning systems and satellite systems are widely used for implementation of geodetic engineering works. In full extent it could be also applied to different environmental and hydraulic engineering problems solution.</span></p><p class="TTPParagraphothers"><span lang="EN-US">The satellite navigators, especially with GPS+GLONASS system support, are the promising alternative to handle different planimetric tasks, particularly, water surface and drainage area measurement. </span></p><p class="TTPParagraphothers"><span lang="EN-US">The paper presents an analysis of the results of research carried out in 2012-2014 years and comparison of them with the new field data. Moreover the obtained results are compared with the theoretical values of quadrates’ areas and the dependence of the relative accuracy versus land plot area is built.</span></p><p class="TTPParagraphothers"><span lang="EN-US">Based on a practical research, the accuracy of the method is being estimated. The analysis of different measuring conditions and factors, regarding their effect on accuracy, is made. </span></p><p class="R-MainText"><span lang="EN-US">The suitable areas, where the method could be used, are mentioned. Particularly, the possibility of water surface and drainage area measuring is examined with the usage of previous theoretical base. </span></p><p class="TTPParagraphothers"><span lang="EN-US">The paper presents an analysis of the results of research carried out in 2012-2014 years and comparison of them with the new field data. Moreover the obtained results are compared with the theoretical values of quadrates’ areas and the dependence of the relative accuracy versus land plot area is built.</span></p><p class="TTPParagraphothers"><span lang="EN-US">Based on a practical research, the accuracy of the method is being estimated. The analysis of different measuring conditions and factors, regarding their effect on accuracy, is made. </span></p><p class="R-MainText"><span lang="EN-US">The suitable areas, where the method could be used, are mentioned. Particularly, the possibility of water surface and drainage area measuring is examined with the usage of previous theoretical base. </span></p>

Estimation of River Discharge using Multi-Mission Satellite Altimetry and Optical Remote Sensing Imagery

2020 ◽  
Author(s):  
Daniel Scherer ◽  
Christian Schwatke ◽  
Denise Dettmering
Keyword(s):  
Remote Sensing ◽  
Time Series ◽  
Water Level ◽  
River Discharge ◽  
Water Surface ◽  
Satellite Altimetry ◽  
Remote Sensing Data ◽  
Sensing Data

&lt;p&gt;Despite increasing interest in monitoring the global water cycle, the availability of in-situ discharge time series is decreasing. However, this lack of ground data can be compensated by using remote sensing techniques to observe river discharge.&lt;/p&gt;&lt;p&gt;In this contribution, a new approach for estimating the discharge of large rivers by combining various long-term remote sensing data with physical flow equations is presented. For this purpose, water levels derived from multi-mission satellite altimetry and water surface extents extracted from optical satellite images are used, both provided by DGFI-TUM&amp;#8217;s &amp;#8220;Database of Hydrological Time series of Inland Waters&amp;#8221; (DAHITI, https://dahiti.dgfi.tum.de). The datasets are combined by fitting a hypsometric curve in order to describe the stage-width relation, which is then used to derive the water level for each acquisition epoch of the long-term multi-spectral remote sensing missions. In this way, the chance of detecting water level extremes is increased and a bathymetry can be estimated from water surface extent observations. Below the minimum hypsometric water level, the river bed elevation is estimated using an empirical width-to-depth relationship in order to determine the final cross-sectional geometry. The required flow gradient is computed based on a linear adjustment of river surface slope using all altimetry-observed water level differences between synchronous measurements at various virtual stations along the river. The roughness coefficient is set based on geomorphological features quantified by adjustment factors. These are chosen using remote sensing data and a literature decision guide.&lt;/p&gt;&lt;p&gt;Within this study, all parameters are estimated purely based on remote sensing data, without using any ground data. In-situ data is only used for the validation of the method at the Lower Mississippi River. It shows that the presented approach yields best results for uniform and straight river sections. The resulting normalized root mean square error for those targets varies between 10% to 35% and is comparable with other studies.&lt;/p&gt;

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