DYNAMIC MEASUREMENT OF UNDULATING WATER SURFACES IN A LOCK FILL

One of the principal concerns in lock operation is the question of how the dynamics of the wafer surface during the fill (or emptying) cycle translate to forces on vessels in the lock. Drift forces are greatly influenced by water surface oscillations, and, thus, their modeling is considerably enhanced by the mapping of the undulating water surface at frequent intervals during the fill cycle. Close-range photogrammetry offers a practical and accurate means for water surface mapping. This paper reports on a project in which an array of 71 floating targets, distributed throughout the 160- by 33-m surface area of the Bay Springs Lock in Mississippi, were monitored photogrammetrically. Two synchronized large-format CRC-1 cameras were employed in a convergent imaging configuration to record XYZ coordinate data to better than 2-cm accuracy, at and second intervals over several 8-minute, 26-metre lift cycles. Automatic image coordinate mensuration was then used for the 100 or so photographs taken at each fill/empty cycle. From the resulting time-tagged digital elevation model, data-pertinent hydraulic parameters were computed and graphics visualization sequences were generated to illustrate water surface oscillation harmonics.