scholarly journals Bedform Morphology in the Area of the Confluence of the Negro and Solimões-Amazon Rivers, Brazil

Water ◽  
2020 ◽  
Vol 12 (6) ◽  
pp. 1630 ◽  
Author(s):  
Carlo Gualtieri ◽  
Ivo Martone ◽  
Naziano Pantoja Filizola Junior ◽  
Marco Ianniruberto
Keyword(s):  
Wave Height ◽  
Complex Structure ◽  
Acoustic Doppler Current Profiler ◽  
Low Flow ◽  
Flow Conditions ◽  
Average Value ◽  
Flow Features ◽  
Current Profiler ◽  
Converging Flow ◽  
Riverine Systems

Confluences are common components of all riverine systems, characterized by converging flow streamlines and the mixing of separate flows. The fluid dynamics of confluences possesses a highly complex structure with several common types of flow features observed. A field study was recently conducted in the area of the confluence of the Negro and Solimões/Amazon Rivers, Brazil, collecting a series of Acoustic Doppler Current Profiler (ADCP) transects in different flow conditions. These data were used to investigate the morphology of the bedforms observed in that area. First, the bedforms were mostly classified as large and very large dunes according to Ashley et al. (1990), with an observed maximum wavelength and wave height of 350 and 12 m, respectively. Second, a comparison between low flow and relatively high flow conditions showed that wavelength and wave height increased as the river discharge increased in agreement with previous literature studies. Third, the lee side angle was consistently below 10°, with an average value of about 3.0°, without flow separation confirming past findings on low-angle dunes. Finally, a comparison between the bedform sizes and past literature studies on large rivers suggested that while several dunes were in equilibrium with the flow, several largest bedforms were found to be probably adapting to discharge changes in the river.

scholarly journals A Robust Estimation Method for Correcting Dynamic Draft Error in PPK GPS Elevation Using ADCP Tilt Data

2014 ◽  
Vol 31 (3) ◽  
pp. 729-738 ◽  
Author(s):  
Pascal Matte ◽  
Yves Secretan ◽  
Jean Morin
Keyword(s):  
Estimation Method ◽  
Acoustic Doppler Current Profiler ◽  
Water Levels ◽  
Positioning Systems ◽  
Global Positioning ◽  
Elevation Data ◽  
Current Profiler ◽  
Rtk Gps ◽  
Using Data ◽  
Riverine Systems

Abstract Measuring temporal and spatial variations in water level with high resolution and accuracy can provide fundamental insights into the hydrodynamics of marine and riverine systems. Real-time kinematic global positioning systems (RTK GPS), and by extension postprocessed kinematic (PPK) positioning, have provided the opportunity to achieve this goal, by allowing fast and straightforward measurements with subdecimeter accuracy. However, boat-mounted GPS are subject to movements of the water surface (e.g., waves, long-period heaves) as well as to the effects of dynamic draft. The latter contaminate the records and need to be separated and removed from the data. A method is proposed to postcorrect the elevation data using tilt information measured by an attitude sensor—in this case, an acoustic Doppler current profiler (ADCP) equipped with internal pitch and roll sensors. The technique uses iteratively reweighted least squares (IRLS) regressions to determine the position of the center of rotation (COR) of the boat that leads to optimal corrections. The COR is also allowed to change in time by performing the IRLS analyses on data subsamples, thus accounting for changes in weight distribution, for example, due to personnel movements. An example of application is presented using data collected in the Saint Lawrence fluvial estuary. The corrections exhibit significant reductions associated with the boat motion while keeping subtle variations in water levels likely related to local hydrodynamics.

scholarly journals Numerical investigation on the impact of wind-induced hydraulics on dissolved oxygen characteristics in a shallow stormwater pond

2019 ◽  
Vol 54 (4) ◽  
pp. 309-325 ◽  
Author(s):  
Liyu Chen ◽  
Patrick M. D'Aoust ◽  
Colin D. Rennie ◽  
Alexandre Poulain ◽  
Frances Pick ◽  
...  
Keyword(s):  
Water Quality ◽  
Wind Speed ◽  
Dissolved Oxygen ◽  
Surface Wind ◽  
Acoustic Doppler Current Profiler ◽  
Low Flow ◽  
Water Quality Control ◽  
Current Profiler ◽  
Wind Driven Currents ◽  
The Impact

Abstract Stormwater ponds (SWPs) are widely utilized for flood and water quality control. Low-flow rates are common in SWPs, sometimes causing wind-driven currents to become the dominant hydrodynamic force during ice-free periods. Hence, it is essential to understand the influence of the wind-induced flow on stratification and dissolved oxygen (DO) concentrations in shallow SWPs to predict the performance and water quality of these systems. The objective of this study is to evaluate the influence of wind-driven circulation on the spatial distribution of DO in an SWP using a numerical model. A bottom-mounted acoustic Doppler current profiler (ADCP) was utilized to measure small wind-induced currents and to validate a hydrodynamic model, which suggested that a wind-dominated circulation was generated even with the moderate wind speed. Countercurrents opposite in the direction to surface wind-generated flow were also present. The DO model demonstrated that complete mixing can be produced by higher wind speed, leading to fully oxic conditions throughout the water column (7.00 mg/L DO or higher), wherein low DO water at depth was carried to the surface by upwelling circulation and was possibly replenished during the surface transportation. This sheds some light on the impact of wind-induced mixing on the water quality in shallow SWPs.

scholarly journals Discharge Measurements In Low Flow Conditions With ADCP Technology – First Experiences In Nepal

1970 ◽  
Vol 7 (1) ◽  
pp. 40-48 ◽  
Author(s):  
J Merz
Keyword(s):  
Cross Sections ◽  
Measurement Errors ◽  
New Technology ◽  
Acoustic Doppler Current Profiler ◽  
Low Flow ◽  
Accurate Information ◽  
Flow Measurements ◽  
Low Flows ◽  
Current Profiler ◽  
Discharge Measurements

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

scholarly journals Jokiuoman kartoitus ja virtausolosuhteiden mallinnus tukena perkauksen suunnittelussa: esimerkkinä Eurajoki

Terra ◽  
2021 ◽  
Vol 133 (2) ◽  
Author(s):  
Linnea Blåfield ◽  
Teija Kirkkala ◽  
Petteri Alho
Keyword(s):  
Laser Scanning ◽  
Geometric Model ◽  
Acoustic Doppler Current Profiler ◽  
Flow Conditions ◽  
Current Form ◽  
Study Approach ◽  
Current Profiler ◽  
Riverine Environment ◽  
Land Survey ◽  
Gis Software

Dredging has a significant effect on sediment transportation, water quality and flow conditions in a river channel. However, often the effects of dredging are not studied carefully in advance. One reason for this is the lack of suitable study approach. Studies on river dynamics require high quality geometric models of riverbed, banks and floodplain. Accurate terrain and bathymetric data are also crucial components of reliable hydraulic modelling. In this study, we created an approach to model the presumable impacts of dredging. We modelled high discharges and annual flooding magnitudes in Eurajoki River, SW Finland in its current form and after dredging. As the low-sloped channel is heavily vegetated, the aim of the dredging is to improve flow conditions by removing sediment and vegetation within a reach of 8 km. First, we created a geometric model of the riverine environment by combining riverbank topography from national Airborne Laser Scanning (ALS) data by the Finnish National Land Survey and bathymetry, gathered with an Acoustic Doppler Current Profiler (ADCP). The ADCP was attached to a kayak to enable access to shallow areas as well. This way, we were able to model the geometry of the fluvial forms within a few centimetres’ accuracy. Next, we modified the model of the river geometry using GIS software according to the dredging plan. Finally, we used a 2D Computational Fluid Dynamics to model the current and after dredging flow conditions during various flow events. We analysed the effects on dredging on the flood magnitudes and flow conditions based on the models and compared these to the present situation. These models offer improvements on river management and observing the effects on dredging.

scholarly journals Flow patterns over vegetation patches in the natural channel

2018 ◽  
Vol 40 ◽  
pp. 02059
Author(s):  
Yonguk Ryu ◽  
Joongu Kang ◽  
Un Ji ◽  
Sanghwa Jung ◽  
Changlae Jang ◽  
...  
Keyword(s):  
Cross Sections ◽  
Longitudinal Velocity ◽  
Three Dimensional ◽  
Acoustic Doppler Current Profiler ◽  
Low Flow ◽  
Cross Sectional ◽  
Hydraulic Conditions ◽  
Current Profiler ◽  
Vegetation Patches ◽  
Submerged Conditions

This study carried out experiments to investigate the effects of vegetation patches of rooted willows on the flow pattern. Stream-scale experiments on vegetated flows were performed for various hydraulic conditions: emergent and submerged conditions of vegetation. Vegetation patches were arranged by alternative bar formation and the flows in vegetated and non-vegetated sections were compared. Three-dimensional flow velocity was measured by ADV (Acoustic Doppler Velocimeter) and ADCP (Acoustic Doppler Current Profiler). Vertical, cross-sectional, and longitudinal velocity distributions were provided for different hydraulic conditions at various points. Flow velocities through the sparse patch were similar to those of non-vegetation area for low flow condition of emergent vegetation. Dense and submerged vegetation produced more complicated and non-uniform flows over the cross-sections of vegetation patches.

Klamath River Water Quality and Acoustic Doppler Current Profiler Data from Link River Dam to Keno Dam, 2007

2008 ◽  
Author(s):  
Annett B. Sullivan ◽  
Michael L. Deas ◽  
Jessica Asbill ◽  
Julie D. Kirshtein ◽  
Kenna D. Butler ◽  
...  
Keyword(s):  
Water Quality ◽  
River Water ◽  
Acoustic Doppler Current Profiler ◽  
River Water Quality ◽  
Klamath River ◽  
Current Profiler ◽  
Profiler Data
Sign in / Sign up

Export Citation Format

Share Document