Monday 13 August 2012

Cycle commute from de Goot to campsite

Dan Howe filmed the commute from de Goot to the camp site by strapping a camera on the handle bars. The video link is here: Thanks Dan for contributing this steller piece of cinematography!

Monday 2 July 2012

Overwash series continues

After a recreative visit to Amsterdam, the overwash series proceeds according to plan and schedule. Last week we finished D1 and D2; today we finished D3; and hopefully will finish D4 and commence with D5. Overwash depths are deliberately being kept shallow to avoid damage to the backbarrier. The downside is that the horizontal array of current meters are not seeing a lot of action, if at all. Thermal camera and video cameras are capturing the overtopping and overwashing nicely (see picture below).

Camera 1 looks straight down onto the backslope of the barrier and the time stack (stripmean)  is capturing here a couple of overtopping swashes and at the end a large overwashing event. X-axiso represents distance (c. 10 m across) and the Y-axis is time (100 s from top to bottom).

Thursday 28 June 2012

First overwash run

Today we finished first overwash run D1 (0.8 m high and 4 second waves) with the new instrument set-up. Bit of a slow start because the beach kept adjusting to the increasing water level by building up the nearshore bar. Finally with water level at 4.2 m overwash occurred. A deep channel rapidly developed at the back of the barrier which compromised the measurements somewhat. After brief discussion, it was decided to fill in the channel by hand to prepare for the next overwash run. After a solid 1 hour of digging, involving the entire team and two wheel barrows the beach is now ready for the next overwash run with 5 second waves.

Top view of back-barrier overwash channel being filled in through manual labour: bootcamp BARDEX! Video below shows activities at ground level. Commentary by Jack Puleo and sand kicking activities by Aart Kroon.

Wednesday 27 June 2012

Ready for overwash

Today a massive effort of the team. We rebuild the scaffold frame (some 2.5 m poles were practically covered and other were practically exposed); moved 15 bed-level sensors from the bottom of the beach to the top and back of the barrier; took out all Vectrino II and sheetflow probes; moved the three swash rigs to the back of the barrier and morphed them into 4 overwash rigs; moved back the video trolley and installed all the video ground control points; reconfigured the 2 vertical pressure sensor arrays into a cross-barrier pressure sensor array; and surveyed all new instrument positions in. The Deltaflume team had the wave paddle repaired very conveniently while we were adjusting our rigs. Bring on the overwash!

Tuesday 26 June 2012

Arrival of the Portugese

BARDEX II has now been taken over by the Portugese (Ana, Barbara, Pedro and Rita) and the French (Bruno, Benjamin and Florent) in preparation for the overwash runs. Series A, B and C are now all successfully completed, and the tidal run provided a taster for what overwash will look like.

Thursday 21 June 2012

All the way to New Zealand!

#Update: added even more heroic pictures

Heroic scenes today in the wave flume, as the University of New South Wales (Australia) boys, with aid from the other teams, dug a massive hole in the beach to retrieve their groundwater kit. After about 3 hours, the kit was retrieved, the holes were filled and the beach profile was restored to its original state.
Afterwards, test series B1 was run with waves of Hs=0.8 m and Tp = 8s (the same as series A1) in order to rebuild the bar. Based on the beach profile at the end of the day, it seems like we managed to create a (modest) bar indeed.

Wednesday 20 June 2012

Groundwater effects!

Run A7 has given some problems. The accretionary swashes have really build up the beachface, but the combination of a very steep beach and high lagoon level has resulted in the development of groundwater drainage channels around the rig that have sufficient flow power to move sediment.

Thijs kneeling in the drainage channel trying to adjust sensor elevation.

Comparison of beach profile before the experiment and after test A7 - note that the nearshore bar that developed during tests A1-A5 is now completely gone and that the newly-formed berm represents almost 1 m of accretion.