Tidal predictions in ungauged estuaries for boat-ramp access windows

McFadden, Patrick (2016) Tidal predictions in ungauged estuaries for boat-ramp access windows. [USQ Project]

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Abstract

Many boat ramps in Central Queensland are only accessible in the upper half of the tidal cycle. Currently predicting when the ramp is accessible is a mixture of local knowledge and some educated guesses. Central Queensland, like most areas in Queensland has experienced a huge growth in recreational boating. This has increased pressure on the boat ramp access and created demand for greater use of marginal ramps. The ability to optimize the use of availability time at these ramps may reduce the pressure on more established ramps.

The aim of this study is to predict access times at tide dependent boat-ramps using a novel and innovative method at three locations in central Queensland. Two models were tested.

At each site sea level was recorded at regular time intervals. This was done once during one of the larger tides of the month, and again during one of the smaller tides. From each set of data, the time that the boat-ramp was accessible (access window) and the actual time of the high tide was derived. A comparison was made between the observed windows and the simultaneously obtained times and amplitudes of the same tide at a nearby standard port, Mackay Outer Harbour (MoH). Model 1 used the relationship between the measured access windows at each site, and the predicted amplitudes at MoH. Model 2, in an attempt to negate some of the meteorological impacts, used the actual recorded amplitudes at MoH rather than the predicted as in Model 1. Each model than used the MoH predicted time and amplitude of a tide to predict access times at each site for that same tide.

This study showed that from a two tide observation at each location and using nearby standard port tide table, the access times was predicted at two of the three test sites. Model 1 and 2 produced similar predictions. It also showed that access times and lag vary accordingly to the amplitude of the tide. It also suggests that atmospheric factors can influence the arrival and departure times of tides.

Currently, to do an accurate prediction of tide levels, a full harmonic analysis of a particular location is required. This is usually a continuous observation of the tidal cycle for 29 days. Trends of diminishing Government resources means the communities can’t rely on government agencies to provide this information for all sites. Using this method many more tide restricted boat ramps can have an adequate predictor of access times for a fraction of the cost of a full harmonic analysis.


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Item Type: USQ Project
Item Status: Live Archive
Additional Information: Bachelor of Spatial Science (Honours) Major Surveying project
Faculty / Department / School: Current - Faculty of Health, Engineering and Sciences - School of Civil Engineering and Surveying
Supervisors: Zhang, Zhenyu
Date Deposited: 21 Jul 2017 01:11
Last Modified: 21 Jul 2017 01:11
Uncontrolled Keywords: tides; tidal prediction; access windows; boat-ramps
Fields of Research : 09 Engineering > 0909 Geomatic Engineering > 090906 Surveying (incl. Hydrographic Surveying)
URI: http://eprints.usq.edu.au/id/eprint/31442

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