Field Notes

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Gilbert Tract: 2022-05-20 10:30:00 (DOY 140)
Author: Joe Verfaillie
Others: Dennis, Ariane, Daphne, Janet Byron

Summary: Janet Byron interview, Added more boardwalk and moved water sensors, added staff gauge, standard data collection, Revamped ADCP installation with water weed barrier.

Gilbert Tract
2022-05-20

Dennis, Ariane, Daphne and I arrived at about 10:30 PDT. The gate was open and there was a Department of the Interior SUV parked at the turnout near our tower. We heard some voices and pounding in the distance but never saw anyone. It was clear and sunny and super-duper windy – Daphne found it hard to balance against the wind on the upper boardwalk. But down below the reeds and levees it was not so bad. The wetland looks green with tules flowering. Janet Byron from Estuary News arrived at about 11am and spent an hour or so talking to Dennis and Ariane and taking photos.

This was mostly a maintenance trip but Daphne also did the regular data collection since she will be away the next 10days. Dennis, Ari and I added another 8ft length of boardwalk. This section has fixed legs made from treated 2x4s. The legs are 5ft long, have pointed bottoms and we pounded them in as far as they would go – not very far. Then the boardwalk is bolted to the legs with single central 3/8” bolts for load and two deck screws to prevent twisting. The new section seemed more stable than the sections with adjustable legs. On the old sections, the legs held in place by set screws have all failed. Maybe better to replace the adjustable legs with fixed 2x4s.

I pounded in a post near the end of the boardwalk and hung the staff gauge on it. The bottom of the staff gauge is near the ground surface hopefully below low tide level. High tide will usually be above the top of the staff gauge and above the boardwalks. The CTD and Campbell conductivity sensor had enough cable to be hung off the end of the boardwalk at about 10cm above the ground. The Eosense only had enough cable to go to the mid-point of the new section and is also about 10cm agl there. At 12:00 PDT the water level was 65cm on the staff gauge. On our way out we made a quick stop to measure the locations of the water sensors when the tide was lower. At 14:50 the water level was 33.5cm on the staff gauge.

Daphne serviced the tower collecting flux, met and camera data. She cleaned the sensors and the camera window. The camera is still missing photos especially from mid-morning onward but resetting the next day. There might be some corrosion causing power problems on the plug at the camera. This can probably be replaced. The Ethernet hub was also off initially. Cycling power there a couple of times worked. Daphne connected the camera’s Ethernet line directly to the laptop and that also worked. So we decided to connect the camera directly to the CR1000 and skip the hub. At this site I think the camera is continuously power because otherwise it loses its clock overnight. But the Ethernet hub was turned off over night to prevent photos after dark. Now the camera should take photos 4am to 8pm I think.
The 7500 read: 415ppm CO2, 260mmol/m3 H2O, 18.9C, 100.8kPa, 98SS
The 7700 read: 2.04ppm CO2, 37RSSI – 71 after cleaning
The wash reservoir was topped off.

We also tested the CTD conductivity reading against the handheld YSI sensor.
DI Water 1000 us standard wetland
YSI 3.5uS @ 27.4C 945 uS 555-562 uS @ 19.4C
CTD 0-9uS 995-1005 uS 565uS

Ari installed the remaining tea bags for the elementary school project. These are in a shallower location than the others near the beginning of the boardwalk.

At about 12:30 we went to the breach to work on Flow aka the ADCP. A bank of weeds has grown up around the ADCP and reported velocities have dropped in the last month or so. There are at least two different weeds – one more leafy and one dense fern like (maybe coontail Ceratophyllum demersum). We pulled the ADCP out and off the track. Then pried the cinder blocks free of the mud and pulled the track most of the way out of the water. We took three 5ftx3ft sheets of concrete board and stitched them together on the long edge with cable ties. In the water we were able to push them out and let them sink to the bottom of the channel. The first sheet ended up near the end of the track and the other two further into the channel covering the ground and weeds directly in front of the ADCP. We added some bolts about 4cm from the end of the track to prevent the ADCP from falling off the end again and then put the track back in. The deepest cinder block ended up just above the first concrete sheet and the track extended on over the sheet. There seems to be a drop off after the first sheet that isn’t noticeable in the cross sectional measurements. We tried to align the track more squarely with the channel rotating it slightly clockwise from north. Ari has the new position of the ADCP and updated the configuration with the new numbers. We put a pair of fence posts in about 10m west of the ADCP on either side of the channel for the upcoming 24hr sampling campaign. We left the ADCP site at about 14:45

1 photos found

20220520GT_RevampAdcp.jpg ( 2022-05-20 13:35:59 ) Full size: 1440x1920
Daphne, Ari, Joe improving the ADCP setup. We laid down three 3'x5' concrete boards along the bottom of the channel to suppress weed growth. We also shifted the track slightly so that it was more perpendicular to the channel.