BARDEX LOGBOOK 02/07/08 - 03/07/08

Wednesday 02/07/08

Started with 3 mins of 10s monochromatic waves at SL=3m to remove the berm. Successfully did so

Another deltares PT (#8) has packed up - not good, so Cilia is investigating buying a corer to retrieve and replace it

Charlie and Andre worked on the offshore rig, finishing tests, hanging instruments, and having another go at making a better connection inside the sontek adv for the compass to work. When finished the offshore rig was placed inside the flume, on the western wall near the depth of closure. It took most of the afternoon to do this, including final adjustments to rig design and conversations as to the best location for it.

Sediment samples

Thursday 03/07/08

· Profiler checked it could get past the offshore rig as it was placed yesterday – it could.
· EMCM issue resolved – gerd swapped the channels for offshore EMs [1,2] and [3,4] and worked fine – suggests a mistake in main logging cylinder. Velocity profile now achieved but EMs on other two (landwards) swash rigs not working. Will have to reconsider this approach for the later overwash experiments. Note now that corresponding channels for the PTs will now be different. The channels in the data files for the UoP swash rigs are now as follows:

6-7 - +3 main rig
8-9 - +6 main rig
10-11 – auxillary rig 1 (presently not working)
12-13 - auxillary rig 2 (presently not working)
14-15 - +10 main rig
16-17 - +14 main rig
18-21 – for EMs not present
22-onwards = PTs

· PTs and Ems corrected so at same height (for some reason they had been at different heights)
· Series B3 – 0.8m, 6s, 2.5 sea, 2.5 lagoon, [5,5,5,5,10,10,15,15,20,5 mono, reset]. Response was again berm building and beachface steepening
· Offshore rig also logged – vectrino (Southampton) data seemed to be fine, so happy that that is functioning correctly. Logged at 200Hz continuously, Charlie started and stopped each run to coincide with measurement runs. Tomorrow the SRP and ADV will be downloaded and checked
· Offshore rig taken out and placed on the barrier crest. The instruments will be downloaded and reprogrammed for another installation on Monday. The data will be checked to test for any faults etc. It is believed the chosen rig position is desirable.
· Sediment samples
· Lawrence carried out a porosity test on the beach gravel
· Barrier profile reset as yesterday (3 mins of 10s monochromatic waves at SL=3m) – not the desired effect achieved. Instead, crest accretion occurred, breakpoint scour and very little berm erosion. It is thought this is because the previous run had caused some accretion offshore, therefore the area of wave breaking was shallower and waves broke further out. Waves were thus not able to breach the berm, and backwashes were weaker. The result is that the boundary condition for tomorrows run is different from todays, which is not ideal. Preceding tomorrows run therefore we will run an hour of today’s waves (0.8, 6s, lagoon 2.5, sea 2.5m) in order to achieve a better equilibrium with the test run.
· An attempt was made to core a hole in the barrier to replace a broken deltares PT (#12). However, the corer supplied has a head which was unsuitable for the job so another corer head will have to be found.
· Matlab was reinstalled on SRP laptop so an attempt will be made tomorrow to log the video with that as before

The likely sequence of subsequent tests is as follows:

name Sea level (m) Lagoon level (m) Hs (m) Tp (s)
C6 2.5 3.5 0.8 6
C5 2.5 1 0.8 6
B2 2.5 2.5 0.8 3
C4 2.5 1 0.8 3
C3 2.5 3.5 0.8 3
A3 tide 2.5 No waves No waves

Note that A3 needs to go ahead before series D (with tide) takes place. A3 also requires the availability of pump specialists. The hope is that the offshore rig will be placed in the flume on Monday for a week of logging series.