Dredge (and Rainey) Report Dredging resumed; Aerial photography, September 28, 2011

Wednesday, September 28 – Aerial photography by Remote Plane

Eddie Weeks from LSU was scheduled to arrive with his remote plane this morning. At 8am, I followed the airboat to Christian Marsh, where Timmy and I deployed the 4’ x 4’ markers we had constructed just for this purpose. Each marker had a number painted on it, and we had added floatation to the underside so that it would float just above the water level. We lined them up on a N-S axis and pinned them with poles. The GPS of one of the corners was recorded for geo-referencing purposes.

Figure 4. Numbered 4ft square markers were held on a north/south axis at a recorded GPS location.

 

 

 

 

 

 

Eddie and his assistant arrived around 11 am and they followed us back to the site. Eddie controlled the flight of the remote plane and his assistant controlled the camera. They had a monitor set up that displayed the image through the camera lens, so that Eddie could see where the plane needed to go, and his assistant knew when to click the shutter. Timmy was recruited to launch the plane since the wind was too high for a ground launch. This entailed tossing it into the air after the propellers were fully engaged.

We had them take pictures of the Christian Marsh area, Goose Pond and the dredge site before weather shut us down. Cole Bayou area will have to wait. It was quite windy, so there was some difficulty in acquiring the intended photos. The best photos are acquired when the electric motor is turned off and the plane glides, but with high winds, the motor had to be turned back on more frequently to maintain position.

Figure 5. Timmy launching the remote plane. Figure 6. Eddie Weeks directing the plane in for a landing.

While Timmy took the airboat to pick up markers, I led the LSU crew to the Goose Pond. Surprisingly, the birds at the Goose Pond were less concerned with the remote plane than they were with the 2 peregrine falcons soaring above the water. The peregrines appeared to treat the plane as another raptor and calmly circled with it.

Figure 7. Launching the plane at the Goose Pond. Figure 8. A peregrine falcon circling unconcerned along with the remote plane.

From the ground, the Goose Pond was full of birds and movement. There were flocks of avocets, peeps, spotted sandpipers, yellowlegs, dowitchers and blue-winged teal flowing from one end to the other or feeding along the shallows, along with a few roseatte spoonbills, snowy egrets and white egrets. Birds were flying into the pond area as well as away from it, so it was difficult to tell if they were frightened by the plane at all. With the high winds and a few technical difficulties, we didn’t spend much time testing the altitude of the plane with bird responses. Looking at the photos later proved that the high altitude did not afford enough resolution for counting birds much less identifying them.

Figure 9. A flock of teal rose and descended on the far side of the pond. Figure 10. A mixed flock of avocets and teal.

Our next site was planned to be Cole Bayou restoration area. I led the LSU crew back up past our dredge to the dock for our rendezvous with the airboat, but storm clouds were building on the northern horizon and thunder was starting to rumble through. The dredge area is smaller than the Cole Bayou area, so the decision was made to do that next to try to beat the storm. I joined Timmy in the airboat and we flew out to the Deep Lake area to deploy markers. The wind had picked up, making deployment difficult as the airboat was pushed around by the wind. We managed 3 markers, then had to go catch one that was flipped and carried away, and re-positioned it. Eddie set up his station on the bow of the airboat and did his best against the 15-20 knot winds.

The photos captured great views of the dredging operation, showing the test area, the LSU experimental area, the delta in Cell 5 and the plume throughout Cell 4 that was the result of yesterday’s 5.5 hours of pumping.

Figure 11. Aerial photo of the dredging operation. Test site is at the top left corner of the photo with a boardwalk and curved containment. The LSU experimental sites are on the right side of the photo with dredge and boats in the canal, boardwalk, plywood containment, and dredge outfall with delta and plume.

Figure 12. Diagram of dredge cells.

Figure 13. Aerial photo from a lower altitude of cells 4 (left) and 5 (right) showing the discharge pontoon (white square), the new delta (light grey crescent) and sediment plume resulting from yesterday's dredging. The tiny white dots are the PVC marker poles set out by LSU, and the straight line at the top left is the plywood containment on the outside of Cell 1.

Reviewing a few of the images later, I wasn’t impressed with the resolution of the camera that was used for the altitude chosen. At the Goose Pond, I had hoped to acquire some photos that would allow us to identify and count birds, but only the bigger, lighter birds could be picked out on the photos. Even the markers that we spent so much time making, deploying and moving, were seen only as tiny white spots – the 4-foot numbers were not legible. I will reserve final judgement until after LSU has a chance to work with the photos for geo-referencing.

Figure 14. Cottonmouth crossing the camp lawn.

After the weather turned ominous and thunder chased Eddie and his assistant back to high ground, Timmy and I returned to the camp, leaving the last few markers floating in the pond at the dredge site. The weather moved through, and as we relaxed on the back deck, Timmy pointed out a rather large cottonmouth moccasin working its way across the lawn then off toward the shed. Hmmm. Have to be careful where I walk tomorrow.

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