Monday 14/07/08
JW asked us to delay deployment of rig – SRP settings need to be changed in order to minimise echo problems.
Levels brought back down in lagoon to 2.5m. Sea level brought down to 1.75m. No problems in the front of the barrier with seepage.
Series A3 started approx 10.30am. It was calculated that the pumping out takes 78% of the time as pumping in, however this estimate was based on only half the tidal run performed on Friday, and the system is nonlinear, so in reality it is hard to estimate the required pumping rate on the ebb required to make the tidal curve perfectly symmetrical. Also probably not good the pumps on flood work at 100%, especially when the wave runs begin. Wave paddle movements etc will make difference to the tidal curves. So today’s run controlled using a txt file which specifies the water level every minute – each row is a minute, and the figure is the level the sea should be, and the pumps work at a given percentage to achieve that level. A 150 minute flood and ebb was specified, plus 30 mins of still stands either side, so the tidal curve is
30 mins at 1.75m
150 mins to 3.25m
30 mins at 3.25m
150 mins to 1.75m
30 mins at 1.75m
The total run is thus 490 minutes or 8 hours.
UNSW bed level sensors were logged throughout – to catch the bed for the first time at low tide, and interesting to compare the water levels with the tidal levels and the pt records
It is likely the pumps can work at least twice as fast, so the wave runs should be:
[30 + 75 + 30 + 75 + 30] or 4 hours total. Perhaps the sequence should then be:
[30, profile, 25, profile, 25, profile, 25, profile, 30, profile, 25, profile, 25, profile, 25, profile, 30]
Assuming each profile takes 10 minutes (8*10=80 minutes), the run length will then be 5 hours 20 mins
Alternatively, cut the still-stands down to 15 mins
[15+75+15+75+15] = 275min run (4.5 hours) and profile every 15 mins during the flood and ebb
[15, profile, 15, profile, 15, profile, 15, profile, 15, profile, 15, profile, 15, profile, 15, profile, 15, profile, 15, profile, 15, profile, 15, profile, 15, profile]
Assuming each profile takes 10 minutes (13*10=130 minutes), the run length will then be 6 hours 45 mins. This latter sequence seems preferable.
New attachment added to wave following staff so wave followers can reach the troughs of the waves at low tide.
SRP and ADV reprogrammed to start with new settings tomorrow 9am. Instruments altered on offshore rig – SRPs lowered to 1m from bed, lower vectrino raised 10cm.
Trial of camera set up to log breaking waves over offshore rig on tidal runs. Powered from survey cabin and logged onto spare laptop using firewire cable and firewire PCMCIA card. Cilia to order an external hard drive to store the extra video data. This video set up may also come in useful for the overwash experiments – different/extra angle of view.
Some discussions regarding wave sequence during the tidal runs. Decided to keep Hs constant at 0.8m – previously was discussed that wave height could be allowed to vary with the tide (tidal modulation) but it was decided that the experiments should only vary one thing at a time (lagoon level), and keep the rest constant.
Tuesday 15/07/08
Series D1 – sea level 2.5, lagoon level 2.5, tide varying 1.75—3.25. Tidal ramp over 75 mins, with 15 mins LT and 15 mins HT.
Offshore rig logging. Gerd arrived for a day
Decision was made not to have the 15 mins of waves at the LT following the ebb tide, because it would build a LT berm and the profile would thus not be primed for the following test run.
Sediment photos before and after. Swash rigs not logged but bed level sensors logged.
Some problems with the rig camera all day – could not charge and log at same time – eventually realised had to take the battery out when running on mains power. Also problems with the video stream. So the record of waves over the offshore was patchy to say the least.
Run was stopped about 13:20 when the wave paddle filter flooded. Pumps working too hard to achieve a steady sea level on the flood tide– decided to re-run this series tomorrow with a longer flood and ebb, so the pumps have more time to respond to the sea-level variations
After run, middle line of bed level sensors raised (a couple on the berm crest too low to record) – also in readiness for the tidal and overwash runs.
Gate/Buffer seepage was logged overnight – series D1A. Jon arrived in evening
Wednesday 16/07/08
Series DD1 – lagoon 2.5m, sea level 1.75—3.25 over 90 mins on flood and ebb. Extra 15 mins means extra profile (so 6*15 on flood and 6*15 on ebb)
Offshore rig once again logging. Resolved issues with rig camera – not a firewire logging problem at all – camera goes onto demo mode after a while. Needs to be looked on – touch screen touched every 10 minutes or so. Also logging laptop timestamped with the other video laptop, which receives its time over a wireless network from gps. Tried to log with avi files but too big, and unable to log with compression, so carry on with wmv files. Have a special program to load these files into matlab.
11:10 swash rigs put back into position and logged. Just offshore rigs
After run, offshore rig removed. Does not need to be deployed until Monday so have time to download and reprogram for a longer run during the overwash experiments.
Sediment photos at end
Gerd left. Oscar and Ana arrived from Portugal
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