The estimation of surface flow velocity for Indonesian flow (ITF) using Himawari-8 SST data

2018 ◽  
Author(s):  
Yuji Sakuno ◽  
Norimitsu Kurokawa ◽  
Naokazu Taniguchi
Keyword(s):  
Flow Velocity ◽  
Surface Flow

scholarly journals Discharge Estimation Using Tsallis and Shannon Entropy Theory in Natural Channels

Water ◽  
2020 ◽  
Vol 12 (6) ◽  
pp. 1786
Author(s):  
Jitendra Kumar Vyas ◽  
Muthiah Perumal ◽  
Tommaso Moramarco
Keyword(s):  
Flow Velocity ◽  
Surface Flow ◽  
Tsallis Entropy ◽  
Accurate Estimation ◽  
Mean Flow ◽  
Flow Area ◽  
Cross Sectional ◽  
The Cross ◽  
Discharge Estimation ◽  
Mean Flow Velocity

Streamflow measurements during high floods is a challenge for which the World Meteorological Organization fosters the development of innovative technologies for achieving an accurate estimation of the discharge. The use of non-contact sensors for monitoring surface flow velocities is of interest to turn these observed values into a cross-sectional mean flow velocity, and subsequently, into discharge if bathymetry is given. In this context, several techniques are available for the estimation of mean flow velocity, starting from observed surface velocities. Among them, the entropy-based methodology for river discharge assessment is often applied by leveraging the theoretical entropic principles of Shannon and Tsallis, both of which link the maximum flow velocity measured at a vertical of the flow area, named the y-axis, and the cross-sectional mean flow velocity at a river site. This study investigates the performance of the two different entropic approaches in estimating the mean flow velocity, starting from the maximum surface flow velocity sampled at the y-axis. A velocity dataset consisting of 70 events of measurements collected at two gauged stations with different geometric and hydraulic characteristics on the Po and Tiber Rivers in Italy was used for the analysis. The comparative evaluation of the velocity distribution observed at the y-axis of all 70 events of measurement was closely reproduced using both the Shannon and Tsallis entropy approaches. Accurate values in terms of the cross-sectional mean flow velocity and discharge were obtained with average errors not exceeding 10%, demonstrating that the Shannon and Tsallis entropy concepts were equally efficient for discharge estimation in any flow conditions.

Development of a Surface Flow Sensor for Measuring Turbulent Drag Force

2019 ◽  
Author(s):  
Il Doh ◽  
Il-Bum Kwon ◽  
Jiho Chang ◽  
Sejong Chun
Keyword(s):  
Wind Tunnel ◽  
Flow Velocity ◽  
Drag Force ◽  
Mass Flow ◽  
Surface Flow ◽  
Flow Sensor ◽  
Constant Current ◽  
Thermal Mass ◽  
Turbulent Drag ◽  
Mass Flow Sensor

Abstract A surface flow sensor is needed if turbulent drag force is to be measured over a vehicle, such as a car, a ship, and an airplane. In case of automobile industry, there are no automobile manufacturers which measure surface flow velocity over a car for wind tunnel testing. Instead, they rely on particle image velocimetry (PIV), pressure sensitive paint (PSP), laser Doppler anemometry (LDA), pitot tubes, and tufts to get information regarding the turbulent drag force. Surface flow sensors have not devised yet. This study aims at developing a surface flow sensor for measuring turbulent drag force over a rigid body in a wind tunnel. Two sensing schemes were designed for the fiber-optic distributed sensor and the thermal mass flow sensor. These concepts are introduced in this paper. As the first attempt, a thermal mass flow sensor has been fabricated. It was flush-mounted on the surface of a test section in the wind tunnel to measure the surface flow velocity. The thermal mass flow sensor was operated by either constant current or constant resistance modes. Resistance ratio was changed as the electric current was increased by the constant current mode, while power ratio was saturated as the resistance was increased by the constant resistance mode. Either the resistance ratio or the power ratio was changed with the flow velocity measured by a Pitot tube, located at the center of test section.

scholarly journals Basal roughness of the East Antarctic Ice Sheet in relation to flow speed and basal thermal state

2020 ◽  
Vol 61 (81) ◽  
pp. 162-175
Author(s):  
Olaf Eisen ◽  
Anna Winter ◽  
Daniel Steinhage ◽  
Thomas Kleiner ◽  
Angelika Humbert
Keyword(s):  
Flow Velocity ◽  
Thermal State ◽  
Ice Sheet ◽  
Flow Speed ◽  
Surface Flow ◽  
Roughness Parameters ◽  
Antarctic Ice Sheet ◽  
Flow Models ◽  
Radio Echo Sounding ◽  
East Antarctic Ice Sheet

AbstractBasal motion of ice sheets depends in part on the roughness and material properties of the subglacial bed and the occurrence of water. To date, basal motion represents one of the largest uncertainties in ice-flow models. It is that component of the total flow velocity that can change most rapidly and can, therefore, facilitate rapid variations in dynamic behaviour. In this study, we investigate the subglacial properties of the East Antarctic Ice Sheet by statistically analysing the roughness of the bed topography, inferred from radio-echo sounding measurements. We analyse two sets of roughness parameters, one derived in the spatial and the other in the spectral domain, with two roughness parameters each. This enables us to compare the suitability of the four roughness parameters to classify the subglacial landscapes below the ice sheet. We further investigate the relationship of the roughness parameters with observed surface flow velocity and modelled basal temperatures of the ice sheet. We find that one of the roughness parameters, the Hurst exponent derived in the spatial domain, coincides with the thermal condition at the base of the ice sheet for slow flow velocities and varies with flow velocity.

Measurement of free-surface flow velocity using controlled surface waves

2005 ◽  
Vol 16 (1) ◽  
pp. 47-55 ◽  
Author(s):  
Marian Muste ◽  
Jörg Schöne ◽  
Jean-Dominique Creutin
Keyword(s):  
Free Surface ◽  
Surface Waves ◽  
Flow Velocity ◽  
Free Surface Flow ◽  
Surface Flow

scholarly journals Outlet Flow Velocity in Circular Culvert

2014 ◽  
Vol 61 (3-4) ◽  
pp. 193-203
Author(s):  
Wojciech Szpakowski
Keyword(s):  
Free Surface ◽  
Flow Velocity ◽  
Flow Regime ◽  
Free Surface Flow ◽  
Bank Erosion ◽  
Surface Flow ◽  
Flowing Water ◽  
Channel Parameters ◽  
Outlet Flow ◽  
Bed Scour

AbstractThe outlet flow velocity in the end section of the culvert barrel depends in most cases on the culvert geometry, including the barrel slope, as well as on upstream and downstream channel parameters. Flowing water can create pressure flow or free surface flow in the culvert barrel. In the case of an unsubmerged barrel outlet, the free-surface flow is more frequent than the full flow. Increased velocities can cause channel bed scour and bank erosion downstream of the culvert outlet. Different culvert flow cases in which the barrel outlet is unsubmerged are presented in this paper. The influence of the flow regime on the outlet velocity is also discussed.

Remote sensing flow velocity of debris-covered glaciers using Landsat 8 data

2015 ◽  
Vol 40 (2) ◽  
pp. 305-321 ◽  
Author(s):  
Lydia Sam ◽  
Anshuman Bhardwaj ◽  
Shaktiman Singh ◽  
Rajesh Kumar
Keyword(s):  
Remote Sensing ◽  
Flow Velocity ◽  
Accuracy Assessment ◽  
Geographical Area ◽  
Surface Flow ◽  
Velocity Estimation ◽  
Surface Velocity ◽  
Landsat 8 ◽  
Glacier Surface ◽  
Glacier Velocity

Changes in ice velocity of a glacier regulate its mass balance and dynamics. The estimation of glacier flow velocity is therefore an important aspect of temporal glacier monitoring. The utilisation of conventional ground-based techniques for detecting glacier surface flow velocity in the rugged and alpine Himalayan terrain is extremely difficult. Remote sensing-based techniques can provide such observations on a regular basis for a large geographical area. Obtaining freely available high quality remote sensing data for the Himalayan regions is challenging. In the present work, we adopted a differential band composite approach, for the first time, in order to estimate glacier surface velocity for non-debris and supraglacial debris covered areas of a glacier, separately. We employed various bandwidths of the Landsat 8 data for velocity estimation using the COSI-Corr (co-registration of optically sensed images and correlation) tool. We performed the accuracy assessment with respect to field measurements for two glaciers in the Indian Himalaya. The panchromatic band worked best for non-debris parts of the glaciers while band 6 (SWIR – short wave infrared) performed best in case of debris cover. We correlated six temporal Landsat 8 scenes in order to ensure the performance of the proposed algorithm on monthly as well as yearly timescales. We identified sources of error and generated a final velocity map along with the flow lines. Over- and underestimates of the yearly glacier velocity were found to be more in the case of slow moving areas with annual displacements less than 5 m. Landsat 8 has great capabilities for such velocity estimation work for a large geographic extent because of its global coverage, improved spectral and radiometric resolutions, free availability and considerable revisit time.

scholarly journals From Surface Flow Velocity Measurements to Discharge Assessment by the Entropy Theory

Water ◽  
2017 ◽  
Vol 9 (2) ◽  
pp. 120 ◽  
Author(s):  
Tommaso Moramarco ◽  
Silvia Barbetta ◽  
Angelica Tarpanelli
Keyword(s):  
Flow Velocity ◽  
Surface Flow ◽  
Entropy Theory ◽  
Velocity Measurements

scholarly journals A novel permanent gauge-cam station for surface flow observations on the Tiber river

2016 ◽  
Author(s):  
Flavia Tauro ◽  
Andrea Petroselli ◽  
Maurizio Porfiri ◽  
Lorenzo Giandomenico ◽  
Guido Bernardi ◽  
...  
Keyword(s):  
Flow Velocity ◽  
Large Scale ◽  
Surface Flow ◽  
Video Data ◽  
Engineering Practice ◽  
Surface Hydrology ◽  
Flow Monitoring ◽  
Tiber River ◽  
Scale Particle ◽  
Local Water

Abstract. Flow monitoring of riverine environments is crucial for hydrology and hydraulic engineering practice. Besides few experimental implementations, flow gauging relies on local water level and surface flow velocity measurements through ultrasonic meters and radars. In this paper, we describe a novel permanent gauge-cam station for large scale and continuous observation of surface flows, based on remote acquisition and calibration of video data. Located on the Tiber river, in the center of Rome, Italy, the station captures one-minute videos every 10 min over an area oriented along the river cross-section of up to 20.6 × 15.5 m2. In a feasibility study, we demonstrate that accurate surface flow velocity estimations can be obtained by analyzing experimental images via particle tracking velocimetry (PTV). In medium illumination conditions (70–75 lux), PTV leads to velocity estimations in close agreement with radar records and is less affected by uneven lighting than large scale particle image velocimetry. Future efforts will be devoted to the development of a comprehensive testbed infrastructure for investigating the potential of multiple optics-based approaches for surface hydrology.

Hydromorphological monitoring of individual river reaches with UAV-data – image-based measurement of bathymetry and flow velocity

2021 ◽  
Author(s):  
Anette Eltner ◽  
László Bertalan ◽  
Eliisa Lotsari
Keyword(s):  
Flow Velocity ◽  
Acoustic Doppler Current Profiler ◽  
Surface Flow ◽  
Ease Of Use ◽  
Morphological Data ◽  
Measurement Tool ◽  
River Channels ◽  
Spatiotemporal Resolution ◽  
Morphodynamic Modelling ◽  
Flow Velocities

<p>Unmanned Aerial Vehicles (UAV) have become a commonly used measurement tool in geomorphology due to their affordable cost, flexibility, and ease of use. They are regularly used in fluvial geomorphology, among other fields, because the high spatiotemporal resolution of UAV data makes it possible to assess the continuum rather than relying on single samples.</p><p>In this study, UAV data are used to hydro-morphologically describe three different river reaches of lengths between 150 and 1000 m. Specifically, the surface flow velocity and bathymetry of the rivers were reconstructed. The flow velocities were calculated using the Particle Tracking Velocimetry (PTV) method applied to UAV video sequences. In addition, UAV-based imagery was acquired to perform 3D reconstruction above and below the water surface using SfM (Structure from Motion) photogrammetry, taking into account refraction effects as well as frame processing to increase the visibility of underwater features. Reference data for flow velocities were generated at selected positions using current meters as well as ADCP (Acoustic Doppler Current Profiler) readings. The image-based calculated bathymetry was compared with RTK-GNSS sampling depth measurements and also ADCP data.</p><p>The developed workflow enables rapid and regular measurement of hydrological and morphological data of river channels. This ultimately enables multi-temporal assessment and significantly improves hydro-morphodynamic modelling, in particular their calibration.</p>

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