TY - GEN
T1 - Noncontact methods for measuring water-surface elevations and velocities in rivers
T2 - International Conference on Fluvial Hydraulics, RIVER FLOW 2016
AU - Nelson, J. M.
AU - Kinzel, P. J.
AU - McDonald, R. R.
AU - Schmeeckle, M. W.
PY - 2016/1/1
Y1 - 2016/1/1
N2 - Recently developed optical and videographic methods for measuring water-surface properties in a noninvasive manner hold great promise for extracting river hydraulic and bathymetric information. This paper describes such a technique, concentrating on the method of infrared videography for measuring surface velocities and both acoustic (laboratory-based) and laser-scanning (fieldbased) techniques for measuring water-surface elevations. In ideal laboratory situations with simple flows, appropriate spatial and temporal averaging results in accurate water-surface elevations and water-surface velocities. In test cases, this accuracy is sufficient to allow direct inversion of the governing equations of motion to produce estimates of depth and discharge. Unlike other optical techniques for determining local depth that rely on transmissivity of the water column (bathymetric lidar, multi/hyperspectral correlation), this method uses only water-surface information, so even deep and/or turbid flows can be investigated. However, significant errors arise in areas of nonhydrostatic spatial accelerations, such as those associated with flow over bedforms or other relatively steep obstacles. Using laboratory measurements for test cases, the cause of these errors is examined and both a simple semi-empirical method and computational results are presented that can potentially reduce bathymetric inversion errors.
AB - Recently developed optical and videographic methods for measuring water-surface properties in a noninvasive manner hold great promise for extracting river hydraulic and bathymetric information. This paper describes such a technique, concentrating on the method of infrared videography for measuring surface velocities and both acoustic (laboratory-based) and laser-scanning (fieldbased) techniques for measuring water-surface elevations. In ideal laboratory situations with simple flows, appropriate spatial and temporal averaging results in accurate water-surface elevations and water-surface velocities. In test cases, this accuracy is sufficient to allow direct inversion of the governing equations of motion to produce estimates of depth and discharge. Unlike other optical techniques for determining local depth that rely on transmissivity of the water column (bathymetric lidar, multi/hyperspectral correlation), this method uses only water-surface information, so even deep and/or turbid flows can be investigated. However, significant errors arise in areas of nonhydrostatic spatial accelerations, such as those associated with flow over bedforms or other relatively steep obstacles. Using laboratory measurements for test cases, the cause of these errors is examined and both a simple semi-empirical method and computational results are presented that can potentially reduce bathymetric inversion errors.
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U2 - 10.1201/9781315644479-101
DO - 10.1201/9781315644479-101
M3 - Conference contribution
AN - SCOPUS:85015303955
SN - 9781138029132
T3 - River Flow - Proceedings of the International Conference on Fluvial Hydraulics, RIVER FLOW 2016
SP - 637
EP - 645
BT - River Flow - Proceedings of the International Conference on Fluvial Hydraulics, RIVER FLOW 2016
A2 - Constantinescu, George
A2 - Garcia, Marcelo
A2 - Hanes, Dan
PB - CRC Press/Balkema
Y2 - 11 July 2016 through 14 July 2016
ER -