scholarly journals Combining flow routing modelling and direct velocity measurement for optimal discharge estimation

2011 ◽  
Vol 8 (2) ◽  
pp. 2699-2738
Author(s):  
G. Corato ◽  
T. Moramarco ◽  
T. Tucciarelli
Keyword(s):  
Boundary Conditions ◽  
Flow Velocity ◽  
Hydraulic Model ◽  
Surface Flow ◽  
Water Levels ◽  
Surface Velocity ◽  
Rating Curve ◽  
Velocity Measurements ◽  
Flow Routing ◽  
Maximum Surface

Abstract. A new procedure is proposed for estimating river discharge hydrographs during flood events, using only water level data measured at a gauged site, as well as 1-D shallow water modelling and sporadic maximum surface flow velocity measurements. During flood, the piezometric level is surmised constant in the vertical plane of the river section, where the top of the banks is always above the river level, and is well represented by the recorded stage hydrograph. The river is modelled along the reach directly located downstream the upstream gauged section, where discharge hydrograph is sought after. For the stability with respect to the topographic error, as well as for the simplicity of the data required to satisfy the boundary conditions, a diffusive hydraulic model is adopted for flow routing. Assigned boundary conditions are: (1) the recorded stage hydrograph at the upstream river site and (2) the zero diffusion condition at the downstream end of the reach. The MAST algorithm is used for the numerical solution of the flow routing problem, which is embedded in the Brent algorithm used for the computation of the optimum Manning coefficient. Based on synthetic tests concerning a broad prismatic channel, the optimal reach length is chosen so that the approximated downstream boundary condition effects on discharge hydrograph assessment at upstream end are negligible. The roughness Manning coefficient is calibrated by using sporadic instantaneous surface velocity measurements during the rising limb of flood that are turned into instantaneous discharges through the solid of velocity estimated by a two-dimensional entropic model. Several historical events, occurring in three gauged sites along the upper Tiber River wherein a reliable rating curve is available, have been used for the validation. The analysis outcomes can be so summarized: (1) criteria adopted for selecting the optimal channel length and based on synthetic tests have been proved reliable by using field data of three gauged river sites. Indeed, for each of them a downstream reach, long not more than 500 m, is turned out fair for achieving good performances of the diffusive hydraulic model, thus allowing to drastically reducing the topographical data of river cross-sections; (2) the procedure for Manning's coefficient calibration allowed to get high performance of the hydraulic model just considering the observed water levels and sporadic measurements of maximum surface flow velocity during the rising limb of flood. Indeed, in terms of errors in magnitude on peak discharge, for the optimal calibration, they were found, in average, not exceeding 5% for all events observed in the three investigated gauged sections, while the Nash-Sutcliff efficiency was, in average, greater than 0.95. Therefore, the proposed procedure, apart from to have turned out reliable for the rating curve assessment at ungauged sites, can be applied in realtime for whatever flood conditions and this is of great interest for the practice hydrology seeing that, looking at new monitoring technologies, it will be possible to carry out velocity measurements by hand-held radar sensors in different river sites and for the same flood.

scholarly journals Discharge estimation combining flow routing and occasional measurements of velocity

2011 ◽  
Vol 15 (9) ◽  
pp. 2979-2994 ◽  
Author(s):  
G. Corato ◽  
T. Moramarco ◽  
T. Tucciarelli
Keyword(s):  
Boundary Condition ◽  
Flow Velocity ◽  
Cross Sections ◽  
Hydraulic Model ◽  
Surface Flow ◽  
Roughness Coefficient ◽  
Velocity Measurements ◽  
Maximum Surface ◽  
Manning’S Roughness Coefficient ◽  
Discharge Estimation

Abstract. A new procedure is proposed for estimating river discharge hydrographs during flood events, using only water level data at a single gauged site, as well as 1-D shallow water modelling and occasional maximum surface flow velocity measurements. One-dimensional diffusive hydraulic model is used for routing the recorded stage hydrograph in the channel reach considering zero-diffusion downstream boundary condition. Based on synthetic tests concerning a broad prismatic channel, the "suitable" reach length is chosen in order to minimize the effect of the approximated downstream boundary condition on the estimation of the upstream discharge hydrograph. The Manning's roughness coefficient is calibrated by using occasional instantaneous surface velocity measurements during the rising limb of flood that are used to estimate instantaneous discharges by adopting, in the flow area, a two-dimensional velocity distribution model. Several historical events recorded in three gauged sites along the upper Tiber River, wherein reliable rating curves are available, have been used for the validation. The outcomes of the analysis can be summarized as follows: (1) the criterion adopted for selecting the "suitable" channel length based on synthetic test studies has proved to be reliable for field applications to three gauged sites. Indeed, for each event a downstream reach length not more than 500 m is found to be sufficient, for a good performances of the hydraulic model, thereby enabling the drastic reduction of river cross-sections data; (2) the procedure for Manning's roughness coefficient calibration allowed for high performance in discharge estimation just considering the observed water levels and occasional measurements of maximum surface flow velocity during the rising limb of flood. Indeed, errors in the peak discharge magnitude, for the optimal calibration, were found not exceeding 5% for all events observed in the three investigated gauged sections, while the Nash-Sutcliffe efficiency was, on average, greater than 0.95. Therefore, the proposed procedure well lend itself to be applied for: (1) the extrapolation of rating curve over the field of velocity measurements (2) discharge estimations in different cross sections during the same flood event using occasional surface flow velocity measures carried out, for instance, by hand-held radar sensors.

scholarly journals Basal Sliding and Conditions at the Glacier Bed as Revealed by Bore-hole Photography

1978 ◽  
Vol 20 (84) ◽  
pp. 469-508 ◽  
Author(s):  
H. F. Engelhardt ◽  
W. D. Harrison ◽  
Barclay Kamb
Keyword(s):  
Flow Direction ◽  
Water Pressure ◽  
Surface Flow ◽  
Water Levels ◽  
Surface Velocity ◽  
Internal Motions ◽  
Basal Sliding ◽  
Bed Roughness ◽  
Atmospheric Factors ◽  
Basal Shear

AbstractBore-hole photography demonstrates that the glacier bed was reached by cable-tool drilling in five bore holes in Blue Glacier, Washington. Basal sliding velocities measured by bore-hole photography, and confirmed by inclinometry, range from 0.3 to 3.0 cm/d and average 1.0 cm/d, much less than half the surface velocity of 15 cm/d. Sliding directions deviate up to 30° from the surface flow direction. Marked lateral and time variations in sliding velocity occur. The glacier bed consists of bedrock overlain by a ≈ 10 cm layer ofactive subsole drift, which intervenes between bedrock and ice sole and is actively involved in the sliding process. It forms a mechanically and visibly distinct layer, partially to completely ice-free, beneath the zone of debris-laden ice at the base of the glacier. Internal motions in the subsole drift include rolling of clasts caught between bedrock and moving ice. The largest sliding velocities occur in places where a basal gap, of width up to a few centimeters, intervenes between ice sole and subsole drift. The gap may result from ice—bed separation due to pressurization of the bed by bore-hole water. Water levels in bore holes reaching the bed drop to the bottom when good hydraulic connection is established with sub-glacial conduits; the water pressure in the conduits is essentially atmospheric. Factors responsible for the generally low sliding velocities are high bed roughness due to subsole drift, partial support of basal shear stress by rock friction, and minimal basal cavitation because of low water pressure in subglacial conduits. The observed basal conditions do not closely correspond to those assumed in existing theories of sliding.

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 Application of an Entropic Method Coupled with STIV for Discharge Measurement in Actual Rivers

2021 ◽  
Vol 945 (1) ◽  
pp. 012036
Author(s):  
Yoshiro Omori ◽  
Ichiro Fujita ◽  
Ken Watanabe
Keyword(s):  
Velocity Distribution ◽  
Flow Velocity ◽  
River Flow ◽  
Measurement Techniques ◽  
Vertical Direction ◽  
Acoustic Doppler Current Profiler ◽  
Surface Flow ◽  
Surface Velocity ◽  
Cross Sectional ◽  
Current Profiler

Abstract In recent years, due to the frequent occurrence of floods that exceed the facility maintenance level due to climate change, non-contact flood flow measurement techniques have been paid attention and actually some measurements have been conducted by applying them instead of the conventional float method. The space-time image velocimetry (STIV) which can measure the surface flow velocity distribution from video images is one of such techniques. In order to calculate the river flow from the surface velocity distribution, it is necessary to determine an appropriate surface velocity coefficient, which is the ratio of the average depth velocity to the surface velocity. However, at present, empirical default value has been still used in practice. In this study, the cross-sectional velocity distribution was calculated using an entropic method by utilizing the surface velocity distribution measured by STIV and compared with Acoustic Doppler Current Profiler (ADCP) observation. It was confirmed that the introduction of the velocity dip system express the flow velocity distribution in the vertical direction, where the velocity dip occurs due to the influence of vegetation.

DOPPLER VS. SPINNER PLT SENSING FOR HYDROCARBON VELOCITY ESTIMATE BY DEEP-LEARNING APPROACH

2021 ◽  
Author(s):  
Klemens Katterbauer ◽  
◽  
Alberto Marsala ◽  
Virginie Schoepf ◽  
Linda Abbassi ◽  
...  
Keyword(s):  
Deep Learning ◽  
Flow Velocity ◽  
Oil And Gas ◽  
Surface Flow ◽  
Sound Waves ◽  
Velocity Measurements ◽  
Data Set ◽  
Flowing Fluid ◽  
Flow Meters ◽  
Doppler Flow

Logging hydrocarbon production potential of wells has been at the forefront of enhancing oil and gas exploration and maximize productivity from oil and gas reservoirs. A major challenge is accurate downhole fluid phases flow velocity measurements in production logging (PLT) due to the criticality of mechanical spinner-based sensor devices. Ultrasonic Doppler-based sensors are more robust and deployable either in wireline or logging while drilling (LWD) conditions; however, due to the different sensing physics, the measurement results may vary. Ultrasonic Doppler flow meters utilize the Doppler effect that is a change in frequency of the sound waves that are reflected on a moving target. A common example is the change in pitch when a vehicle sounding a horn approaches and recedes from an observer. The frequency shift is in direct proportion of the relative velocity of the fluid with respect to the emitter-receiver and allows to infer the speed of the flowing fluid. Doppler flow meters offer many advantages over mechanical spinners such as the ability to measure without requiring calibration passes, the absence of mechanical moving parts, the sensors robustness to shocks and hits, easy installation and minimal affection by changes in temperature, density and viscosity of the fluid thus capability to work even in highly contaminated conditions such as tar, asphaltene deposits on equipment. Despite being widely used in surface flow metering, ultrasonic Doppler sensor applications to downhole environment have been so far very limited. We present in this work an innovative deep learning framework to estimate spinner phase velocities from Doppler based sensor velocities. Tests of the framework on a benchmark data set displayed strong estimation results, in particular outlining the ability to utilize Doppler-based sensors for downhole phase velocity measurements and allows the comparison of the estimates with previously recorded spinner velocity measurements. This allows for the real-time automated interpretative framework implementation and flow velocity estimations either in conventional wireline production logging technologies and potentially also in LWD conditions, when the well is flowing in underbalanced conditions.

scholarly journals Basal Sliding and Conditions at the Glacier Bed as Revealed by Bore-hole Photography

1978 ◽  
Vol 20 (84) ◽  
pp. 469-508 ◽  
Author(s):  
H. F. Engelhardt ◽  
W. D. Harrison ◽  
Barclay Kamb
Keyword(s):  
Flow Direction ◽  
Water Pressure ◽  
Surface Flow ◽  
Water Levels ◽  
Surface Velocity ◽  
Internal Motions ◽  
Basal Sliding ◽  
Bed Roughness ◽  
Atmospheric Factors ◽  
Basal Shear

AbstractBore-hole photography demonstrates that the glacier bed was reached by cable-tool drilling in five bore holes in Blue Glacier, Washington. Basal sliding velocities measured by bore-hole photography, and confirmed by inclinometry, range from 0.3 to 3.0 cm/d and average 1.0 cm/d, much less than half the surface velocity of 15 cm/d. Sliding directions deviate up to 30° from the surface flow direction. Marked lateral and time variations in sliding velocity occur. The glacier bed consists of bedrock overlain by a ≈ 10 cm layer of active subsole drift, which intervenes between bedrock and ice sole and is actively involved in the sliding process. It forms a mechanically and visibly distinct layer, partially to completely ice-free, beneath the zone of debris-laden ice at the base of the glacier. Internal motions in the subsole drift include rolling of clasts caught between bedrock and moving ice. The largest sliding velocities occur in places where a basal gap, of width up to a few centimeters, intervenes between ice sole and subsole drift. The gap may result from ice—bed separation due to pressurization of the bed by bore-hole water. Water levels in bore holes reaching the bed drop to the bottom when good hydraulic connection is established with sub-glacial conduits; the water pressure in the conduits is essentially atmospheric. Factors responsible for the generally low sliding velocities are high bed roughness due to subsole drift, partial support of basal shear stress by rock friction, and minimal basal cavitation because of low water pressure in subglacial conduits. The observed basal conditions do not closely correspond to those assumed in existing theories of sliding.

Exploring the optimal experimental setup for surface flow velocity measurements using PTV

2018 ◽  
Vol 190 (8) ◽  
Author(s):  
S. F. Dal Sasso ◽  
A. Pizarro ◽  
C. Samela ◽  
L. Mita ◽  
S. Manfreda
Keyword(s):  
Flow Velocity ◽  
Surface Flow ◽  
Experimental Setup ◽  
Velocity Measurements

Unsteady and porous media flow of reactive non-Newtonian fluids subjected to buoyancy and suction/injection

2015 ◽  
Vol 25 (7) ◽  
pp. 1682-1704 ◽  
Author(s):  
Tirivanhu Chinyoka ◽  
Daniel Oluwole Makinde
Keyword(s):  
Heat Transfer ◽  
Porous Media ◽  
Boundary Conditions ◽  
Flow Velocity ◽  
Flow System ◽  
Finite Difference Methods ◽  
Porous Media Flow ◽  
Convective Boundary Conditions ◽  
Convective Boundary ◽  
Content Type

Purpose – The purpose of this paper is to examine the unsteady pressure-driven flow of a reactive third-grade non-Newtonian fluid in a channel filled with a porous medium. The flow is subjected to buoyancy, suction/injection asymmetrical and convective boundary conditions. Design/methodology/approach – The authors assume that exothermic chemical reactions take place within the flow system and that the asymmetric convective heat exchange with the ambient at the surfaces follow Newton’s law of cooling. The authors also assume unidirectional suction injection flow of uniform strength across the channel. The flow system is modeled via coupled non-linear partial differential equations derived from conservation laws of physics. The flow velocity and temperature are obtained by solving the governing equations numerically using semi-implicit finite difference methods. Findings – The authors present the results graphically and draw qualitative and quantitative observations and conclusions with respect to various parameters embedded in the problem. In particular the authors make observations regarding the effects of bouyancy, convective boundary conditions, suction/injection, non-Newtonian character and reaction strength on the flow velocity, temperature, wall shear stress and wall heat transfer. Originality/value – The combined fluid dynamical, porous media and heat transfer effects investigated in this paper have to the authors’ knowledge not been studied. Such fluid dynamical problems find important application in petroleum recovery.

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