Google Earth before/after 2014-2016

I recently discovered that Google Earth imagery was updated with January 2016 imagery of the Marsh Restoration by Small Dredge  Technology area. It revealed answers to many things we have been questioning, such as where the water flow through the marsh carries sediment and how the topography within the fill area is developing due to natural reworking. We have attempted to do this with the estimated status maps by triangulating views of the water level poles and what substrate was exposed by specific water levels. The aerial view has allowed us to make these maps much more accurate.

Here are some interesting visual comparisons. Figure 1 is April 9, 2014, showing the new grass spreading through the original small dredge project to the right and the test site in the middle just left of the boardwalk.

Figure 2 is January 16, 2016 and shows the pond 2 months after the Amphibex quit pumping. Natural forces have been at work from Day 1, with tidal flow, wind-driven waves, alligator and creature passage reworking the soft mobile sediment. It was quite interesting to observe the sediment plume through the marsh to the south because we had expected it to move more to the southeast through the small bayou and control structure.

Figure 3 is an interpretation of Figure 2, with elevations superimposed on the imagery based on observations of marker poles and exposed sediment at various water levels. We recently obtained bathymetry of the area outside of our containment to see if we have transferred significant fill outside of our target area.

Future imagery by drone will be used to clarify our map and increase accuracy in our measurements and conclusions.

Figure 1. This "before' imagery was from Google Earth imagery dated April 9, 2014.

Figure 2. This Google Earth imagery is date January 16, 2016 and is after the Amphibex 400 filled the remaining 15 acres of the dredge pond.

Figure 3. This is an interpretation of the 2016 imagery with elevations imposed based on observations in the field. The water levels are in relation to marsh substrate as our target level or "0", and -2" is still a good level to expect marsh growth. Natural drainage is developing as the tidal flow moves in and out, but you can see that a lot of material is flowing through the marsh to the south.

 

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