Correction to “Role of turbulence fluctuations on uncertainties of acoustic Doppler current profiler discharge measurements”

2012 ◽  
Vol 48 (8) ◽  
Author(s):  
Leticia Tarrab ◽  
Carlos M. García ◽  
Mariano I. Cantero ◽  
Kevin Oberg
2021 ◽  
Vol 9 ◽  
Author(s):  
William P. Meurer ◽  
John Blum ◽  
Greg Shipman

The role of methane as a green-house gas is widely recognized and has sparked considerable efforts to quantify the contribution from natural methane sources including submarine seeps. A variety of techniques and approaches have been directed at quantifying methane fluxes from seeps from just below the sediment water interface all the way to the ocean atmosphere interface. However, there have been no systematic efforts to characterize the amount and distribution of dissolved methane around seeps. This is critical to understanding the fate of methane released from seeps and its role in the submarine environment. Here we summarize the findings of two field studies of the Bush Hill mud volcano (540 m water depth) located in the Gulf of Mexico. The studies were carried out using buoyancy driven gliders equipped with methane sensors for near real time in situ detection. One glider was equipped with an Acoustic Doppler Current Profiler (ADCP) for simultaneous measurement of currents and methane concentrations. Elevated methane concentrations in the water column were measured as far away as 2 km from the seep source and to a height of about 100 m above the seep. Maximum observed concentrations were ∼400 nM near the seep source and decreased away steadily in all directions from the source. Weak and variable currents result in nearly radially symmetric dispersal of methane from the source. The persistent presence of significant methane concentrations in the water column points to a persistent methane seepage at the seafloor, that has implications for helping stabilize exposed methane hydrates. Elevated methane concentrations in the water column, at considerable distances away from seeps potentially support a much larger methane-promoted biological system than is widely appreciated.


2019 ◽  
Vol 27 (1) ◽  
pp. 7-13
Author(s):  
Roman Výleta ◽  
Peter Valent

Abstract Accurate measurements and analyses of river discharges are one of the key tasks of hydrology. Nowadays, the traditional methods of discharge measurements are being supplemented or even replaced by novel approaches that utilize state-of-the-art technologies. One approach, which has recently become very popular in the hydrological practice both in Slovakia and abroad, is a method utilizing the Doppler effect of sound waves. In this study, a dataset of 185 discharge measurements on the River Danube was created using a RiverRay portable Acoustic Doppler Current Profiler (ADCP). All the measurements were taken on the River Danube at four different cross-sections in Slovakia. The measurements were processed using the manufacturer’s WinRiver II software and further adjusted in Agila, which is a specialised third-party post-processing software aimed at correcting measurement errors from ADCP discharge measurements. Currently, some but not all countries lying in the Danube basin have included Agila post-processing in their methodologies. This causes problems and disputes between national water authorities when exchanging information about discharge measurements in the border regions. In order to respond to this problem, the main objective of this study was to compare the results of both original and corrected discharges, which were measured under a number of different circumstances, and to propose recommendations about the suitability of using Agila post-processing for discharge measurements of the River Danube.


1970 ◽  
Vol 7 (1) ◽  
pp. 40-48 ◽  
Author(s):  
J Merz

Low flows prevail during about nine months of the year in Himalayan rivers as a result of the influence of the monsoon climate. They account for a large portion of the annual water balance and accurate information about these flows is therefore critical for water resources planning, development, management and hydropower design. Issues that occur with the neighbouring country India are often related to low flows and make exact information on low flows a prerequisite for successful transboundary water management. However, reliable and long-term information on low flows are generally not available as most basins are ungauged. In addition low flow measurements are often associated with measurement errors as measurement cross-sections change during the flood season. Changes in measurement cross-sections are natural, but need frequent re-surveying of the sections in order to obtain good quality discharge measurements. This is often done on in-frequent basis and changes between big flood events are not recorded. The equipment used for discharge measurements is rarely recalibrated leading to additional errors. Internationally, in the last two decades river and stream discharge measurements have been improved with the introduction of Acoustic Doppler Current Profiler (ADCP) technology. This new technology for hydrologic data acquirement has so far not been used extensively in the Himalayan region. First experiences with a StreamPro ADCP in Nepal as a part of a technology evaluation confirmed the commonly stated advantages of this technology compared to current-meter measurements, and showed its promising potential for various future applications including the application for accurate low flow measurements. Keywords: Discharge measurement; ADCP; low flowDOI: http://dx.doi.org/10.3126/jhm.v7i1.5615 JHM 2010; 7(1): 40-48


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